.gitignore Meson subprojects

Meson projects using Meson subprojects have a project directory structure like:

meson.build
main.c
subprojects/
  lapack/
  lapack.wrap

where “subprojects/lapack/” is automatically created as a Meson subproject from the metadata in “subprojects/lapack.wrap”. It’s desirable to ignore the subprojects code directories in Git.

For Meson subprojects, using the negate .gitignore syntax Git will ignore subdirectories but track the subprojects/*.wrap files, by including in the project top-level .gitignore:

/subprojects/*

!/subprojects/*.wrap

This technique can be applied to similar non-Meson scenarios.

NOTE: The .gitignore syntax has a precise meaning. For example, /subprojects/* means to ignore the directory contents of top-level directory “subprojects”, but not the directory itself. This is important for the next stanza !/subprojects/*.wrap, which means to not ignore files with .wrap suffix in top-level directory “subprojects”.

Thanks to @lunasorcery for pointing out the correct .gitignore syntax.