[cfe] Improve experiment not enabled messages

The updates the messaging for when experimental features are not
enabled to take into account whether the feature has been released
and whether an explicit or implicit language version opt out the
feature.

Change-Id: I77c31e7e327d1beca2dd4a82dbaf648711894e7a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/239663
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -3462,27 +3462,29 @@ Message _withArgumentsExperimentDisabled(String string) {
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<Message Function(String string2)>
+const Template<Message Function(String string, String string2)>
     templateExperimentDisabledInvalidLanguageVersion =
-    const Template<Message Function(String string2)>(
+    const Template<Message Function(String string, String string2)>(
         problemMessageTemplate:
-            r"""This requires the null safety language feature, which requires language version of #string2 or higher.""",
+            r"""This requires the '#string' language feature, which requires language version of #string2 or higher.""",
         withArguments: _withArgumentsExperimentDisabledInvalidLanguageVersion);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String string2)>
+const Code<Message Function(String string, String string2)>
     codeExperimentDisabledInvalidLanguageVersion =
-    const Code<Message Function(String string2)>(
+    const Code<Message Function(String string, String string2)>(
         "ExperimentDisabledInvalidLanguageVersion",
         analyzerCodes: <String>["ParserErrorCode.EXPERIMENT_NOT_ENABLED"]);
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsExperimentDisabledInvalidLanguageVersion(String string2) {
+Message _withArgumentsExperimentDisabledInvalidLanguageVersion(
+    String string, String string2) {
+  if (string.isEmpty) throw 'No string provided';
   if (string2.isEmpty) throw 'No string provided';
   return new Message(codeExperimentDisabledInvalidLanguageVersion,
       problemMessage:
-          """This requires the null safety language feature, which requires language version of ${string2} or higher.""",
-      arguments: {'string2': string2});
+          """This requires the '${string}' language feature, which requires language version of ${string2} or higher.""",
+      arguments: {'string': string, 'string2': string2});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
@@ -3517,6 +3519,123 @@ Message _withArgumentsExperimentNotEnabled(String string, String string2) {
       arguments: {'string': string, 'string2': string2});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String
+            string)> templateExperimentNotEnabledOffByDefault = const Template<
+        Message Function(String string)>(
+    problemMessageTemplate:
+        r"""This requires the experimental '#string' language feature to be enabled.""",
+    correctionMessageTemplate:
+        r"""Try passing the '--enable-experiment=#string' command line option.""",
+    withArguments: _withArgumentsExperimentNotEnabledOffByDefault);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string)>
+    codeExperimentNotEnabledOffByDefault =
+    const Code<Message Function(String string)>(
+        "ExperimentNotEnabledOffByDefault",
+        analyzerCodes: <String>["ParserErrorCode.EXPERIMENT_NOT_ENABLED"]);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsExperimentNotEnabledOffByDefault(String string) {
+  if (string.isEmpty) throw 'No string provided';
+  return new Message(codeExperimentNotEnabledOffByDefault,
+      problemMessage:
+          """This requires the experimental '${string}' language feature to be enabled.""",
+      correctionMessage: """Try passing the '--enable-experiment=${string}' command line option.""",
+      arguments: {'string': string});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String
+            string)> templateExperimentOptOutComment = const Template<
+        Message Function(String string)>(
+    problemMessageTemplate:
+        r"""This is the annotation that opts out this library from the '#string' language feature.""",
+    withArguments: _withArgumentsExperimentOptOutComment);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string)> codeExperimentOptOutComment =
+    const Code<Message Function(String string)>("ExperimentOptOutComment",
+        severity: Severity.context);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsExperimentOptOutComment(String string) {
+  if (string.isEmpty) throw 'No string provided';
+  return new Message(codeExperimentOptOutComment,
+      problemMessage:
+          """This is the annotation that opts out this library from the '${string}' language feature.""",
+      arguments: {'string': string});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String string,
+        String
+            string2)> templateExperimentOptOutExplicit = const Template<
+        Message Function(String string, String string2)>(
+    problemMessageTemplate:
+        r"""The '#string' language feature is disabled for this library.""",
+    correctionMessageTemplate:
+        r"""Try removing the `@dart=` annotation or setting the language version to #string2 or higher.""",
+    withArguments: _withArgumentsExperimentOptOutExplicit);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string, String string2)>
+    codeExperimentOptOutExplicit =
+    const Code<Message Function(String string, String string2)>(
+  "ExperimentOptOutExplicit",
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsExperimentOptOutExplicit(String string, String string2) {
+  if (string.isEmpty) throw 'No string provided';
+  if (string2.isEmpty) throw 'No string provided';
+  return new Message(codeExperimentOptOutExplicit,
+      problemMessage:
+          """The '${string}' language feature is disabled for this library.""",
+      correctionMessage:
+          """Try removing the `@dart=` annotation or setting the language version to ${string2} or higher.""",
+      arguments: {'string': string, 'string2': string2});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String string,
+        String
+            string2)> templateExperimentOptOutImplicit = const Template<
+        Message Function(String string, String string2)>(
+    problemMessageTemplate:
+        r"""The '#string' language feature is disabled for this library.""",
+    correctionMessageTemplate:
+        r"""Try removing the package language version or setting the language version to #string2 or higher.""",
+    withArguments: _withArgumentsExperimentOptOutImplicit);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string, String string2)>
+    codeExperimentOptOutImplicit =
+    const Code<Message Function(String string, String string2)>(
+  "ExperimentOptOutImplicit",
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsExperimentOptOutImplicit(String string, String string2) {
+  if (string.isEmpty) throw 'No string provided';
+  if (string2.isEmpty) throw 'No string provided';
+  return new Message(codeExperimentOptOutImplicit,
+      problemMessage:
+          """The '${string}' language feature is disabled for this library.""",
+      correctionMessage:
+          """Try removing the package language version or setting the language version to ${string2} or higher.""",
+      arguments: {'string': string, 'string2': string2});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeExplicitExtensionArgumentMismatch =
     messageExplicitExtensionArgumentMismatch;
@@ -8113,72 +8232,6 @@ Message _withArgumentsNonNullableNotAssignedError(String name) {
       arguments: {'name': name});
 }
 
