[libcxx-commits] [PATCH] D146190: Fix EBO on std::optional and std::variant when targeting the MSVC ABI

[Eric Fiselier via Phabricator via libcxx-commits]

EricWF accepted this revision as: EricWF.
EricWF added inline comments.


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Comment at: libcxx/include/optional:641
 template <class _Tp>
-class optional
+class _LIBCPP_DECLSPEC_EMPTY_BASES optional
     : private __optional_move_assign_base<_Tp>
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Mordante wrote:
> Why not guard this attribute with a `_LIBCPP_ABI_FOO_FLAG` instead of breaking the ABI unconditionally?
Because that would prevent most users from ever getting value from it.

If we don't have any libc++ users who care about ABI compatibility with MSVC, then we should do this unconditionally.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D146190/new/

https://reviews.llvm.org/D146190