[Analyzer] Cause CompileTimeError in analyzer when use 'Function' as a type:

pkg/analyzer/lib/error/error.dart

@@ -497,7 +497,6 @@ const List<ErrorCode> errorCodeValues = [
   HintCode.DEAD_CODE_CATCH_FOLLOWING_CATCH,
   HintCode.DEAD_CODE_ON_CATCH_SUBTYPE,
   HintCode.DEPRECATED_EXTENDS_FUNCTION,
-  HintCode.DEPRECATED_FUNCTION_CLASS_DECLARATION,
   HintCode.DEPRECATED_MEMBER_USE,
   HintCode.DEPRECATED_MEMBER_USE_FROM_SAME_PACKAGE,
   HintCode.DEPRECATED_MEMBER_USE_FROM_SAME_PACKAGE_WITH_MESSAGE,

pkg/analyzer/lib/src/error/codes.dart

@@ -13720,7 +13720,6 @@ class CompileTimeErrorCode extends AnalyzerErrorCode {
           "The type '{0}' implied by the 'yield' expression must be assignable "
               "to '{1}'.",
           hasPublishedDocs: true);
-
   /**
    * Initialize a newly created error code to have the given [name]. The message
    * associated with the error will be created from the given [message]

pkg/analyzer/lib/src/generated/error_verifier.dart

@@ -609,6 +609,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       _checkForBuiltInIdentifierAsName(
           name, CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_EXTENSION_NAME);
     }
+    _checkExtensionBadFunctionUse(node);
     super.visitExtensionDeclaration(node);
     _enclosingExtension = null;
   }
@@ -959,6 +960,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
       _checkForMainFunction(node.name);
       _checkForWrongTypeParameterVarianceInSuperinterfaces();
       //      _checkForBadFunctionUse(node);
+      _checkMixinBasFunctionUse(node);
       super.visitMixinDeclaration(node);
     } finally {
       _enclosingClass = outerClass;
@@ -1575,20 +1577,89 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     }
   }
 
+  /// Verifies that the mixin is not named `Function` and that its type
+  /// parameters don't named `Function`.
+  void _checkMixinBasFunctionUse(MixinDeclaration node) {
+    final functionToken = "Function";
+    var typeParams = node.typeParameters;
+    var onClause = node.onClause;
+    if (node.name.name == functionToken) {
+      errorReporter.reportErrorForNode(
+          CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, node.name,
+          [functionToken]);
+    }
+    if (typeParams != null) {
+      for (TypeParameter parameter in typeParams.typeParameters) {
+        if (parameter.name.name == functionToken) {
+          errorReporter.reportErrorForNode(
+              CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME,
+              parameter, [functionToken]);
+        }
+      }
+    }
+    // Check Mixin OnClause
+    if (onClause != null) {
+      for (TypeName type in onClause.superclassConstraints) {
+        var mixinElement = type.name.staticElement;
+        if (mixinElement != null && mixinElement.name == functionToken) {
+          errorReporter.reportErrorForNode(
+            CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE, type,
+            [type.name],
+          );
+        }
+      }
+    }
+  }
+
+  /// Verifies that the extension is not named `Function` and that its type
+  /// parameters don't named `Function`.
+  void _checkExtensionBadFunctionUse(ExtensionDeclaration node) {
+    final functionToken = "Function";
+    var typeParams = node.typeParameters;
+    if (node.name != null && node.name?.name == functionToken) {
+      errorReporter.reportErrorForNode(
+          CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_EXTENSION_NAME, node.name
+          !, [functionToken]);
+    }
+    if (typeParams != null) {
+      for (TypeParameter parameter in typeParams.typeParameters) {
+        if (parameter.name.name == functionToken) {
+          errorReporter.reportErrorForNode(
+              CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME,
+              parameter, [functionToken]);
+        }
+      }
+    }
+  }
+
   /// Verifies that the class is not named `Function` and that it doesn't
   /// extends/implements/mixes in `Function`.
+  /// Also Verifies that the class's type parameters is not named `Function`.
   void _checkForBadFunctionUse(ClassDeclaration node) {
     var extendsClause = node.extendsClause;
     var withClause = node.withClause;
+    var typeParams = node.typeParameters;
+    final functionToken = "Function";
 
