[libcxx-commits] [libcxx] [libc++] Add internal checks for some basic_streambuf invariants (PR #144602)

[Nikolas Klauser via libcxx-commits]

https://github.com/philnik777 approved this pull request.

I guess this LGTM. I'd much rather have some other way to say "this is an invariant", but I don't know how we'd do it.

https://github.com/llvm/llvm-project/pull/144602