From 4f0d0347d2b27689f91dda9723c48f6d37f4a05e Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@cryptonomic.net>
Date: Thu, 7 Oct 2021 15:44:10 -0400
Subject: fix gitversion.h to rebuild only when changed

---
 Makefile | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index f14f7da..7555f2f 100644
--- a/Makefile
+++ b/Makefile
@@ -20,8 +20,14 @@ etcdir ?= /etc
 # Targets
 all: tuntox tuntox_nostatic
 
-gitversion.h: FORCE
-	@if [ -f .git/HEAD ] ; then echo "  GEN   $@"; echo "#define GITVERSION \"$(shell echo -n $$(git rev-parse HEAD) && (git diff --quiet || printf %s -dirty)  )\"" > $@; fi
+gitversion != printf %s $$(git rev-parse HEAD) && (git diff --quiet || printf %s -dirty)
+gitversion_on_disk != read _ _ v < gitversion.h; echo $$v
+ifneq ("$(gitversion)", $(gitversion_on_disk))
+.PHONY: gitversion.h
+endif
+
+gitversion.h:
+	echo '#define GITVERSION "$(gitversion)"' > $@
 
 FORCE:
 
-- 
cgit v1.2.3