Use a script to clean-up custom-target output dirs

The script will manually delete all custom_target outputs that are
directories instead of files. This is needed because on platforms other
than Windows, Ninja only deletes directories while cleaning if they are
empty.

Closes #1220

mesonbuild/backend/backends.py

@@ -22,6 +22,15 @@ import json
 import subprocess
 from ..mesonlib import MesonException, get_compiler_for_source, classify_unity_sources
 
+class CleanTrees():
+    '''
+    Directories outputted by custom targets that have to be manually cleaned
+    because on Linux `ninja clean` only deletes empty directories.
+    '''
+    def __init__(self, build_dir, trees):
+        self.build_dir = build_dir
+        self.trees = trees
+
 class InstallData():
     def __init__(self, source_dir, build_dir, prefix):
         self.source_dir = source_dir

mesonbuild/backend/ninjabackend.py

@@ -20,7 +20,7 @@ from .. import mlog
 from .. import dependencies
 from .. import compilers
 from ..mesonlib import File, MesonException, get_compiler_for_source, Popen_safe
-from .backends import InstallData
+from .backends import CleanTrees, InstallData
 from ..build import InvalidArguments
 import os, sys, pickle, re
 import subprocess, shutil
@@ -2109,6 +2109,22 @@ rule FORTRAN_DEP_HACK
             except OSError:
                 mlog.debug("Library versioning disabled because we do not have symlink creation privileges.")
 
+    def generate_custom_target_clean(self, outfile, trees):
+        e = NinjaBuildElement(self.all_outputs, 'clean-ctlist', 'CUSTOM_COMMAND', 'PHONY')
+        d = CleanTrees(self.environment.get_build_dir(), trees)
+        d_file = os.path.join(self.environment.get_scratch_dir(), 'cleantrees.dat')
+        script_root = self.environment.get_script_dir()
+        clean_script = os.path.join(script_root, 'cleantrees.py')
+        e.add_item('COMMAND', [sys.executable,
+                               self.environment.get_build_command(),
+                               '--internal', 'cleantrees', d_file])
+        e.add_item('description', 'Cleaning CustomTarget directories')
+        e.write(outfile)
+        # Write out the data file passed to the script
+        with open(d_file, 'wb') as ofile:
+            pickle.dump(d, ofile)
+        return 'clean-ctlist'
+
     def generate_gcov_clean(self, outfile):
             gcno_elem = NinjaBuildElement(self.all_outputs, 'clean-gcno', 'CUSTOM_COMMAND', 'PHONY')
             script_root = self.environment.get_script_dir()
@@ -2136,14 +2152,19 @@ rule FORTRAN_DEP_HACK
 
     def generate_ending(self, outfile):
         targetlist = []
+        ctlist = []
         for t in self.build.get_targets().values():
             # RunTargets are meant to be invoked manually
             if isinstance(t, build.RunTarget):
                 continue
-            # CustomTargets that aren't installed should only be built if they
-            # are used by something else or are meant to be always built
-            if isinstance(t, build.CustomTarget) and not (t.install or t.build_always):
-                continue
+            if isinstance(t, build.CustomTarget):
+                # Create a list of all custom target outputs
+                for o in t.get_outputs():
+                    ctlist.append(os.path.join(self.get_target_dir(t), o))
+                # CustomTargets that aren't installed should only be built if
+                # they are used by something else or are to always be built
+                if not (t.install or t.build_always):
+                    continue
             # Add the first output of each target to the 'all' target so that
             # they are all built
             targetlist.append(os.path.join(self.get_target_dir(t), t.get_outputs()[0]))
@@ -2160,6 +2181,14 @@ rule FORTRAN_DEP_HACK
         elem = NinjaBuildElement(self.all_outputs, 'clean', 'CUSTOM_COMMAND', 'PHONY')
         elem.add_item('COMMAND', [ninja_command, '-t', 'clean'])
         elem.add_item('description', 'Cleaning')
+        # If we have custom targets in this project, add all their outputs to
+        # the list that is passed to the `cleantrees.py` script. The script
+        # will manually delete all custom_target outputs that are directories
+        # instead of files. This is needed because on platforms other than
+        # Windows, Ninja only deletes directories while cleaning if they are
+        # empty. https://github.com/mesonbuild/meson/issues/1220
+        if ctlist:
+            elem.add_dep(self.generate_custom_target_clean(outfile, ctlist))
         if 'b_coverage' in self.environment.coredata.base_options and \
            self.environment.coredata.base_options['b_coverage'].value:
             self.generate_gcov_clean(outfile)

mesonbuild/mesonmain.py

@@ -198,6 +198,9 @@ def run_script_command(args):
     if cmdname == 'exe':
         import mesonbuild.scripts.meson_exe as abc
         cmdfunc = abc.run
+    elif cmdname == 'cleantrees':
+        import mesonbuild.scripts.cleantrees as abc
+        cmdfunc = abc.run
     elif cmdname == 'install':
         import mesonbuild.scripts.meson_install as abc
         cmdfunc = abc.run

mesonbuild/scripts/cleantrees.py

@@ -0,0 +1,43 @@
+# Copyright 2016 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import sys
+import shutil
+import pickle
+
+def rmtrees(build_dir, trees):
+    for t in trees:
+        # Never delete trees outside of the builddir
+        if os.path.isabs(t):
+            print('Cannot delete dir with absolute path {!r}'.format(t))
+            continue
+        bt = os.path.join(build_dir, t)
+        # Skip if it doesn't exist, or if it is not a directory
+        if os.path.isdir(bt):
+            shutil.rmtree(bt, ignore_errors=True)
+
+def run(args):
+    if len(args) != 1:
+        print('Cleaner script for Meson. Do not run on your own please.')
+        print('cleantrees.py <data-file>')
+        return 1
+    with open(args[0], 'rb') as f:
+        data = pickle.load(f)
+    rmtrees(data.build_dir, data.trees)
+    # Never fail cleaning
+    return 0
+
+if __name__ == '__main__':
+    run(sys.argv[1:])