Adding dependency from shared_module to gnome.generate_gir

[Daniele Nicolodi]

Hello,

I have a GObject library for which I generate introspection data with a
gnome.generate_gir() target. For dependency decoupling, the library
dynamically loads (in the dlopen sense) modules generate with a
shared_module() target. The modules are necessary for the library to
work properly and g-ir-scanner fails if they are not present.

I haven't found a way to express the fact that the shared_module()
targets need to be built before the gnome.generate_gir() target thus
sometimes the project build fails, depending on how ninja decides to
order the build steps.

Is there a way to trick meson into adding a dependency between the two
targets other than modifying the gnome.generate_gir() function to accept
a new "depends" argument in the style of the one accepted by the
custom_target() function?

Thank you.

Cheers,
Dan

[Eli Schwartz]

I'm not the expert on gobject-introspection but can you just treat the
shared module the same as the library by adding it as an e.g. link_with?

--
Eli Schwartz

[Daniele Nicolodi]

The documentation says that linking with a shared_module is explicitly
forbidden thus I didn't try. However, trying it I obtain a linker error
on macOS:

ld: can't link with bundle (MH_BUNDLE) only dylibs (MH_DYLIB) file...

The shared_module is loaded just fine by the library if it exists, the
issue is to have meson build the targets in the right order.

Cheers,
Dan

[Daniele Nicolodi]

I found a solution that is not pretty but not that ugly either: I use a
custom_target() with a depends list including the dynamically loaded
modules to generate an empty source file that then I add to the
gnome.generate_gir() sources list.

It looks something like this (simplified and abbreviated):

libtracker_sparql_modules = []

libtracker_remote_soup3 = shared_module('tracker-remote-soup3', ...)
libtracker_sparql_modules += libtracker_remote_soup3

# This custom target has the only purpose to inject a dependency from
# the libtracker_sparql_modules into the tarcker_sparql_gir target to
# force meson to build the loadable shared modules before attempting
# to run g-ir-scanner.
libtracker_sparql_modules_stamp = custom_target(
'libtracker-sparql-modules-stamp',
output: 'tracker-sparql-modules-stamp.c',
command: ['touch', '@OUTPUT@'],
depends: libtracker_sparql_modules,
)

tracker_sparql_gir = gnome.generate_gir(libtracker_sparql,
sources: [libtracker_sparql_modules_stamp, ...],
...
)

It seems a pattern that can be reused.

Cheers,
Dan

[Daniele Nicolodi]

Unfortunately this works only staring with meson 0.59. I think previous
versions did not generate correct dependency rules for gnome.generate_gir()

Cheers,
Dan