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

[via cfe-commits]

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

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

>From b1e6f441212f8f430c525c879f4c84751a51100b 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/SemaCXX/MicrosoftSuper.cpp | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

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/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;