It was reported by glibc conform test [1].
[1] https://sourceware.org/git/?p=glibc.git;a=blob;f=conform/data/float.h-data;h=
7b98fc03447b8918da4a0cf47d41fb3e17f4f791;hb=HEAD
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D137267
/* Characteristics of floating point types, C99 5.2.4.2.2 */
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
+ (defined(__cplusplus) && __cplusplus >= 201103L)
#define FLT_EVAL_METHOD __FLT_EVAL_METHOD__
+#endif
#define FLT_ROUNDS (__builtin_flt_rounds())
#define FLT_RADIX __FLT_RADIX__