[FYI] {maint} release: revamp rules to tag and upload the releases

[Stefano Lattarini]

The older Makefile rules used to create and tag the releases were
based on an approach we now consider flawed: they over-mechanized
some delicate operations that are better performed manually *and*
double-checked by a developer, and at the same time they did not
run enough safety checks.

* Makefile.am (GIT, version_rx, stable_version_rx, beta_version_rx,
match_version, git_must_have_clean_workdir, determine_release_type):
New variables.
(git-release, git-dist): Remove, they are superseded by ...
(git-tag-release, git-upload-release): ... these new targets.
---
 Makefile.am |   84 +++++++++++++++++++++++++++++++++++++++++-----------------
 1 files changed, 59 insertions(+), 25 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 7c9a8f4..56784ca 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -607,32 +607,66 @@ sc_at_in_texi:
          exit 1; \
        fi
 
-
-git-dist: maintainer-check
-## Make sure the NEWS file is up-to-date.
-       @if sed 1q $(srcdir)/NEWS | grep -e "$(VERSION)" > /dev/null; then :; 
else \
-         echo "NEWS not updated; not releasing" 1>&2; \
-         exit 1;                               \
-       fi
-## Build the distribution.  We expect the developer to have already run
-## "make check" and "make distcheck" on his own (as required in the
-## HACKING file, section "Release procedure").
-       $(MAKE) $(AM_MAKEFLAGS) dist
-## Finally, if anything was successful, commit the last changes and tag
-## the release in the repository.  We don't use RCS keywords so it's OK
-## to distribute the files before they were committed.
-       cd $(srcdir) && git commit -a -s && \
-          git tag -s "v$(VERSION)" -m "Release $(VERSION)"
-
-git-release: git-dist
-       case $(VERSION) in \
-         *[a-z]) dest=alpha;; \
-         *)      dest=ftp;; \
+## Tagging and/or uploading stable and beta releases.
+
+GIT = git
+
+version_rx = ^[1-9][0-9]*\.[0-9][0-9]*(\.[0-9][0-9]*)?
+stable_version_rx = $(version_rx)$$
+beta_version_rx = $(version_rx)[bdfhjlnprtvxz]$$
+match_version = echo "$(VERSION)" | $(EGREP) >/dev/null
+
+## Check that we don't have uncommitted or unstaged changes.
+## TODO: Maybe the git suite already offers a shortcut to verify if the
+## TODO: working directory is "clean" or not?  If yes, use that instead
+## TODO: of duplicating the logic here.
+git_must_have_clean_workdir = \
+  $(GIT) rev-parse --verify HEAD >/dev/null \
+    && $(GIT) update-index -q --refresh \
+    && $(GIT) diff-files --quiet \
+    && $(GIT) diff-index --quiet --cached HEAD \
+    || fatal "you have uncommitted or unstaged changes"
+
+determine_release_type = \
+  if $(match_version) '$(stable_version_rx)'; then \
+    release_type='Release' dest=ftp; \
+  elif $(match_version) '$(beta_version_rx)'; then \
+    release_type='Beta release' dest=alpha; \
+  else \
+    fatal "invalid version '$(VERSION)' for a release"; \
+  fi
+
+git-tag-release: maintainer-check
+       @set -e; set -u; \
+       fatal () { echo "$@: $$*; not tagging" >&2; exit 1; }; \
+       case '$(AM_TAG_DRYRUN)' in \
+         ""|[nN]|[nN]o|NO) run="";; \
+         *) run="echo Running:";; \
        esac; \
-       $(srcdir)/lib/gnupload $(GNUPLOADFLAGS) \
-         --to $$dest.gnu.org:automake $(DIST_ARCHIVES)
-
-.PHONY: git-release git-dist
+       $(determine_release_type); \
+       $(git_must_have_clean_workdir); \
+## Make sure the NEWS file is up-to-date.
+       sed 1q $(srcdir)/NEWS | grep '$(VERSION)' >/dev/null \
+         || fatal "NEWS not updated"; \
+## If all was successful, tag the release in the local repository.
+       $$run $(GIT) tag -s "v$(VERSION)" -m "$$release_type $(VERSION)"
+
+git-upload-release:
+       @set -e; set -u; \
+       fatal () { echo "$@: $$*; not releasing" >&2; exit 1; }; \
+       $(determine_release_type); \
+       dest=$$dest.gnu.org:automake; \
+       $(git_must_have_clean_workdir); \
+## Check that we are releasing from a valid tag.
+       tag=`$(GIT) describe` \
+         && case $$tag in "v$(VERSION)") true;; *) false;; esac \
+         || fatal "you can only create a release from a tagged version"; \
+## Build and upload the distribution tarball(s).
+       $(MAKE) $(AM_MAKEFLAGS) dist || exit 1; \
+       echo Will upload to $$dest: $(DIST_ARCHIVES); \
+       $(srcdir)/lib/gnupload $(GNUPLOADFLAGS) --to $$dest $(DIST_ARCHIVES)
+
+.PHONY: git-upload-release git-tag-release
 
 ## Visually comparing differences between the Makefile.in files in
 ## automake's own build system as generated in two different branches
-- 
1.7.7.3