[libc-commits] [libc] [libc] Add getc, ungetc, fflush to enable libc++ iostream on baremetal (PR #175530)

[Petr Hosek via libc-commits]

petrhosek wrote:

Would it be possible to split this PR into two? First one for `getc` and `fflush` which can be merged right away. Second one for `ungetc` which might need more discussion. Specifically, I'm still a bit concerned that we're treating `stdin` specially which may lead to inconsistent behavior and I think we should consider introducing the embedding API for `ungetc` right away, but I could be also convinced that we should land this implementation as a stopgap solution.

https://github.com/llvm/llvm-project/pull/175530