Add semaphore-compat v2 implementation (!8) · Merge requests · Glasgow Haskell Compiler / semaphore-compat · GitLab

Due to a large amount of spam we do not allow new users to create repositories, they are "external" users. If you are a new user and want to create a repository, for example for forking GHC, open a new issue on ghc/ghc using the "get-verified" issue template

Zubin requested to merge wip/semaphore-v2 into master Mar 17, 2026

In the context of gitlab.haskell.org/ghc/ghc/-/issues/25087, https://github.com/haskell/cabal/issues/9993 and https://github.com/ghc-proposals/ghc-proposals/pull/673, we implemenent semaphore-comapt v2, featuring:

A new version of the protocol, maintaining backwards compatibility and graceful degradation as far as possible. See BackwardsCompatibility.md for more details.
Replacing the POSIX implementation from shared memory/libc based to one based on unix domain sockets.
A comprehensive testsuite
CI jobs to test and verify backwards compatibility guarantees.