[CFE] add 'Function' as type identifier check in CFE

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

@@ -4385,6 +4385,15 @@ const MessageCode messageForInLoopWithConstVariable = const MessageCode(
     message: r"""A for-in loop-variable can't be 'const'.""",
     tip: r"""Try removing the 'const' modifier.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeFunctionAsTypeParameter = messageFunctionAsTypeParameter;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageFunctionAsTypeParameter = const MessageCode(
+    "FunctionAsTypeParameter",
+    message:
+        r"""'Function' is a built-in identifier, could not used as a type identifier.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeFunctionTypeDefaultValue = messageFunctionTypeDefaultValue;
 
@@ -4406,6 +4415,30 @@ const MessageCode messageFunctionTypedParameterVar = const MessageCode(
         r"""Function-typed parameters can't specify 'const', 'final' or 'var' in place of a return type.""",
     tip: r"""Try replacing the keyword with a return type.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+    Message Function(String name)> templateFunctionUsedAsDec = const Template<
+        Message Function(String name)>(
+    messageTemplate:
+        r"""'Function' is a built-in identifier, could not used as a #name name.""",
+    withArguments: _withArgumentsFunctionUsedAsDec);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeFunctionUsedAsDec =
+    const Code<Message Function(String name)>(
+  "FunctionUsedAsDec",
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsFunctionUsedAsDec(String name) {
+  if (name.isEmpty) throw 'No name provided';
+  name = demangleMixinApplicationName(name);
+  return new Message(codeFunctionUsedAsDec,
+      message:
+          """'Function' is a built-in identifier, could not used as a ${name} name.""",
+      arguments: {'name': name});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeGeneratorReturnsValue = messageGeneratorReturnsValue;
 

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

@@ -1464,6 +1464,48 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
           new VoidTypeDeclarationBuilder(const VoidType(), this, charOffset));
   }
 
+  void _checkBadFunctionParameter(List<TypeVariableBuilder> typeVariables) {
+    if (typeVariables == null || typeVariables.isEmpty) {
+      return;
+    }
+
+    for (TypeVariableBuilder type in typeVariables) {
+      if (type.name == "Function") {
+        addProblem(messageFunctionAsTypeParameter, type.charOffset,
+          type.name.length, type.fileUri);
+      }
+    }
+  }
+
+  void _checkBadFunctionDeclUse(String className, TypeParameterScopeKind kind,
+      int charOffset) {
+    String decType;
+    switch (kind) {
+      case TypeParameterScopeKind.classDeclaration:
+        decType = "class";
+        break;
+      case TypeParameterScopeKind.mixinDeclaration:
+        decType = "mixin";
+        break;
+      case TypeParameterScopeKind.extensionDeclaration:
+        decType = "extension";
+        break;
+      default:
+        break;
+    }
+    if (className != "Function") {
+      return;
+    }
+    if (decType == "class" && importUri.scheme == "dart") {
+      // Allow declaration of class Function in the sdk.
+      return;
+    }
+    if (decType != null) {
+      addProblem(templateFunctionUsedAsDec.withArguments(decType), charOffset,
+          className?.length, fileUri);
+    }
+  }
+
   /// Add a problem that might not be reported immediately.
   ///
   /// Problems will be issued after source information has been added.
@@ -1573,6 +1615,8 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
       int nameOffset,
       int endOffset,
       int supertypeOffset) {
+    _checkBadFunctionDeclUse(className, kind, nameOffset);
+    _checkBadFunctionParameter(typeVariables);
     // Nested declaration began in `OutlineBuilder.beginClassDeclaration`.
     TypeParameterScopeBuilder declaration =
         endNestedDeclaration(kind, className)
@@ -1805,6 +1849,9 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
       int startOffset,
       int nameOffset,
       int endOffset) {
+    _checkBadFunctionDeclUse(
+        extensionName, TypeParameterScopeKind.extensionDeclaration, nameOffset);
+    _checkBadFunctionParameter(typeVariables);
     // Nested declaration began in `OutlineBuilder.beginExtensionDeclaration`.
     TypeParameterScopeBuilder declaration = endNestedDeclaration(
         TypeParameterScopeKind.extensionDeclaration, extensionName)
@@ -1836,7 +1883,6 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
         nameOffset,
         endOffset,
         referenceFrom);
-
     constructorReferences.clear();
     Map<String, TypeVariableBuilder> typeVariablesByName =
         checkTypeVariables(typeVariables, extensionBuilder);

