Generate introspection data

Currently, the introspection data for GLib and its sub-libraries is
generated by gobject-introspection, to avoid the cyclic dependency
between the two projects.

Since gobject-introspection is generally available on installed systems,
we can check for its presence, and generate the introspection data
directly from GLib.

This does introduce a cyclic dependency, which is why it's possible to
build GLib without introspection, then build gobject-introspection, and
finally rebuild GLib.

By having introspection data available during the GLib build, we can do
things like generating documentation; validating newly added API; and
close the loop between adding new API and it becoming available to non-C
consumers of the C ABI (i.e. language bindings).

gio/meson.build

@@ -472,7 +472,7 @@ else
   install_headers(gio_win32_include_headers, subdir : 'gio-win32-2.0/gio')
 endif
 
-gio_sources = files(
+gio_base_sources = files(
   'gappinfo.c',
   'gasynchelper.c',
   'gasyncinitable.c',
@@ -603,6 +603,8 @@ gio_sources = files(
   'gliststore.c',
 )
 
+gio_sources = gio_base_sources
+
 if glib_build_shared
   gio_sources += files ('../glib/gtrace.c')
 endif
@@ -1101,6 +1103,58 @@ if multiarch_bindir != get_option('bindir')
   endforeach
 endif
 
+if enable_gir
+  gio_gir_sources = [
+    gio_visibility_h,
+    gioenumtypes_h,
+    gnetworking_h,
+    gio_headers,
+    gio_base_sources,
+    application_sources,
+    gdbus_sources,
+    appinfo_sources,
+    contenttype_sources,
+    unix_sources,
+    win32_sources,
+    settings_sources,
+  ]
+  gio_gir_packages = [ 'gio-2.0' ]
+  gio_gir_args = [
+    '-DGIO_COMPILATION',
+    '-DG_SETTINGS_ENABLE_BACKEND',
+    '--symbol-prefix=gio',
+  ]
+  if host_system == 'windows'
+    gio_gir_sources += gio_win32_include_headers
+    foreach h: gio_win32_include_headers
+      gio_gir_args += '--c-include=@0@'.format(h)
+    endforeach
+    gio_gir_packages += 'gio-win32-2.0'
+    gio_gir_args += '--pkg=gio-win32-2.0'
+  else
+    gio_gir_sources += gio_unix_include_headers
+    foreach h: gio_unix_include_headers
+      gio_gir_args += '--c-include=@0@'.format(h)
+    endforeach
+    gio_gir_packages += 'gio-unix-2.0'
+    gio_gir_args += '--pkg=gio-unix-2.0'
+  endif
+
+  gio_gir = gnome.generate_gir(libgio,
+    sources: gio_gir_sources,
+    namespace: 'Gio',
+    nsversion: '2.0',
+    identifier_prefix: 'G',
+    symbol_prefix: 'g',
+    export_packages: gio_gir_packages,
+    header: 'gio/gio.h',
+    includes: [ glib_gir[0], gmodule_gir[0], gobject_gir[0] ],
+    install: true,
+    dependencies: [ libglib_dep, libgobject_dep, libgmodule_dep ],
+    extra_args: gir_args + gio_gir_args,
+  )
+endif
+
 if build_tests
     subdir('tests')
 endif

glib/meson.build

@@ -253,7 +253,7 @@ glib_sub_headers = files(
 
 install_headers(glib_sub_headers, install_dir : glib_sub_includedir)
 
-deprecated_sources = files(
+glib_deprecated_sources = files(
   'deprecated/gallocator.c',
   'deprecated/gcache.c',
   'deprecated/gcompletion.c',
@@ -407,7 +407,7 @@ endif
 glib_c_args = ['-DG_LOG_DOMAIN="GLib"'] + glib_c_args_internal + pcre2_static_args
 libglib = library('glib-2.0',
   glib_dtrace_obj, glib_dtrace_hdr,
-  sources : [deprecated_sources, glib_sources],
+  sources : [glib_deprecated_sources, glib_sources],
   version : library_version,
   soversion : soversion,
   darwin_versions : darwin_versions,

gmodule/meson.build

@@ -147,6 +147,31 @@ meson.override_dependency('gmodule-no-export-2.0', libgmodule_dep)
 meson.override_dependency('gmodule-export-2.0', libgmodule_dep)
 meson.override_dependency('gmodule-2.0', libgmodule_dep)
 
