[Feature request] Encode runtime dependencies of exe

[pwithnall]

There is an executable in GLib (called glib-compile-resources) which is built as part of the main project build, and then run to build some files for the unit tests. On Windows, glib-compile-resources needs to spawn a subprocess (gspawn-win32-helper) which is built in a separate part of the build.

Currently, this means that building the files for the unit tests can sometimes fail if glib-compile-resources is built early, then the unit tests are attempted to be built before gspawn-win32-helper is built.

The only way we can come up with encoding this in Meson is to add gspawn-win32-helper to the depends of every test’s custom_target() if it uses glib-compile-resources. This is repetitive and hard to maintain: it’ll be easy to add another call to glib-compile-resources in future but forget to add the depends: gspawn-win32-helper to it.

It would be helpful if Meson provided a way to specify runtime dependencies of an executable, as a property of that executable. They would only affect the build dependency tree in the case where that executable is run as part of a custom_target() (or similar), and wouldn’t have to be explicitly/manually passed to the custom_target (as is our current workaround).

See: https://gitlab.gnome.org/GNOME/glib/-/merge_requests/4125

[dnicolodi]

If I were to solve this issue, I would add gspawn-win32-helper to the extra dependencies of the glib-compile-resources executable. This would remove some parallelism in the build (gspawn-win32-helper and glib-compile-resources cannot be built concurrently anymore) but it would ensure that when glib-compile-resources is used in the tests, also gspawn-win32-helper has been built.

[benoit-pierre]

@dnicolodi:

• You can't add it to the glib-compile-resources executable dependencies, because it's not a dependency object.
• You can't add it to its sources (well, you can, but it does no do anything).
• You could add it to link_depends: glib-compile-resources & gspawn-win32-helper would still be built in parallel, but the former would always be linked after the later.