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Null> codeNonNullableOptOutComment = messageNonNullableOptOutComment;
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const MessageCode messageNonNullableOptOutComment = const MessageCode(
-    "NonNullableOptOutComment",
-    severity: Severity.context,
-    problemMessage:
-        r"""This is the annotation that opts out this library from null safety features.""");
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<
-    Message Function(
-        String
-            string)> templateNonNullableOptOutExplicit = const Template<
-        Message Function(String string)>(
-    problemMessageTemplate:
-        r"""Null safety features are disabled for this library.""",
-    correctionMessageTemplate:
-        r"""Try removing the `@dart=` annotation or setting the language version to #string or higher.""",
-    withArguments: _withArgumentsNonNullableOptOutExplicit);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String string)> codeNonNullableOptOutExplicit =
-    const Code<Message Function(String string)>(
-  "NonNullableOptOutExplicit",
-);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsNonNullableOptOutExplicit(String string) {
-  if (string.isEmpty) throw 'No string provided';
-  return new Message(codeNonNullableOptOutExplicit,
-      problemMessage: """Null safety features are disabled for this library.""",
-      correctionMessage:
-          """Try removing the `@dart=` annotation or setting the language version to ${string} or higher.""",
-      arguments: {'string': string});
-}
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Template<
-    Message Function(
-        String
-            string)> templateNonNullableOptOutImplicit = const Template<
-        Message Function(String string)>(
-    problemMessageTemplate:
-        r"""Null safety features are disabled for this library.""",
-    correctionMessageTemplate:
-        r"""Try removing the package language version or setting the language version to #string or higher.""",
-    withArguments: _withArgumentsNonNullableOptOutImplicit);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Message Function(String string)> codeNonNullableOptOutImplicit =
-    const Code<Message Function(String string)>(
-  "NonNullableOptOutImplicit",
-);
-
-// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-Message _withArgumentsNonNullableOptOutImplicit(String string) {
-  if (string.isEmpty) throw 'No string provided';
-  return new Message(codeNonNullableOptOutImplicit,
-      problemMessage: """Null safety features are disabled for this library.""",
-      correctionMessage:
-          """Try removing the package language version or setting the language version to ${string} or higher.""",
-      arguments: {'string': string});
-}
-
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeNonPartOfDirectiveInPart = messageNonPartOfDirectiveInPart;
 
@@ -8395,6 +8448,96 @@ const MessageCode messageNullAwareCascadeOutOfOrder = const MessageCode(
     correctionMessage:
         r"""Try moving the '?..' operator to be the first cascade operator in the sequence.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String string2)>
+    templateNullSafetyDisabledInvalidLanguageVersion =
+    const Template<Message Function(String string2)>(
+        problemMessageTemplate:
+            r"""This requires the null safety language feature, which requires language version of #string2 or higher.""",
+        withArguments: _withArgumentsNullSafetyDisabledInvalidLanguageVersion);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string2)>
+    codeNullSafetyDisabledInvalidLanguageVersion =
+    const Code<Message Function(String string2)>(
+        "NullSafetyDisabledInvalidLanguageVersion",
+        analyzerCodes: <String>["ParserErrorCode.EXPERIMENT_NOT_ENABLED"]);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNullSafetyDisabledInvalidLanguageVersion(String string2) {
+  if (string2.isEmpty) throw 'No string provided';
+  return new Message(codeNullSafetyDisabledInvalidLanguageVersion,
+      problemMessage:
+          """This requires the null safety language feature, which requires language version of ${string2} or higher.""",
+      arguments: {'string2': string2});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeNullSafetyOptOutComment = messageNullSafetyOptOutComment;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageNullSafetyOptOutComment = const MessageCode(
+    "NullSafetyOptOutComment",
+    severity: Severity.context,
+    problemMessage:
+        r"""This is the annotation that opts out this library from null safety features.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String
+            string)> templateNullSafetyOptOutExplicit = const Template<
+        Message Function(String string)>(
+    problemMessageTemplate:
+        r"""Null safety features are disabled for this library.""",
+    correctionMessageTemplate:
+        r"""Try removing the `@dart=` annotation or setting the language version to #string or higher.""",
+    withArguments: _withArgumentsNullSafetyOptOutExplicit);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string)> codeNullSafetyOptOutExplicit =
+    const Code<Message Function(String string)>(
+  "NullSafetyOptOutExplicit",
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNullSafetyOptOutExplicit(String string) {
+  if (string.isEmpty) throw 'No string provided';
+  return new Message(codeNullSafetyOptOutExplicit,
+      problemMessage: """Null safety features are disabled for this library.""",
+      correctionMessage:
+          """Try removing the `@dart=` annotation or setting the language version to ${string} or higher.""",
+      arguments: {'string': string});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        String
+            string)> templateNullSafetyOptOutImplicit = const Template<
+        Message Function(String string)>(
+    problemMessageTemplate:
+        r"""Null safety features are disabled for this library.""",
+    correctionMessageTemplate:
+        r"""Try removing the package language version or setting the language version to #string or higher.""",
+    withArguments: _withArgumentsNullSafetyOptOutImplicit);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String string)> codeNullSafetyOptOutImplicit =
+    const Code<Message Function(String string)>(
+  "NullSafetyOptOutImplicit",
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsNullSafetyOptOutImplicit(String string) {
+  if (string.isEmpty) throw 'No string provided';
+  return new Message(codeNullSafetyOptOutImplicit,
+      problemMessage: """Null safety features are disabled for this library.""",
+      correctionMessage:
+          """Try removing the package language version or setting the language version to ${string} or higher.""",
+      arguments: {'string': string});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(String name)> templateNullableInterfaceError =
     const Template<Message Function(String name)>(

pkg/front_end/lib/src/api_prototype/experimental_flags.dart

@@ -4,8 +4,6 @@
 
 import 'package:kernel/kernel.dart' show Version;
 
