[libcxx-commits] [PATCH] D61139: (ABI break) Remove could-be-defaulted SMFs from `stack` and `queue` and `priority_queue`.

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

Quuxplusone added a comment.

> So, why would we want to do this? What's the benefit?

Benefit: maintainability (less code) and micro performance (defaulted SMFs are easier to optimize) and macro performance (defaulted SMFs are conditionally trivial/noexcept/constexpr whereas non-defaulted ones aren't).
Cost: ABI break for trivial container types.

There are no trivial container types yet in C++17, but my understanding is that C++2a (or at most, C++2b) is likely to support `fixed_capacity_vector` under the name `std::static_vector`, and that type //will// be conditionally trivial. So if libc++ were ever going to take an ABI break to gain trivial/noexcept/constexpr/defaulted SMFs, libc++ might want to do it sooner rather than later.


Repository:
  rCXX libc++

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  https://reviews.llvm.org/D61139/new/

https://reviews.llvm.org/D61139