$(DEPDIR)/deps-ver: $(top_srcdir)/deps-ver
	@[ -f $@ ] ||							\
		cp $(top_srcdir)/deps-ver $@
	@[ -w $@ ] ||							\
		chmod ug+w $@
	@cmp $(top_srcdir)/deps-ver $@ > /dev/null || (			\
		$(MAKE) clean &&					\
		echo -n "Prior $(subdir)/$(DEPDIR) version " &&		\
		cat $@ &&						\
		rm -rf $(DEPDIR) &&					\
		mkdir $(DEPDIR) && 					\
		case "$(top_builddir)" in				\
		 .)							\
		    ./config.status Makefile depfiles			\
		    ;;							\
		 ..)							\
			cd .. &&					\
			./config.status $(subdir)/Makefile depfiles &&	\
			cd $(subdir)					\
		    ;;							\
		 *)							\
		    echo 'Fatal: depsver.mf Automake fragment limited'	\
			 'to immediate subdirectories.'	&&		\
		    echo "top_builddir:	$(top_builddir)" &&		\
		    echo "subdir:	$(subdir)" &&			\
		    exit 1						\
		    ;;							\
		esac &&							\
		echo -n "Cleaned $(subdir)/$(DEPDIR) version " &&	\
		cat $(top_srcdir)/deps-ver				\
	)
	cp $(top_srcdir)/deps-ver $@

.deps-ver: $(top_srcdir)/deps-ver
	@[ ! -d $(DEPDIR) ] || $(MAKE) $(DEPDIR)/deps-ver
	@touch $@

BUILT_SOURCES += .deps-ver
CLEANFILES += .deps-ver

#
# depsver.mf	included in Makefile.am for directories with .deps
#
# When building in the same directory with sources that change over
# time, such as when tracking using bk, the .deps files can become
# stale with respect to moved, deleted, or superceded headers.  Most
# commonly, this would exhibit as make reporting a failure to make a
# header file which is no longer in the location given.  To address
# this issue, we use a deps-ver file which is updated with each change
# that breaks old .deps files.  A copy of deps-ver is made into
# $(DEPDIR) if not already present.  If $(DEPDIR)/deps-ver is present
# with different contents than deps-ver, we make clean to ensure all
# .o files built before the incompatible change are rebuilt along with
# their updated .deps files, then remove $(DEPDIR) and recreate it as
# empty stubs.
#
# It is normal when configured with --disable-dependency-tracking for
# the DEPDIR to not have been created.  For this reason, we use the
# intermediate target .deps-ver, which invokes make recursively if
# DEPDIR exists.
#
# If you modify depsver.mf, please make the changes to the master
# copy, the one in sntp is copied by the bootstrap script from it.
#
# This comment block follows rather than leads the related code so that
# it stays with it in the generated Makefile.in and Makefile.
#