-import '../fasta/fasta_codes.dart';
-
 part 'experimental_flags_generated.dart';
 
 /// The set of experiments enabled for SDK and packages.
@@ -262,11 +260,4 @@ class LibraryFeature extends ExperimentalFeature {
   LibraryFeature(ExperimentalFlag flag, this.isSupported, this.enabledVersion,
       this.isEnabled)
       : super(flag);
-
-  // TODO(johnniwinther): We should emit a different message when the
-  // experiment is not released yet. The current message indicates that
-  // changing the sdk version can solve the problem.
-  /// Returns a [Message] for reporting that this feature is not enabled.
-  Message get notEnabledMessage => templateExperimentNotEnabled.withArguments(
-      flag.name, enabledVersion.toText());
 }

pkg/front_end/lib/src/fasta/builder/named_type_builder.dart

@@ -269,11 +269,13 @@ class NamedTypeBuilder extends TypeBuilder {
     if (_declaration!.isExtension &&
         library is SourceLibraryBuilder &&
         !library.libraryFeatures.extensionTypes.isEnabled) {
-      Message message =
-          library.libraryFeatures.extensionTypes.notEnabledMessage;
       int typeNameLength = nameLength;
       int typeNameOffset = nameOffset;
-      library.addProblem(message, typeNameOffset, typeNameLength, fileUri);
+      Message message = library.reportFeatureNotEnabled(
+          library.libraryFeatures.extensionTypes,
+          fileUri!,
+          typeNameOffset,
+          typeNameLength);
       _declaration = buildInvalidTypeDeclarationBuilder(
           message.withLocation(fileUri!, typeNameOffset, typeNameLength));
     } else if (_declaration!.isTypeVariable) {

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -7198,8 +7198,11 @@ class BodyBuilder extends StackListenerImpl
           ..fileOffset = openAngleBracket.charOffset);
       }
     } else {
-      addProblem(libraryFeatures.constructorTearoffs.notEnabledMessage,
-          openAngleBracket.charOffset, noLength);
+      libraryBuilder.reportFeatureNotEnabled(
+          libraryFeatures.constructorTearoffs,
+          uri,
+          openAngleBracket.charOffset,
+          noLength);
     }
   }
 

pkg/front_end/lib/src/fasta/source/outline_builder.dart

@@ -3076,8 +3076,8 @@ class OutlineBuilder extends StackListenerImpl {
           // For entries that consist of their name only, all of the elements
           // of the constructor reference should be null.
           if (typeArguments != null || suffix != null) {
-            addProblem(libraryFeatures.enhancedEnums.notEnabledMessage,
-                charOffset, noLength);
+            libraryBuilder.reportFeatureNotEnabled(
+                libraryFeatures.enhancedEnums, uri, charOffset, noLength);
           }
           push(NullValue.ConstructorReference);
         }

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

@@ -317,6 +317,50 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
       _libraryFeatures ??= new LibraryFeatures(loader.target.globalFeatures,
           _packageUri ?? importUri, languageVersion.version);
 
+  /// Reports that [feature] is not enabled, using [charOffset] and
+  /// [length] for the location of the message.
+  ///
+  /// Return the primary message.
+  Message reportFeatureNotEnabled(
+      LibraryFeature feature, Uri fileUri, int charOffset, int length) {
+    assert(!feature.isEnabled);
+    Message message;
+    if (feature.isSupported) {
+      if (languageVersion.isExplicit) {
+        message = templateExperimentOptOutExplicit.withArguments(
+            feature.flag.name, feature.enabledVersion.toText());
+        addProblem(message, charOffset, length, fileUri,
+            context: <LocatedMessage>[
+              templateExperimentOptOutComment
+                  .withArguments(feature.flag.name)
+                  .withLocation(languageVersion.fileUri!,
+                      languageVersion.charOffset, languageVersion.charCount)
+            ]);
+      } else {
+        message = templateExperimentOptOutImplicit.withArguments(
+            feature.flag.name, feature.enabledVersion.toText());
+        addProblem(message, charOffset, length, fileUri);
+      }
+    } else {
+      if (feature.flag.isEnabledByDefault) {
+        if (languageVersion.version < feature.enabledVersion) {
+          message =
+              templateExperimentDisabledInvalidLanguageVersion.withArguments(
+                  feature.flag.name, feature.enabledVersion.toText());
+          addProblem(message, charOffset, length, fileUri);
+        } else {
+          message = templateExperimentDisabled.withArguments(feature.flag.name);
+          addProblem(message, charOffset, length, fileUri);
+        }
+      } else {
+        message = templateExperimentNotEnabledOffByDefault
+            .withArguments(feature.flag.name);
+        addProblem(message, charOffset, length, fileUri);
+      }
+    }
+    return message;
+  }
+
   void _updateLibraryNNBDSettings() {
     library.isNonNullableByDefault = isNonNullableByDefault;
     switch (loader.nnbdMode) {

