[cfe] Update messages for invalid returns

Closes #42527

Change-Id: Ic240dd7a8822c85c550941923bf9ce3b5cfe0dba
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153348
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>

pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart

@@ -2040,6 +2040,84 @@ Message _withArgumentsInvalidCastTopLevelFunction(
       arguments: {'type': _type, 'type2': _type2});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        DartType _type,
+        DartType _type2,
+        bool
+            isNonNullableByDefault)> templateInvalidReturn = const Template<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>(
+    messageTemplate:
+        r"""A value of type '#type' can't be returned from a function with return type '#type2'.""",
+    withArguments: _withArgumentsInvalidReturn);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>
+    codeInvalidReturn = const Code<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>(
+  "InvalidReturn",
+  templateInvalidReturn,
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsInvalidReturn(
+    DartType _type, DartType _type2, bool isNonNullableByDefault) {
+  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
+  List<Object> typeParts = labeler.labelType(_type);
+  List<Object> type2Parts = labeler.labelType(_type2);
+  String type = typeParts.join();
+  String type2 = type2Parts.join();
+  return new Message(codeInvalidReturn,
+      message:
+          """A value of type '${type}' can't be returned from a function with return type '${type2}'.""" +
+              labeler.originMessages,
+      arguments: {'type': _type, 'type2': _type2});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(
+        DartType _type,
+        DartType _type2,
+        bool
+            isNonNullableByDefault)> templateInvalidReturnAsync = const Template<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>(
+    messageTemplate:
+        r"""A value of type '#type' can't be returned from an async function with return type '#type2'.""",
+    withArguments: _withArgumentsInvalidReturnAsync);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>
+    codeInvalidReturnAsync = const Code<
+        Message Function(
+            DartType _type, DartType _type2, bool isNonNullableByDefault)>(
+  "InvalidReturnAsync",
+  templateInvalidReturnAsync,
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsInvalidReturnAsync(
+    DartType _type, DartType _type2, bool isNonNullableByDefault) {
+  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
+  List<Object> typeParts = labeler.labelType(_type);
+  List<Object> type2Parts = labeler.labelType(_type2);
+  String type = typeParts.join();
+  String type2 = type2Parts.join();
+  return new Message(codeInvalidReturnAsync,
+      message:
+          """A value of type '${type}' can't be returned from an async function with return type '${type2}'.""" +
+              labeler.originMessages,
+      arguments: {'type': _type, 'type2': _type2});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
         Message Function(DartType _type, DartType _type2, DartType _type3,

pkg/front_end/lib/src/fasta/type_inference/closure_context.dart

@@ -195,7 +195,8 @@ class _SyncClosureContext implements ClosureContext {
           // nor dynamic, and S is void.
           statement.expression = inferrer.helper.wrapInProblem(
               statement.expression,
-              messageVoidExpression,
+              templateInvalidReturn.withArguments(expressionType,
+                  _declaredReturnType, inferrer.isNonNullableByDefault),
               statement.expression.fileOffset,
               noLength)
             ..parent = statement;
@@ -204,7 +205,9 @@ class _SyncClosureContext implements ClosureContext {
           // S is not assignable to T.
           Expression expression = inferrer.ensureAssignable(
               _returnContext, expressionType, statement.expression,
-              fileOffset: statement.expression.fileOffset, isVoidAllowed: true);
+              fileOffset: statement.expression.fileOffset,
+              isVoidAllowed: true,
+              errorTemplate: templateInvalidReturn);
           statement.expression = expression..parent = statement;
         }
       }
@@ -481,7 +484,8 @@ class _AsyncClosureContext implements ClosureContext {
           // flatten(S) is neither void, dynamic, Null.
           statement.expression = inferrer.helper.wrapInProblem(
               new NullLiteral()..fileOffset = statement.fileOffset,
-              messageReturnFromVoidFunction,
+              templateInvalidReturnAsync.withArguments(expressionType,
+                  _declaredReturnType, inferrer.isNonNullableByDefault),
               statement.expression.fileOffset,
               noLength)
             ..parent = statement;
@@ -492,25 +496,11 @@ class _AsyncClosureContext implements ClosureContext {
           // nor dynamic, and flatten(S) is void.
           statement.expression = inferrer.helper.wrapInProblem(
               new NullLiteral()..fileOffset = statement.fileOffset,
-              messageVoidExpression,
+              templateInvalidReturnAsync.withArguments(expressionType,
+                  _declaredReturnType, inferrer.isNonNullableByDefault),
               statement.expression.fileOffset,
               noLength)
             ..parent = statement;
-/*        } else if (flattenedExpressionType is! VoidType &&
-            !inferrer.isAssignable(futureValueType, expressionType) &&
-            !inferrer.typeSchemaEnvironment
-                .performNullabilityAwareSubtypeCheck(
-                    flattenedExpressionType, futureValueType)
-                .isSubtypeWhenUsingNullabilities()) {
-          // It is a compile-time error if s is `return e;`, flatten(S) is not
-          // void, S is not assignable to T_v, and flatten(S) is not a subtype
-          // of T_v.
-          statement.expression = inferrer.helper.wrapInProblem(
-              new NullLiteral()..fileOffset = statement.fileOffset,
-              messageReturnWithoutExpressionAsync,
-              statement.expression.fileOffset,
-              noLength)
-            ..parent = statement;*/
         } else if (flattenedExpressionType is! VoidType &&
             !inferrer.typeSchemaEnvironment
                 .performNullabilityAwareSubtypeCheck(
@@ -523,7 +513,9 @@ class _AsyncClosureContext implements ClosureContext {
               futureValueType, expressionType, statement.expression,
               fileOffset: statement.expression.fileOffset,
               runtimeCheckedType: _returnContext,
-              isVoidAllowed: false)
+              declaredContextType: _declaredReturnType,
+              isVoidAllowed: false,
+              errorTemplate: templateInvalidReturnAsync)
             ..parent = statement;
         }
       }

