Please describe the problem.
Installing git-annex via the Makefile results in a zsh completion installed to $(PREFIX)/$(SHAREDIR)/zsh/vendor-completions
This is not used by zsh, since the builtin zsh fpath is $(PREFIX)/$(SHAREDIR)/zsh/site-functions -- as a result, zsh completions do not work.
Some system distributions of zsh may change the builtin fpath, in which case git-annex may have working zsh completions out of the box -- I believe the current installation method is designed based on Debian's preferred layout.
What steps will reproduce the problem?
Install git-annex on a non-Debian system
What version of git-annex are you using? On what operating system?
version 7.20190730 on an Arch Linux system.
Recommended fix
Make the installation directory configurable. Use /etc/os-release to check if the system is a Debian-based system, and if so, continue to use vendor-completions, if not, use site-functions.
Debian also supports /usr/local/share/zsh/site-functions/, it's just that it's for local sysadmin use and not a place that packages should install files, so they added /usr/share/zsh/vendor-completions/ for that.
However, checking
/etc/os_releaseprobably entails keeping track of the name of every debian derivative, so I'd really rather not do that.Also, even if the Makefile were changed to use /usr/local/share/zsh/site-functions/, it sounds as if that might not be a path that works universally either.
Surely there must be a way to ask zsh where to install completions to? But short of taking the first item from $fpath, which doesn't seem robust, I don't know how to. And zsh may not even be installed when building a package that should later integrate with zsh.
FWIW, I checked half a dozen packages like curl that include zsh completions, and none of them installed them with
make install, they were just there to be installed manually. It seems zsh is making this too hard for software to bother integrating with it.The greatness of os-release (dash, not underscore) is that you can use the ID_LIKE field. From the os-release(5) man page:
"A space-separated list of operating system identifiers in the same syntax as the ID= setting. It should list identifiers of operating systems that are closely related to the local operating system in regards to packaging and programming interfaces [...]". If "debian" is the value of ID, or is contained in the space-separated value of ID_LIKE, then you don't need to know what the specific OS is.
Before os-release, it was common to check if the file /etc/debian_version existed, and if not, check for other distros using /etc/arch-release, /etc/fedora-release, and so on. Ubuntu historically included /etc/debian_version just so tools could identify the distro as debian-compatible, while identifying as Ubuntu only if you used lsb-release...
...
The site-functions directory should work everywhere, I think, since both the /usr/share and /usr/local/share equivalents are defined by the zsh build system (and I'm not aware of any distributors other than Debian which override the former). On my Arch system:
Specifically, if you look at the configure.ac, it will:
It's regrettable that unlike bash-completion, there is no pkg-config file for this.
That would at least allow the build system to build-depend on zsh in order to automatically grab this information. But ultimately, the only thing you need to worry about is which distribution-modified value to use for/instead of /usr/share/zsh/site-functions
In the case of curl, the make install only installs to site-functions, but provides an option --with-zsh-functions-dir=/usr/share/zsh/vendor-completions used at https://salsa.debian.org/debian/curl/blob/27e07a35cb9c727d6005c0afa291e2a3dc3bc5af/debian/rules#L20
Various other programs I have seen will often install to site-functions and let debian's packaging move it if needed, or try to check whether any of several known directories exist. Here is an elaborate detection mechanism which works for a proliferation of possible locations, and can be successfully packaged in a distro build recipe if you first mkdir -p "$DESTDIR/usr/share/zsh/site-functions" (or vendor-completions, depending): https://github.com/kovidgoyal/calibre/blob/7460a12a4bcd05efc822f7fe421626772e2f6575/src/calibre/linux.py#L192-L210
The downside of that is that the packager needs to know they should do this first.