Build the API references with the generated GIR data

Gate the API reference on the availability of the introspection data as
well, so we don't accidentally try and generate the documentation
without a description of our API.

docs/reference/gio/meson.build

@@ -235,11 +235,10 @@ expand_content_files = [
   'overview.md',
 ]
 
-gio_gir = meson.current_source_dir() / 'Gio-2.0.gir'
 gio_toml = configure_file(input: 'gio.toml.in', output: 'gio.toml', configuration: toml_conf)
 
 custom_target('gio-docs',
-  input: [ gio_toml, gio_gir ],
+  input: [ gio_toml, gio_gir[0] ],
   output: 'gio',
   command: [
     gidocgen,

docs/reference/glib/meson.build

@@ -166,11 +166,10 @@ expand_content_files = [
   'unicode.md',
 ]
 
-glib_gir = meson.current_source_dir() / 'GLib-2.0.gir'
 glib_toml = configure_file(input: 'glib.toml.in', output: 'glib.toml', configuration: toml_conf)
 
 custom_target('glib-docs',
-  input: [ glib_toml, glib_gir ],
+  input: [ glib_toml, glib_gir[0] ],
   output: 'glib',
   command: [
     gidocgen,

docs/reference/gmodule/meson.build

@@ -2,11 +2,10 @@ expand_content_files = [
   'modules.md',
 ]
 
-gmodule_gir = meson.current_source_dir() / 'GModule-2.0.gir'
 gmodule_toml = configure_file(input: 'gmodule.toml.in', output: 'gmodule.toml', configuration: toml_conf)
 
 custom_target('gmodule-docs',
-  input: [ gmodule_toml, gmodule_gir ],
+  input: [ gmodule_toml, gmodule_gir[0] ],
   output: 'gmodule',
   command: [
     gidocgen,

docs/reference/gobject/meson.build

@@ -76,11 +76,10 @@ expand_content_files = [
   'signals.md',
 ]
 
-gobject_gir = meson.current_source_dir() / 'GObject-2.0.gir'
 gobject_toml = configure_file(input: 'gobject.toml.in', output: 'gobject.toml', configuration: toml_conf)
 
 custom_target('gobject-docs',
-  input: [ gobject_toml, gobject_gir ],
+  input: [ gobject_toml, gobject_gir[0] ],
   output: 'gobject',
   command: [
     gidocgen,

docs/reference/meson.build

@@ -54,7 +54,7 @@ if get_option('gtk_doc')
 endif
 
 # gi-docgen version
-if get_option('gtk_doc')
+if get_option('gtk_doc') and enable_gir
   gidocgen_dep = dependency('gi-docgen', version: '>= 2023.1',
                           fallback: ['gi-docgen', 'dummy_dep'],
                           required: true)