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

@@ -387,6 +387,13 @@ class TypeInferrerImpl implements TypeInferrer {
   /// [contextType], and inserts an implicit downcast, inserts a tear-off, or
   /// reports an error if appropriate.
   ///
+  /// If [declaredContextType] is provided, this is used instead of
+  /// [contextType] for reporting the type against which [expressionType] isn't
+  /// assignable. This is used when checking the assignability of return
+  /// statements in async functions in which the assignability is checked
+  /// against the future value type but the reporting should refer to the
+  /// declared return type.
+  ///
   /// If [runtimeCheckedType] is provided, this is used for the implicit cast,
   /// otherwise [contextType] is used. This is used for return from async
   /// where the returned expression is wrapped in a `Future`, if necessary,
@@ -395,6 +402,7 @@ class TypeInferrerImpl implements TypeInferrer {
   Expression ensureAssignable(
       DartType contextType, DartType expressionType, Expression expression,
       {int fileOffset,
+      DartType declaredContextType,
       DartType runtimeCheckedType,
       bool isVoidAllowed: false,
       Template<Message Function(DartType, DartType, bool)> errorTemplate}) {
@@ -444,8 +452,8 @@ class TypeInferrerImpl implements TypeInferrer {
         break;
       case AssignabilityKind.unassignable:
         // Error: not assignable.  Perform error recovery.
-        result = _wrapUnassignableExpression(
-            expression, expressionType, contextType, errorTemplate);
+        result = _wrapUnassignableExpression(expression, expressionType,
+            contextType, declaredContextType, errorTemplate);
         break;
       case AssignabilityKind.unassignableVoid:
         // Error: not assignable.  Perform error recovery.
@@ -465,8 +473,12 @@ class TypeInferrerImpl implements TypeInferrer {
       case AssignabilityKind.unassignableTearoff:
         TypedTearoff typedTearoff =
             _tearOffCall(expression, expressionType, fileOffset);
-        result = _wrapUnassignableExpression(typedTearoff.tearoff,
-            typedTearoff.tearoffType, contextType, errorTemplate);
+        result = _wrapUnassignableExpression(
+            typedTearoff.tearoff,
+            typedTearoff.tearoffType,
+            contextType,
+            declaredContextType,
+            errorTemplate);
         break;
       case AssignabilityKind.unassignableCantTearoff:
         result = _wrapTearoffErrorExpression(
@@ -505,6 +517,7 @@ class TypeInferrerImpl implements TypeInferrer {
       Expression expression,
       DartType expressionType,
       DartType contextType,
+      DartType declaredContextType,
       Template<Message Function(DartType, DartType, bool)> template) {
     Expression errorNode = new AsExpression(
         expression,
@@ -520,7 +533,9 @@ class TypeInferrerImpl implements TypeInferrer {
       errorNode = helper.wrapInProblem(
           errorNode,
           (template ?? templateInvalidAssignmentError).withArguments(
-              expressionType, contextType, isNonNullableByDefault),
+              expressionType,
+              declaredContextType ?? contextType,
+              isNonNullableByDefault),
           errorNode.fileOffset,
           noLength);
     }

pkg/front_end/messages.status

@@ -415,6 +415,8 @@ InvalidContinueTarget/example: Fail
 InvalidInitializer/example: Fail
 InvalidPackageUri/analyzerCode: Fail
 InvalidPackageUri/example: Fail
+InvalidReturn/analyzerCode: Fail
+InvalidReturnAsync/analyzerCode: Fail
 InvalidSuperInInitializer/example: Fail
 InvalidThisInInitializer/example: Fail
 InvalidTypeVariableInSupertype/analyzerCode: Fail

pkg/front_end/messages.yaml

@@ -3413,6 +3413,16 @@ ReturnWithoutExpressionAsync:
   configuration: nnbd-strong
   declaration: "Future<int> foo() async { return; }"
 
+InvalidReturn:
+  template: "A value of type '#type' can't be returned from a function with return type '#type2'."
+  configuration: nnbd-strong
+  declaration: "int foo() { return true; }"
+
+InvalidReturnAsync:
+  template: "A value of type '#type' can't be returned from an async function with return type '#type2'."
+  configuration: nnbd-strong
+  declaration: "Future<int> foo() async { return true; }"
+
 ImplicitReturnNull:
   template: "A non-null value must be returned since the return type '#type' doesn't allow null."
   configuration: nnbd-strong

pkg/front_end/testcases/nnbd/dynamic_object_call.dart.textual_outline.expect

@@ -0,0 +1,9 @@
+class Class {
+  @override
+  noSuchMethod(Object o, {String foo = ''}) => 42;
+  @override
+  toString({String foo = ''}) => 'foo';
+}
+
+main() {}
+test() {}

pkg/front_end/testcases/nnbd/dynamic_object_call.dart.textual_outline_modelled.expect

@@ -0,0 +1,9 @@
+class Class {
+  @override
+  noSuchMethod(Object o, {String foo = ''}) => 42;
+  @override
+  toString({String foo = ''}) => 'foo';
+}
+
+main() {}
+test() {}

pkg/front_end/testcases/nnbd/issue41386.dart.textual_outline.expect

@@ -0,0 +1,3 @@
+bool Function(T) predicate<T>(bool Function(T) fn) => (T val) => fn(val);
+void test() {}
+void main() {}

pkg/front_end/testcases/nnbd/issue41386.dart.textual_outline_modelled.expect

@@ -0,0 +1,3 @@
+bool Function(T) predicate<T>(bool Function(T) fn) => (T val) => fn(val);
+void main() {}
+void test() {}

