Cannot install emptydirs to a prefixed path when prefix is default

[andrei-pavel]

Describe the bug
I cannot easily install emptydirs to the prefixed path when prefix is default because meson is opinionated about what the target path should be.

To Reproduce

1. Have this standalone meson.build. I understand the subsequent calls to install_emptydir are redundant and maybe even not idiomatic to meson. By writing those, I'm trying to show that almomst whatever I do, meson overrides my choice. Only the last call with the hardcoded path works. But hardcoded path may not be an option in complex projects.

project('a', 'c')

LOCALSTATEDIR = get_option('localstatedir')
PREFIX = get_option('prefix')

dir = LOCALSTATEDIR / 'run'
dir_with_prefix = PREFIX / dir
dir_with_prefix_2 = '/usr/local' / dir
dir_with_prefix_3 = '/usr/local/run'
install_emptydir(dir)
install_emptydir(dir_with_prefix)
install_emptydir(dir_with_prefix_2)
install_emptydir(dir_with_prefix_3)

2. Try with no prefix.

$ rm -rf build && meson setup build && sudo meson install -C build
Installing new directory /var/local/run
Installing new directory /var/local/run
Installing new directory /var/local/run
Installing new directory /usr/local/run

3. Try with prefix.

$ rm -rf build && meson setup build --prefix=/opt && sudo meson install -C build
Installing new directory /opt/var/run
Installing new directory /opt/var/run
Installing new directory /usr/local/var/run
Installing new directory /usr/local/run

Expected behavior
I expected to have a way to be able to install empty directories somewhere inside /usr/local without resorting to hardcoded paths, just like I can install inside /usr/local with something as simple as configure_file(copy: true, install: true, install_true: SBINDIR).

Installing a dummy file with configure_file(input:'dummy', output: 'dummy', copy: true, install: true, install_dir: 'run') is a valid workaround until this is fixed or if it is not fixed at all. I guess I'll use that.

system parameters

• Not a cross build.
• Endeavour OS 2024.09.22
• Python 3.13.2
• meson 1.7.99 - a recent build
• ninja 1.11.1.git.kitware.jobserver-1

[andrei-pavel]

Except configure_file does not work either in my project where preferably I need to use LOCALSTATEDIR / 'run'. I'm using hardcoded values to work around it instead now.

There must be a good reason for why meson is doing this.

I also have a macro define that I have to adjust based on prefix too.

if PREFIX == '/usr' or PREFIX == '/usr/local'
    SYSCONFDIR_INSTALLED = SYSCONFDIR
else
    SYSCONFDIR_INSTALLED = PREFIX / SYSCONFDIR
endif

I'll consider migrating to the new defaults in the future.