[clang] [clang] Reject __super when preceded by a scope specifier (PR #221492)

[via cfe-commits]

https://github.com/AZero13 updated https://github.com/llvm/llvm-project/pull/221492

>From 271c9e10a12e418b3f7f8882fef70e1571366171 Mon Sep 17 00:00:00 2001
From: AZero13 <gfunni234 at gmail.com>
Date: Sat, 5 Sep 2026 16:50:25 -0400
Subject: [PATCH] [clang] Reject __super when preceded by a scope specifier

The `__super` keyword is an MSVC extension that refers to the base class of the current class context. It is fundamentally invalid for `__super` to be qualified by another scope specifier (e.g. `::__super` or `N::__super`).

Fixes #212988
---
 clang/lib/Parse/ParseExprCXX.cpp      | 2 +-
 clang/test/Parser/recovery.cpp        | 2 +-
 clang/test/SemaCXX/MicrosoftSuper.cpp | 7 +++++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index ae741af7249cf..63f7938c6fc64 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -153,7 +153,7 @@ bool Parser::ParseOptionalCXXScopeSpecifier(
     }
   }
 
-  if (Tok.is(tok::kw___super)) {
+  if (!HasScopeSpecifier && Tok.is(tok::kw___super)) {
     SourceLocation SuperLoc = ConsumeToken();
     if (!Tok.is(tok::coloncolon)) {
       Diag(Tok.getLocation(), diag::err_expected_coloncolon_after_super);
diff --git a/clang/test/Parser/recovery.cpp b/clang/test/Parser/recovery.cpp
index 0637d4cbe72ae..be0b847b9ceb7 100644
--- a/clang/test/Parser/recovery.cpp
+++ b/clang/test/Parser/recovery.cpp
@@ -210,7 +210,7 @@ namespace InvalidEmptyNames {
 // These shouldn't crash, the diagnostics aren't important.
 struct ::, struct ::; // expected-error 2 {{expected identifier}} expected-error 2 {{declaration of anonymous struct must be a definition}} expected-warning {{declaration does not declare anything}}
 enum ::, enum ::; // expected-error 2 {{expected identifier}}
-struct ::__super, struct ::__super; // expected-error 2 {{expected identifier}} expected-error 2 {{expected '::' after '__super'}}
+struct ::__super, struct ::__super; // expected-error 2 {{expected identifier}} expected-error 2 {{declaration of anonymous struct must be a definition}} expected-warning {{declaration does not declare anything}}
 struct ::template foo, struct ::template bar; // expected-error 2 {{expected identifier}} expected-error 2 {{declaration of anonymous struct must be a definition}} expected-warning {{declaration does not declare anything}}
 struct ::foo struct::; // expected-error {{no struct named 'foo' in the global namespace}} expected-error {{expected identifier}}
 class :: : {} a;  // expected-error {{expected identifier}} expected-error {{expected class name}}
diff --git a/clang/test/SemaCXX/MicrosoftSuper.cpp b/clang/test/SemaCXX/MicrosoftSuper.cpp
index d117b93523363..98f087708d72d 100644
--- a/clang/test/SemaCXX/MicrosoftSuper.cpp
+++ b/clang/test/SemaCXX/MicrosoftSuper.cpp
@@ -21,6 +21,13 @@ struct Base1 {
   typedef int XXX;
 };
 
+struct InvalidGlobalQualifier : Base1 {
+  // A parser that drops the global qualifier is left with the valid
+  // declaration `__super::XXX x;` and accepts this line silently; expecting
+  // a diagnostic here catches that even in builds without assertions.
+  ::__super::XXX x; // expected-error {{expected unqualified-id}}
+};
+
 struct Derived : Base1 {
   __super::XXX x;
   typedef __super::XXX Type;