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

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

---------

Signed-off-by: yronglin <yronglin777@gmail.com>

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
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/Basic/DiagnosticLexKinds.td

@@ -694,6 +694,9 @@ def err_pragma_push_pop_macro_malformed : Error<
 def warn_pragma_pop_macro_no_push : Warning<
    "pragma pop_macro could not pop '%0', no matching push_macro">,
   InGroup<IgnoredPragmas>;
+def warn_pargma_push_pop_macro_empty_string : Warning<
+   "'#pragma %select{push_macro|pop_macro}0' expected a non-empty string">,
+  InGroup<IgnoredPragmas>;
 def warn_pragma_message : Warning<"%0">,
    InGroup<PoundPragmaMessage>, DefaultWarnNoWerror;
 def err_pragma_message : Error<"%0">;

clang/lib/Lex/Pragma.cpp

@@ -591,7 +591,8 @@ IdentifierInfo *Preprocessor::ParsePragmaPushOrPopMacro(Token &Tok) {
   }
 
   // Remember the macro string.
-  std::string StrVal = getSpelling(Tok);
+  Token StrTok = Tok;
+  std::string StrVal = getSpelling(StrTok);
 
   // Read the ')'.
   Lex(Tok);
@@ -604,6 +605,15 @@ IdentifierInfo *Preprocessor::ParsePragmaPushOrPopMacro(Token &Tok) {
   assert(StrVal[0] == '"' && StrVal[StrVal.size()-1] == '"' &&
          "Invalid string token!");
 
+  if (StrVal.size() <= 2) {
+    Diag(StrTok.getLocation(), diag::warn_pargma_push_pop_macro_empty_string)
+        << SourceRange(
+               StrTok.getLocation(),
+               StrTok.getLocation().getLocWithOffset(StrTok.getLength()))
+        << PragmaTok.getIdentifierInfo()->isStr("pop_macro");
+    return nullptr;
+  }
+
   // Create a Token from the string.
   Token MacroTok;
   MacroTok.startToken();

clang/test/Preprocessor/pragma-pushpop-macro-diag.c

@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -fms-extensions %s -fsyntax-only -verify
+
+#pragma push_macro("") // expected-warning {{'#pragma push_macro' expected a non-empty string}}
+#pragma pop_macro("") // expected-warning {{'#pragma pop_macro' expected a non-empty string}}

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("")