modules: add SUBDIRS support for vlc_modules_list generation

Move the vlc_modules_list generation logic to a shared modulelist.mk file
that can be included by both modules/Makefile.am and modules/gui/qt/Makefile.am.

Now each directory generates its own vlc_modules_list using LTLIBRARIES,
and the parent concatenates lists from SUBDIRS.

modules/Makefile.am

@@ -127,22 +127,6 @@ SUFFIXES += -client-protocol.h -protocol.c .xml
 	$(AM_V_GEN)$(WAYLAND_SCANNER) private-code < "$^" > "$@.tmp"
 	$(AM_V_at)mv -f -- "$@.tmp" "$@"
 
-# Remove the non-plugins, it needs intermediate steps because
+# Generate vlc_modules_list (local plugins + SUBDIRS)
-# we can only replace and not match inverse. Instead we;
+include modulelist.mk
-#  1/ replace plugins .la targets by plugins names
-#  2/ remove every word which is a .la target (ie. non-plugins)
-#  3/ rename every plugin name back into the target name
-ALL_TARGETS_PLUGIN_RENAMED := $(LTLIBRARIES:lib%_plugin.la=%_plugin)
-PLUGINS_NAMES := $(ALL_TARGETS_PLUGIN_RENAMED:%.la=)
-
-# Generate a list containing the name and path of every plugin being built
-# Format: plugin_name: relative/path/to/plugin.dylib
-# This allows plugins from SUBDIRS (like Qt) to specify their actual location
-vlc_modules_list: Makefile
-	$(AM_V_GEN)rm -f $@.tmp; for plugin in $(PLUGINS_NAMES); do \
-	printf "$${plugin}: $(subdir)/.libs/lib$${plugin}.dylib\n" >> $@.tmp; done
-	mv $@.tmp $@
-
-BUILT_SOURCES += vlc_modules_list
-CLEANFILES += vlc_modules_list
 SUBDIRS += .

modules/modulelist.mk

@@ -0,0 +1,30 @@
+# modulelist.mk - Generate vlc_modules_list from LTLIBRARIES and SUBDIRS
+# Paths are relative to top_builddir using automake's $(subdir)
+
+
+# Remove the non-plugins, it needs intermediate steps because
+# we can only replace and not match inverse. Instead we:
+#  1/ replace plugins .la targets by plugins names
+#  2/ remove every word which is a .la target (ie. non-plugins)
+#  3/ rename every plugin name back into the target name
+VLC_PLUGINS_RENAMED = $(LTLIBRARIES:lib%_plugin.la=%_plugin)
+VLC_PLUGINS = $(VLC_PLUGINS_RENAMED:%.la=)
+
+# Generate a list containing the name and path of every plugin being built
+# Format: plugin_name: relative/path/to/plugin$(LIBEXT)
+# This allows plugins from SUBDIRS (like Qt) to specify their actual location
+# The recipee concatenates records from local plugins and those from SUBDIRS
+vlc_modules_list: Makefile
+	$(AM_V_GEN)rm -f $@.tmp; \
+	for plugin in $(VLC_PLUGINS); do \
+		printf "$${plugin}: $(subdir)/.libs/lib$${plugin}$(LIBEXT)\n" >> $@.tmp; \
+	done; \
+	for subdir in $(SUBDIRS); do \
+		[ "$$subdir" = "." ] && continue; \
+		[ -f "$$subdir/vlc_modules_list" ] && \
+			cat "$$subdir/vlc_modules_list" >> $@.tmp; \
+	done; \
+	if [ -s "$@.tmp" ]; then mv $@.tmp $@; else rm -f $@.tmp && touch $@; fi
+
+BUILT_SOURCES += vlc_modules_list
+CLEANFILES += vlc_modules_list