[cfe] Const factories when const functions enabled.

Change-Id: Ifd24678c0ac191c5cc6f1d60443ab96f56cbba7d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/192400
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Kallen Tu <kallentu@google.com>

pkg/_fe_analyzer_shared/lib/src/parser/forwarding_listener.dart

@@ -1173,6 +1173,11 @@ class ForwardingListener implements Listener {
     listener?.handleConditionalExpressionColon();
   }
 
+  @override
+  void handleConstFactory(Token constKeyword) {
+    listener?.handleConstFactory(constKeyword);
+  }
+
   @override
   void handleContinueStatement(
       bool hasTarget, Token continueKeyword, Token endToken) {

pkg/_fe_analyzer_shared/lib/src/parser/listener.dart

@@ -1360,6 +1360,10 @@ class Listener implements UnescapeErrorListener {
     logEvent("ConstExpression");
   }
 
+  void handleConstFactory(Token constKeyword) {
+    logEvent("ConstFactory");
+  }
+
   /// Called before parsing a "for" control flow list, set, or map entry.
   /// Ended by either [endForControlFlow] or [endForInControlFlow].
   void beginForControlFlow(Token? awaitToken, Token forToken) {}

pkg/_fe_analyzer_shared/lib/src/parser/parser_impl.dart

@@ -4063,7 +4063,7 @@ class Parser {
     } else {
       if (varFinalOrConst != null && !optional('native', next)) {
         if (optional('const', varFinalOrConst)) {
-          reportRecoverableError(varFinalOrConst, codes.messageConstFactory);
+          listener.handleConstFactory(varFinalOrConst);
         }
       }
       token = parseFunctionBody(

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -11,6 +11,7 @@ import 'package:_fe_analyzer_shared/src/messages/codes.dart'
         messageAbstractLateField,
         messageAbstractStaticField,
         messageConstConstructorWithBody,
+        messageConstFactory,
         messageConstructorWithTypeParameters,
         messageDirectiveAfterDeclaration,
         messageExpectedStatement,
@@ -2574,6 +2575,13 @@ class AstBuilder extends StackListener {
     push(referenceOffset);
   }
 
+  @override
+  void handleConstFactory(Token constKeyword) {
+    debugEvent("ConstFactory");
+    // TODO(kallentu): Removal of const factory error for const function feature
+    handleRecoverableError(messageConstFactory, constKeyword, constKeyword);
+  }
+
   @override
   void handleContinueStatement(
       bool hasTarget, Token continueKeyword, Token semicolon) {

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

@@ -4768,6 +4768,15 @@ class BodyBuilder extends ScopeListener<JumpTarget>
         inMetadata: false);
   }
 
+  @override
+  void handleConstFactory(Token constKeyword) {
+    debugEvent("ConstFactory");
+    if (!libraryBuilder.enableConstFunctionsInLibrary) {
+      handleRecoverableError(
+          fasta.messageConstFactory, constKeyword, constKeyword);
+    }
+  }
+
   @override
   void beginIfControlFlow(Token ifToken) {
     // TODO(danrubel): consider removing this when control flow support is added

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

@@ -2783,6 +2783,11 @@ class ConstantEvaluator implements ExpressionVisitor<Constant> {
       } else {
         name = '${target.enclosingClass.name}.${name}';
       }
+
+      if (enableConstFunctions) {
+        return _handleFunctionInvocation(
+            node.target.function, typeArguments, positionals, named);
+      }
     }
     return createInvalidExpressionConstant(node, "Invocation of $name");
   }

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

@@ -632,6 +632,11 @@ class DietListener extends StackListenerImpl {
     _inRedirectingFactory = true;
   }
 
+  @override
+  void handleConstFactory(Token constKeyword) {
+    debugEvent("ConstFactory");
+  }
+
   @override
   void handleNativeFunctionBody(Token nativeToken, Token semicolon) {
     debugEvent("NativeFunctionBody");

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

@@ -2044,6 +2044,14 @@ class OutlineBuilder extends StackListenerImpl {
     push(MethodBody.RedirectingFactoryBody);
   }
 
+  @override
+  void handleConstFactory(Token constKeyword) {
+    debugEvent("ConstFactory");
+    if (!libraryBuilder.enableConstFunctionsInLibrary) {
+      handleRecoverableError(messageConstFactory, constKeyword, constKeyword);
+    }
+  }
+
   @override
   void endFieldInitializer(Token assignmentOperator, Token token) {
     debugEvent("FieldInitializer");

pkg/front_end/lib/src/fasta/util/direct_parser_ast_helper.dart

@@ -1970,6 +1970,13 @@ abstract class AbstractDirectParserASTListener implements Listener {
     seen(data);
   }
 