pkg/front_end/testcases/nnbd/issue41386b.dart.textual_outline.expect

@@ -0,0 +1,2 @@
+void test() {}
+main() {}

pkg/front_end/testcases/nnbd/issue41386b.dart.textual_outline_modelled.expect

@@ -0,0 +1,2 @@
+main() {}
+void test() {}

pkg/front_end/testcases/nnbd/issue41437a.dart.strong.expect

@@ -2,12 +2,12 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 // Future<bool> test5() => getFutureNull(); // error
 //                         ^
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 //   Future<bool> test5() => getFutureNull(); // error
 //                           ^
@@ -48,7 +48,7 @@ static method test3() → core::bool
 static method test4() → asy::Future<core::bool> async 
   return await self::getFutureNull() as{TypeError,ForDynamic,ForNonNullableByDefault} FutureOr<core::bool>;
 static method test5() → asy::Future<core::bool>
-  return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+  return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
 Future<bool> test5() => getFutureNull(); // error
                         ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;
@@ -66,7 +66,7 @@ static method test() → dynamic async {
   function test4() → asy::Future<core::bool> async 
     return await self::getFutureNull() as{TypeError,ForDynamic,ForNonNullableByDefault} FutureOr<core::bool>;
   function test5() → asy::Future<core::bool>
-    return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+    return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
   Future<bool> test5() => getFutureNull(); // error
                           ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;

pkg/front_end/testcases/nnbd/issue41437a.dart.strong.transformed.expect

@@ -2,12 +2,12 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 // Future<bool> test5() => getFutureNull(); // error
 //                         ^
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 //   Future<bool> test5() => getFutureNull(); // error
 //                           ^
@@ -150,7 +150,7 @@ static method test4() → asy::Future<core::bool> /* originally async */ {
   return :async_completer.{asy::Completer::future};
 }
 static method test5() → asy::Future<core::bool>
-  return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+  return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
 Future<bool> test5() => getFutureNull(); // error
                         ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;
@@ -258,7 +258,7 @@ static method test() → dynamic /* originally async */ {
           return :async_completer.{asy::Completer::future};
         }
         function test5() → asy::Future<core::bool>
-          return let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+          return let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
   Future<bool> test5() => getFutureNull(); // error
                           ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;

pkg/front_end/testcases/nnbd/issue41437a.dart.weak.expect

@@ -2,12 +2,12 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 // Future<bool> test5() => getFutureNull(); // error
 //                         ^
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 //   Future<bool> test5() => getFutureNull(); // error
 //                           ^
@@ -48,7 +48,7 @@ static method test3() → core::bool
 static method test4() → asy::Future<core::bool> async 
   return await self::getFutureNull() as{TypeError,ForDynamic,ForNonNullableByDefault} FutureOr<core::bool>;
 static method test5() → asy::Future<core::bool>
-  return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+  return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
 Future<bool> test5() => getFutureNull(); // error
                         ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;
@@ -66,7 +66,7 @@ static method test() → dynamic async {
   function test4() → asy::Future<core::bool> async 
     return await self::getFutureNull() as{TypeError,ForDynamic,ForNonNullableByDefault} FutureOr<core::bool>;
   function test5() → asy::Future<core::bool>
-    return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+    return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
   Future<bool> test5() => getFutureNull(); // error
                           ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;

pkg/front_end/testcases/nnbd/issue41437a.dart.weak.transformed.expect

@@ -2,12 +2,12 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 // Future<bool> test5() => getFutureNull(); // error
 //                         ^
 //
-// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
 //  - 'Future' is from 'dart:async'.
 //   Future<bool> test5() => getFutureNull(); // error
 //                           ^
@@ -150,7 +150,7 @@ static method test4() → asy::Future<core::bool> /* originally async */ {
   return :async_completer.{asy::Completer::future};
 }
 static method test5() → asy::Future<core::bool>
-  return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+  return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:18:25: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
 Future<bool> test5() => getFutureNull(); // error
                         ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;
@@ -258,7 +258,7 @@ static method test() → dynamic /* originally async */ {
           return :async_completer.{asy::Completer::future};
         }
         function test5() → asy::Future<core::bool>
-          return let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be assigned to a variable of type 'Future<bool>'.
+          return let final<BottomType> #t6 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437a.dart:27:27: Error: A value of type 'Future<dynamic>' can't be returned from a function with return type 'Future<bool>'.
  - 'Future' is from 'dart:async'.
   Future<bool> test5() => getFutureNull(); // error
                           ^" in self::getFutureNull() as{TypeError,ForNonNullableByDefault} asy::Future<core::bool>;

pkg/front_end/testcases/nnbd/issue41437b.dart.strong.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getIterableNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 // Iterable<bool> test5() => getIterableNull(); // error
 //                           ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getIterableNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 //   Iterable<bool> test5() => getIterableNull(); // error
 //                             ^
@@ -62,7 +62,7 @@ static method test4() → core::Iterable<core::bool> sync* {
          ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
 }
 static method test5() → core::Iterable<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
 Iterable<bool> test5() => getIterableNull(); // error
                           ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
@@ -86,7 +86,7 @@ static method test() → dynamic async {
            ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
   }
   function test5() → core::Iterable<core::bool>
-    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
   Iterable<bool> test5() => getIterableNull(); // error
                             ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;

pkg/front_end/testcases/nnbd/issue41437b.dart.strong.transformed.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getIterableNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 // Iterable<bool> test5() => getIterableNull(); // error
 //                           ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getIterableNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 //   Iterable<bool> test5() => getIterableNull(); // error
 //                             ^
@@ -115,7 +115,7 @@ static method test4() → core::Iterable<core::bool> /* originally sync* */ {
   return new core::_SyncIterable::•<core::bool>(:sync_op_gen);
 }
 static method test5() → core::Iterable<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
 Iterable<bool> test5() => getIterableNull(); // error
                           ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
@@ -189,7 +189,7 @@ static method test() → dynamic /* originally async */ {
           return new core::_SyncIterable::•<core::bool>(:sync_op_gen);
         }
         function test5() → core::Iterable<core::bool>
-          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
   Iterable<bool> test5() => getIterableNull(); // error
                             ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;

