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

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: None (yronglin)

<details>
<summary>Changes</summary>

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


---
Full diff: https://github.com/llvm/llvm-project/pull/149982.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2) 
- (modified) clang/lib/Lex/Pragma.cpp (+4) 
- (modified) clang/test/Preprocessor/pragma-pushpop-macro.c (+3) 


``````````diff
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("")

``````````

</details>


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