While I was trying out the `expl3` package debugging options, I got errors in some of the packages that come installed with TeXLive. (It's `tabularray`, specifically.)
Naturally, the first thing to try should be checking whether there's still an error in the latest development version from the package's Git repository. I know that the relevant `.sty` file does have some changes in the Git repo.
Is it possible to clone the Git repo and then somehow point my `pdftex`, `xetex` and `luatex` programs to the cloned repo, so they would ignore the old version that's installed as a part of TeXLive?
What do people usually do when they want to hack on a LaTeX package or class?
This is on Archlinux.
you can place the .sty in your `TEXMFHOME` (that's a location that has precedence over the distribution), on Linux this is usually `~/texmf` (you can run `kpsewhich -var-value TEXMFHOME` to make sure), therein run `mkdir -p tex/latex/<package-name>` and place the files which should overwrite your TeXLive distribution in that folder.
in the case of `tabularray` you'll have a much easier job, since it uses `l3build` (a very handy build tool for TeX-packages). Just use
git clone https://github.com/lvjr/tabularray.git
l3build check && l3build install
The `l3build check` will test whether the cloned version has any regressions against the package's own test files. You could as well omit that step.
`l3build install` will run everything necessary to do the stuff from the "Generally" section (as long as the configuration is correct).
You can recognize packages that use `l3build` by the configuration file `build.lua`. `l3build` is part of TeXLive (if it isn't for you don't use the TeXLive from the repositories but upstream vanilla -- which is more the Arch way anyways).
If you want to remove the package again simply run `l3build uninstall`.