pkg/front_end/lib/src/fasta/source/stack_listener_impl.dart

@@ -81,19 +81,19 @@ abstract class StackListenerImpl extends StackListener {
     if (libraryFeatures.nonNullable.isSupported) {
       if (libraryBuilder.languageVersion.isExplicit) {
         addProblem(
-            templateNonNullableOptOutExplicit.withArguments(
+            templateNullSafetyOptOutExplicit.withArguments(
                 libraryFeatures.nonNullable.enabledVersion.toText()),
             token.charOffset,
             token.charCount,
             context: <LocatedMessage>[
-              messageNonNullableOptOutComment.withLocation(
+              messageNullSafetyOptOutComment.withLocation(
                   libraryBuilder.languageVersion.fileUri!,
                   libraryBuilder.languageVersion.charOffset,
                   libraryBuilder.languageVersion.charCount)
             ]);
       } else {
         addProblem(
-            templateNonNullableOptOutImplicit.withArguments(
+            templateNullSafetyOptOutImplicit.withArguments(
                 libraryFeatures.nonNullable.enabledVersion.toText()),
             token.charOffset,
             token.charCount);
@@ -102,7 +102,7 @@ abstract class StackListenerImpl extends StackListener {
       if (libraryBuilder.languageVersion.version <
           libraryFeatures.nonNullable.enabledVersion) {
         addProblem(
-            templateExperimentDisabledInvalidLanguageVersion.withArguments(
+            templateNullSafetyDisabledInvalidLanguageVersion.withArguments(
                 libraryFeatures.nonNullable.enabledVersion.toText()),
             token.offset,
             noLength);
@@ -119,7 +119,7 @@ abstract class StackListenerImpl extends StackListener {
   /// Return `true` if the [feature] is not enabled.
   bool reportIfNotEnabled(LibraryFeature feature, int charOffset, int length) {
     if (!feature.isEnabled) {
-      addProblem(feature.notEnabledMessage, charOffset, length);
+      libraryBuilder.reportFeatureNotEnabled(feature, uri, charOffset, length);
       return true;
     }
     return false;

pkg/front_end/messages.status

@@ -278,6 +278,11 @@ ExperimentDisabledInvalidLanguageVersion/example: Fail
 ExperimentNotEnabled/example: Fail
 ExperimentNotEnabledNoFlag/example: Fail
 ExperimentNotEnabledNoFlagInvalidLanguageVersion/example: Fail
+ExperimentNotEnabledOffByDefault/example: Fail
+ExperimentOptOutExplicit/analyzerCode: Fail
+ExperimentOptOutExplicit/example: Fail
+ExperimentOptOutImplicit/analyzerCode: Fail
+ExperimentOptOutImplicit/example: Fail
 ExplicitExtensionArgumentMismatch/analyzerCode: Fail
 ExplicitExtensionArgumentMismatch/example: Fail
 ExplicitExtensionAsExpression/analyzerCode: Fail
@@ -678,6 +683,11 @@ NotAnLvalue/example: Fail
 NotBinaryOperator/analyzerCode: Fail
 NotConstantExpression/example: Fail
 NullAwareCascadeOutOfOrder/example: Fail
+NullSafetyDisabledInvalidLanguageVersion/example: Fail
+NullSafetyOptOutExplicit/analyzerCode: Fail
+NullSafetyOptOutExplicit/example: Fail
+NullSafetyOptOutImplicit/analyzerCode: Fail
+NullSafetyOptOutImplicit/example: Fail
 NullableExpressionCallError/analyzerCode: Fail
 NullableExpressionCallError/example: Fail
 NullableExpressionCallWarning/analyzerCode: Fail

pkg/front_end/messages.yaml

@@ -286,15 +286,24 @@ ExperimentNotEnabled:
   correctionMessage: "Try updating your pubspec.yaml to set the minimum SDK constraint to #string2 or higher, and running 'pub get'."
   analyzerCode: ParserErrorCode.EXPERIMENT_NOT_ENABLED
 
+ExperimentNotEnabledOffByDefault:
+  problemMessage: "This requires the experimental '#string' language feature to be enabled."
+  correctionMessage: "Try passing the '--enable-experiment=#string' command line option."
+  analyzerCode: ParserErrorCode.EXPERIMENT_NOT_ENABLED
+
 ExperimentDisabled:
   problemMessage: "This requires the '#string' language feature to be enabled."
   correctionMessage: "The feature is on by default but is currently disabled, maybe because the '--enable-experiment=no-#string' command line option is passed."
   analyzerCode: ParserErrorCode.EXPERIMENT_NOT_ENABLED
 
-ExperimentDisabledInvalidLanguageVersion:
+NullSafetyDisabledInvalidLanguageVersion:
   problemMessage: "This requires the null safety language feature, which requires language version of #string2 or higher."
   analyzerCode: ParserErrorCode.EXPERIMENT_NOT_ENABLED
 
+ExperimentDisabledInvalidLanguageVersion:
+  problemMessage: "This requires the '#string' language feature, which requires language version of #string2 or higher."
+  analyzerCode: ParserErrorCode.EXPERIMENT_NOT_ENABLED
+
 EmptyNamedParameterList:
   problemMessage: "Named parameter lists cannot be empty."
   correctionMessage: "Try adding a named parameter to the list."
@@ -5096,18 +5105,30 @@ FieldNonNullableWithoutInitializerError:
 FieldNonNullableNotInitializedByConstructorError:
   problemMessage: "This constructor should initialize field '#name' because its type '#type' doesn't allow null."
 
-NonNullableOptOutExplicit:
+NullSafetyOptOutExplicit:
   problemMessage: "Null safety features are disabled for this library."
   correctionMessage: "Try removing the `@dart=` annotation or setting the language version to #string or higher."
 
