build: drop -Dout in favor of --prefix

$ meson --prefix=/tmp/foo _build
$ ninja install -C _build
[49/50] Installing files.
Installing waybar to /tmp/foo/bin
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/mesonbuild/mesonmain.py", line 127, in run
    return options.run_func(options)
  File "/usr/lib/python3.6/site-packages/mesonbuild/minstall.py", line 514, in run
    installer.do_install(datafilename)
  File "/usr/lib/python3.6/site-packages/mesonbuild/minstall.py", line 346, in do_install
    self.install_data(d)
  File "/usr/lib/python3.6/site-packages/mesonbuild/minstall.py", line 375, in install_data
    d.dirmaker.makedirs(outdir, exist_ok=True)
  File "/usr/lib/python3.6/site-packages/mesonbuild/minstall.py", line 55, in makedirs
    os.makedirs(path, exist_ok=exist_ok)
  File "/usr/lib/python3.6/os.py", line 210, in makedirs
    makedirs(head, mode, exist_ok)
  File "/usr/lib/python3.6/os.py", line 220, in makedirs
    mkdir(name, mode)
PermissionError: [Errno 13] Permission denied: '/etc/xdg'
FAILED: meson-install

meson.build

@@ -89,9 +89,12 @@ systemd = dependency('systemd', required: get_option('systemd'))
 tz_dep = dependency('date', default_options : [ 'use_system_tzdb=true' ], fallback: [ 'date', 'tz_dep' ])
 
 prefix = get_option('prefix')
+sysconfdir = get_option('sysconfdir')
 conf_data = configuration_data()
 conf_data.set('prefix', prefix)
 
+add_project_arguments('-DSYSCONFDIR="/@0@"'.format(join_paths(prefix, sysconfdir)), language : 'cpp')
+
 if systemd.found()
   user_units_dir = systemd.get_pkgconfig_variable('systemduserunitdir')
 
@@ -198,7 +201,7 @@ executable(
 install_data(
     './resources/config',
     './resources/style.css',
-    install_dir: join_paths(get_option('out'), 'etc/xdg/waybar')
+    install_dir: sysconfdir + '/xdg/waybar'
 )
 
 scdoc = dependency('scdoc', version: '>=1.9.2', native: true, required: get_option('man-pages'))

meson_options.txt

@@ -6,5 +6,4 @@ option('systemd', type: 'feature', value: 'auto', description: 'Install systemd
 option('dbusmenu-gtk', type: 'feature', value: 'auto', description: 'Enable support for tray')
 option('man-pages', type: 'feature', value: 'auto', description: 'Generate and install man pages')
 option('mpd', type: 'feature', value: 'auto', description: 'Enable support for the Music Player Daemon')
-option('out', type: 'string', value : '/', description: 'output prefix directory')
 option('gtk-layer-shell', type: 'feature', value: 'auto', description: 'Use gtk-layer-shell library for popups support')

src/client.cpp

@@ -161,7 +161,7 @@ std::tuple<const std::string, const std::string> waybar::Client::getConfigs(
                                           "$XDG_CONFIG_HOME/waybar/config",
                                           "$HOME/.config/waybar/config",
                                           "$HOME/waybar/config",
-                                          "/etc/xdg/waybar/config",
+                                          SYSCONFDIR "/xdg/waybar/config",
                                           "./resources/config",
                                       })
                                     : config;
@@ -169,7 +169,7 @@ std::tuple<const std::string, const std::string> waybar::Client::getConfigs(
                                       "$XDG_CONFIG_HOME/waybar/style.css",
                                       "$HOME/.config/waybar/style.css",
                                       "$HOME/waybar/style.css",
-                                      "/etc/xdg/waybar/style.css",
+                                      SYSCONFDIR "/xdg/waybar/style.css",
                                       "./resources/style.css",
                                   })
                                 : style;