Add 'subprojects purge' command

This will help facilitate cache busting in certain situations, and
replaces hand-rolled solutions of writing a length command to remove
various files/folders within the subprojects directory.

docs/markdown/snippets/subprojects_purge.md

@@ -0,0 +1,18 @@
+## Purge subprojects folder
+
+It is now possible to purge a subprojects folder of artifacts created
+from wrap-based subprojects including anything in `packagecache`. This is useful
+when you want to return to a completely clean source tree or busting caches with
+stale patch directories or caches. By default the command will only print out
+what it is removing. You need to pass `--confirm` to the command for actual
+artifacts to be purged.
+
+By default all wrap-based subprojects will be purged.
+
+- `meson subprojects purge` prints non-cache wrap artifacts which will be
+purged.
+- `meson subprojects purge --confirm` purges non-cache wrap artifacts.
+- `meson subprojects purge --confirm --include-cache` also removes the cache
+artifacts.
+- `meson subprojects purge --confirm subproj1 subproj2` removes non-cache wrap
+artifacts associated with the listed subprojects.

mesonbuild/msubprojects.py

@@ -4,7 +4,7 @@ from pathlib import Path
 
 from . import mlog
 from .mesonlib import quiet_git, verbose_git, GitException, Popen_safe, MesonException, windows_proof_rmtree
-from .wrap.wrap import API_ROOT, Resolver, WrapException, ALL_TYPES
+from .wrap.wrap import API_ROOT, PackageDefinition, Resolver, WrapException, ALL_TYPES
 from .wrap import wraptool
 
 ALL_TYPES_STRING = ', '.join(ALL_TYPES)
@@ -312,6 +312,61 @@ def foreach(r, wrap, repo_dir, options):
     mlog.log(out, end='')
     return True
 
+def purge(r: Resolver, wrap: PackageDefinition, repo_dir: str, options: argparse.Namespace) -> bool:
+    # if subproject is not wrap-based, then don't remove it
+    if not wrap.type:
+        return True
+
+    if wrap.type == 'redirect':
+        redirect_file = Path(wrap.filename).resolve()
+        if options.confirm:
+            redirect_file.unlink()
+        mlog.log(f'Deleting {redirect_file}')
+
+    if options.include_cache:
+        packagecache = Path(r.cachedir).resolve()
+        subproject_cache_file = packagecache / wrap.get("source_filename")
+        if subproject_cache_file.is_file():
+            if options.confirm:
+                subproject_cache_file.unlink()
+            mlog.log(f'Deleting {subproject_cache_file}')
+
+        try:
+            subproject_patch_file = packagecache / wrap.get("patch_filename")
+            if subproject_patch_file.is_file():
+                if options.confirm:
+                    subproject_patch_file.unlink()
+                mlog.log(f'Deleting {subproject_patch_file}')
+        except WrapException:
+            pass
+
+        # Don't log that we will remove an empty directory
+        if packagecache.exists() and not any(packagecache.iterdir()):
+            packagecache.rmdir()
+
+    subproject_source_dir = Path(repo_dir).resolve()
+
+    # Don't follow symlink. This is covered by the next if statement, but why
+    # not be doubly sure.
+    if subproject_source_dir.is_symlink():
+        if options.confirm:
+            subproject_source_dir.unlink()
+        mlog.log(f'Deleting {subproject_source_dir}')
+        return True
+
+    if not subproject_source_dir.is_dir():
+        return True
+
+    try:
+        if options.confirm:
+            windows_proof_rmtree(str(subproject_source_dir))
+        mlog.log(f'Deleting {subproject_source_dir}')
+    except OSError as e:
+        mlog.error(f'Unable to remove: {subproject_source_dir}: {e}')
+        return False
+
+    return True
+
 def add_common_arguments(p):
     p.add_argument('--sourcedir', default='.',
                    help='Path to source directory')
@@ -361,6 +416,13 @@ def add_arguments(parser):
     p.set_defaults(subprojects=[])
     p.set_defaults(subprojects_func=foreach)
 
+    p = subparsers.add_parser('purge', help='Remove all wrap-based subproject artifacts')
+    add_common_arguments(p)
+    add_subprojects_argument(p)
+    p.add_argument('--include-cache', action='store_true', default=False, help='Remove the package cache as well')
+    p.add_argument('--confirm', action='store_true', default=False, help='Confirm the removal of subproject artifacts')
+    p.set_defaults(subprojects_func=purge)
+
 def run(options):
     src_dir = os.path.relpath(os.path.realpath(options.sourcedir))
     if not os.path.isfile(os.path.join(src_dir, 'meson.build')):

run_unittests.py

@@ -9675,6 +9675,8 @@ class SubprojectsCommandTests(BasePlatformTests):
 
         self.subprojects_dir = self.project_dir / 'subprojects'
         os.makedirs(str(self.subprojects_dir))
+        self.packagecache_dir = self.subprojects_dir / 'packagecache'
+        os.makedirs(str(self.packagecache_dir))
 
     def _create_project(self, path, project_name='dummy'):
         os.makedirs(str(path), exist_ok=True)
@@ -9752,10 +9754,12 @@ class SubprojectsCommandTests(BasePlatformTests):
         path = self.root_dir / tarball
         with open(str((self.subprojects_dir / name).with_suffix('.wrap')), 'w') as f:
             f.write(textwrap.dedent(
-                '''
+                f'''
                 [wrap-file]
-                source_url={}
+                source_url={os.path.abspath(str(path))}
-                '''.format(os.path.abspath(str(path)))))
+                source_filename={tarball}
+                '''))
+        Path(self.packagecache_dir / tarball).touch()
 
     def _subprojects_cmd(self, args):
         return self._run(self.meson_command + ['subprojects'] + args, workdir=str(self.project_dir))
@@ -9864,6 +9868,27 @@ class SubprojectsCommandTests(BasePlatformTests):
         out = self._subprojects_cmd(['foreach', '--types', 'git'] + dummy_cmd)
         self.assertEqual(ran_in(out), ['subprojects/sub_git'])
 
+    def test_purge(self):
+        self._create_project(self.subprojects_dir / 'sub_file')
+        self._wrap_create_file('sub_file')
+
+        def deleting(s) -> T.List[str]:
+            ret = []
+            prefix = 'Deleting '
+            for l in s.splitlines():
+                if l.startswith(prefix):
+                    ret.append(l[len(prefix):])
+            return sorted(ret)
+
+        out = self._subprojects_cmd(['purge'])
+        self.assertEqual(deleting(out), [str(self.subprojects_dir / 'sub_file')])
+        out = self._subprojects_cmd(['purge', '--include-cache'])
+        self.assertEqual(deleting(out), [str(self.subprojects_dir / 'packagecache' / 'dummy.tar.gz'), str(self.subprojects_dir / 'sub_file')])
+        out = self._subprojects_cmd(['purge', '--include-cache', '--confirm'])
+        self.assertEqual(deleting(out), [str(self.subprojects_dir / 'packagecache' / 'dummy.tar.gz'), str(self.subprojects_dir / 'sub_file')])
+        self.assertFalse(Path(self.subprojects_dir / 'packagecache' / 'dummy.tar.gz').exists())
+        self.assertFalse(Path(self.subprojects_dir / 'sub_file').exists())
+
 def _clang_at_least(compiler: 'Compiler', minver: str, apple_minver: T.Optional[str]) -> bool:
     """
     check that Clang compiler is at least a specified version, whether AppleClang or regular Clang