absl::synchronization is banned, but absl::Cord depends on it.

[Jelle Foks]

Hi there,

`absl::synchronization` is banned, but `absl::Cord` is not but it depends on `absl::synchronization` for a few uses of `absl::Mutex`.

Is that known, on purpose, or should something be changed there?

Cheers,

Jelle

[Peter Kasting]

On Wed, Jan 17, 2024 at 8:54 AM 'Jelle Foks' via cxx <c...@chromium.org> wrote:

`absl::synchronization` is banned, but `absl::Cord` is not but it depends on `absl::synchronization` for a few uses of `absl::Mutex`.

AFAICT, only code in the internal implementation uses Abseil's synchronization APIs; such usage is not exposed through the Cord APIs.

This is not a problem; the c++-features.md rules govern what APIs first-party code in Chromium is allowed to call, not what APIs third-party code is allowed to call. Lots of existing third-party code uses APIs that we ban in first-party code. The only problematic cases are when such APIs are actually _broken_ in Chromium (e.g. usage of absl::Any/std::any in component builds).

PK