-NonNullableOptOutImplicit:
+ExperimentOptOutExplicit:
+  problemMessage: "The '#string' language feature is disabled for this library."
+  correctionMessage: "Try removing the `@dart=` annotation or setting the language version to #string2 or higher."
+
+NullSafetyOptOutImplicit:
   problemMessage: "Null safety features are disabled for this library."
   correctionMessage: "Try removing the package language version or setting the language version to #string or higher."
 
-NonNullableOptOutComment:
+NullSafetyOptOutComment:
   problemMessage: "This is the annotation that opts out this library from null safety features."
   severity: CONTEXT
 
+ExperimentOptOutImplicit:
+  problemMessage: "The '#string' language feature is disabled for this library."
+  correctionMessage: "Try removing the package language version or setting the language version to #string2 or higher."
+
+ExperimentOptOutComment:
+  problemMessage: "This is the annotation that opts out this library from the '#string' language feature."
+  severity: CONTEXT
+
 AwaitInLateLocalInitializer:
   problemMessage: "`await` expressions are not supported in late local initializers."
 

pkg/front_end/test/extensions/data/use_as_type.dart

@@ -34,19 +34,19 @@ class B1<T> {}
 extension B2<T> on B1<T> {}
 
 main() {
-  /*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/
+  /*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/
   A2 var1;
-  /*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/
+  /*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/
   B2<A1> var2;
-  B1</*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/A2> var3;
+  B1</*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/A2> var3;
 }
 
-/*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/
+/*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/
 A2 method1() => null;
 
 // TODO(johnniwinther): We should report an error on the number of type
 // arguments here.
-/*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/
+/*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/
 B2<A1> method2() => null;
 
-B1</*error: errors=[This requires the 'extension-types' language feature to be enabled.]*/A2> method3() => null;
+B1</*error: errors=[This requires the experimental 'extension-types' language feature to be enabled.]*/A2> method3() => null;

pkg/front_end/testcases/general/constants/issue46925.dart.weak.expect

@@ -2,47 +2,65 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: Member not found: 'new'.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v2 = MyClass<int>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:15:27: Error: Member not found: 'constr'.
 //   const v2 = MyClass<int>.constr;
 //                           ^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: Member not found: 'new'.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v4 = MyClass<String>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:17:30: Error: Member not found: 'constr'.
 //   const v4 = MyClass<String>.constr;

pkg/front_end/testcases/general/constants/issue46925.dart.weak.modular.expect

@@ -2,47 +2,65 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: Member not found: 'new'.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v2 = MyClass<int>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:15:27: Error: Member not found: 'constr'.
 //   const v2 = MyClass<int>.constr;
 //                           ^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: Member not found: 'new'.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v4 = MyClass<String>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:17:30: Error: Member not found: 'constr'.
 //   const v4 = MyClass<String>.constr;

pkg/front_end/testcases/general/constants/issue46925.dart.weak.transformed.expect

@@ -2,47 +2,65 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:14:30: Error: Member not found: 'new'.
 //   const v1 = MyClass<String>.new;
 //                              ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:15:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v2 = MyClass<int>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:15:27: Error: Member not found: 'constr'.
 //   const v2 = MyClass<int>.constr;
 //                           ^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:16:27: Error: Member not found: 'new'.
 //   const v3 = MyClass<int>.new;
 //                           ^^^
 //
-// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/constants/issue46925.dart:17:21: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const v4 = MyClass<String>.constr;
 //                     ^
+// pkg/front_end/testcases/general/constants/issue46925.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/constants/issue46925.dart:17:30: Error: Member not found: 'constr'.
 //   const v4 = MyClass<String>.constr;

pkg/front_end/testcases/general/duplicate_instantiation.dart.weak.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:15:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.
@@ -34,33 +37,45 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>();
 //                    ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:17:14: Error: Member not found: 'named'.
 //   Class<int>.named;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //                   ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:19:14: Error: Member not found: 'named'.
 //   Class<int>.named<int>;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>();
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:20:14: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -94,10 +109,13 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>.named<int>;
 //                  ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int><int>.named<int>;
 //                        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:24:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.

pkg/front_end/testcases/general/duplicate_instantiation.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:15:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.
@@ -34,33 +37,45 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>();
 //                    ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:17:14: Error: Member not found: 'named'.
 //   Class<int>.named;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //                   ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:19:14: Error: Member not found: 'named'.
 //   Class<int>.named<int>;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>();
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:20:14: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -94,10 +109,13 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>.named<int>;
 //                  ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int><int>.named<int>;
 //                        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:24:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.

pkg/front_end/testcases/general/duplicate_instantiation.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:13:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:15:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.
@@ -34,33 +37,45 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>();
 //                    ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:17:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:17:14: Error: Member not found: 'named'.
 //   Class<int>.named;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:19:19: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>;
 //                   ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:19:14: Error: Member not found: 'named'.
 //   Class<int>.named<int>;
 //              ^^^^^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:20:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int>.named<int>();
 //        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:20:14: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -94,10 +109,13 @@ library /*isNonNullableByDefault*/;
 //   Class<int><int>.named<int>;
 //                  ^
 //
-// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:23:24: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   Class<int><int>.named<int>;
 //                        ^
+// pkg/front_end/testcases/general/duplicate_instantiation.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/duplicate_instantiation.dart:24:12: Error: A comparison expression can't be an operand of another comparison expression.
 // Try putting parentheses around one of the comparisons.