pkg/front_end/messages.status

@@ -369,9 +369,11 @@ ForInLoopNotAssignable/part_wrapped_statement: Fail
 ForInLoopNotAssignable/statement: Fail
 ForInLoopTypeNotIterablePartNullability/example: Fail # Cannot occur but needed for symmetry with ForInLoopTypeNotIterableNullability
 ForInLoopWithConstVariable/example: Fail
+FunctionAsTypeParameter/analyzerCode: Fail
 FunctionTypeDefaultValue/example: Fail
 FunctionTypedParameterVar/part_wrapped_script1: Fail
 FunctionTypedParameterVar/script1: Fail
+FunctionUsedAsDec/analyzerCode: Fail
 GeneratorReturnsValue/example: Fail
 GetterNotFound/example: Fail
 GetterWithFormals/example: Fail

pkg/front_end/messages.yaml

@@ -1797,6 +1797,20 @@ NotAPrefixInTypeAnnotation:
           T.String field;
         }
 
+FunctionUsedAsDec:
+  template: "'Function' is a built-in identifier, could not used as a #name name."
+  script:
+    - class Function {}
+    - extension Function on int {}
+    - mixin Function {}
+
+FunctionAsTypeParameter:
+  template: "'Function' is a built-in identifier, could not used as a type identifier."
+  script:
+    - class C<Function> {}
+    - mixin A<Function> {}
+    - extension A<Function> on List<Function> {}
+
 UnresolvedPrefixInTypeAnnotation:
   template: "'#name.#name2' can't be used as a type because '#name' isn't defined."
   analyzerCode: NOT_A_TYPE

pkg/front_end/testcases/general/function_bad_use.dart

@@ -0,0 +1,7 @@
+class Function {}
+
+class C<Function> {}
+
+mixin M<Function> implements List<Function> {}
+
+main() {}

pkg/front_end/testcases/general/function_bad_use.dart.textual_outline.expect

@@ -0,0 +1,6 @@
+class Function {}
+
+class C<Function> {}
+
+mixin M<Function> implements List<Function> {}
+main() {}

pkg/front_end/testcases/general/function_bad_use.dart.textual_outline_modelled.expect

@@ -0,0 +1,6 @@
+class C<Function> {}
+
+class Function {}
+
+main() {}
+mixin M<Function> implements List<Function> {}

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

@@ -0,0 +1,32 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:1:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {}
+//       ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:3:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// class C<Function> {}
+//         ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:5:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// mixin M<Function> implements List<Function> {}
+//         ^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Function extends core::Object {
+  synthetic constructor •() → self::Function
+    : super core::Object::•()
+    ;
+}
+class C<Function extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::Function%>
+    : super core::Object::•()
+    ;
+}
+abstract class M<Function extends core::Object? = dynamic> extends core::Object implements core::List<self::M::Function%> /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}

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

@@ -0,0 +1,31 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:1:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {}
+//       ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:3:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// class C<Function> {}
+//         ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:5:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// mixin M<Function> implements List<Function> {}
+//         ^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Function extends core::Object {
+  synthetic constructor •() → self::Function
+    ;
+}
+class C<Function extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::Function%>
+    ;
+}
+abstract class M<Function extends core::Object? = dynamic> extends core::Object implements core::List<self::M::Function%> /*isMixinDeclaration*/  {
+}
+static method main() → dynamic
+  ;

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

@@ -0,0 +1,32 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:1:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {}
+//       ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:3:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// class C<Function> {}
+//         ^^^^^^^^
+//
+// pkg/front_end/testcases/general/function_bad_use.dart:5:9: Error: 'Function' is a built-in identifier, could not used as a type identifier.
+// mixin M<Function> implements List<Function> {}
+//         ^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Function extends core::Object {
+  synthetic constructor •() → self::Function
+    : super core::Object::•()
+    ;
+}
+class C<Function extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::Function%>
+    : super core::Object::•()
+    ;
+}
+abstract class M<Function extends core::Object? = dynamic> extends core::Object implements core::List<self::M::Function%> /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}

pkg/front_end/testcases/general/ignore_function.dart

@@ -14,8 +14,9 @@ class B implements Function {
   operator ==(other) => false;
 }
 
+// CFE Error here: Function is built-in id, could not used as type id.
 class Function {
   core.bool operator ==(core.Object other) => false;
 }
 
-main() {}
+main() {}

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

@@ -1,4 +1,11 @@
 library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/ignore_function.dart:18:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {
+//       ^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 

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

@@ -1,4 +1,11 @@
 library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/ignore_function.dart:18:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {
+//       ^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 

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

@@ -1,4 +1,11 @@
 library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/ignore_function.dart:18:7: Error: 'Function' is a built-in identifier, could not used as a class name.
+// class Function {
+//       ^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;