[gnome-tweaks/wip/christopherdavis/python3-deprecation-fix: 87/87] build: Use python module instead of deprecated python3 module

[Evan Welsh <ewlsh src gnome org>]

commit f0deae535481bd6e728add84017ca0d7a703e406
Author: Mart Raudsepp <leio gentoo org>
Date:   Tue Feb 26 13:43:27 2019 -0500

    build: Use python module instead of deprecated python3 module
    
    The meson python3 module is deprecated and tends install only
    to a python version that meson is installed for too, possibly
    breaking some expectations downstream that want it installed to
    a specific python3 version.
    
    The python module exists since 0.46, which should be safe to require
    by now.
    
    Co-authored-by: Christopher Davis <brainblasted disroot org>

 gtweak/meson.build |  5 ++---
 meson.build        | 13 +++++++++----
 2 files changed, 11 insertions(+), 7 deletions(-)
---
diff --git a/gtweak/meson.build b/gtweak/meson.build
index 052b7cb4..a491f6a4 100644
--- a/gtweak/meson.build
+++ b/gtweak/meson.build
@@ -11,7 +11,6 @@ configure_file(
   input: 'defs.py.in',
   output: 'defs.py',
   configuration: defs_conf,
-  install: true,
   install_dir: gtweakdir
 )
 
@@ -44,5 +43,5 @@ tweak_sources = [
   'tweaks/tweak_wacom.py',
 ]
 
-install_data(shell_sources, install_dir: gtweakdir)
-install_data(tweak_sources, install_dir: gtweakdir + '/tweaks')
+python3.install_sources(shell_sources, subdir: 'gtweak')
+python3.install_sources(tweak_sources, subdir: join_paths('gtweak', 'tweaks'))
diff --git a/meson.build b/meson.build
index b7da5186..b1571df9 100644
--- a/meson.build
+++ b/meson.build
@@ -1,11 +1,16 @@
 project('gnome-tweaks',
   version: '3.34.0',
-  meson_version: '>= 0.40.0'
+  meson_version: '>= 0.46.0'
 )
 
 gnome = import('gnome')
 i18n = import('i18n')
-python3 = import('python3')
+python = import('python')
+python3 = python.find_installation('python3')
+
+if not python3.found()
+    error('No valid python3 installation found!')
+endif
 
 prefix = get_option('prefix')
 
@@ -13,13 +18,13 @@ bindir = join_paths(prefix, get_option('bindir'))
 datadir = join_paths(prefix, get_option('datadir'))
 libexecdir = join_paths(prefix, get_option('libexecdir'))
 localedir = join_paths(prefix, get_option('localedir'))
-pythondir = join_paths(prefix, python3.sysconfig_path('purelib'))
+pythondir = join_paths(prefix, python3.get_path('purelib'))
 
 pkgdatadir = join_paths(datadir, meson.project_name())
 
 appdatadir = join_paths(datadir, 'metainfo')
 desktopdir = join_paths(datadir, 'applications')
-gtweakdir = join_paths(pythondir, 'gtweak')
+gtweakdir = python3.get_install_dir(subdir: 'gtweak')
 icondir = join_paths(datadir, 'icons', 'hicolor')
 schemadir = join_paths(datadir, 'glib-2.0', 'schemas')