-    if (node.name.name == "Function") {
+    if (node.name.name == functionToken) {
       errorReporter.reportErrorForNode(
-          HintCode.DEPRECATED_FUNCTION_CLASS_DECLARATION, node.name);
+          CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, node.name,
+          [functionToken]);
+    }
+
+    if (typeParams != null) {
+      for (TypeParameter parameter in typeParams.typeParameters) {
+        if (parameter.name.name == functionToken) {
+          errorReporter.reportErrorForNode(
+              CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME,
+              parameter, [functionToken]);
+        }
+      }
     }
 
     if (extendsClause != null) {
       var superElement = extendsClause.superclass.name.staticElement;
-      if (superElement != null && superElement.name == "Function") {
+      if (superElement != null && superElement.name == functionToken) {
         errorReporter.reportErrorForNode(
             HintCode.DEPRECATED_EXTENDS_FUNCTION, extendsClause.superclass);
       }
@@ -1597,7 +1668,7 @@ class ErrorVerifier extends RecursiveAstVisitor<void>
     if (withClause != null) {
       for (TypeName type in withClause.mixinTypes) {
         var mixinElement = type.name.staticElement;
-        if (mixinElement != null && mixinElement.name == "Function") {
+        if (mixinElement != null && mixinElement.name == functionToken) {
           errorReporter.reportErrorForNode(
               HintCode.DEPRECATED_MIXIN_FUNCTION, type);
         }

pkg/analyzer/test/src/diagnostics/deprecated_extends_function_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/src/dart/error/hint_codes.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -28,7 +29,7 @@ class A extends Function {}
 class Function {}
 class A extends Function {}
 ''', [
-      error(HintCode.DEPRECATED_FUNCTION_CLASS_DECLARATION, 6, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, 6, 8),
       error(HintCode.DEPRECATED_EXTENDS_FUNCTION, 34, 8),
     ]);
   }

pkg/analyzer/test/src/diagnostics/deprecated_function_as_type_identifier_test.dart

@@ -0,0 +1,37 @@
+// 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.
+
+import 'package:analyzer/src/dart/error/syntactic_errors.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/context_collection_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(DeprecatedFunctionAsTypeIdentifierTest);
+  });
+}
+
+@reflectiveTest
+class DeprecatedFunctionAsTypeIdentifierTest extends PubPackageResolutionTest {
+  test_typedef() async {
+    await assertErrorsInCode('''
+typedef Function = int;
+typedef F<Function> = int;
+''', [
+      error(ParserErrorCode.EXPECTED_IDENTIFIER_BUT_GOT_KEYWORD, 8, 8),
+    ]);
+  }
+
+  test_extension() async {
+    await assertErrorsInCode('''
+extension Function on List {}
+extension E<Function> on List<Function> {}    
+''', [
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_EXTENSION_NAME, 10, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME, 42, 8),
+    ]);
+  }
+}

pkg/analyzer/test/src/diagnostics/deprecated_function_class_declaration_test.dart

@@ -2,7 +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 file.
 
-import 'package:analyzer/src/dart/error/hint_codes.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -19,7 +19,17 @@ class DeprecatedFunctionClassDeclarationTest extends PubPackageResolutionTest {
     await assertErrorsInCode('''
 class Function {}
 ''', [
-      error(HintCode.DEPRECATED_FUNCTION_CLASS_DECLARATION, 6, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, 6, 8),
+    ]);
+  }
+
+  test_typeparameter() async {
+    await assertErrorsInCode('''
+class Function {}
+class C<Function> {}
+''', [
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, 6, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME, 26, 8),
     ]);
   }
 }

pkg/analyzer/test/src/diagnostics/deprecated_mixin_function_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/src/dart/error/hint_codes.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
@@ -28,8 +29,26 @@ class A extends Object with Function {}
 class Function {}
 class A extends Object with Function {}
 ''', [
-      error(HintCode.DEPRECATED_FUNCTION_CLASS_DECLARATION, 6, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, 6, 8),
       error(HintCode.DEPRECATED_MIXIN_FUNCTION, 46, 8),
     ]);
   }
+
+  test_mixin() async {
+    await assertErrorsInCode('''
+mixin Function {}
+mixin M<Function> implements List<Function> {}    
+''', [
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_NAME, 6, 8),
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE_PARAMETER_NAME, 26, 8),
+    ]);
+  }
+
+  test_mixin_onclause() async {
+    await assertErrorsInCode('''
+mixin A on Function {}
+''', [
+      error(CompileTimeErrorCode.BUILT_IN_IDENTIFIER_AS_TYPE, 11, 8),
+    ]);
+  }
 }

pkg/analyzer/test/src/diagnostics/test_all.dart

@@ -121,6 +121,8 @@ import 'deferred_import_of_extension_test.dart' as deferred_import_of_extension;
 import 'definitely_unassigned_late_local_variable_test.dart'
     as definitely_unassigned_late_local_variable;
 import 'deprecated_extends_function_test.dart' as deprecated_extends_function;
+import 'deprecated_function_as_type_identifier_test.dart'
+    as deprecated_function_as_type_identifier;
 import 'deprecated_function_class_declaration_test.dart'
     as deprecated_function_class_declaration;
 import 'deprecated_member_use_test.dart' as deprecated_member_use;
@@ -766,6 +768,7 @@ main() {
     deferred_import_of_extension.main();
     definitely_unassigned_late_local_variable.main();
     deprecated_extends_function.main();
+    deprecated_function_as_type_identifier.main();
     deprecated_function_class_declaration.main();
     deprecated_member_use.main();
     deprecated_mixin_function.main();