Handle generic local functions without a return type (issue 27965)

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

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index 411f6a945aef94b069713388d253027542167140..c16281ee5b4b91c871d2a0476d07226972377398 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -6876,6 +6876,14 @@ class Parser {
           keyword != Keyword.OPERATOR &&
           (_tokenMatchesIdentifier(next) ||
               _tokenMatches(next, TokenType.LT))) {
+        Token afterTypeParameters = _skipTypeParameterList(next);
+        if (afterTypeParameters != null &&
+            _tokenMatches(afterTypeParameters, TokenType.OPEN_PAREN)) {
+          // If the identifier is followed by type parameters and a parenthesis,
+          // then the identifier is the name of a generic method, not a return
+          // type.
+          return null;
+        }
         return parseReturnType();
       }
       Token next2 = next.next;