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().

1 files changed, 7 insertions, 0 deletions

diff --git a/docs/markdown/snippets/subproject-foreach.md b/docs/markdown/snippets/subproject-foreach.md
new file mode 100644
index 0000000..3a8ffc4
--- /dev/null
+++ b/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.