+  void handleConstFactory(Token constKeyword) {
+    DirectParserASTContentConstFactoryHandle data =
+        new DirectParserASTContentConstFactoryHandle(DirectParserASTType.HANDLE,
+            constKeyword: constKeyword);
+    seen(data);
+  }
+
   void beginForControlFlow(Token awaitToken, Token forToken) {
     DirectParserASTContentForControlFlowBegin data =
         new DirectParserASTContentForControlFlowBegin(DirectParserASTType.BEGIN,
@@ -5814,6 +5821,18 @@ class DirectParserASTContentConstExpressionEnd extends DirectParserASTContent {
       };
 }
 
+class DirectParserASTContentConstFactoryHandle extends DirectParserASTContent {
+  final Token constKeyword;
+
+  DirectParserASTContentConstFactoryHandle(DirectParserASTType type,
+      {this.constKeyword})
+      : super("ConstFactory", type);
+
+  Map<String, Object> get deprecatedArguments => {
+        "constKeyword": constKeyword,
+      };
+}
+
 class DirectParserASTContentForControlFlowBegin extends DirectParserASTContent {
   final Token awaitToken;
   final Token forToken;

pkg/front_end/test/parser_test_listener.dart

@@ -1765,6 +1765,11 @@ class ParserTestListener implements Listener {
     doPrint('endConstExpression(' '$token)');
   }
 
+  void handleConstFactory(Token constKeyword) {
+    seen(constKeyword);
+    doPrint('handleConstFactory(' '$constKeyword)');
+  }
+
   void beginForControlFlow(Token? awaitToken, Token forToken) {
     seen(awaitToken);
     seen(forToken);

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart

@@ -0,0 +1,30 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests const factories with const functions.
+
+import "package:expect/expect.dart";
+
+const printConst = MessageType.parse("print");
+
+class MessageType {
+  static const print = MessageType._('print');
+
+  static const skip = MessageType._('skip');
+
+  final String name;
+
+  const factory MessageType.parse(String name) {
+    if (name == 'print') {
+      return MessageType.print;
+    }
+    return MessageType.skip;
+  }
+
+  const MessageType._(this.name);
+}
+
+void main() {
+  Expect.equals(printConst, MessageType.print);
+}

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.strong.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class MessageType extends core::Object /*hasConstConstructor*/  {
+  static const field self::MessageType print = #C2;
+  static const field self::MessageType skip = #C4;
+  final field core::String name;
+  const constructor _(core::String name) → self::MessageType
+    : self::MessageType::name = name, super core::Object::•()
+    ;
+  static factory parse(core::String name) → self::MessageType {
+    if(name.{core::String::==}("print")) {
+      return #C2;
+    }
+    return #C4;
+  }
+}
+static const field self::MessageType printConst = #C2;
+static method main() → void {
+  exp::Expect::equals(#C2, #C2);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::MessageType {name:#C1}
+  #C3 = "skip"
+  #C4 = self::MessageType {name:#C3}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_factory.dart:
+- MessageType._ (from org-dartlang-testcase:///const_functions_const_factory.dart:25:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.strong.transformed.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class MessageType extends core::Object /*hasConstConstructor*/  {
+  static const field self::MessageType print = #C2;
+  static const field self::MessageType skip = #C4;
+  final field core::String name;
+  const constructor _(core::String name) → self::MessageType
+    : self::MessageType::name = name, super core::Object::•()
+    ;
+  static factory parse(core::String name) → self::MessageType {
+    if(name.{core::String::==}("print")) {
+      return #C2;
+    }
+    return #C4;
+  }
+}
+static const field self::MessageType printConst = #C2;
+static method main() → void {
+  exp::Expect::equals(#C2, #C2);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::MessageType {name:#C1}
+  #C3 = "skip"
+  #C4 = self::MessageType {name:#C3}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_factory.dart:
+- MessageType._ (from org-dartlang-testcase:///const_functions_const_factory.dart:25:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.textual_outline.expect

@@ -0,0 +1,10 @@
+import "package:expect/expect.dart";
+const printConst = MessageType.parse("print");
+class MessageType {
+  static const print = MessageType._('print');
+  static const skip = MessageType._('skip');
+  final String name;
+  const factory MessageType.parse(String name) {}
+  const MessageType._(this.name);
+}
+void main() {}

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.textual_outline_modelled.expect

@@ -0,0 +1,12 @@
+import "package:expect/expect.dart";
+
+class MessageType {
+  const MessageType._(this.name);
+  const factory MessageType.parse(String name) {}
+  final String name;
+  static const print = MessageType._('print');
+  static const skip = MessageType._('skip');
+}
+
+const printConst = MessageType.parse("print");
+void main() {}

