Fix parsing of generic local functions (issue 25769)

pkg/analyzer/test/generated/parser_test.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.test.generated.parser_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 487 matching lines @@
     EngineTestCase.assertInstanceOf((obj) => obj is BinaryExpression,
         BinaryExpression, expression.rightOperand);
   }
 
   void test_shiftExpression_super() {
     BinaryExpression expression = parseExpression("super >> 4 << 3");
     EngineTestCase.assertInstanceOf((obj) => obj is BinaryExpression,
         BinaryExpression, expression.leftOperand);
   }
 
+  void test_topLevelFunction_nestedGenericFunction() {
+    enableGenericMethods = true;
+    parseCompilationUnitWithOptions('''
+void f() {
+  void g<T>() {
+  }
+}
+''');
+  }
+
   void _validate_assignableExpression_arguments_normal_chain_typeArguments(
       String code) {
     PropertyAccess propertyAccess1 = parseExpression(code);
     expect(propertyAccess1.propertyName.name, "f");
     //
     // a<E>(b)<F>(c).d<G>(e)
     //
     MethodInvocation invocation2 = EngineTestCase.assertInstanceOf(
         (obj) => obj is MethodInvocation,
         MethodInvocation,
@@ skipping 2346 matching lines @@
    * @return the result of invoking the method
    * @throws Exception if the method could not be invoked or throws an exception
    * @throws AssertionFailedError if the result is `null` or the errors produced while
    *           scanning and parsing the source do not match the expected errors
    */
   Object parse4(String methodName, String source,
           [List<ErrorCode> errorCodes = ErrorCode.EMPTY_LIST]) =>
       parse3(methodName, _EMPTY_ARGUMENTS, source, errorCodes);
 
   /**
+   * Parse the given [source] as a compilation unit. Throw an exception if the
+   * source could not be parsed, if the compilation errors in the source do not
+   * match those that are expected, or if the result would have been `null`.
+   */
+  CompilationUnit parseCompilationUnitWithOptions(String source,
+      [List<ErrorCode> errorCodes = ErrorCode.EMPTY_LIST]) {
+    GatheringErrorListener listener = new GatheringErrorListener();
+    Scanner scanner =
+        new Scanner(null, new CharSequenceReader(source), listener);
+    listener.setLineInfo(new TestSource(), scanner.lineStarts);
+    Token token = scanner.tokenize();
+    Parser parser = createParser(listener);
+    parser.parseAsync = parseAsync;
+    parser.parseFunctionBodies = parseFunctionBodies;
+    parser.parseConditionalDirectives = enableConditionalDirectives;
+    parser.parseGenericMethods = enableGenericMethods;
+    parser.parseGenericMethodComments = enableGenericMethodComments;
+    CompilationUnit unit = parser.parseCompilationUnit(token);
+    expect(unit, isNotNull);
+    listener.assertErrorsWithCodes(errorCodes);
+    return unit;
+  }
+
+  /**
    * Parse the given source as an expression.
    *
    * @param source the source to be parsed
    * @param errorCodes the error codes of the errors that are expected to be found
    * @return the expression that was parsed
    * @throws Exception if the source could not be parsed, if the compilation errors in the source do
    *           not match those that are expected, or if the result would have been `null`
    */
   Expression parseExpression(String source,
       [List<ErrorCode> errorCodes = ErrorCode.EMPTY_LIST]) {
@@ skipping 8618 matching lines @@
         new Scanner(null, new CharSequenceReader(source), listener);
     Token tokenStream = scanner.tokenize();
     //
     // Parse the source.
     //
     Parser parser = new Parser(null, listener);
     return invokeParserMethodImpl(
         parser, methodName, <Object>[tokenStream], tokenStream) as Token;
   }
 }