gio: Optionally install trigger executables to architecture-specific paths

In Debian-style multiarch (libdir = lib/x86_64-linux-gnu or similar),
Red-Hat-style multilib (libdir = lib64 or lib) and Arch-style multilib
(libdir = lib or lib32), we have to run a separate version of
gio-querymodules to discover 32- or 64-bit modules on x86. Installing
modules in the directory used for each word size needs to trigger
recompilation of the correct modules list.

Debian, Fedora and Arch currently all have patches to facilitate this:
Debian moves gio-querymodules into ${libdir}/glib-2.0 and provides a
compat symlink in ${bindir}, while Fedora and Arch rename one or both
of the gio-querymodules executables to give it a -32 or -64 suffix.

We can avoid the need for these patches by making this a build option.
Doing this upstream has the advantage that the pkg-config metadata for
each architecture points to the correct executable and is in sync with
reality.

I'm using Debian's installation scheme with a separate directory here,
because the word-size suffix used in Fedora and Arch only works for the
common case of 32- and 64-bit multilib, and does not cover scenarios
where there can be more than one ABI with the same word size, such as
multiarch cross-compilation or alternative ABIs like x32.

Now that we have this infrastructure, it's also convenient to use it for
glib-compile-schemas. This works with /usr/share, so it only needs to
be run for one architecture (typically the system's primary
architecture), but using /usr/bin/glib-compile-schemas for the trigger
would result in either primary and secondary architectures trying to
overwrite each other's /usr/bin/glib-compile-schemas binaries, or a
circular dependency (the GLib library would have to depend on a
common package that contains glib-compile-schemas, but
glib-compile-schemas depends on the GLib library). Installing a
glib-compile-schemas binary in an architecture-specific location
alongside each GLib library bypasses this problem.

Signed-off-by: Simon McVittie <smcv@collabora.com>

gio/meson.build

@@ -846,8 +846,8 @@ pkg.generate(libgio,
                'bindir=' + join_paths('${prefix}', get_option('bindir')),
                'giomoduledir=' + pkgconfig_giomodulesdir,
                'gio=' + join_paths('${bindir}', 'gio'),
-               'gio_querymodules=' + join_paths('${bindir}', 'gio-querymodules'),
-               'glib_compile_schemas=' + join_paths('${bindir}', 'glib-compile-schemas'),
+               'gio_querymodules=@0@'.format(pkgconfig_multiarch_bindir / 'gio-querymodules'),
+               'glib_compile_schemas=@0@'.format(pkgconfig_multiarch_bindir / 'glib-compile-schemas'),
                'glib_compile_resources=' + join_paths('${bindir}', 'glib-compile-resources'),
                'gdbus=' + join_paths('${bindir}', 'gdbus'),
                'gdbus_codegen=' + join_paths('${bindir}', 'gdbus-codegen'),
@@ -958,6 +958,7 @@ executable('gresource', 'gresource-tool.c',
 
 gio_querymodules = executable('gio-querymodules', 'gio-querymodules.c', 'giomodule-priv.c',
   install : true,
+  install_dir : multiarch_bindir,
   c_args : gio_c_args,
   # intl.lib is not compatible with SAFESEH
   link_args : noseh_link_args,
@@ -966,6 +967,7 @@ gio_querymodules = executable('gio-querymodules', 'gio-querymodules.c', 'giomodu
 glib_compile_schemas = executable('glib-compile-schemas',
   ['glib-compile-schemas.c'],
   install : true,
+  install_dir : multiarch_bindir,
   # intl.lib is not compatible with SAFESEH
   link_args : noseh_link_args,
   dependencies : [libgio_dep, libgobject_dep, libgmodule_dep, libglib_dep, gvdb_dep])
@@ -1023,6 +1025,25 @@ if enable_systemtap
   )
 endif
 
+if multiarch_bindir != get_option('bindir')
+  foreach exe : ['gio-querymodules', 'glib-compile-schemas']
+    if meson.version().version_compare('>=0.61.0')
+      install_symlink(
+        exe,
+        install_dir : get_option('bindir'),
+        pointing_to : get_option('prefix') / multiarch_bindir / exe,
+      )
+    else
+      warning(
+        'Please use Meson >= 0.61.0 or create a symlink @1@ -> @2@ in packaging'.format(
+          get_option('prefix') / get_option('bindir') / exe,
+          get_option('prefix') / multiarch_bindir / exe,
+        )
+      )
+    endif
+  endforeach
+endif
+
 if build_tests
     subdir('tests')
 endif

meson.build

@@ -82,6 +82,20 @@ else
   glib_giomodulesdir = join_paths(glib_libdir, 'gio', 'modules')
 endif
 
+if get_option('multiarch')
+  # For multiarch/multilib distributions, install each architecture's
+  # build of executables used in packaging triggers (like gio-querymodules)
+  # to an architecture-dependent location, with a compatibility symlink
+  # in the PATH.
+  multiarch_bindir = get_option('libdir') / 'glib-2.0'
+  pkgconfig_multiarch_bindir = '${libdir}/glib-2.0'
+else
+  # For single-architecture distributions, just install them into the PATH
+  # as was traditionally done.
+  multiarch_bindir = get_option('bindir')
+  pkgconfig_multiarch_bindir = '${bindir}'
+endif
+
 glib_pkgconfigreldir = join_paths(glib_libdir, 'pkgconfig')
 
 if get_option('charsetalias_dir') != ''

meson_options.txt

@@ -117,3 +117,8 @@ option('libelf',
        type : 'feature',
        value : 'auto',
        description : 'Enable support for listing and extracting from ELF resource files with gresource tool')
+
+option('multiarch',
+       type : 'boolean',
+       value : false,
+       description : 'Install some helper executables in per-architecture locations')