514b00cf08 exposed another bug in the
existing wrapper logic: Darwin SDK variables are only exported by
the SDK package hook, so if those variables aren’t already exported
inside the wrappers, the modified versions are not passed down to the
compiler tools, breaking the fallback SDK logic. This was previously
partially masked by passing down a normally‐redundant `-isysroot`
to the compiler, but now we fix it at the source.
This broke e.g. running `clang(1)` without any environment, something
the GHC binary package `installCheckPhase` does indirectly to verify
that there’s nothing missing from the wrapped GHC `$PATH`. It may
also have caused issues building for the build platform inside a
Darwin‐to‐non‐Darwin cross‐compilation build.
55dfed83c0