On Wednesday, 19 January 2022 13:07:26 CET Jonathan Wakely wrote: > On Wed, 19 Jan 2022 at 08:10, Matthias Kretz wrote: > > Follow-up to my last patch. This one is a more thorough fix. Tested on > > x86_64- > > linux. OK for trunk? > > > > ---- 8< ---- > > > > Use SFINAE magic to support: "It is unspecified whether math_errhandling > > is a macro or an identifier with external linkage." [C Standard] > > The patch is OK for trunk, but I don't understand what the C standard means > here. > > "the macro math_errhandling expands to [...]. It is unspecified whether > math_errhandling is a macro or an identifier with external linkage." > > So is it a macro or not?
I agree the quote I used is unclear. The complete paragraph: The macros MATH_ERRNO MATH_ERREXCEPT expand to the integer constants 1 and 2, respectively; the macro math_errhandling expands to an expression that has type int and the value MATH_ERRNO, MATH_ERREXCEPT, or the bitwise OR of both. The value of math_errhandling is constant for the duration of the program. It is unspecified whether math_errhandling is a macro or an identifier with external linkage. If a macro definition is suppressed or a program defines an identifier with the name math_errhandling, the behavior is undefined. If the expression math_errhandling & MATH_ERREXCEPT can be nonzero, the implementation shall define the macros FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in <fenv.h>. -- ────────────────────────────────────────────────────────────────────────── Dr. Matthias Kretz https://mattkretz.github.io GSI Helmholtz Centre for Heavy Ion Research https://gsi.de stdₓ::simd ──────────────────────────────────────────────────────────────────────────