pkg/front_end/testcases/general/enum_super_constructor.dart.weak.expect

@@ -2,19 +2,25 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   A() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: Generative enum constructors must be marked as 'const'.
 //   A() : super();
 //   ^
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const B() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:14:15: Error: Enum constructors can't contain super-initializers.
 //   const B() : super();

pkg/front_end/testcases/general/enum_super_constructor.dart.weak.modular.expect

@@ -2,19 +2,25 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   A() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: Generative enum constructors must be marked as 'const'.
 //   A() : super();
 //   ^
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const B() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:14:15: Error: Enum constructors can't contain super-initializers.
 //   const B() : super();

pkg/front_end/testcases/general/enum_super_constructor.dart.weak.outline.expect

@@ -2,19 +2,25 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   A() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: Generative enum constructors must be marked as 'const'.
 //   A() : super();
 //   ^
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const B() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:14:15: Error: Enum constructors can't contain super-initializers.
 //   const B() : super();

pkg/front_end/testcases/general/enum_super_constructor.dart.weak.transformed.expect

@@ -2,19 +2,25 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   A() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:9:3: Error: Generative enum constructors must be marked as 'const'.
 //   A() : super();
 //   ^
 //
-// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/enum_super_constructor.dart:14:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const B() : super();
 //   ^
+// pkg/front_end/testcases/general/enum_super_constructor.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/enum_super_constructor.dart:14:15: Error: Enum constructors can't contain super-initializers.
 //   const B() : super();

pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart.weak.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // test(E e) {} // Error.
 //      ^
 //

pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart.weak.modular.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // test(E e) {} // Error.
 //      ^
 //

pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart.weak.outline.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // test(E e) {} // Error.
 //      ^
 //

pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart.weak.transformed.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_type_when_experiment_not_enabled.dart:11:6: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // test(E e) {} // Error.
 //      ^
 //

pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart.weak.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // extension type E on A {} // Error because of 'type'.
 //           ^^^^
 //

pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart.weak.modular.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // extension type E on A {} // Error because of 'type'.
 //           ^^^^
 //

pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart.weak.outline.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // extension type E on A {} // Error because of 'type'.
 //           ^^^^
 //

pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart.weak.transformed.expect

@@ -2,8 +2,8 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the 'extension-types' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/extension_types_feature_not_enabled.dart:9:11: Error: This requires the experimental 'extension-types' language feature to be enabled.
+// Try passing the '--enable-experiment=extension-types' command line option.
 // extension type E on A {} // Error because of 'type'.
 //           ^^^^
 //

pkg/front_end/testcases/general/issue46719.dart.weak.expect

@@ -26,24 +26,33 @@ library /*isNonNullableByDefault*/;
 //   self.m<String>.applyAndPrint(['three']);
 //                  ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<int>.applyAndPrint([2]);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<String>.applyAndPrint(['three']);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:35:5: Error: Member not found: 'named'.
 //   A.named.toString();
 //     ^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   A<int>.named.toString();
 //    ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:36:10: Error: Member not found: 'named'.
 //   A<int>.named.toString();

pkg/front_end/testcases/general/issue46719.dart.weak.modular.expect

@@ -26,24 +26,33 @@ library /*isNonNullableByDefault*/;
 //   self.m<String>.applyAndPrint(['three']);
 //                  ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<int>.applyAndPrint([2]);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<String>.applyAndPrint(['three']);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:35:5: Error: Member not found: 'named'.
 //   A.named.toString();
 //     ^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   A<int>.named.toString();
 //    ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:36:10: Error: Member not found: 'named'.
 //   A<int>.named.toString();

pkg/front_end/testcases/general/issue46719.dart.weak.transformed.expect

@@ -26,24 +26,33 @@ library /*isNonNullableByDefault*/;
 //   self.m<String>.applyAndPrint(['three']);
 //                  ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:33:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<int>.applyAndPrint([2]);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:34:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   self.A.n<String>.applyAndPrint(['three']);
 //           ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:35:5: Error: Member not found: 'named'.
 //   A.named.toString();
 //     ^^^^^
 //
-// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue46719.dart:36:4: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   A<int>.named.toString();
 //    ^
+// pkg/front_end/testcases/general/issue46719.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/issue46719.dart:36:10: Error: Member not found: 'named'.
 //   A<int>.named.toString();

pkg/front_end/testcases/general/issue48487.dart.weak.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   void test() {
 //   ^
+// pkg/front_end/testcases/general/issue48487.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   void test() {
 //   ^
+// pkg/front_end/testcases/general/issue48487.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487.dart.weak.outline.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   void test() {
 //   ^
+// pkg/front_end/testcases/general/issue48487.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   void test() {
 //   ^
+// pkg/front_end/testcases/general/issue48487.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487b.dart.weak.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const T.named();
 //   ^
+// pkg/front_end/testcases/general/issue48487b.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487b.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const T.named();
 //   ^
+// pkg/front_end/testcases/general/issue48487b.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487b.dart.weak.outline.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const T.named();
 //   ^
+// pkg/front_end/testcases/general/issue48487b.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/issue48487b.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: This requires the 'enhanced-enums' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/issue48487b.dart:9:3: Error: The 'enhanced-enums' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   const T.named();
 //   ^
+// pkg/front_end/testcases/general/issue48487b.dart:5:1: Context: This is the annotation that opts out this library from the 'enhanced-enums' language feature.
+// // @dart=2.16
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/macro_class.dart.weak.expect

