[PATCH] D157331: [clang] Implement C23 <stdckdint.h>

[Elliott Hughes via Phabricator via cfe-commits]

enh added inline comments.


================
Comment at: clang/lib/Headers/stdckdint.h:13
+
+#if defined(__GNUC__)
+#define ckd_add(R, A, B) __builtin_add_overflow((A), (B), (R))
----------------
enh wrote:
> enh wrote:
> > ZijunZhao wrote:
> > > enh wrote:
> > > > is this ever _not_ set for clang?
> > > https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/stdbool.h#L23
> > > I think it is set?
> > i get an error from
> > ```
> > /tmp$ cat x.c
> > #if defined(__GNUC__)
> > #error foo
> > #endif
> > ```
> > regardless of whether i compile with -std=c11 or -std=gnu11.
> > neither -ansi nor -pedantic seem to stop it either.
> it does look like it _should_ be possible to not have it set though? llvm/llvm-project/clang/lib/Frontend/InitPreprocessor.cpp has:
> ```
>   if (LangOpts.GNUCVersion != 0) {
>     // Major, minor, patch, are given two decimal places each, so 4.2.1 becomes
>     // 40201.
>     unsigned GNUCMajor = LangOpts.GNUCVersion / 100 / 100;
>     unsigned GNUCMinor = LangOpts.GNUCVersion / 100 % 100;
>     unsigned GNUCPatch = LangOpts.GNUCVersion % 100;
>     Builder.defineMacro("__GNUC__", Twine(GNUCMajor));
>     Builder.defineMacro("__GNUC_MINOR__", Twine(GNUCMinor));
>     Builder.defineMacro("__GNUC_PATCHLEVEL__", Twine(GNUCPatch));
>     Builder.defineMacro("__GXX_ABI_VERSION", "1002");
> 
>     if (LangOpts.CPlusPlus) {
>       Builder.defineMacro("__GNUG__", Twine(GNUCMajor));
>       Builder.defineMacro("__GXX_WEAK__");
>     }
>   }
> ```
/me wonders whether the right test here is actually `#if __has_feature(__builtin_add_overflow)` (etc)...

but at this point, you definitely need an llvm person :-)


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  https://reviews.llvm.org/D157331/new/

https://reviews.llvm.org/D157331