[libcxx-commits] [libcxx] [libc++] Resolve LWG4308, correct `iterator` availability for `optional<T&>` (PR #173948)

[William Tran-Viet via libcxx-commits]

smallp-o-p wrote:

Couldn't replicate the `libc++abi` test failure on my machine running the CI container...

https://github.com/llvm/llvm-project/pull/173948