[cfe] Report error on trailing comma in extension type declarations

Part of #53625
Part of #49731

Change-Id: I793ef6329d99b1a4e829491f454f42c2ede941b4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/331185
Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

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

@@ -12476,6 +12476,17 @@ const MessageCode messageRepresentationFieldModifier = const MessageCode(
     analyzerCodes: <String>["REPRESENTATION_FIELD_MODIFIER"],
     problemMessage: r"""Representation fields can't have modifiers.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeRepresentationFieldTrailingComma =
+    messageRepresentationFieldTrailingComma;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageRepresentationFieldTrailingComma = const MessageCode(
+    "RepresentationFieldTrailingComma",
+    analyzerCodes: <String>["REPRESENTATION_FIELD_TRAILING_COMMA"],
+    problemMessage:
+        r"""The representation field can't have a trailing comma.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(String name)>
     templateRequiredNamedParameterHasDefaultValueError =

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

@@ -2721,6 +2721,15 @@ class OutlineBuilder extends StackListenerImpl {
         assert(last != null);
         formals = [last as FormalParameterBuilder];
       }
+
+      Token? tokenBeforeEnd = endToken.previous;
+      if (tokenBeforeEnd != null &&
+          optional(",", tokenBeforeEnd) &&
+          kind == MemberKind.PrimaryConstructor &&
+          declarationContext == DeclarationContext.ExtensionType) {
+        libraryBuilder.addProblem(messageRepresentationFieldTrailingComma,
+            tokenBeforeEnd.charOffset, 1, uri);
+      }
     } else if (count > 1) {
       Object? last = pop();
       count--;

pkg/front_end/messages.yaml

@@ -7447,3 +7447,10 @@ ExtensionTypeRepresentationTypeBottom:
   script: |
     extension type E1(Never foo) {}
   analyzerCode: EXTENSION_TYPE_REPRESENTATION_TYPE_BOTTOM
+
+RepresentationFieldTrailingComma:
+  problemMessage: "The representation field can't have a trailing comma."
+  experiments: inline-class
+  script: |
+    extension type E(int foo,) {}
+  analyzerCode: REPRESENTATION_FIELD_TRAILING_COMMA

pkg/front_end/testcases/extension_types/representation_field_error.dart

@@ -12,3 +12,5 @@ extension type E7(const var foo) {} // Error.
 extension type E8() {} // Error.
 extension type E9(int foo, String bar) {} // Error.
 extension type E10(num foo, bool bar, double baz) {} // Error.
+extension type E11(bool foo,) {} // Error.
+extension type E12(bool foo = false,) {} // Error.

pkg/front_end/testcases/extension_types/representation_field_error.dart.strong.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */ {
   lowered final self::E1 /* = dynamic */ #this = foo;
   return #this;
@@ -180,3 +203,19 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
 }
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */ {
+  lowered final self::E11 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(core::bool foo = #C1) → self::E12 /* = core::bool */ {
+  lowered final self::E12 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);
+
+constants  {
+  #C1 = false
+}

pkg/front_end/testcases/extension_types/representation_field_error.dart.strong.transformed.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */ {
   lowered final self::E1 /* = dynamic */ #this = foo;
   return #this;
@@ -180,3 +203,19 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
 }
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */ {
+  lowered final self::E11 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(core::bool foo = #C1) → self::E12 /* = core::bool */ {
+  lowered final self::E12 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);
+
+constants  {
+  #C1 = false
+}

pkg/front_end/testcases/extension_types/representation_field_error.dart.textual_outline.expect

@@ -8,3 +8,5 @@ extension type E7(const var foo) {}
 extension type E8() {}
 extension type E9(int foo, String bar) {}
 extension type E10(num foo, bool bar, double baz) {}
+extension type E11(bool foo,) {}
+extension type E12(bool foo = false,) {}

pkg/front_end/testcases/extension_types/representation_field_error.dart.textual_outline_modelled.expect

