This adds GCC's runtime lib directory to the RPATH of every build on
Linux (unconditionally!).
This is useful for three things:
1. It fixes versioned GCC linkage for formulae that users build from
source instead of pouring from a bottle. We currently only handle
bottle installs. See #13633.
2. It helps minimise the GCC dependency explosion. When a formula has a
Linux-only GCC dependency, then all its dependents that link with
some GCC runtime library (typically `libstdc++`) must, before this
change, also adopt a GCC dependency. This is a consequence of our
injecting GCC's runtime library directory into RPATH only when a
formula is built with GCC (this is done through the specs file). We
can avoid the need to do this by always injecting this path instead.
3. This enables us to automatically install Homebrew GCC whenever the
user's GCC is too old and the formula may need it. Without this
change, auto-installing GCC is not that useful because formulae that
need it may not know to look for our GCC, unless the formula already
happened to be built with our GCC. With this change, these formulae
will always be able to find our GCC when it is installed. This is
particularly useful for when we start building with a version of GCC
that is much closer to the latest than we currently do.
This approach comes with at least two drawbacks:
1. We will see spurious linkage warnings in CI about an undeclared
dependency with linkage as soon as Homebrew GCC is installed, because
formulae will link with our GCC instead of the host's. Users will
also see a similar complaint if they do `brew linkage`.
2. This leans _very_ heavily on GCC delivering backward compatibility of
their runtime libraries. If they do not, we could see different
behaviour across different CI runs for the same formula depending on
whether Homebrew GCC is installed.
It's worth noting that item 3 in the "useful" list above may rely on
features not yet implement in `brew`.
This should help keep bottles that require GCC working when
Homebrew/homebrew-core#106755 is merged.
This only works on freshly-poured bottles. Previously installed bottles
will still break on systems with a host GCC older than GCC 11.
Results in searching a list of tokens from official Homebrew cask taps and fully-qualified tokens from other taps, matching the list when searching formulae.
ruby-macho chokes on changing duplicate RPATHs, so we need to strip the
duplicates before trying to relocate them.
This continues #11405. We need this to unblock
Homebrew/homebrew-core#91224.
While we're here, let's get rid of `HOMEBREW_RELOCATE_RPATHS`. We've
been using it for nearly a year with essentially no problems (barring
`pdnsrec`), so I think it is safe to do unconditionally.
Upon reflection, I realised that this is probably a bug in `ruby-macho`,
and should be fixed there instead.
Needs https://github.com/Homebrew/ruby-macho/pull/362.
This reverts commit e8b5eb7e42c925b7cc10c78a029b8c70e4d7965b.
