dexonsmith added a comment.
In D124974#3504986 <https://reviews.llvm.org/D124974#3504986>, @porglezomp
wrote:
> Ah, so it'd be a test that passes pretty trivially on any bot that doesn't
> have a custom version of `CLANG_DEFAULT_STD_C` and `CLANG_DEFAULT_STD_CXX`
> like the default config, but could get caught by any other bots that do set
> it?
>
> What's the best way to get the compiler to report the standard it's using for
> this test?
>
> For C++ I can do:
>
> clang++ -xc++ -dM -E - < /dev/null | grep cplusplus
>
> And it will print e.g.
>
> #define __cplusplus 199711L
>
> But that requires quite some decoding to compare against
> `CLANG_DEFAULT_STD_CXX` which would look like `LangStandard::lang_gnucxx98`.
Yeah, that seems awkward.
My concern with lacking a test is that someone could easily remove this in the
future when trying to prune unused `#include`s.
Another solution might be to change this to a compile error. I think it'd work
to change the `#cmakedefine` logic to:
#cmakedefine CLANG_DEFAULT_STD_C LangStandard::lang_${CLANG_DEFAULT_STD_C}
// Always #define something so that missing the config.h #include at use sites
// becomes a compile error.
#ifndef CLANG_DEFAULT_STD_C
#define CLANG_DEFAULT_STD_C LangStandard::lang_unknown
#endif
and then update the code to:
case Language::C:
if (CLANG_DEFAULT_STD_C != LangStandard::lang_unknown)
return CLANG_DEFAULT_STD_C;
// The PS4 uses C99 as the default C standard.
if (T.isPS4())
return LangStandard::lang_gnu99;
return LangStandard::lang_gnu17;
(without the `#ifdef`)
WDYT?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D124974/new/
https://reviews.llvm.org/D124974
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