[clang] [clang] Check empty macro name in `#pragma push_macro("")` or `#pragma pop_macro("")` (PR #149982)

[via cfe-commits]

https://github.com/yronglin created https://github.com/llvm/llvm-project/pull/149982

Fixes https://github.com/llvm/llvm-project/issues/149762.


>From d7f00bde68176aab93d4da50a12aea00c29d5276 Mon Sep 17 00:00:00 2001
From: yronglin <yronglin777 at gmail.com>
Date: Tue, 22 Jul 2025 17:18:36 +0800
Subject: [PATCH] [clang] Check empty macro name in #pragma push_macro("") or
 #pragma pop_macro("")

Signed-off-by: yronglin <yronglin777 at gmail.com>
---
 clang/docs/ReleaseNotes.rst                    | 2 ++
 clang/lib/Lex/Pragma.cpp                       | 4 ++++
 clang/test/Preprocessor/pragma-pushpop-macro.c | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 81483c12c8fe9..461902701bc48 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -814,6 +814,8 @@ Bug Fixes in This Version
 - Fixed a failed assertion with an operator call expression which comes from a
   macro expansion when performing analysis for nullability attributes. (#GH138371)
 - Fixed a concept equivalent checking crash due to untransformed constraint expressions. (#GH146614)
+- Fix a crash when marco name is empty in ``#pragma push_macro("")`` or
+  ``#pragma pop_macro("")``. (GH149762).
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Lex/Pragma.cpp b/clang/lib/Lex/Pragma.cpp
index 01c85e6ad95d5..7f1190c4dcce6 100644
--- a/clang/lib/Lex/Pragma.cpp
+++ b/clang/lib/Lex/Pragma.cpp
@@ -604,6 +604,10 @@ IdentifierInfo *Preprocessor::ParsePragmaPushOrPopMacro(Token &Tok) {
   assert(StrVal[0] == '"' && StrVal[StrVal.size()-1] == '"' &&
          "Invalid string token!");
 
+  // FIXME: Should we emit a warning?
+  if (StrVal.size() <= 2)
+    return nullptr;
+
   // Create a Token from the string.
   Token MacroTok;
   MacroTok.startToken();
diff --git a/clang/test/Preprocessor/pragma-pushpop-macro.c b/clang/test/Preprocessor/pragma-pushpop-macro.c
index 0aee074c55c77..238e3ed5eddb3 100644
--- a/clang/test/Preprocessor/pragma-pushpop-macro.c
+++ b/clang/test/Preprocessor/pragma-pushpop-macro.c
@@ -56,3 +56,6 @@ int P;
 // CHECK: int pmy2 = 4
 // CHECK: int Q;
 // CHECK: int P;
+
+#pragma push_macro("")
+#pragma pop_macro("")