[gegl] Add Makefile.am rule to generate ChangeLog

[Martin Nordholts <martinn src gnome org>]

commit a2a1a10ec4df4f953c80b5530d9dde335fb29ffa
Author: Martin Nordholts <martinn src gnome org>
Date:   Thu Jul 2 18:22:09 2009 +0200

    Add Makefile.am rule to generate ChangeLog
    
    Add Makefile.am rule to generate ChangeLog copied from pango and
    Behdad Esfahbod.

 Makefile.am |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 918cfdb..3a03a83 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -42,3 +42,24 @@ dist-hook: dist-check-w3m
 website: all
 	$(MAKE) -C docs website
 
+
+### ChangeLog generation
+
+CHANGELOG_START = 5e2cc2146486ce0c1ebc0cbf68770dafafcb123f
+
+ChangeLog: $(srcdir)/ChangeLog
+$(srcdir)/ChangeLog:
+	@echo Creating $@
+	@if test -d "$(srcdir)/.git"; then \
+	  (GIT_DIR=$(top_srcdir)/.git ./missing --run \
+	   git log $(CHANGELOG_START)^.. --stat) | fmt --split-only > $  tmp \
+	  && mv -f $  tmp $@ \
+	  || ($(RM) $  tmp; \
+	      echo Failed to generate ChangeLog, your ChangeLog may be outdated >&2; \
+	      (test -f $@ || echo git-log is required to generate this file >> $@)); \
+	else \
+	  test -f $@ || \
+	  (echo A git checkout and git-log is required to generate ChangeLog >&2 && \
+	  echo A git checkout and git-log is required to generate this file >> $@); \
+	fi
+.PHONY: $(srcdir)/ChangeLog