[libgudev] build: let meson handle gir, vala, gtk-doc dependencies

[Bastien Nocera <hadess src gnome org>]

commit 4216ecd4513bd4c8af73543817a51d6f72f166cc
Author: Artturi <artturin artturin com>
Date:   Mon Jul 11 08:35:09 2022 +0000

    build: let meson handle gir, vala, gtk-doc dependencies

 gudev/meson.build |  2 +-
 meson.build       | 23 ++++++-----------------
 2 files changed, 7 insertions(+), 18 deletions(-)
---
diff --git a/gudev/meson.build b/gudev/meson.build
index fd06a11..e904203 100644
--- a/gudev/meson.build
+++ b/gudev/meson.build
@@ -97,7 +97,7 @@ pkg.generate(
   ]
 )
 
-if introspection_dep.found()
+if gir_dep.found()
   libgudev_gir = gnome.generate_gir(
     libgudev,
     sources: libgudev_sources + libgudev_public_h,
diff --git a/meson.build b/meson.build
index eae2c80..f547a6d 100644
--- a/meson.build
+++ b/meson.build
@@ -42,9 +42,6 @@ cc = meson.get_compiler('c')
 
 glib_req = '>= 2.38.0'
 libudev_req = '>= 199'
-introspection_req = '>= 1.31.1'
-vapigen_req = '>= 0.38.0'
-gtk_doc_req = '>= 1.18'
 
 glib_dep = dependency('glib-2.0', version: glib_req)
 gobject_dep = dependency('gobject-2.0', version: glib_req)
@@ -58,20 +55,12 @@ umockdev_dep = dependency(
   required: get_option('tests')
 )
 
-introspection_dep = dependency(
-  'gobject-introspection-1.0', version: introspection_req,
-  required: get_option('introspection')
-)
-
-vapigen_dep = dependency(
-  'vapigen', version: vapigen_req,
-  required: get_option('vapi')
-)
+gir_dep = find_program('g-ir-scanner', required: get_option('introspection'))
+vapigen_dep = find_program('vapigen', required : get_option('vapi'))
 
-gtk_doc_dep = dependency(
-  'gtk-doc', version: gtk_doc_req,
-  required: get_option('gtk_doc')
-)
+if vapigen_dep.found()
+  assert(gir_dep.found(), 'vapi requires introspection')
+endif
 
 # Configurations
 config_h = configuration_data()
@@ -95,7 +84,7 @@ if get_option('gtk_doc')
 endif
 
 summary('Documentation', get_option('gtk_doc'), section: 'Build')
-summary('Introspection', introspection_dep.found(), section: 'Build')
+summary('Introspection', gir_dep.found(), section: 'Build')
 summary('Vala API', vapigen_dep.found(), section: 'Build')
 summary('Tests', umockdev_dep.found(), section: 'Build')