pkg/front_end/testcases/nnbd/issue41437b.dart.textual_outline.expect

@@ -0,0 +1,12 @@
+dynamic getNull() => null;
+Iterable<dynamic> getIterableNull() sync* {}
+Iterable<bool> getIterableBool() sync* {}
+Iterable<bool> test1() sync* {}
+Iterable<bool> test2() => getNull();
+bool test3() => getNull();
+Iterable<bool> test4() sync* {}
+Iterable<bool> test5() => getIterableNull();
+Iterable<bool> test6() => getIterableBool();
+Iterable<bool> test7() sync* {}
+test() async {}
+main() {}

pkg/front_end/testcases/nnbd/issue41437b.dart.textual_outline_modelled.expect

@@ -0,0 +1,12 @@
+Iterable<bool> getIterableBool() sync* {}
+Iterable<bool> test1() sync* {}
+Iterable<bool> test2() => getNull();
+Iterable<bool> test4() sync* {}
+Iterable<bool> test5() => getIterableNull();
+Iterable<bool> test6() => getIterableBool();
+Iterable<bool> test7() sync* {}
+Iterable<dynamic> getIterableNull() sync* {}
+bool test3() => getNull();
+dynamic getNull() => null;
+main() {}
+test() async {}

pkg/front_end/testcases/nnbd/issue41437b.dart.weak.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getIterableNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 // Iterable<bool> test5() => getIterableNull(); // error
 //                           ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getIterableNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 //   Iterable<bool> test5() => getIterableNull(); // error
 //                             ^
@@ -62,7 +62,7 @@ static method test4() → core::Iterable<core::bool> sync* {
          ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
 }
 static method test5() → core::Iterable<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
 Iterable<bool> test5() => getIterableNull(); // error
                           ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
@@ -86,7 +86,7 @@ static method test() → dynamic async {
            ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
   }
   function test5() → core::Iterable<core::bool>
-    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
   Iterable<bool> test5() => getIterableNull(); // error
                             ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;

pkg/front_end/testcases/nnbd/issue41437b.dart.weak.transformed.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getIterableNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 // Iterable<bool> test5() => getIterableNull(); // error
 //                           ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getIterableNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
 //  - 'Iterable' is from 'dart:core'.
 //   Iterable<bool> test5() => getIterableNull(); // error
 //                             ^
@@ -115,7 +115,7 @@ static method test4() → core::Iterable<core::bool> /* originally sync* */ {
   return new core::_SyncIterable::•<core::bool>(:sync_op_gen);
 }
 static method test5() → core::Iterable<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:24:27: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
 Iterable<bool> test5() => getIterableNull(); // error
                           ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;
@@ -189,7 +189,7 @@ static method test() → dynamic /* originally async */ {
           return new core::_SyncIterable::•<core::bool>(:sync_op_gen);
         }
         function test5() → core::Iterable<core::bool>
-          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be assigned to a variable of type 'Iterable<bool>'.
+          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437b.dart:41:29: Error: A value of type 'Iterable<dynamic>' can't be returned from a function with return type 'Iterable<bool>'.
  - 'Iterable' is from 'dart:core'.
   Iterable<bool> test5() => getIterableNull(); // error
                             ^" in self::getIterableNull() as{TypeError,ForNonNullableByDefault} core::Iterable<core::bool>;

pkg/front_end/testcases/nnbd/issue41437c.dart.strong.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getStreamNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 // Stream<bool> test5() => getStreamNull(); // error
 //                         ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getStreamNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 //   Stream<bool> test5() => getStreamNull(); // error
 //                           ^
@@ -63,7 +63,7 @@ static method test4() → asy::Stream<core::bool> async* {
          ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
 }
 static method test5() → asy::Stream<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
 Stream<bool> test5() => getStreamNull(); // error
                         ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
@@ -87,7 +87,7 @@ static method test() → dynamic async {
            ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
   }
   function test5() → asy::Stream<core::bool>
-    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
   Stream<bool> test5() => getStreamNull(); // error
                           ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;

pkg/front_end/testcases/nnbd/issue41437c.dart.strong.transformed.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getStreamNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 // Stream<bool> test5() => getStreamNull(); // error
 //                         ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getStreamNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 //   Stream<bool> test5() => getStreamNull(); // error
 //                           ^
@@ -191,7 +191,7 @@ static method test4() → asy::Stream<core::bool> /* originally async* */ {
   return :controller_stream;
 }
 static method test5() → asy::Stream<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
 Stream<bool> test5() => getStreamNull(); // error
                         ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
@@ -322,7 +322,7 @@ static method test() → dynamic /* originally async */ {
           return :controller_stream;
         }
         function test5() → asy::Stream<core::bool>
-          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
   Stream<bool> test5() => getStreamNull(); // error
                           ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;

pkg/front_end/testcases/nnbd/issue41437c.dart.textual_outline.expect

@@ -0,0 +1,12 @@
+dynamic getNull() => null;
+Stream<dynamic> getStreamNull() async* {}
+Stream<bool> getStreamBool() async* {}
+Stream<bool> test1() async* {}
+Stream<bool> test2() => getNull();
+bool test3() => getNull();
+Stream<bool> test4() async* {}
+Stream<bool> test5() => getStreamNull();
+Stream<bool> test6() => getStreamBool();
+Stream<bool> test7() async* {}
+test() async {}
+main() {}

pkg/front_end/testcases/nnbd/issue41437c.dart.textual_outline_modelled.expect

@@ -0,0 +1,12 @@
+Stream<bool> getStreamBool() async* {}
+Stream<bool> test1() async* {}
+Stream<bool> test2() => getNull();
+Stream<bool> test4() async* {}
+Stream<bool> test5() => getStreamNull();
+Stream<bool> test6() => getStreamBool();
+Stream<bool> test7() async* {}
+Stream<dynamic> getStreamNull() async* {}
+bool test3() => getNull();
+dynamic getNull() => null;
+main() {}
+test() async {}

