From c04640262ac7f4afa19f750744a5e3aff0071d5f Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodarima@gmail.com>
Date: Wed, 11 Dec 2024 22:55:28 +0100
Subject: Avoid rebuild when the git commit is the same

Compare the commit used in the last rebuild to determine if it has
changed, rather than using a phony target which always causes a rebuild.
---
 src/Makefile.am | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/Makefile.am b/src/Makefile.am
index c0205f7d..9943b088 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -144,10 +144,14 @@ dillo.$(OBJEXT): commit.h
 CLEANFILES = commit.h
 
 if GIT_AVAILABLE
-# Always rebuild
-.PHONY: commit.h
-commit.h:
-	printf '#define GIT_COMMIT "%s"\n' `git --work-tree="$(top_srcdir)" describe --dirty` > commit.h
+# Rebuild commit.tmp.h every time, but only change commit.h
+# if the version is different to avoid rebuilds.
+commit.h: commit.tmp.h
+	test -f $@ || (echo "" > $@)
+	if diff $@ $^ >/dev/null; then rm $^; else mv $^ $@; fi
+
+commit.tmp.h:
+	printf '#define GIT_COMMIT "%s"\n' `git --work-tree="$(top_srcdir)" describe --dirty` > $@
 else
 # No need to rebuild
 commit.h:
-- 
cgit v1.2.3