+if enable_gir
+  gmodule_gir = gnome.generate_gir(libgmodule,
+    sources: [
+      gmoduleconf_h,
+      gmodule_h,
+      gmodule_c,
+      'gmodule-deprecated.c',
+    ],
+    namespace: 'GModule',
+    nsversion: '2.0',
+    identifier_prefix: 'G',
+    symbol_prefix: 'g',
+    export_packages: 'gmodule-2.0',
+    header: 'gmodule.h',
+    includes: [ glib_gir[0] ],
+    install: true,
+    dependencies: libglib_dep,
+    extra_args: gir_args + [
+      '-DGMODULE_COMPILATION',
+      '-DGETTEXT_PACKAGE="dummy"',
+      '--symbol-prefix=gmodule',
+    ],
+  )
+endif
+
 if build_tests
   subdir('tests')
 endif

gobject/meson.build

@@ -163,6 +163,58 @@ pkg.generate(libgobject,
   description : 'GLib Type, Object, Parameter and Signal Library',
 )
 
+if enable_gir
+  # We generate GLib-2.0 here, as we need various GTypes
+  glib_gir = gnome.generate_gir(libglib,
+    sources: [
+      glibconfig_h,
+      gversionmacros_h,
+      glib_visibility_h,
+      glib_headers,
+      glib_deprecated_headers,
+      glib_sub_headers,
+      glib_enumtypes_h,
+      glib_types_h,
+      glib_deprecated_sources,
+      glib_sources,
+    ],
+    namespace: 'GLib',
+    nsversion: '2.0',
+    identifier_prefix: 'G',
+    symbol_prefix: 'g',
+    export_packages: 'glib-2.0',
+    header: 'glib.h',
+    install: true,
+    dependencies: libglib_dep,
+    extra_args: gir_args + [
+      '-DGLIB_COMPILATION',
+      '-DGETTEXT_PACKAGE="dummy"',
+      '--symbol-prefix=glib',
+      '--library=gobject-2.0',
+    ],
+  )
+
+  gobject_gir = gnome.generate_gir(libgobject,
+    sources: [
+      gobject_visibility_h,
+      gobject_install_headers,
+      gobject_sources,
+    ],
+    namespace: 'GObject',
+    nsversion: '2.0',
+    identifier_prefix: 'G',
+    symbol_prefix: 'g',
+    export_packages: 'gobject-2.0',
+    header: 'glib-object.h',
+    includes: [ glib_gir[0] ],
+    install: true,
+    extra_args: gir_args + [
+      '-DGOBJECT_COMPILATION',
+      '--symbol-prefix=gobject',
+    ],
+  )
+endif
+
 libgobject_dep = declare_dependency(link_with : libgobject,
   include_directories : [gobjectinc],
   sources : [gobject_visibility_h, glib_enumtypes_h],

meson.build

@@ -2456,8 +2456,22 @@ if want_systemtap and enable_dtrace
   enable_systemtap = true
 endif
 
+# introspection
+gir_scanner = find_program('g-ir-scanner', required: get_option('introspection'))
+enable_gir = get_option('introspection').allowed() and gir_scanner.found() and meson.can_run_host_binaries()
+
+if get_option('introspection').enabled() and not meson.can_run_host_binaries()
+  error('Running binaries on the build host needs to be supported to build with -Dintrospection=enabled')
+endif
+
+gir_args = [
+  '--quiet',
+]
+
 pkg = import('pkgconfig')
 windows = import('windows')
+gnome = import('gnome')
+
 subdir('tools')
 subdir('glib')
 subdir('gobject')
@@ -2579,4 +2593,5 @@ summary({
   'glib_checks' : get_option('glib_checks'),
   'libelf' : get_option('libelf'),
   'multiarch' : get_option('multiarch'),
+  'introspection' : enable_gir,
 }, section: 'Options')

meson_options.txt

@@ -125,3 +125,8 @@ option('multiarch',
        type : 'boolean',
        value : false,
        description : 'Install some helper executables in per-architecture locations')
+
+option('introspection',
+       type: 'feature',
+       value: 'auto',
+       description: 'Enable generating introspection data (requires gobject-introspection)')