[PATCH] D116337: [clang] set __NO_MATH_ERRNO__ if -fno-math-errno

[Alex Xu (Hello71) via Phabricator via cfe-commits]

alxu created this revision.
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This causes modern glibc to unset math_errhandling MATH_ERRNO. gcc 12 also sets some other macros, but most of them are associated with flags ignored by clang, so without library examples, it is difficult to determine whether they should be set. I think setting this one macro is OK for now.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116337

Files:
  clang/lib/Frontend/InitPreprocessor.cpp


Index: clang/lib/Frontend/InitPreprocessor.cpp    
===================================================================
--- clang/lib/Frontend/InitPreprocessor.cpp    
+++ clang/lib/Frontend/InitPreprocessor.cpp    
@@ -1019,6 +1019,9 @@

   Builder.defineMacro("__USER_LABEL_PREFIX__", TI.getUserLabelPrefix());

+  if (LangOpts.FastMath || !LangOpts.MathErrno)
+    Builder.defineMacro("__NO_MATH_ERRNO__");
+
   if (LangOpts.FastMath || LangOpts.FiniteMathOnly)
     Builder.defineMacro("__FINITE_MATH_ONLY__", "1");
   else


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