Issue #11317: make Python plug-ins mandatory.

Unlike the other bindings (Lua, JS, Vala) where we only have a demo
plug-in, we actually have a bunch of interesting and useful Python
plug-ins.

Furthermore, we are running several Python scripts through GIMP during
our build (to generate a few images), so pygobject becomes a build
dependency anyway, even if it may not be a run dependency with
-Dpython=disabled.

This all becomes a bit confusing and in fact handling this case (of not
installing Python plug-ins) seems like an annoyance while we lose good
core plug-ins. So let's just make Python plug-ins mandatory. It's not
like Python is very controversial these days, and AFAWK, it is available
on every platform out there.

extensions/goat-exercises/meson.build

@@ -65,13 +65,11 @@ endif
 
 # Python 3 (pygobject) version.
 
-if have_python
-  install_data(
-    'goat-exercise-py3.py',
-    install_dir: gimpplugindir /  'extensions' / extension_name,
-  )
-  plug_ins = plug_ins + ':goat-exercise-py3.py'
-endif
+install_data(
+  'goat-exercise-py3.py',
+  install_dir: gimpplugindir /  'extensions' / extension_name,
+)
+plug_ins = plug_ins + ':goat-exercise-py3.py'
 
 # Javascript (GJS) version.
 

libgimp/meson.build

@@ -570,7 +570,7 @@ else
   endif
 endif
 
-if have_python and not platform_windows and not platform_osx
+if not platform_windows and not platform_osx
   # Verify .def files for Windows.
   # Ironically we only check this on non-Windows platform, since the
   # script expects .so libraries, and I'm not sure that the `nm` tool is

meson.build

@@ -1075,46 +1075,27 @@ perl = find_program('perl5', 'perl', 'perl5.005', 'perl5.004', 'perl')
 
 python3_minver = '>=3.6'
 
-python = pythonmod.find_installation('python3')
+python = pythonmod.find_installation('python3', required: true)
 message('Found Python @0@'.format(python.language_version()))
 
-have_python = get_option('python').enabled()
-
-if get_option('python').allowed()
-  python_found = (
-    python.found() and
-    python.language_version().version_compare(python3_minver)
-  )
-  if python_found
-    pygobject_found = run_command(
-      python, '-c',
-      '\n'.join([
-        '''import sys, gi''',
-        '''version = '@0@' '''.format('3.0'),
-        '''sys.exit(gi.check_version(version))''',
-      ]),
-      check: false
-    ).returncode() == 0
-    message('Found Pygobject: @0@'.format(pygobject_found))
-    python_found = python_found and pygobject_found
-  endif
-
-  if python_found
-    have_python = true
-  elif have_python
-    python_warning = '''
-    Python @0@ or PyGObject was not found.
-    Python plug-ins will be installed anyway but you should make sure that
-    a compatible Python interpreter is available at installation, otherwise
-    installed plug-ins won't be usable.
-    '''.format(python3_minver)
-    warning(python_warning)
-    warnings += python_warning
-  endif
-
-  MIMEtypes += 'image/openraster'
+if not python.language_version().version_compare(python3_minver)
+  error('Minimum supported Python version: @0@'.format(python3_minver))
 endif
 
+pygobject_found = run_command(python, '-c',
+                              '\n'.join([
+                              '''import sys, gi''',
+                              '''version = '@0@' '''.format('3.0'),
+                              '''sys.exit(gi.check_version(version))''']),
+                              check: false).returncode() == 0
+message('Found PyGObject: @0@'.format(pygobject_found))
+
+if not pygobject_found
+  error('PyGObject is required.')
+endif
+
+MIMEtypes += 'image/openraster'
+
 ## Javascript
 
 gjs = find_program('gjs', required: get_option('javascript'))
@@ -2081,7 +2062,6 @@ final_message = [
                                 .format(can_import_avif, can_export_avif),
 '''  PDF (export):        @0@'''.format(cairopdf.found()),
 '''  Print:               @0@'''.format(have_print),
-'''  Python 3 plug-ins:   @0@'''.format(have_python),
 '''  Javascript plug-ins: @0@'''.format(have_javascript),
 '''  Lua plug-ins:        @0@'''.format(have_lua),
 '''  Vala plug-ins:       @0@'''.format(have_vala),

meson_options.txt

@@ -66,4 +66,3 @@ option('vector-icons',      type: 'boolean', value: true,   description: 'Use ve
 option('vala',              type: 'feature', value: 'auto', description: 'Build VAPI and Vala plugins')
 option('javascript',        type: 'feature', value: 'auto', description: 'Install Javascript plug-ins')
 option('lua',               type: 'feature', value: 'auto', description: 'Install Lua plug-ins')
-option('python',            type: 'feature', value: 'auto', description: 'Install Python 3 plug-ins')

plug-ins/python/meson.build

@@ -24,10 +24,8 @@ foreach plugin : plugins
   name = plugin.get('name')
   srcs = plugin.get('srcs', [name + '.py'])
 
-  if have_python
-    install_data(srcs, install_dir: gimpplugindir / 'plug-ins' / name,
-                 install_mode: 'rwxr-xr-x')
-  endif
+  install_data(srcs, install_dir: gimpplugindir / 'plug-ins' / name,
+               install_mode: 'rwxr-xr-x')
 
   foreach src : srcs
     # Ugly trick to copy Python plug-ins into subfolders so that we can run GIMP
@@ -39,16 +37,14 @@ foreach plugin : plugins
   endforeach
 endforeach
 
-if have_python
-  # Fallback fix to the problem of non-configured interpreters
-  if platform_windows and not meson.is_cross_build() and python.found()
-    python_config = configuration_data()
-    python_config.set('PYTHON_PATH', '')
+# Fallback fix to the problem of non-configured interpreters
+if platform_windows and not meson.is_cross_build() and python.found()
+  python_config = configuration_data()
+  python_config.set('PYTHON_PATH', '')
 
-    configure_file(input : 'pygimp.interp.in',
-                   output: 'pygimp.interp',
-                   configuration: python_config,
-                   install: true,
-                   install_dir: gimpplugindir / 'interpreters')
-  endif
+  configure_file(input : 'pygimp.interp.in',
+                 output: 'pygimp.interp',
+                 configuration: python_config,
+                 install: true,
+                 install_dir: gimpplugindir / 'interpreters')
 endif

plug-ins/python/tests/meson.build

@@ -1,5 +1 @@
-if not have_python
-  subdir_done()
-endif
-
-subdir('test-file-plug-ins')
+subdir('test-file-plug-ins')