pkg/front_end/testcases/nnbd/issue41437c.dart.weak.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getStreamNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 // Stream<bool> test5() => getStreamNull(); // error
 //                         ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getStreamNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 //   Stream<bool> test5() => getStreamNull(); // error
 //                           ^
@@ -63,7 +63,7 @@ static method test4() → asy::Stream<core::bool> async* {
          ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
 }
 static method test5() → asy::Stream<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
 Stream<bool> test5() => getStreamNull(); // error
                         ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
@@ -87,7 +87,7 @@ static method test() → dynamic async {
            ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
   }
   function test5() → asy::Stream<core::bool>
-    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
   Stream<bool> test5() => getStreamNull(); // error
                           ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;

pkg/front_end/testcases/nnbd/issue41437c.dart.weak.transformed.expect

@@ -7,7 +7,7 @@ library /*isNonNullableByDefault*/;
 //   yield* getStreamNull(); // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 // Stream<bool> test5() => getStreamNull(); // error
 //                         ^
@@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 //     yield* getStreamNull(); // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+// pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
 //  - 'Stream' is from 'dart:async'.
 //   Stream<bool> test5() => getStreamNull(); // error
 //                           ^
@@ -191,7 +191,7 @@ static method test4() → asy::Stream<core::bool> /* originally async* */ {
   return :controller_stream;
 }
 static method test5() → asy::Stream<core::bool>
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:24:25: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
 Stream<bool> test5() => getStreamNull(); // error
                         ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;
@@ -322,7 +322,7 @@ static method test() → dynamic /* originally async */ {
           return :controller_stream;
         }
         function test5() → asy::Stream<core::bool>
-          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be assigned to a variable of type 'Stream<bool>'.
+          return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/issue41437c.dart:41:27: Error: A value of type 'Stream<dynamic>' can't be returned from a function with return type 'Stream<bool>'.
  - 'Stream' is from 'dart:async'.
   Stream<bool> test5() => getStreamNull(); // error
                           ^" in self::getStreamNull() as{TypeError,ForNonNullableByDefault} asy::Stream<core::bool>;

pkg/front_end/testcases/nnbd/issue41520.dart.textual_outline.expect

@@ -0,0 +1,4 @@
+void errors() {}
+void _takesObject(Object o) {}
+void _takesStackTrace(StackTrace o) {}
+void main() {}

pkg/front_end/testcases/nnbd/issue41520.dart.textual_outline_modelled.expect

@@ -0,0 +1,4 @@
+void _takesObject(Object o) {}
+void _takesStackTrace(StackTrace o) {}
+void errors() {}
+void main() {}

pkg/front_end/testcases/nnbd/issue41700a.dart.textual_outline.expect

@@ -0,0 +1,2 @@
+test() {}
+main() {}

pkg/front_end/testcases/nnbd/issue41700a.dart.textual_outline_modelled.expect

@@ -0,0 +1,2 @@
+main() {}
+test() {}

pkg/front_end/testcases/nnbd/issue41700b.dart.textual_outline.expect

@@ -0,0 +1,4 @@
+class Null {}
+
+test() {}
+main() {}

pkg/front_end/testcases/nnbd/issue41700b.dart.textual_outline_modelled.expect

@@ -0,0 +1,4 @@
+class Null {}
+
+main() {}
+test() {}

pkg/front_end/testcases/nnbd/never_calls.dart.textual_outline.expect

@@ -0,0 +1,6 @@
+propertyGet(Never never) {}
+propertySet(Never never) {}
+methodInvocation(Never never, Invocation invocation) {}
+equals(Never never) {}
+operator(Never never) {}
+main() {}

pkg/front_end/testcases/nnbd/never_calls.dart.textual_outline_modelled.expect

@@ -0,0 +1,6 @@
+equals(Never never) {}
+main() {}
+methodInvocation(Never never, Invocation invocation) {}
+operator(Never never) {}
+propertyGet(Never never) {}
+propertySet(Never never) {}

pkg/front_end/testcases/nnbd/never_equals.dart.textual_outline.expect

@@ -0,0 +1,2 @@
+test(Never nonNullableNever, Never? nullableNever) {}
+main() {}

pkg/front_end/testcases/nnbd/never_equals.dart.textual_outline_modelled.expect

@@ -0,0 +1,2 @@
+main() {}
+test(Never nonNullableNever, Never? nullableNever) {}

pkg/front_end/testcases/nnbd/redundant_type_casts.dart.textual_outline.expect

@@ -0,0 +1,6 @@
+class A<T> {
+  T? _current;
+  T get current => _current as T;
+}
+
+main() {}

pkg/front_end/testcases/nnbd/redundant_type_casts.dart.textual_outline_modelled.expect

@@ -0,0 +1,6 @@
+class A<T> {
+  T get current => _current as T;
+  T? _current;
+}
+
+main() {}

pkg/front_end/testcases/nnbd/return_null.dart.strong.expect

@@ -6,11 +6,11 @@ library /*isNonNullableByDefault*/;
 // String returnImplicit() /*error*/ {
 //        ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //   return null; // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
@@ -31,11 +31,11 @@ library /*isNonNullableByDefault*/;
 //   String returnImplicit() /* error */ {
 //   ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //       return null; // error
 //              ^
 //
@@ -82,14 +82,14 @@ String returnImplicit() /*error*/ {
 }
 static method returnExplicit() → core::String {
   core::print("foo");
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
   return null; // error
          ^" in null as{TypeError,ForNonNullableByDefault} core::String;
 }
 static method returnMixed(core::bool b) → core::String {
   if(b) {
     core::print("foo");
-    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null as{TypeError,ForNonNullableByDefault} core::String;
   }
@@ -151,14 +151,14 @@ static method localFunctions() → dynamic {
   }
   function returnExplicit() → core::String {
     core::print("foo");
-    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null as{TypeError,ForNonNullableByDefault} core::String;
   }
   function returnMixed(core::bool b) → core::String {
     if(b) {
       core::print("foo");
-      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
       return null; // error
              ^" in null as{TypeError,ForNonNullableByDefault} core::String;
     }

