[PATCH] D99834: Don't check that std::pair is trivially copyable on FreeBSD

Tue Apr 6 12:19:10 PDT 2021

ldionne added inline comments.

================
Comment at: llvm/unittests/Support/TypeTraitsTest.cpp:113
   TrivialityTester<std::function<int()>, false, false>();
+#if !defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
   TrivialityTester<std::pair<int, bool>, true, true>();
----------------
dim wrote:
> ldionne wrote:
> > I'm really not fond of using a libc++ internal macro here. I think we should instead detect that we're on FreeBSD.
> At the moment in `__config` the part where this macro gets defined is indeed only when `__FreeBSD__` is defined:
> 
> ```
> // Feature macros for disabling pre ABI v1 features. All of these options
> // are deprecated.
> #  if defined(__FreeBSD__)
> #    define _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
> #  endif
> #endif
> ```
> 
> So this could as well be `#if !defined(__FreeBSD__)`, yes. At some point though we'll have to migrate to libc++ ABI v2 (whenever that comes), so then this check would have to be adjusted too...
> 
Then it can be adjusted if you want to move to a different ABI based on some other detection. I'm very very uncomfortable with letting people use implementation details of libc++, that is the source of huge headache for us.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99834/new/

https://reviews.llvm.org/D99834