Generate & install completion scripts in build system

The previous commit added a means to generating the completion scripts
and this one plugs that into the build system.

A new build option 'install_completions' has been introduced.

Completions for bash and fish use pkg-config for getting the preferred
install locations for the completions. If the packages are not
available, fallbacks are in-place.

The 'completion' subdir has been kept to work around the ideology of
Meson that does not allow creating/outputing files in subdirectories nor
using the output of custom_target() in install_data().

containers#840

Author: HarryMichal

README.md

@@ -79,8 +79,9 @@ The following dependencies are required to build it:
 - ninja
 - patchelf
 
-The following dependencies enable various optional features:
+The following dependencies provide information on where to install shell completions:
 - bash-completion
+- fish
 
 It can be built and installed as any other typical Meson-based project:
 ```console

completion/bash/toolbox

@@ -0,0 +1,34 @@
+if bash_completion.found()
+  bash_comp_dir = bash_completion.get_pkgconfig_variable('completionsdir')
+else
+  bash_comp_dir = get_option('datadir') / 'bash-completion' / 'completions'
+  message('bash-completion not found: using', get_option('prefix') / bash_comp_dir, 'as a falback install directory')
+endif
+
+if fish.found()
+  fish_comp_dir = fish.get_pkgconfig_variable('completionsdir')
+else
+  fish_comp_dir = get_option('datadir') / 'fish' / 'completions'
+  message('fish not found: using', get_option('prefix') / fish_comp_dir, 'as a fallback install directory')
+endif
+
+completion_bash = custom_target('bash-completion',
+  capture: true,
+  command: [toolbox_bin, 'completion', 'bash'],
+  install: true,
+  install_dir: bash_comp_dir,
+  output: 'toolbox')
+
+completion_zsh = custom_target('zsh-completion',
+  capture: true,
+  command: [toolbox_bin, 'completion', 'zsh'],
+  install: true,
+  install_dir: get_option('datadir') / 'zsh' / 'site_functions',
+  output: '_toolbox')
+
+completion_fish = custom_target('fish-completion',
+  capture: true,
+  command: [toolbox_bin, 'completion', 'fish'],
+  install: true,
+  install_dir: fish_comp_dir,
+  output: 'toolbox.fish')

completion/meson.build

@@ -2,7 +2,7 @@ project(
   'toolbox',
   version: '0.0.99.2',
   license: 'ASL 2.0',
-  meson_version: '>= 0.53.0',
+  meson_version: '>= 0.54.0',
 )
 
 go = find_program('go')
@@ -12,6 +12,7 @@ shellcheck = find_program('shellcheck', required: false)
 skopeo = find_program('skopeo', required: false)
 
 bash_completion = dependency('bash-completion', required: false)
+fish = dependency('fish', required: false)
 
 profiledir = get_option('profile_dir')
 
@@ -21,13 +22,6 @@ if tmpfilesdir == ''
   tmpfilesdir = systemd_dep.get_pkgconfig_variable('tmpfilesdir')
 endif
 
-if bash_completion.found()
-  install_data(
-    'completion/bash/toolbox',
-    install_dir: bash_completion.get_pkgconfig_variable('completionsdir')
-  )
-endif
-
 if not skopeo.found()
     message('Running system tests requires Skopeo for OCI image manipulation.')
 endif
@@ -59,3 +53,6 @@ subdir('data')
 subdir('doc')
 subdir('profile.d')
 subdir('src')
+if get_option('install_completions')
+  subdir('completion')
+endif

meson.build

@@ -10,3 +10,10 @@ option(
   description: 'Directory for system-wide tmpfiles.d(5) files',
   type: 'string',
 )
+
+option(
+  'install_completions',
+  description: 'Install bash, zsh and fish command completions',
+  type: 'boolean',
+  value: true,
+)

meson_options.txt

@@ -20,7 +20,7 @@ sources = files(
   'pkg/version/version.go',
 )
 
-custom_target(
+toolbox_bin = custom_target(
   'toolbox',
   build_by_default: true,
   command: [