pkg/front_end/testcases/nnbd/return_null.dart.strong.transformed.expect

@@ -6,11 +6,11 @@ library /*isNonNullableByDefault*/;
 // String returnImplicit() /*error*/ {
 //        ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //   return null; // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
@@ -31,11 +31,11 @@ library /*isNonNullableByDefault*/;
 //   String returnImplicit() /* error */ {
 //   ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //       return null; // error
 //              ^
 //
@@ -82,14 +82,14 @@ String returnImplicit() /*error*/ {
 }
 static method returnExplicit() → core::String {
   core::print("foo");
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
   return null; // error
          ^" in let core::Null? #t3 = null in #t3.==(null) ?{core::String} #t3 as{TypeError,ForNonNullableByDefault} core::String : #t3{core::String};
 }
 static method returnMixed(core::bool b) → core::String {
   if(b) {
     core::print("foo");
-    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t4 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in let core::Null? #t5 = null in #t5.==(null) ?{core::String} #t5 as{TypeError,ForNonNullableByDefault} core::String : #t5{core::String};
   }
@@ -351,14 +351,14 @@ static method localFunctions() → dynamic {
   }
   function returnExplicit() → core::String {
     core::print("foo");
-    return let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t10 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in let core::Null? #t11 = null in #t11.==(null) ?{core::String} #t11 as{TypeError,ForNonNullableByDefault} core::String : #t11{core::String};
   }
   function returnMixed(core::bool b) → core::String {
     if(b) {
       core::print("foo");
-      return let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+      return let final<BottomType> #t12 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
       return null; // error
              ^" in let core::Null? #t13 = null in #t13.==(null) ?{core::String} #t13 as{TypeError,ForNonNullableByDefault} core::String : #t13{core::String};
     }

pkg/front_end/testcases/nnbd/return_null.dart.weak.expect

@@ -6,11 +6,11 @@ library /*isNonNullableByDefault*/;
 // String returnImplicit() /*error*/ {
 //        ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //   return null; // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
@@ -31,11 +31,11 @@ library /*isNonNullableByDefault*/;
 //   String returnImplicit() /* error */ {
 //   ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //       return null; // error
 //              ^
 //
@@ -82,14 +82,14 @@ String returnImplicit() /*error*/ {
 }
 static method returnExplicit() → core::String {
   core::print("foo");
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
   return null; // error
          ^" in null as{TypeError,ForNonNullableByDefault} core::String;
 }
 static method returnMixed(core::bool b) → core::String {
   if(b) {
     core::print("foo");
-    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null as{TypeError,ForNonNullableByDefault} core::String;
   }
@@ -151,14 +151,14 @@ static method localFunctions() → dynamic {
   }
   function returnExplicit() → core::String {
     core::print("foo");
-    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null as{TypeError,ForNonNullableByDefault} core::String;
   }
   function returnMixed(core::bool b) → core::String {
     if(b) {
       core::print("foo");
-      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
       return null; // error
              ^" in null as{TypeError,ForNonNullableByDefault} core::String;
     }

pkg/front_end/testcases/nnbd/return_null.dart.weak.transformed.expect

@@ -6,11 +6,11 @@ library /*isNonNullableByDefault*/;
 // String returnImplicit() /*error*/ {
 //        ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //   return null; // error
 //          ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
@@ -31,11 +31,11 @@ library /*isNonNullableByDefault*/;
 //   String returnImplicit() /* error */ {
 //   ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //     return null; // error
 //            ^
 //
-// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+// pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
 //       return null; // error
 //              ^
 //
@@ -82,14 +82,14 @@ String returnImplicit() /*error*/ {
 }
 static method returnExplicit() → core::String {
   core::print("foo");
-  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+  return let final<BottomType> #t2 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:13:10: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
   return null; // error
          ^" in null;
 }
 static method returnMixed(core::bool b) → core::String {
   if(b) {
     core::print("foo");
-    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t3 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:19:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null;
   }
@@ -351,14 +351,14 @@ static method localFunctions() → dynamic {
   }
   function returnExplicit() → core::String {
     core::print("foo");
-    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+    return let final<BottomType> #t8 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:69:12: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
     return null; // error
            ^" in null;
   }
   function returnMixed(core::bool b) → core::String {
     if(b) {
       core::print("foo");
-      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be assigned to a variable of type 'String'.
+      return let final<BottomType> #t9 = invalid-expression "pkg/front_end/testcases/nnbd/return_null.dart:75:14: Error: A value of type 'Null' can't be returned from a function with return type 'String'.
       return null; // error
              ^" in null;
     }

pkg/front_end/testcases/nnbd/type_constraint_solving_closures_in_upper_and_lower_bounds.dart.textual_outline.expect

@@ -0,0 +1,7 @@
+class C<X> {
+  C(void Function(X) x);
+}
+
+T check<T>(C<List<T>> f) {}
+void test() {}
+main() {}

pkg/front_end/testcases/nnbd/type_constraint_solving_closures_in_upper_and_lower_bounds.dart.textual_outline_modelled.expect

