should meson introspect ignore DESTDIR?

[germandiagogomez]

This is not necessarily a bug.

Just my two cents here about whether this should be discussed. I am generating a installer for Windows. I need to get the list of installed files to put them in a wix toolset database (this is a xml with all files to be used by the installer as input).

I want to install the files in DESTDIR as a first step, using set DESTDIR=%cd%/build/staging and doing ninja -C build install and later gather staged files and put them in a msi installer through a run_target('create_msi_installer'). These are the correct files to gather, and not the ones in the build directory actually. But meson introspect ignores DESTDIR.

• Should DESTDIR be ignored by meson introspect (this is what it does, so the installation directory is not correct).

[mensinda]

No, meson introspect should not handle DESTDIR. More generally, the entire introspection API should not depend on any environment variable. It must only depend on the results of the last meson run. This is because the meson introspect command is only a small frontend for the *.json files located in the meson-info directory. So the only thing meson introspect --installed <build dir> does, is to read the correct JSON file (here <build dir>/meson-info/intro-installed.json) and paste it to stdout.

The only exception here are those options that can also work without a configured build directory. However, this can be thought of as an entirely different API, since meson does its best to guess the correct values and the output format may differ from the normal introspection API.

[mensinda]

Also, I might not entirely know what DESTDIR does, but can't you just slightly post-process the introspection output by prepending $DESTDIR/ to each installed file in your installation script?

[germandiagogomez]

Hello @mensinda ,

The solution you suggested is what I did. However, handling DESTDIR is not as simple as it looks. It has some corner cases (especially on Windows).

I also agree that depending on an environment variable by default would open the door to surprises. However, maybe (and I say maybe, since I have no clear idea of the consequences) augmenting in some way meson introspect --installed, maybe adding --no-ignore-destdir or similar.

The fact here is that staging builds are regularly done and there is where files that will be further packaged live.

Examples of its importance are that In Linux, for example, these staged files are the ones who have the correct RPATH set up and maybe you want to package them in a .deb, etc.

I think it would be a good idea to have an option to point to those files. This would ease package creation quite a bit.

When I create packages for the different systems (mac, linux, windows, maybe others), I try to take advantage of meson as much as possible and give a last tweak with some script. The less we rely on scripts, the more reliable and portable the solution would be.

[mensinda]

After thinking about it, I would say that meson introspect definitely should not handle DESTDIR. Doing so would require duplicating the complete installation logic from minstall.py to correctly cover all the corner cases. The only thing I might consider doing (with an opt-in) would be to simply prepend $DESTDIR to all the installation paths. However, this is apparently not possible since there are corner cases on Windows (like always).

That doesn't mean that listing all installation files correctly won't be possible, just that the introspection API is not the right place for this. Again a meson install --dry-run --list should still be possible.

[eli-schwartz]

What are the corner cases, above and beyond using mesonbuild.scripts.destdir_join(destdir, introspect_path)?

Not saying that introspect should or shouldn't implement this, but if it did then it shouldn't be too hard?