[libcxx-commits] [libcxx] [libc++] Complete `<charconv>` for 64-bit `long double` platforms (PR #117125)

[Michael Jones via libcxx-commits]

================
@@ -1231,6 +1231,12 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_HAS_EXPLICIT_THIS_PARAMETER 0
 #  endif
 
+#  if defined(_MSC_VER) || __SIZEOF_LONG_DOUBLE__ == __SIZEOF_DOUBLE__
----------------
michaelrj-google wrote:

The way to properly check that long double is the same as double is to use `LDBL_MANT_DIG == 53`.

https://github.com/llvm/llvm-project/pull/117125