@@ -0,0 +1,8 @@
+T check<T>(C<List<T>> f) {}
+
+class C<X> {
+  C(void Function(X) x);
+}
+
+main() {}
+void test() {}

pkg/front_end/testcases/nnbd_mixed/never_opt_out.dart.weak.expect

@@ -122,7 +122,7 @@ library /*isNonNullableByDefault*/;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/nnbd_mixed/never_opt_out_lib.dart:19:28: Error: A value of type 'Type' can't be assigned to a variable of type 'Null'.
+// pkg/front_end/testcases/nnbd_mixed/never_opt_out_lib.dart:19:28: Error: A value of type 'Type' can't be returned from a function with return type 'Null'.
 //  - 'Type' is from 'dart:core'.
 //   Null get nullProperty => Null;
 //                            ^
@@ -147,7 +147,7 @@ class A extends core::Object {
   method nullMethod(core::Null? value) → core::Null?
     return value;
   get nullProperty() → core::Null?
-    return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd_mixed/never_opt_out_lib.dart:19:28: Error: A value of type 'Type' can't be assigned to a variable of type 'Null'.
+    return let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd_mixed/never_opt_out_lib.dart:19:28: Error: A value of type 'Type' can't be returned from a function with return type 'Null'.
  - 'Type' is from 'dart:core'.
   Null get nullProperty => Null;
                            ^" in core::Null? as{TypeError,ForNonNullableByDefault} core::Null?;

tests/language/factory/return_type_checked_test.dart

@@ -8,7 +8,7 @@ class A {
   factory A() => 42;
   //             ^^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] A value of type 'int' can't be assigned to a variable of type 'A'.
+  // [cfe] A value of type 'int' can't be returned from a function with return type 'A'.
 }
 
 main() {

tests/language/implicit_downcast_during/function_literal_arrow_test.dart

@@ -11,5 +11,5 @@ void main() {
   B Function(A) f = (A a) => a;
   //                         ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE_FROM_CLOSURE
-  // [cfe] A value of type 'A' can't be assigned to a variable of type 'B'.
+  // [cfe] A value of type 'A' can't be returned from a function with return type 'B'.
 }

tests/language/implicit_downcast_during/function_literal_return_test.dart

@@ -12,6 +12,6 @@ void main() {
     return a;
     //     ^
     // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE_FROM_CLOSURE
-    // [cfe] A value of type 'A' can't be assigned to a variable of type 'B'.
+    // [cfe] A value of type 'A' can't be returned from a function with return type 'B'.
   };
 }

tests/language/implicit_downcast_during/return_async_test.dart

@@ -13,14 +13,14 @@ Future<B> f1(A a) async {
   //     ^^^^^^^^^^^^^^^^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
   //       ^
-  // [cfe] A value of type 'FutureOr<A>' can't be assigned to a variable of type 'B'.
+  // [cfe] A value of type 'FutureOr<A>' can't be returned from an async function with return type 'Future<B>'.
 }
 
 Future<B> f2(A a) async => a as FutureOr<A>;
 //                         ^^^^^^^^^^^^^^^^
 // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
 //                           ^
-// [cfe] A value of type 'FutureOr<A>' can't be assigned to a variable of type 'B'.
+// [cfe] A value of type 'FutureOr<A>' can't be returned from an async function with return type 'Future<B>'.
 
 main() async {
   Object b;

tests/language/implicit_downcast_during/return_test.dart

@@ -10,13 +10,13 @@ B f1(A a) {
   return a;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] A value of type 'A' can't be assigned to a variable of type 'B'.
+  // [cfe] A value of type 'A' can't be returned from a function with return type 'B'.
 }
 
 B f2(A a) => a;
 //           ^
 // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-// [cfe] A value of type 'A' can't be assigned to a variable of type 'B'.
+// [cfe] A value of type 'A' can't be returned from a function with return type 'B'.
 
 void main() {
   Object b;

tests/language/invalid_returns/async_invalid_return_00_test.dart

@@ -12,14 +12,14 @@ Object test1() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 Object? test2() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 // Inferred return type of function literal is `Future<Null>`, no error.

tests/language/invalid_returns/async_invalid_return_01_test.dart

@@ -12,14 +12,14 @@ Future<int> test1() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 Future<int> Function() test2 = () async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_02_test.dart

@@ -12,14 +12,14 @@ FutureOr<int> test1() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 FutureOr<int> Function() test2 = () async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_03_test.dart

@@ -12,7 +12,7 @@ Future<Object?> test1() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 // Inferred return type of function literal is `Future<Null>`, no error.

tests/language/invalid_returns/async_invalid_return_04_test.dart

@@ -12,7 +12,7 @@ FutureOr<Object?> test1() async {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void async function.
 }
 
 // Inferred return type of function literal is `Future<Null>`, no error.

tests/language/invalid_returns/async_invalid_return_05_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_08_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Object' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<Object>`, no error.

tests/language/invalid_returns/async_invalid_return_11_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>?' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<int?>`, no error.

tests/language/invalid_returns/async_invalid_return_14_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<int>' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_17_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<Object>' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<Object>`, no error.

tests/language/invalid_returns/async_invalid_return_20_test.dart

@@ -15,7 +15,7 @@ void test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<Object>' can't be returned from an async function with return type 'void'.
 }
 
 // Inferred return type of function literal is `Future<Object>`, no error.

tests/language/invalid_returns/async_invalid_return_23_test.dart

@@ -15,14 +15,14 @@ Object test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'Object'.
 }
 
 Object? test2() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'Object?'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_24_test.dart

@@ -15,14 +15,14 @@ Object test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>?' can't be returned from an async function with return type 'Object'.
 }
 
 Object? test2() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>?' can't be returned from an async function with return type 'Object?'.
 }
 
 // Inferred return type of function literal is `Future<void?>`, no error.

tests/language/invalid_returns/async_invalid_return_25_test.dart

@@ -15,14 +15,14 @@ Object test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Object'.
 }
 
 Object? test2() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Object?'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_26_test.dart

@@ -18,7 +18,7 @@ Future<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'Future<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_27_test.dart

@@ -17,7 +17,7 @@ Future<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'Future<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_28_test.dart

@@ -17,7 +17,7 @@ Future<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Future<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_29_test.dart

@@ -18,7 +18,7 @@ FutureOr<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'FutureOr<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_30_test.dart

@@ -17,7 +17,7 @@ FutureOr<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_31_test.dart

@@ -17,7 +17,7 @@ FutureOr<int> test() async {
   return v;
   //     ^
   // [analyzer] STATIC_TYPE_WARNING.RETURN_OF_INVALID_TYPE
-  // [cfe] This expression has type 'void' and can't be used.
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'FutureOr<int>'.
 }
 
 void main() {

tests/language/invalid_returns/async_invalid_return_32_test.dart

@@ -15,7 +15,7 @@ Future<Object?> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'Future<Object?>'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_33_test.dart

