[libcxx-commits] [PATCH] D109066: [libc++] Implement P1951, default arguments for pair's forwarding constructor

[Arthur O'Dwyer via Phabricator via libcxx-commits]

Quuxplusone added a comment.

> I mean the code previously would work just as well, but it would make a copy instead by using the `pair(T1 const&, T2 const&)` ctor.

Well, now I'm even //less// sure I understand the procedural issues here. Surely if `std::pair<T,U>({}, {})` was supposed to compile in C++20, then //we should have some tests to **prove** that it compiles in C++20//. It seems like those tests are the ones you're adding in `U_V.pass.cpp`; maybe we had no such tests before? But we're not running those tests pre-C++23 (except on libc++), so we still have no tests that test the expected C++20-and-earlier behavior? But on libc++ we don't even expect the expected behavior, anyway? 😛


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  https://reviews.llvm.org/D109066/new/

https://reviews.llvm.org/D109066