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.weak.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class MessageType extends core::Object /*hasConstConstructor*/  {
+  static const field self::MessageType print = #C2;
+  static const field self::MessageType skip = #C4;
+  final field core::String name;
+  const constructor _(core::String name) → self::MessageType
+    : self::MessageType::name = name, super core::Object::•()
+    ;
+  static factory parse(core::String name) → self::MessageType {
+    if(name.{core::String::==}("print")) {
+      return #C2;
+    }
+    return #C4;
+  }
+}
+static const field self::MessageType printConst = #C2;
+static method main() → void {
+  exp::Expect::equals(#C2, #C2);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::MessageType {name:#C1}
+  #C3 = "skip"
+  #C4 = self::MessageType {name:#C3}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_factory.dart:
+- MessageType._ (from org-dartlang-testcase:///const_functions_const_factory.dart:25:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.weak.outline.expect

@@ -0,0 +1,25 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class MessageType extends core::Object /*hasConstConstructor*/  {
+  static const field self::MessageType print = const self::MessageType::_("print");
+  static const field self::MessageType skip = const self::MessageType::_("skip");
+  final field core::String name;
+  const constructor _(core::String name) → self::MessageType
+    : self::MessageType::name = name, super core::Object::•()
+    ;
+  static const factory parse(core::String name) → self::MessageType
+    ;
+}
+static const field self::MessageType printConst = const self::MessageType::parse("print");
+static method main() → void
+  ;
+
+
+Extra constant evaluation status:
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_factory.dart:12:36 -> InstanceConstant(const MessageType{MessageType.name: "print"})
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_factory.dart:14:35 -> InstanceConstant(const MessageType{MessageType.name: "skip"})
+Extra constant evaluation: evaluated: 4, effectively constant: 2

pkg/front_end/testcases/const_functions/const_functions_const_factory.dart.weak.transformed.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class MessageType extends core::Object /*hasConstConstructor*/  {
+  static const field self::MessageType print = #C2;
+  static const field self::MessageType skip = #C4;
+  final field core::String name;
+  const constructor _(core::String name) → self::MessageType
+    : self::MessageType::name = name, super core::Object::•()
+    ;
+  static factory parse(core::String name) → self::MessageType {
+    if(name.{core::String::==}("print")) {
+      return #C2;
+    }
+    return #C4;
+  }
+}
+static const field self::MessageType printConst = #C2;
+static method main() → void {
+  exp::Expect::equals(#C2, #C2);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::MessageType {name:#C1}
+  #C3 = "skip"
+  #C4 = self::MessageType {name:#C3}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_factory.dart:
+- MessageType._ (from org-dartlang-testcase:///const_functions_const_factory.dart:25:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)

pkg/front_end/testcases/outline.status

@@ -2,6 +2,7 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE.md file.
 
+const_functions/const_functions_const_factory: VerificationError
 extension_types/simple: ExpectationFileMismatchSerialized
 extension_types/simple_getter_resolution: ExpectationFileMismatchSerialized
 extension_types/simple_method_resolution: ExpectationFileMismatchSerialized

pkg/front_end/testcases/textual_outline.status

@@ -20,7 +20,7 @@ regress/issue_39035.crash: EmptyOutput
 regress/issue_39091_2: EmptyOutput
 regress/utf_16_le_content.crash: EmptyOutput
 
-
+const_functions/const_functions_const_factory: FormatterCrash
 extensions/extension_constructor: FormatterCrash
 extensions/extension_field_with_type_parameter_usage: FormatterCrash
 extensions/issue38600: FormatterCrash

tests/language/const_functions/const_functions_const_factory_disabled_test.dart

@@ -0,0 +1,29 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests const factories with const functions disabled.
+
+import "package:expect/expect.dart";
+
+const printConst = MessageType.parse("print");
+
+class MessageType {
+  static const print = MessageType._('print');
+
+  static const skip = MessageType._('skip');
+
+  final String name;
+
+  const factory MessageType.parse(String name) {
+//^^^^^
+// [analyzer] SYNTACTIC_ERROR.CONST_FACTORY
+// [cfe] Only redirecting factory constructors can be declared to be 'const'.
+    if (name == 'print') {
+      return MessageType.print;
+    }
+    return MessageType.skip;
+  }
+
+  const MessageType._(this.name);
+}

tests/language/const_functions/const_functions_const_factory_test.dart

@@ -0,0 +1,34 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Tests const factories with const functions.
+
+// SharedOptions=--enable-experiment=const-functions
+
+import "package:expect/expect.dart";
+
+const printConst = MessageType.parse("print");
+
+class MessageType {
+  static const print = MessageType._('print');
+
+  static const skip = MessageType._('skip');
+
+  final String name;
+
+  const factory MessageType.parse(String name) {
+//^^^^^
+// [analyzer] SYNTACTIC_ERROR.CONST_FACTORY
+    if (name == 'print') {
+      return MessageType.print;
+    }
+    return MessageType.skip;
+  }
+
+  const MessageType._(this.name);
+}
+
+void main() {
+  Expect.equals(printConst, MessageType.print);
+}