@@ -15,7 +15,7 @@ Future<Object?> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'Future<Object?>'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_34_test.dart

@@ -15,7 +15,7 @@ Future<Object?> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Future<Object?>'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_35_test.dart

@@ -15,7 +15,7 @@ FutureOr<Object?> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'void' can't be returned from an async function with return type 'FutureOr<Object?>'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_36_test.dart

@@ -15,21 +15,21 @@ FutureOr<Object> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<Object>'.
 }
 
 FutureOr<Object?> test2() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<Object?>'.
 }
 
 FutureOr<Object> Function() test3 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<Object>'.
 };
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_37_test.dart

@@ -15,7 +15,7 @@ FutureOr<Object?> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'FutureOr<Object?>'.
 }
 
 // Inferred return type of function literal is `Future<void>`, no error.

tests/language/invalid_returns/async_invalid_return_38_test.dart

@@ -15,14 +15,14 @@ Future<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'Future<String>'.
 }
 
 Future<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'Future<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_39_test.dart

@@ -15,14 +15,14 @@ Future<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'Future<String>'.
 }
 
 Future<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'Future<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_40_test.dart

@@ -15,14 +15,14 @@ Future<int> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<num>' can't be returned from an async function with return type 'Future<int>'.
 }
 
 Future<int> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<num>' can't be returned from an async function with return type 'Future<int>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_41_test.dart

@@ -15,14 +15,14 @@ Future<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<Future<String>>' can't be returned from an async function with return type 'Future<String>'.
 }
 
 Future<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<Future<String>>' can't be returned from an async function with return type 'Future<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_42_test.dart

@@ -15,14 +15,14 @@ FutureOr<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'FutureOr<String>'.
 }
 
 FutureOr<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'FutureOr<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_43_test.dart

@@ -15,14 +15,14 @@ FutureOr<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'FutureOr<String>'.
 }
 
 FutureOr<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'FutureOr<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_44_test.dart

@@ -15,14 +15,14 @@ FutureOr<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<int>' can't be returned from an async function with return type 'FutureOr<String>'.
 }
 
 FutureOr<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<int>' can't be returned from an async function with return type 'FutureOr<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_45_test.dart

@@ -15,14 +15,14 @@ FutureOr<String> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<Future<String>>' can't be returned from an async function with return type 'FutureOr<String>'.
 }
 
 FutureOr<String> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<Future<String>>' can't be returned from an async function with return type 'FutureOr<String>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_47_test.dart

@@ -15,7 +15,7 @@ Future<Null> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'Future<Null>'.
 }
 
 // Inferred return type of function literal is `Future<Null>`.
@@ -23,7 +23,7 @@ Future<Null> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'Future<Null>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_48_test.dart

@@ -15,7 +15,7 @@ Future<Null> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Future<Null>'.
 }
 
 // Inferred return type of function literal is `Future<Null>`.
@@ -23,7 +23,7 @@ Future<Null> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'Future<Null>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_50_test.dart

@@ -15,7 +15,7 @@ FutureOr<Null> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<Null>'.
 }
 
 // Inferred return type of function literal is `Future<Null>`.
@@ -23,7 +23,7 @@ FutureOr<Null> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<void>' can't be returned from an async function with return type 'FutureOr<Null>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_51_test.dart

@@ -15,7 +15,7 @@ FutureOr<Null> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'FutureOr<Null>'.
 }
 
 // Inferred return type of function literal is `Future<Null>`.
@@ -23,7 +23,7 @@ FutureOr<Null> Function() test2 = () async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<void>' can't be returned from an async function with return type 'FutureOr<Null>'.
 };
 
 void main() {

tests/language/invalid_returns/async_invalid_return_52_test.dart

@@ -15,7 +15,7 @@ Future<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'Future<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_53_test.dart

@@ -15,7 +15,7 @@ Future<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Object' can't be returned from an async function with return type 'Future<void>'.
 }
 
 // Inferred return type of function literal is `Future<Object>`, no error.

tests/language/invalid_returns/async_invalid_return_54_test.dart

@@ -15,7 +15,7 @@ Future<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<int>' can't be returned from an async function with return type 'Future<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_55_test.dart

@@ -15,7 +15,7 @@ Future<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'Future<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_56_test.dart

@@ -15,7 +15,7 @@ FutureOr<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'int' can't be returned from an async function with return type 'FutureOr<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_57_test.dart

@@ -15,7 +15,7 @@ FutureOr<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Object' can't be returned from an async function with return type 'FutureOr<void>'.
 }
 
 // Inferred return type of function literal is `Future<Object>`, no error.

tests/language/invalid_returns/async_invalid_return_58_test.dart

@@ -15,7 +15,7 @@ FutureOr<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'FutureOr<int>' can't be returned from an async function with return type 'FutureOr<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/async_invalid_return_59_test.dart

@@ -15,7 +15,7 @@ FutureOr<void> test1() async {
   return v;
   //     ^
   // [analyzer] unspecified
-  // [cfe] unspecified
+  // [cfe] A value of type 'Future<int>' can't be returned from an async function with return type 'FutureOr<void>'.
 }
 
 // Inferred return type of function literal is `Future<int>`, no error.

tests/language/invalid_returns/sync_invalid_return_00_test.dart

@@ -11,7 +11,7 @@ int? test() {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void function.
 }
 
 void main() {

tests/language/invalid_returns/sync_invalid_return_01_test.dart

@@ -11,7 +11,7 @@ Object? test() {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void function.
 }
 
 void main() {

tests/language/invalid_returns/sync_invalid_return_02_test.dart

@@ -11,7 +11,7 @@ Future<int>? test() {
   return;
 //^
 // [analyzer] unspecified
-// [cfe] unspecified
+// [cfe] A value must be explicitly returned from a non-void function.
 }
 
 void main() {