[pygobject] meson: Make the `pycairo` option a feature

[Christoph Reiter <creiter src gnome org>]

commit 505c4b22d58d1e0e9a4dae53f1b55a9a4a39d945
Author: Thibault Saunier <tsaunier igalia com>
Date:   Wed Jun 3 15:24:52 2020 -0400

    meson: Make the `pycairo` option a feature
    
    So user have more control on whether to build it or not

 gi/meson.build    | 2 +-
 meson.build       | 5 ++++-
 meson_options.txt | 2 +-
 tests/meson.build | 4 ++--
 4 files changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/gi/meson.build b/gi/meson.build
index 4a049479..8edf8328 100644
--- a/gi/meson.build
+++ b/gi/meson.build
@@ -79,7 +79,7 @@ giext = python.extension_module('_gi', sources,
   c_args: pyext_c_args + main_c_args
 )
 
-if with_pycairo
+if cairo_dep.found()
   gicairoext = python.extension_module('_gi_cairo', ['pygi-foreign-cairo.c'],
     dependencies : [python_ext_dep, glib_dep, gi_dep, ffi_dep, pycairo_dep, cairo_dep, cairo_gobject_dep],
     install: true,
diff --git a/meson.build b/meson.build
index 948a09f0..4826600c 100644
--- a/meson.build
+++ b/meson.build
@@ -43,7 +43,7 @@ with_pycairo = get_option('pycairo')
 
 cc = meson.get_compiler('c')
 
-if with_pycairo
+if not with_pycairo.disabled()
   cairo_dep = dependency('cairo', required: cc.get_id() != 'msvc')
   cairo_gobject_dep = dependency('cairo-gobject', required: cc.get_id() != 'msvc')
 
@@ -59,7 +59,10 @@ if with_pycairo
     version: pycairo_version_req,
     fallback: ['pycairo', 'pycairo_dep'],
     default_options: ['python=' + get_option('python')],
+    required: with_pycairo,
   )
+else
+  pycairo_dep = dependency('', required: false)
 endif
 
 main_c_args = []
diff --git a/meson_options.txt b/meson_options.txt
index 5dd4cbcd..4fb5304c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -1,3 +1,3 @@
 option('python', type : 'string', value : 'python3')
-option('pycairo', type : 'boolean', value : true, description : 'build with pycairo integration')
+option('pycairo', type : 'feature', value : 'auto', description : 'build with pycairo integration')
 option('tests', type : 'boolean', value : true, description : 'build unit tests')
diff --git a/tests/meson.build b/tests/meson.build
index dbb74d17..6a25688e 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -68,7 +68,7 @@ regress_headers += ['regressextra.h']
 regress_deps = [glib_dep, gobject_dep, gio_dep, gmodule_dep]
 regress_c_args = []
 
-if with_pycairo
+if cairo_dep.found()
   regress_deps += [cairo_dep, cairo_gobject_dep]
 else
   regress_c_args += ['-D_GI_DISABLE_CAIRO']
@@ -121,7 +121,7 @@ if host_machine.system() == 'windows'
 endif
 
 python_paths = [join_paths(meson.current_build_dir(), '..')]
-if with_pycairo and pycairo_dep.type_name() == 'internal'
+if pycairo_dep.found() and pycairo_dep.type_name() == 'internal'
   python_paths += [join_paths(meson.build_root(), 'subprojects', 'pycairo')]
 endif
 envdata.append('PYTHONPATH', python_paths)