env2mfile: Use a cross vapigen on Debian if available

As with many compilers and other tools relevant to cross-compiling,
an executable prefixed with the host architecture's GNU architecture
tuple might or might not exist, but if it does exist, we can be quite
confident that it's the appropriate executable to use for that host
architecture.

Vala's vapigen tool reads GIR XML files that can vary between
architectures (for example GLib-2.0.gir and GstAudio-1.0.gir contain
constants that take architecture-specific values), so on Debian it
needs to search an architecture-specific location. Accordingly, the
valac (>= 0.56.18-3) package provides a `${DEB_HOST_GNU_TYPE}-vapigen`
script which wraps the vapigen binary and sets appropriate search paths.

Bug-Debian: https://bugs.debian.org/1116552
Signed-off-by: Simon McVittie <smcv@debian.org>

Author: smcv

mesonbuild/scripts/env2mfile.py

@@ -234,6 +234,7 @@ def dpkg_architecture_to_machine_info(output: str, options: T.Any) -> MachineInf
         'g-ir-inspect',
         'g-ir-scanner',
         'pkg-config',
+        'vapigen',
     ]:
         try:
             infos.binaries[tool] = locate_path("%s-%s" % (host_arch, tool))

unittests/internaltests.py

@@ -1782,6 +1782,7 @@ def expected_binaries(gnu_tuple: str) -> T.Dict[str, T.List[str]]:
                 'g-ir-generate': [f'/usr/bin/{gnu_tuple}-g-ir-generate'],
                 'g-ir-inspect': [f'/usr/bin/{gnu_tuple}-g-ir-inspect'],
                 'g-ir-scanner': [f'/usr/bin/{gnu_tuple}-g-ir-scanner'],
+                'vapigen': [f'/usr/bin/{gnu_tuple}-vapigen'],
             }
 
         for title, dpkg_arch, gccsuffix, env, expected in [