@@ -1,5 +1,7 @@
 extension type E1(var foo) {}
 extension type E10(num foo, bool bar, double baz) {}
+extension type E11(bool foo,) {}
+extension type E12(bool foo = false,) {}
 extension type E2(final foo) {}
 extension type E3(final String foo) {}
 extension type E4(covariant num foo) {}

pkg/front_end/testcases/extension_types/representation_field_error.dart.weak.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */ {
   lowered final self::E1 /* = dynamic */ #this = foo;
   return #this;
@@ -180,3 +203,19 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
 }
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */ {
+  lowered final self::E11 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(core::bool foo = #C1) → self::E12 /* = core::bool */ {
+  lowered final self::E12 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);
+
+constants  {
+  #C1 = false
+}

pkg/front_end/testcases/extension_types/representation_field_error.dart.weak.modular.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */ {
   lowered final self::E1 /* = dynamic */ #this = foo;
   return #this;
@@ -180,3 +203,19 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
 }
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */ {
+  lowered final self::E11 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(core::bool foo = #C1) → self::E12 /* = core::bool */ {
+  lowered final self::E12 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);
+
+constants  {
+  #C1 = false
+}

pkg/front_end/testcases/extension_types/representation_field_error.dart.weak.outline.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */
   ;
 static inline-class-member method E1|constructor#_#new#tearOff(dynamic foo) → self::E1 /* = dynamic */
@@ -160,3 +183,11 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
   ;
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */
+  ;
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  ;
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);

pkg/front_end/testcases/extension_types/representation_field_error.dart.weak.transformed.expect

@@ -65,6 +65,19 @@ library;
 // extension type E10(num foo, bool bar, double baz) {} // Error.
 //                   ^
 //
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:15:28: Error: The representation field can't have a trailing comma.
+// extension type E11(bool foo,) {} // Error.
+//                            ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:29: Error: Non-optional parameters can't have a default value.
+// Try removing the default value or making the parameter optional.
+// extension type E12(bool foo = false,) {} // Error.
+//                             ^
+//
+// pkg/front_end/testcases/extension_types/representation_field_error.dart:16:36: Error: The representation field can't have a trailing comma.
+// extension type E12(bool foo = false,) {} // Error.
+//                                    ^
+//
 import self as self;
 import "dart:core" as core;
 
@@ -120,6 +133,16 @@ extension type E10(core::num foo) {
   constructor • = self::E10|constructor#;
   constructor tearoff • = self::E10|constructor#_#new#tearOff;
 }
+extension type E11(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E11|constructor#;
+  constructor tearoff • = self::E11|constructor#_#new#tearOff;
+}
+extension type E12(core::bool foo) {
+  abstract inline-class-member representation-field get foo() → core::bool;
+  constructor • = self::E12|constructor#;
+  constructor tearoff • = self::E12|constructor#_#new#tearOff;
+}
 static inline-class-member method E1|constructor#(dynamic foo) → self::E1 /* = dynamic */ {
   lowered final self::E1 /* = dynamic */ #this = foo;
   return #this;
@@ -180,3 +203,19 @@ static inline-class-member method E10|constructor#(core::num foo, core::bool bar
 }
 static inline-class-member method E10|constructor#_#new#tearOff(core::num foo, core::bool bar, core::double baz) → self::E10 /* = core::num */
   return self::E10|constructor#(foo, bar, baz);
+static inline-class-member method E11|constructor#(core::bool foo) → self::E11 /* = core::bool */ {
+  lowered final self::E11 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E11|constructor#_#new#tearOff(core::bool foo) → self::E11 /* = core::bool */
+  return self::E11|constructor#(foo);
+static inline-class-member method E12|constructor#(core::bool foo = #C1) → self::E12 /* = core::bool */ {
+  lowered final self::E12 /* = core::bool */ #this = foo;
+  return #this;
+}
+static inline-class-member method E12|constructor#_#new#tearOff(has-declared-initializer core::bool foo) → self::E12 /* = core::bool */
+  return self::E12|constructor#(foo);
+
+constants  {
+  #C1 = false
+}