@@ -2,23 +2,23 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class1 {}
 // ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class2 {}
 //          ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class3 = Super with Mixin;
 //       ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class4 = Super with Mixin;
 //                ^^^^^
 //

pkg/front_end/testcases/general/macro_class.dart.weak.modular.expect

@@ -2,23 +2,23 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class1 {}
 // ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class2 {}
 //          ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class3 = Super with Mixin;
 //       ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class4 = Super with Mixin;
 //                ^^^^^
 //

pkg/front_end/testcases/general/macro_class.dart.weak.outline.expect

@@ -2,23 +2,23 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class1 {}
 // ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class2 {}
 //          ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class3 = Super with Mixin;
 //       ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class4 = Super with Mixin;
 //                ^^^^^
 //

pkg/front_end/testcases/general/macro_class.dart.weak.transformed.expect

@@ -2,23 +2,23 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:8:1: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class1 {}
 // ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:9:10: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class2 {}
 //          ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:10:7: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // macro class Class3 = Super with Mixin;
 //       ^^^^^
 //
-// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the 'macros' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/macro_class.dart:11:16: Error: This requires the experimental 'macros' language feature to be enabled.
+// Try passing the '--enable-experiment=macros' command line option.
 // abstract macro class Class4 = Super with Mixin;
 //                ^^^^^
 //

pkg/front_end/testcases/general/new_as_selector.dart.weak.expect

@@ -12,211 +12,322 @@ library /*isNonNullableByDefault*/;
 //   int new = 42; // error
 //       ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C() : super.new(); // error
 //               ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.named() : this.new(); // error
 //                    ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:31:16: Error: 'new' can't be used as an identifier because it's a keyword.
 // Try renaming this to be an identifier that isn't a keyword.
 //   external int new; // error
 //                ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new<int>(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new = 87; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new = 87; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new = 87; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new; // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new<int>(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new; // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new<int>(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new<int>(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new; // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new<int>(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new; // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:67:3: Error: Undefined name 'unresolved'.
 //   unresolved.new; // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:68:3: Error: Undefined name 'unresolved'.
 //   unresolved.new(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new<int>(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:69:3: Error: Undefined name 'unresolved'.
 //   unresolved.new<int>(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: Member not found: 'new'.
 //   C.new; // error
 //     ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new(); // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/new_as_selector.dart.weak.modular.expect

@@ -12,211 +12,322 @@ library /*isNonNullableByDefault*/;
 //   int new = 42; // error
 //       ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C() : super.new(); // error
 //               ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.named() : this.new(); // error
 //                    ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:31:16: Error: 'new' can't be used as an identifier because it's a keyword.
 // Try renaming this to be an identifier that isn't a keyword.
 //   external int new; // error
 //                ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new<int>(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new = 87; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new = 87; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new = 87; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new; // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new<int>(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new; // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new<int>(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new<int>(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new; // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new<int>(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new; // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:67:3: Error: Undefined name 'unresolved'.
 //   unresolved.new; // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:68:3: Error: Undefined name 'unresolved'.
 //   unresolved.new(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new<int>(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:69:3: Error: Undefined name 'unresolved'.
 //   unresolved.new<int>(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: Member not found: 'new'.
 //   C.new; // error
 //     ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new(); // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/general/new_as_selector.dart.weak.outline.expect

@@ -12,15 +12,21 @@ library /*isNonNullableByDefault*/;
 //   int new = 42; // error
 //       ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C() : super.new(); // error
 //               ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.named() : this.new(); // error
 //                    ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:31:16: Error: 'new' can't be used as an identifier because it's a keyword.
 // Try renaming this to be an identifier that isn't a keyword.

pkg/front_end/testcases/general/new_as_selector.dart.weak.transformed.expect

@@ -12,211 +12,322 @@ library /*isNonNullableByDefault*/;
 //   int new = 42; // error
 //       ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:19:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C() : super.new(); // error
 //               ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:20:20: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.named() : this.new(); // error
 //                    ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:31:16: Error: 'new' can't be used as an identifier because it's a keyword.
 // Try renaming this to be an identifier that isn't a keyword.
 //   external int new; // error
 //                ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:23:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:24:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:25:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new<int>(); // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:26:10: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //     this.new = 87; // error
 //          ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:39:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:40:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:41:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   new C().new = 87; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:43:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:44:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   c.new = 87; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:46:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new; // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:47:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:48:7: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo.new<int>(); // error
 //       ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:49:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:50:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:51:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo?.new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:52:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:53:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:54:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   foo..new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:55:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new; // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:56:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:57:9: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   (foo).new<int>(); // error
 //         ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:58:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new; // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:59:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:60:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix1.new<int>(); // error
 //           ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:61:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new; // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:62:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:63:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   prefix2.c.new<int>(); // error
 //             ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:64:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new; // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:65:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:66:8: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   E(0).new<int>(); // error
 //        ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:67:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new; // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:67:3: Error: Undefined name 'unresolved'.
 //   unresolved.new; // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:68:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:68:3: Error: Undefined name 'unresolved'.
 //   unresolved.new(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:69:14: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   unresolved.new<int>(); // error
 //              ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:69:3: Error: Undefined name 'unresolved'.
 //   unresolved.new<int>(); // error
 //   ^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new; // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/general/new_as_selector.dart:70:5: Error: Member not found: 'new'.
 //   C.new; // error
 //     ^^^
 //
-// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/general/new_as_selector.dart:71:5: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   C.new(); // error
 //     ^^^
+// pkg/front_end/testcases/general/new_as_selector.dart:5:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.14
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart.weak.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<dynamic>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<dynamic>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart.weak.outline.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<dynamic>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<dynamic>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_dynamic_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart.weak.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<int>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<int>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart.weak.outline.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<int>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library test;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:9:11: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // var v = (f<int>)/*@typeArgs=int**/(/*@returnType=int**/() {
 //           ^
+// pkg/front_end/testcases/inference/unsafe_block_closure_inference_function_call_explicit_type_param_via_expr1.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/regress/issue_31188.dart.weak.expect

@@ -22,10 +22,13 @@ library;
 // type T = Map<A, B>
 //                 ^
 //
-// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // type T = Map<A, B>
 //             ^
+// pkg/front_end/testcases/regress/issue_31188.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/regress/issue_31188.dart.weak.modular.expect

@@ -22,10 +22,13 @@ library;
 // type T = Map<A, B>
 //                 ^
 //
-// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // type T = Map<A, B>
 //             ^
+// pkg/front_end/testcases/regress/issue_31188.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/regress/issue_31188.dart.weak.transformed.expect

