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

[Aaron Ballman via cfe-commits]

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@@ -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?
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AaronBallman wrote:

I think we should emit a warning for this because it's a bit of a confusing construct; MSVC does: https://godbolt.org/z/cs1xn5M8T (GCC does not)

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