Generate a ChangeLog file from commit logs

* .gitignore: Add 'ChangeLog'.
* build-aux/gitlog-to-changelog: New file, from Gnulib.
* build-aux/gitlog-to-emacslog: New file.
* CONTRIBUTE: Document the revised workflow.
* Makefile.in (clean): Remove *.tmp and etc/*.tmp*
instead of just special cases.
(CHANGELOG_HISTORY_INDEX_MAX, CHANGELOG_N, gen_origin): New vars.
(ChangeLog, unchanged-history-files, change-history)
(change-history-commit): New rules.
* admin/admin.el (make-manuals-dist--1):
Don't worry about doc/ChangeLog.
* admin/authors.el: Add a FIXME.
* admin/make-tarball.txt:
* lisp/calendar/icalendar.el:
* lisp/gnus/deuglify.el:
* lisp/obsolete/gulp.el:
* lwlib/README:
Adjust to renamed ChangeLog history files.
* admin/merge-gnulib (GNULIB_MODULES): Add gitlog-to-changelog.
* admin/notes/repo: Call it 'master' a la Git, not 'trunk' a la Bzr.
Remove obsolete discussion of merging ChangeLog files.
New section "Maintaining ChangeLog history".
* build-aux/git-hooks/pre-commit:
Reject attempts to commit files named 'ChangeLog'.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* make-dist: Make and distribute top-level ChangeLog if there's a
.git directory.  Distribute the new ChangeLog history files
instead of scattered ChangeLog files.  Distribute the new files
gitlog-to-changelog and gitlog-to-emacslog.
Fixes: bug#19113

1 files changed, 39 insertions, 1 deletions

diff --git a/Makefile.in b/Makefile.in
index 4cdd293ebd..55fb54a156 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -833,7 +833,7 @@ clean: $(clean_dirs:=_clean)
 	for dir in test/automated; do \
 	  [ ! -d $$dir ] || $(MAKE) -C $$dir clean; \
 	done
-	-rm -f etc/emacs.tmpdesktop etc/emacs.tmpappdata
+	-rm -f *.tmp etc/*.tmp*
 	-rm -rf info-dir.*
 
 ### `bootclean'
@@ -1087,6 +1087,44 @@ bootstrap: bootstrap-clean
 	$(MAKE) MAKEFILE_NAME=force-Makefile force-Makefile
 	$(MAKE) all
 
+# The newest revision that should not appear in the generated ChangeLog.
+gen_origin = 9d56a21e6a696ad19ac65c4b405aeca44785884a
+# Convert git commit log to ChangeLog file.  make-dist uses this.
+.PHONY: ChangeLog change-history unchanged-history-files
+ChangeLog:
+	$(AM_V_GEN)distprefix=$(distprefix) srcprefix=$(srcdir)/ \
+	$(srcdir)/build-aux/gitlog-to-emacslog $(gen_origin)
+
+# The ChangeLog history files are called ChangeLog.1, ChangeLog.2, ...,
+# ChangeLog.$(CHANGELOG_HISTORY_INDEX_MAX).  $(CHANGELOG_N) stands for
+# the newest (highest-numbered) ChangeLog history file.
+CHANGELOG_HISTORY_INDEX_MAX = 1
+CHANGELOG_N = ChangeLog.$(CHANGELOG_HISTORY_INDEX_MAX)
+
+# Check that history-relevant files match what's in the repository.
+# Otherwise, 'make change-history' might mess up the ChangeLog history files.
+unchanged-history-files:
+	x=$$(git diff-files --name-only $(CHANGELOG_N) Makefile.in) && \
+	  test -z "$$x"
+
+# Copy newer commit messages to the start of the ChangeLog history file,
+# and consider them to be older.
+change-history: ChangeLog unchanged-history-files
+	(sed '/^Copyright/,$$d' <ChangeLog && cat $(CHANGELOG_N)) \
+	  >$(CHANGELOG_N).tmp
+	new_origin=$$(git log --pretty=format:%H HEAD^!) && \
+	sed 's/^\(gen_origin *= *\).*/\1'"$$new_origin/" \
+	  <Makefile.in >Makefile.in.tmp
+	mv $(CHANGELOG_N).tmp $(CHANGELOG_N)
+	mv Makefile.in.tmp Makefile.in
+	$(MAKE) $@-commit
+
+# If 'make change-history' fails because the newest ChangeLog history
+# file contains invalid text, fix the file by hand and then run
+# 'make change-history-commit'.
+change-history-commit:
+	git commit -m'; make $@' $(CHANGELOG_N) Makefile.in
+
 .PHONY: check-declare
 
 check-declare: