nickdesaulniers

Feb 2, 2024

Argh, sorry for causing confusion here, but I do think we'll benefit in the long run by documenting the state of the world. So some issues we've found: - gcc did not support `_Float128` in C mode until gcc-7, and C++ mode until gcc-13. - gcc defines `__STDC_IEC_60559_BFP__` to `201404L` so we cannot compare `__STDC_IEC_60559_BFP__` to `202311L` (at least doing so won't work for any compiler TODAY). Just having this one check would be ideal, but alas. - clang doesn't support `_Float128`. - glibc will define `__STDC_IEC_60559_BFP__` to `201404L`, so we can't use it to detect compiler support in overlay mode (or not without great pain). So perhaps we can have: ```c // GCC did not support _Float128 in C mode until gcc-7, or C++ mode until g++-13. #if defined(__GNUC__) && !defined(clang) && \ (defined(__cpluscplus) && __GNUC__ >= 13) || \ (!defined(__cplusplus) && __GNUC__ >= 7) #define LIBC_COMPILER_HAS_C23_FLOAT128 #endif // TODO: replace when clang has actual _Float128 support. // https://github.com/llvm/llvm-project/issues/80195 #ifdef __clang__ #define LIBC_COMPILER_HAS_FLOAT128_EXTENSION #endif #ifdef LIBC_COMPILER_HAS_C23_FLOAT128 typedef _Float128 float128; #elif defined(LIBC_COMPILER_HAS_FLOAT128_EXTENSION) typedef __float128 float128; #elif LDBL_MANT_DIG == 113 typedef long double float128; #else #error "no f128 support" #endif ``` I was hopefully naive that we could just have: ```c #if __STDC_IEC_60559_BFP__ < 202311L #error "no _Float128 support" #endif ```

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