meson: add an argument-comments test suite

Run tools/check-argument-comments.py over the sources that are compiled,
one test per top-level source directory, in a suite that a plain "meson
test" leaves out like the other linters. The NSS, PAM and cryptsetup
token modules don't end up in sources, so collect theirs as well. The
source directory is passed explicitly, so the suite works without git,
from a tarball say. The script exits with meson's skip code where the
libclang python bindings are missing.

meson.build

@@ -16,7 +16,7 @@ project('systemd', 'c',
 
 add_test_setup(
         'default',
-        exclude_suites : ['clang-tidy', 'coccinelle', 'unused-symbols', 'integration-tests'],
+        exclude_suites : ['clang-tidy', 'coccinelle', 'argument-comments', 'unused-symbols', 'integration-tests'],
         exe_wrapper : find_program('tools/test-crash-trace.sh'),
         is_default : true,
 )
@@ -2889,6 +2889,7 @@ test_dlopen = executables_by_name.get('test-dlopen')
 nss_targets = []
 pam_targets = []
 module_targets = []
+module_sources = []
 modules_by_name = {}
 foreach dict : modules
         name = dict.get('name')
@@ -2906,6 +2907,8 @@ foreach dict : modules
                 continue
         endif
 
+        module_sources += dict.get('sources', [])
+
         kwargs = {}
         foreach key, val : dict
                 if key in ['name', 'conditions', 'version-script']
@@ -3275,6 +3278,36 @@ if meson.version().version_compare('>=1.4.0')
                         endif
                 endforeach
         endforeach
+
+        # One test per top-level source directory over the compiled .c files, which covers the headers
+        # they include. Generated sources are not below src/ relative to the source directory. The NSS,
+        # PAM and cryptsetup token modules are not in sources.
+        argument_comments_sources = {}
+        foreach source : sources + module_sources
+                if not source.full_path().endswith('.c') or source.full_path().endswith('.bpf.c')
+                        continue
+                endif
+
+                source_parts = fs.relative_to(source.full_path(), meson.project_source_root()).split('/')
+                if source_parts.length() > 2 and source_parts[0] == 'src'
+                        argument_comments_sources += {
+                                source_parts[1] : argument_comments_sources.get(source_parts[1], []) + [source],
+                        }
+                endif
+        endforeach
+
+        argument_comments_args = ['-p', meson.project_build_root(), '--root', meson.project_source_root()]
+        foreach source_dir, source_dir_sources : argument_comments_sources
+                test(
+                        'argument-comments-@0@'.format(source_dir),
+                        check_argument_comments_py,
+                        args : argument_comments_args + source_dir_sources,
+                        suite : 'argument-comments',
+                        depends : generated_sources,
+                        is_parallel : false, # the script parallelizes over its files by itself
+                        timeout : 300,
+                )
+        endforeach
 endif
 
 spatch = find_program('spatch', required : false)

tools/meson.build

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 check_api_docs_sh              = files('check-api-docs.sh')
+check_argument_comments_py     = files('check-argument-comments.py')
 check_coccinelle_sh            = files('check-coccinelle.sh')
 check_efi_alignment_py         = files('check-efi-alignment.py')
 check_help_sh                  = files('check-help.sh')