Add 'meson subprojects foreach' command

Sometimes it is convenient to run an arbitrary command (e.g. 'git diff')
on all subprojects.

Add a 'meson subprojects foreach' command to take care of that.

For this command the common argument 'subprojects' does not make sense,
so only add '--sourcedir' and cover the case of a missing
options.subprojects in run().

docs/markdown/Subprojects.md

@@ -241,6 +241,15 @@ changes.
 To come back to the revision set in wrap file (i.e. master), just run
 `meson subprojects checkout` with no branch name.
 
+## Execute a command on all subprojects
+
+*Since 0.51.0*
+
+The command-line `meson subprojects foreach <command> [...]` will
+execute a command in each subproject directory. For example this can be useful
+to check the status of subprojects (e.g. with `git status` or `git diff`) before
+performing other actions on them.
+
 ## Why must all subprojects be inside a single directory?
 
 There are several reasons.

docs/markdown/snippets/subproject-foreach.md

@@ -0,0 +1,7 @@
+## Add new `meson subprojects foreach` command
+
+`meson subprojects` has learned a new `foreach` command which accepts a command
+with arguments and executes it in each subproject directory.
+
+For example this can be useful to check the status of subprojects (e.g. with
+`git status` or `git diff`) before performing other actions on them.

mesonbuild/msubprojects.py

@@ -1,4 +1,5 @@
 import os, subprocess
+import argparse
 
 from . import mlog
 from .mesonlib import Popen_safe
@@ -167,6 +168,18 @@ def download(wrap, repo_dir, options):
     except WrapException as e:
         mlog.log('  ->', mlog.red(str(e)))
 
+def foreach(wrap, repo_dir, options):
+    mlog.log('Executing command in %s' % repo_dir)
+    if not os.path.isdir(repo_dir):
+        mlog.log('  -> Not downloaded yet')
+        return
+    try:
+        subprocess.check_call([options.command] + options.args, cwd=repo_dir)
+        mlog.log('')
+    except subprocess.CalledProcessError as e:
+        out = e.output.decode().strip()
+        mlog.log('  -> ', mlog.red(out))
+
 def add_common_arguments(p):
     p.add_argument('--sourcedir', default='.',
                    help='Path to source directory')
@@ -197,6 +210,15 @@ def add_arguments(parser):
     add_common_arguments(p)
     p.set_defaults(subprojects_func=download)
 
+    p = subparsers.add_parser('foreach', help='Execute a command in each subproject directory.')
+    p.add_argument('command', metavar='command ...',
+                   help='Command to execute in each subproject directory')
+    p.add_argument('args', nargs=argparse.REMAINDER,
+                   help=argparse.SUPPRESS)
+    p.add_argument('--sourcedir', default='.',
+                   help='Path to source directory')
+    p.set_defaults(subprojects_func=foreach)
+
 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')):
@@ -207,13 +229,14 @@ def run(options):
         mlog.log('Directory', mlog.bold(src_dir), 'does not seem to have subprojects.')
         return 0
     files = []
-    for name in options.subprojects:
+    if hasattr(options, 'subprojects'):
-        f = os.path.join(subprojects_dir, name + '.wrap')
+        for name in options.subprojects:
-        if not os.path.isfile(f):
+            f = os.path.join(subprojects_dir, name + '.wrap')
-            mlog.error('Subproject', mlog.bold(name), 'not found.')
+            if not os.path.isfile(f):
-            return 1
+                mlog.error('Subproject', mlog.bold(name), 'not found.')
-        else:
+                return 1
-            files.append(f)
+            else:
+                files.append(f)
     if not files:
         for f in os.listdir(subprojects_dir):
             if f.endswith('.wrap'):