curdeius requested changes to this revision. curdeius added inline comments. This revision now requires changes to proceed.
================ Comment at: libcxx/include/cstdalign:24 +#include <__config> +#include <stdalign.h> + ---------------- hubert.reinterpretcast wrote: > curdeius wrote: > > curdeius wrote: > > > hubert.reinterpretcast wrote: > > > > sbc100 wrote: > > > > > hubert.reinterpretcast wrote: > > > > > > This seems to be assuming that the underlying C library's > > > > > > `stdalign.h` is C++ friendly. A C11 `stdalign.h` //does// define > > > > > > `alignof` and `alignas` as macros. > > > > > Should I just remove this `#include` then? > > > > The idea would be to //add// a `stdalign.h` alongside this header that > > > > doesn't `#include_next` the underlying C library's `stdalign.h`. > > > I'm not sure if that should be the solution. At least gcc's libstdc++ > > > assumes that `stdalign.h` is C++-compatbile (cf. > > > https://github.com/gcc-mirror/gcc/blob/16e2427f50c208dfe07d07f18009969502c25dc8/libstdc%2B%2B-v3/include/c_global/cstdalign). > > > > > > Clang provides a compatible header: > > > https://github.com/llvm/llvm-project/commit/8acb4044d83ecc9df81b1c9f327d5bd4325e1756. > > > Gcc too of course: > > > https://github.com/gcc-mirror/gcc/blob/16e2427f50c208dfe07d07f18009969502c25dc8/gcc/ginclude/stdalign.h. > > > > > > MSVC's STL on the other hand, doesn't include `<stdalign.h>` > > > (https://github.com/microsoft/STL/blob/main/stl/inc/cstdalign). > > > > > > @hubert.reinterpretcast, are you aware of an environment which has > > > non-friendly `stdalign.h`? > > FYI, musl is also C++ friendly: > > https://git.musl-libc.org/cgit/musl/tree/include/stdalign.h. > >>! Quote: > > @hubert.reinterpretcast, are you aware of an environment which has > > non-friendly stdalign.h? > > The one GCC provides disagrees with the interpretation I gave of which macros > should be present. The one that Clang provides //does// match my > interpretation. It seems the GCC one is non-friendly (albeit a different form > of non-friendly than the one I opened with). Oh, you mean that `__alignas_is_defined` and `__alignof_is_defined` won't be defined in this case, right? In this case, I guess we won't avoid having `stdalign.h` as you had suggested. And indeed the test fails with gcc: ``` bin/llvm-lit -vv ../../libcxx/test/std/language.support/cstdalign/ --param=std=c++17 --param=cxx_under_test=`which g++` ... libcxx/test/std/language.support/cstdalign/cstdalign.pass.cpp:21:2: error: #error __alignas_is_defined not defined 21 | #error __alignas_is_defined not defined | ^~~~~ ``` That's unfortunately a configuration which is not tested in the CI. ================ Comment at: libcxx/test/std/language.support/cstdalign/cstdalign.pass.cpp:16-18 +#ifdef alignas +#error alignas should not be a macro in C++ +#endif ---------------- Please do the same for `alignof`. ================ Comment at: libcxx/test/std/language.support/cstdalign/cstdalign.pass.cpp:27 +#ifndef __alignof_is_defined +#error __alignof_is_defined not defined +#endif ---------------- hubert.reinterpretcast wrote: > sbc100 wrote: > > hubert.reinterpretcast wrote: > > > sbc100 wrote: > > > > ldionne wrote: > > > > > I'm not seeing `__alignof_is_defined` anywhere in the spec? > > > > Removed > > > Seems like a defect in the old standard. The prose doesn't match the > > > synopsis. `__alignof_is_defined` is a macro in C11's `stdalign.h` (and so > > > is `alignof`). That the C++ committee did not intend for an `alignof` > > > macro can probably be assumed. I suspect the lack of an > > > `__alignof_is_defined` macro was also unintended. > > So should I add back the check for `__alignof_is_defined`? > I think so (in addition to also checking that `alignof` is not defined as a > macro). I think the patch needs to be confirmed again either way by the > libc++ approvers though. Please check `__alignof_is_defined` as well, but guard it with `#ifdef _LIBCPP_VERSION` to be conforming. I agree that it seems to be a defect in the old standard. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D46443/new/ https://reviews.llvm.org/D46443 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
