[PATCH 1/3] build: write version.stamp file containing $(VERSION) string

[Tomi Ollila]

This version file will be as prerequisite to the target files
that use the version info for some purpose, like printing
it for the user to examine. The contents of the version.stamp
file is seldom read by the build system itself as the $(VERSION)
variable has the same information.

Thanks to Trevor, David and Mark for their contributions.
---

This is version 6 of

     id:1391956711-21231-1-git-send-email-tomi.ollila at iki.fi

  The only change is $(VERSTAMP) -> version.stamp -- $(VERSTAMP) does not
  get expanded for prerequisities if those are not already defined,
  and as emacs/Makefile.local is included before Makefile.local $(VERSTAMP)
  is useless in emacs/... (expands to nothing). And my original idea for
  $(VERSTAMP) was for typo-checking -- I just did not realize that make does
  not tell me that the variable is undefined so the typo-check I thought of
  just did't happen.


And the following 2 patches version 2 of

        id:1390135903-28167-1-git-send-email-tomi.ollila at iki.fi

  Now utilizes version.stamp to know when notmuch.el is to be
  re-bytecompiled.

 Makefile.local | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/Makefile.local b/Makefile.local
index 174506c..3a56c06 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -22,6 +22,11 @@ VERSION:=$(shell cat ${srcdir}/version)
 ifeq ($(filter release release-message pre-release update-versions,$(MAKECMDGOALS)),)
 ifeq ($(IS_GIT),yes)
 VERSION:=$(shell git describe --match '[0-9.]*'|sed -e s/_/~/ -e s/-/+/ -e s/-/~/)
+# Write the file 'version.stamp' in case its contents differ from $(VERSION)
+FILE_VERSION:=$(shell test -f version.stamp && read vs < version.stamp || vs=; echo $$vs)
+ifneq ($(FILE_VERSION),$(VERSION))
+       $(shell echo "$(VERSION)" > version.stamp)
+endif
 endif
 endif
 
@@ -69,6 +74,11 @@ ifeq ($(shell cat .first-build-message 2>/dev/null),)
 endif
 endif
 
+# Depend (also) on the file 'version'. In case of ifeq ($(IS_GIT),yes)
+# this file may already have been updated.
+version.stamp: version
+	echo $(VERSION) > $@
+
 $(TAR_FILE):
 	if git tag -v $(VERSION) >/dev/null 2>&1; then \
            ref=$(VERSION); \
@@ -280,6 +290,8 @@ notmuch_client_srcs =		\
 
 notmuch_client_modules = $(notmuch_client_srcs:.c=.o)
 
+notmuch.o: version.stamp
+
 notmuch: $(notmuch_client_modules) lib/libnotmuch.a util/libutil.a parse-time-string/libparse-time-string.a
 	$(call quiet,CXX $(CFLAGS)) $^ $(FINAL_LIBNOTMUCH_LDFLAGS) -o $@
 
@@ -318,7 +330,7 @@ install-desktop:
 	desktop-file-install --mode 0644 --dir "$(DESTDIR)$(desktop_dir)" notmuch.desktop
 
 SRCS  := $(SRCS) $(notmuch_client_srcs)
-CLEAN := $(CLEAN) notmuch notmuch-shared $(notmuch_client_modules) notmuch.elc
+CLEAN := $(CLEAN) notmuch notmuch-shared $(notmuch_client_modules) version.stamp
 
 DISTCLEAN := $(DISTCLEAN) .first-build-message Makefile.config
 
-- 
1.8.0