Apple clang 14.0.3 surfaces new default warnings; -Werror breaks Darwin builds
Is this due to a new toolchain?
According to @angerman, there wasn't a OS/toolchain update that would have made this start happening.
Update: The machines do have a newer version of clang than (some) other Darwin machines, so this is probably a factor.
Did something change recently in build configs that exposed these errors?
94f00e9b added -optc-Werror to the +werror transformer,
but that happened back in December. I wouldn't expect to start seeing problems now.
Update: This was only merged last week, so it is definitely related.
Why are they coming piecemeal?
5b6612bc was written because "Darwin's toolchain inexplicably claims that
write_barrier and friends have declarations without prototypes". But now there are more such functions. https://gitlab.haskell.org/ghc/ghc/-/jobs/1571118 complains of
initAdjustors; https://gitlab.haskell.org/ghc/ghc/-/jobs/1571356 complains of
https://gitlab.haskell.org/ghc/ghc/-/jobs/1571120 complains that FFI_GO_CLOSURES is undefined (moved to #23568 (closed) since it's a different problem.) -Werror is complicit in all of these.
Update: This is probably due to the nondeterminism of a multi-core build.