[clang] [clang-tools-extra] [llvm] [clang][headers] Need a way for math.h to share the definitions of INIFINITY and NAN with float.h (PR #164348)

[Michael Spencer via llvm-commits]

================
@@ -7,13 +7,21 @@
  *===-----------------------------------------------------------------------===
  */
 
-#ifndef __CLANG_FLOAT_H
-#define __CLANG_FLOAT_H
-
 #if defined(__MVS__) && __has_include_next(<float.h>)
+#include <__float_header_macro.h>
 #include_next <float.h>
 #else
 
+#if !defined(__need_infinity_nan)
----------------
Bigcheese wrote:

Should this also check for `__need_float_float `? I don't think we have any consumers that need that but not `__need_infinity_nan `, but it would be consistent with how the pattern is applied in the rest of the builtins.

https://github.com/llvm/llvm-project/pull/164348