- Add options to the autotools build to set the path for the "vendor"
or "extra" configuration snippets, functions and completions
directories.
- Remove the vendor_completions directory from the Xcode build, as
these are relocatable and compiling the paths in does not make sense.
This allows packaging tools like Homebrew and Nix to use a common
directory outside of the main prefix for third-party completions, and
to make these available for programmatic discovery through `pkg-config`.
Closes#2113
This allows "vendors" (i.e. third-party upstreams interested in
supporting fish) to add auto-loaded functions and eager-loaded
configuration "snippets", while still allowing both the user and the administrator to
fully override all of that.
This has been inspired by systemd's configuration hierarchy, and implements a similar scheme
whereby files with the same name in higher-ranking directories override files in lower-ranking ones.
Fixes#1956
Assists other packages in finding the path to install completions: call
`pkg-config --variable=completionsdir fish` or so (like
bash-completion).
As discussed in #1485.