@@ -22,10 +22,13 @@ library;
 // type T = Map<A, B>
 //                 ^
 //
-// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_31188.dart:7:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 // type T = Map<A, B>
 //             ^
+// pkg/front_end/testcases/regress/issue_31188.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/regress/issue_34403.dart.weak.expect

@@ -12,10 +12,13 @@ library;
 //   var c2 = new C.bar<int>();
 //                  ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var c3 = C<String>.bar<int>();
 //             ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:20:22: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -37,10 +40,13 @@ library;
 //   const d2 = const D.foo<int>();
 //                      ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const d3 = D<String>.foo<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:29:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -62,10 +68,13 @@ library;
 //   var e2 = new p.E.bar<int>();
 //                    ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var e3 = p.E<String>.bar<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:38:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -87,10 +96,13 @@ library;
 //   const f2 = const p.F.foo<int>();
 //                        ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const f3 = p.F<String>.foo<int>();
 //                 ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:47:26: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.

pkg/front_end/testcases/regress/issue_34403.dart.weak.modular.expect

@@ -12,10 +12,13 @@ library;
 //   var c2 = new C.bar<int>();
 //                  ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var c3 = C<String>.bar<int>();
 //             ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:20:22: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -37,10 +40,13 @@ library;
 //   const d2 = const D.foo<int>();
 //                      ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const d3 = D<String>.foo<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:29:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -62,10 +68,13 @@ library;
 //   var e2 = new p.E.bar<int>();
 //                    ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var e3 = p.E<String>.bar<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:38:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -87,10 +96,13 @@ library;
 //   const f2 = const p.F.foo<int>();
 //                        ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const f3 = p.F<String>.foo<int>();
 //                 ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:47:26: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.

pkg/front_end/testcases/regress/issue_34403.dart.weak.transformed.expect

@@ -12,10 +12,13 @@ library;
 //   var c2 = new C.bar<int>();
 //                  ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:20:13: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var c3 = C<String>.bar<int>();
 //             ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:20:22: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -37,10 +40,13 @@ library;
 //   const d2 = const D.foo<int>();
 //                      ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:29:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const d3 = D<String>.foo<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:29:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -62,10 +68,13 @@ library;
 //   var e2 = new p.E.bar<int>();
 //                    ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:38:15: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   var e3 = p.E<String>.bar<int>();
 //               ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:38:24: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.
@@ -87,10 +96,13 @@ library;
 //   const f2 = const p.F.foo<int>();
 //                        ^^^
 //
-// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: This requires the 'constructor-tearoffs' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.15 or higher, and running 'pub get'.
+// pkg/front_end/testcases/regress/issue_34403.dart:47:17: Error: The 'constructor-tearoffs' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.15 or higher.
 //   const f3 = p.F<String>.foo<int>();
 //                 ^
+// pkg/front_end/testcases/regress/issue_34403.dart:4:1: Context: This is the annotation that opts out this library from the 'constructor-tearoffs' language feature.
+// // @dart=2.9
+// ^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/regress/issue_34403.dart:47:26: Error: A constructor invocation can't have type arguments after the constructor name.
 // Try removing the type arguments or placing them after the class name.

pkg/front_end/testcases/super_parameters/opt_out.dart.strong.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/super_parameters/opt_out.dart:14:3: Error: The superclass, 'A', has no unnamed constructor that takes no arguments.
 //   B(super.field);

pkg/front_end/testcases/super_parameters/opt_out.dart.strong.transformed.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/super_parameters/opt_out.dart:14:3: Error: The superclass, 'A', has no unnamed constructor that takes no arguments.
 //   B(super.field);

pkg/front_end/testcases/super_parameters/opt_out.dart.weak.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/super_parameters/opt_out.dart:14:3: Error: The superclass, 'A', has no unnamed constructor that takes no arguments.
 //   B(super.field);

pkg/front_end/testcases/super_parameters/opt_out.dart.weak.modular.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/super_parameters/opt_out.dart:14:3: Error: The superclass, 'A', has no unnamed constructor that takes no arguments.
 //   B(super.field);

pkg/front_end/testcases/super_parameters/opt_out.dart.weak.outline.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 import self as self;
 import "dart:core" as core;

pkg/front_end/testcases/super_parameters/opt_out.dart.weak.transformed.expect

@@ -2,10 +2,13 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: This requires the 'super-parameters' language feature to be enabled.
-// Try updating your pubspec.yaml to set the minimum SDK constraint to 2.17 or higher, and running 'pub get'.
+// pkg/front_end/testcases/super_parameters/opt_out.dart:14:5: Error: The 'super-parameters' language feature is disabled for this library.
+// Try removing the `@dart=` annotation or setting the language version to 2.17 or higher.
 //   B(super.field);
 //     ^^^^^
+// pkg/front_end/testcases/super_parameters/opt_out.dart:5:1: Context: This is the annotation that opts out this library from the 'super-parameters' language feature.
+// // @dart=2.15
+// ^^^^^^^^^^^^^
 //
 // pkg/front_end/testcases/super_parameters/opt_out.dart:14:3: Error: The superclass, 'A', has no unnamed constructor that takes no arguments.
 //   B(super.field);

tests/language_2/constructor/reference_test.dart

@@ -91,7 +91,7 @@ main() {
   Foo<int>.bar.baz();
   // ^^^^^
   // [analyzer] SYNTACTIC_ERROR.EXPERIMENT_NOT_ENABLED
-  // [cfe] This requires the 'constructor-tearoffs' language feature to be enabled.
+  // [cfe] The 'constructor-tearoffs' language feature is disabled for this library.
   //       ^
   // [cfe] Member not found: 'bar'.
   //           ^^^