Provide a detailed description of the proposed feature

One key difference between macOS and Linux is how we use system Perl (and other scripting languages) on macOS but use brewed Perl on Linux.

This leads to different shebangs in some cases, with macOS pointing to /usr/bin/perl and Linux pointing to HOMEBREW_PREFIX/opt/perl/bin/perl.

In order to achieve cross-platform bottles, we could use keg-relocation logic to replace the shebangs with @@HOMEBREW_PERL@@ which can be replaced with the correct shebang at pour time.

What is the motivation for the feature?

Achieving cross-platform all bottles where possible.

How will the feature be relevant to at least 90% of Homebrew users?

Formulae which have all bottles can be installed on any platform without having to build from source - rather than be limited to just what we run CI on.

What alternatives to the feature have been considered?

An alternative is to stop using system Perl and use brewed Perl universally.