[libcxx-commits] [PATCH] D120064: Fix EBO on std::optional and std::variant when targeting the MSVC ABI

[Martin Storsjö via Phabricator via libcxx-commits]

mstorsjo added a comment.

In D120064#3351148 <https://reviews.llvm.org/D120064#3351148>, @ldionne wrote:

> In D120064#3329840 <https://reviews.llvm.org/D120064#3329840>, @jdoerrie wrote:
>
>> Hi both, PTAL. I was surprised to find out that both `std::variant<int>` and `std::optional<int>` have a sizeof 12 in my environment, this is my attempt to fix it. Please do let me know if there are other places I need to change, or how I would write a test to prevent future regressions.
>
> This is an ABI break on Windows, pinging @mstorsjo.

While I do act as a vendor for the library on Windows platforms, I only do that for the MinGW configuration (which isn't affected here), so this ABI break doesn't affect me. I don't think we've had other users of the MSVC setup speak up about ABI stability though.


Repository:
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  https://reviews.llvm.org/D120064/new/

https://reviews.llvm.org/D120064