[analyzer] Dot shorthands: Error when calling an instance method using a shorthand.

Fixes an analyzer bug where if we are using a dot shorthand to invoke an instance method, it doesn't produce any errors.
We were neglecting to check whether the element is static or not.

Bug: #61954
Change-Id: I3bc7c3656c7fc1f3cfe4c7751bd40e5613926d1f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/461900
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>

Author: kallentu

pkg/analyzer/lib/src/dart/resolver/method_invocation_resolver.dart

@@ -1245,7 +1245,7 @@ class MethodInvocationResolver with ScopeHelpers {
   }) {
     var element = _resolveElement(receiver, node.memberName);
     if (element != null) {
-      if (element is InternalExecutableElement) {
+      if (element is InternalExecutableElement && element.isStatic) {
         node.memberName.element = element;
         if (element is InternalPropertyAccessorElement) {
           return _rewriteAsFunctionExpressionInvocation(

pkg/analyzer/test/src/dart/resolution/dot_shorthand_invocation_test.dart

@@ -396,6 +396,22 @@ void main() {
     );
   }
 
+  test_error_notStatic() async {
+    await assertErrorsInCode(
+      r'''
+class C {
+  C foo() => C();
+}
+
+void main() {
+  final C c = .foo();
+  print(c);
+}
+''',
+      [error(diag.dotShorthandUndefinedInvocation, 60, 3)],
+    );
+  }
+
   test_error_unresolved() async {
     await assertErrorsInCode(
       r'''

tests/language/dot_shorthands/member/static_method_error_test.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2025, 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.
+
+// Using dot shorthand syntax on an instance method.
+
+// SharedOptions=--enable-experiment=dot-shorthands
+
+class C {
+  C foo() => C();
+}
+
+void main() {
+  C c = .foo();
+  //     ^^^
+  // [analyzer] COMPILE_TIME_ERROR.DOT_SHORTHAND_UNDEFINED_MEMBER
+  // [cfe] The static method or constructor 'foo' isn't defined for the type 'C'.
+}