[cfloat.syn], [cmath.syn] Add missing "// optional" comments for some macros - #9254
[cfloat.syn], [cmath.syn] Add missing "// optional" comments for some macros#9254eisenwave wants to merge 2 commits into
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| #define @\libmacro{FLT_SNAN}@ @\seebelow@ | ||
| #define @\libmacro{DBL_SNAN}@ @\seebelow@ | ||
| #define @\libmacro{LDBL_SNAN}@ @\seebelow@ | ||
| #define @\libmacro{INFINITY}@ @\seebelow@ // optional |
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We should also change [cmath.syn] for INFINITY and NAN. Also, we should indent these comments.
INFINITY was mandatory in the published C99/C11/C17, and then N2848 changed it to conditionally-supported. It seems that before N2848 INFINITY was required to be defined as something nonsense if the implementation doesn't support infinity.
I think WG14 N2848 should be treated as DR, but I'm nor sure whether we should add some entry to Annex C.
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I've added the changes to [cmath.syn]. If this is basically a DR, then I don't see a need for an Annex C entry. We have always had the same contents as the C header, and the C header just got some bug-fixes, so it's not really like something changed in C++.
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@jwakely , this seems correct. Please have a look.
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All of these macros are optionally defined, if and only if the constant is actually representable in the type.
See https://cstd.eisie.net/c23#5.2.5.3.3p28