Issue 25650. Generate unique parameter names when create a method or function.

pkg/analysis_server/test/services/correction/fix_test.dart

Index: pkg/analysis_server/test/services/correction/fix_test.dart
diff --git a/pkg/analysis_server/test/services/correction/fix_test.dart b/pkg/analysis_server/test/services/correction/fix_test.dart
index e01bf040e2563b5369bd7b1a0fd24a7d4b605bb0..dfb6a600fb09ed2d681c8cf48852012b60ded840 100644
--- a/pkg/analysis_server/test/services/correction/fix_test.dart
+++ b/pkg/analysis_server/test/services/correction/fix_test.dart
@@ -3782,6 +3782,32 @@ main() {
 ''');
   }
 
+  test_undefinedFunction_create_duplicateArgumentNames() async {
+    resolveTestUnit('''
+class C {
+  int x;
+}
+
+foo(C c1, C c2) {
+  bar(c1.x, c2.x);
+}
+''');
+    await assertHasFix(
+        DartFixKind.CREATE_FUNCTION,
+        '''
+class C {
+  int x;
+}
+
+foo(C c1, C c2) {
+  bar(c1.x, c2.x);
+}
+
+void bar(int x, int x2) {
+}
+''');
+  }
+
   test_undefinedFunction_create_dynamicArgument() async {
     resolveTestUnit('''
 main() {
@@ -4433,6 +4459,34 @@ main() {
     await assertNoFix(DartFixKind.CREATE_METHOD);
   }
 
+  test_undefinedMethod_createUnqualified_duplicateArgumentNames() async {
+    resolveTestUnit('''
+class C {
+  int x;
+}
+
+class D {
+  foo(C c1, C c2) {
+    bar(c1.x, c2.x);
+  }
+}''');
+    await assertHasFix(
+        DartFixKind.CREATE_METHOD,
+        '''
+class C {
+  int x;
+}
+
+class D {
+  foo(C c1, C c2) {
+    bar(c1.x, c2.x);
+  }
+
+  void bar(int x, int x2) {
+  }
+}''');
+  }
+
   test_undefinedMethod_createUnqualified_parameters() async {
     resolveTestUnit('''
 class A {