X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=subdirmk%2Fregen.mk.in;h=d11e05c0a752c1e8a80a93f6cb2ba2db6b611a2c;hb=16bce837ffe3527d4e8ed306f4436a86891d6e60;hp=f7a72192aa8c31319ffd20ba5164da92e2faf071;hpb=9d3365682de5aabe3003fa7af54cfec0d099905a;p=secnet.git

diff --git a/subdirmk/regen.mk.in b/subdirmk/regen.mk.in
index f7a7219..d11e05c 100644
--- a/subdirmk/regen.mk.in
+++ b/subdirmk/regen.mk.in
@@ -1,10 +1,38 @@
+# subdirmk - rules for regenerating makefiles etc.
+#  Copyright 2019 Mark Wooding
+#  Copyright 2019 Ian Jackson
+# SPDX-License-Identifier: LGPL-2.0-or-later
+# There is NO WARRANTY.
+
+# Usage:
+#   include subdirmk/regen.mk
+# (probably in toplevel Dir.sd.mk)
+#
+# Arranges that config.status is automatically rerun to update
+# makefiles from templates, whenever a template *.sd.mk or *.mk.in is
+# edited; and that autoconf is rerun if configure's inputs are edited.
+#
+# If you add includes to configure.ac, add them to CONFIGURE_ACS.
+#
+# Makefiles updated by config.status and passed to SUBDIRMK_MAKEFILES
+# in configure.ac are automatically handled too.  If you have other
+# files updated by config.status (eg, the output of autoheader) you
+# need to put them in CONFIG_STATUS_OUTPUTS (before your inclusion
+# of regen.mk).
+#
+# Also provides a `realclean::' target at the toplevel which deletes
+# the autoconf output.  (This is suitable for being part of a recursive
+# target creaed by setting &TARGETS_realclean in appropriate .sd.mk.)
 
 CONFIGURE	?= configure
-CONFIGURE_AC 	?= $(CONFIGURE).ac
-CONFIG_STATUS 	?= config.status
+CONFIGURE_AC	?= $(CONFIGURE).ac
+CONFIG_STATUS	?= config.status
+
+CONFIGURE_ACS	+= $(CONFIGURE_AC)
+CONFIGURE_ACS	+= subdirmk/subdirmk.ac
 
-CONFIGURE_ACS 	+= $(CONFIGURE_AC)
-CONFIGURE_ACS 	+= subdirmk/subdirmk.ac
+# To turn on debugging here, export SUBDIRMK_REGEN_NDEBUG=''
+SUBDIRMK_REGEN_NDEBUG ?= @
 
 $(top_srcdir)/$(CONFIGURE): $(addprefix $(top_srcdir)/,$(CONFIGURE_ACS))
 	cd $(top_srcdir) && autoconf
@@ -12,19 +40,42 @@ $(top_srcdir)/$(CONFIGURE): $(addprefix $(top_srcdir)/,$(CONFIGURE_ACS))
 $(CONFIG_STATUS): $(top_srcdir)/$(CONFIGURE)
 	./$(CONFIG_STATUS) --recheck
 
-MAKEFILES += subdirmk/regen.mk
+# generate will add all its own inputs and outputs to these variables
+SUBDIRMK_MAKEFILES += @_SUBDIRMK_MAKEFILES@
+MAKEFILE_TEMPLATES += $(addprefix $(top_srcdir)/, $(addsuffix .in, \
+	@_SUBDIRMK_MAKEFILES@ \
+	))
+
+main.mk $(SUBDIRMK_MAKEFILES) $(CONFIG_STATUS_OUTPUTS): .makefiles.stamp
+	$(SUBDIRMK_REGEN_NDEBUG): REGEN STAMP CAUSES TARGET=$@
 
-main.mk $(MAKEFILES): makefiles.phantom ;
-.INTERMEDIATE: makefiles.phantom
-makefiles.phantom: 						\
+.makefiles.stamp:						\
 		$(top_srcdir)/subdirmk/generate			\
 		$(CONFIG_STATUS)				\
-		$(top_srcdir)/Perdir.mk.in			\
-		$(foreach m,$(MAKEFILES),$(top_srcdir)/$(m).in)
-	./$(CONFIG_STATUS)
+		$(MAKEFILE_TEMPLATES)
+# This filtering arranges that we can often run config.status to
+# generate only particular output files.  We look for *inputs* that
+# have changed.  If the only inputs that have changed are ones that we
+# know affect only one output (Dir.sd.mk, Final.sd.mk and *.mk.in),
+# we pass config.status the corresponding output file names.
+# Otherwise we pass nothing and config.status does them all.  We need
+# to mention Dir.sd.mk twice because if $(top_srcdir) is `.', make
+# elides the directory part from $?.  Similarly but not identically
+# Final.sd.mk.
+	$(SUBDIRMK_REGEN_NDEBUG): REGEN STAMP WANTS DEPS=$?
+	./$(CONFIG_STATUS) $(if					\
+		$(filter-out Dir.sd.mk %/Dir.sd.mk		\
+			     Final.sd.mk $(top_srcdir)/Final.sd.mk \
+			     %.mk.in				\
+			, $?),,					\
+		$(patsubst $(top_srcdir)/%,%, $(sort		\
+			$(patsubst %.sd.mk,%.mk,$(filter %.sd.mk,$?)) \
+			$(patsubst %.mk.in,%.mk,$(filter %.mk.in,$?)))))
+	touch $@
 
-realclean: clean
+realclean:: clean
 	$(RM) config.status config.log
-	$(RM) main.mk $(MAKEFILES)
+	$(RM) main.mk $(SUBDIRMK_MAKEFILES) @_SUBDIRMK_MAKEFILES@
+	$(RM) $(addsuffix Makefile,$(dir $(SUBDIRMK_MAKEFILES)))
 
 -include $(ALL_DEPFILES)