From b52d8eb1e35ac1804d9056a32f0fc817e08873dd Mon Sep 17 00:00:00 2001
From: Antonin Portelli <antonin.portelli@me.com>
Date: Sat, 1 Sep 2018 19:49:13 +0100
Subject: [PATCH] better Version.h implementation

---
 .gitignore           |  1 -
 Grid/Makefile.am     | 26 ++++++++++++++++++++++++--
 Grid/util/Init.cc    |  1 -
 Grid/util/version.cc |  2 +-
 Makefile.am          |  5 -----
 5 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/.gitignore b/.gitignore
index e23a1208..45a3ea53 100644
--- a/.gitignore
+++ b/.gitignore
@@ -114,4 +114,3 @@ gh-pages/
 #####################
 Grid/qcd/spin/gamma-gen/*.h
 Grid/qcd/spin/gamma-gen/*.cc
-Grid/version.h
diff --git a/Grid/Makefile.am b/Grid/Makefile.am
index 5cd76b40..fe0832c3 100644
--- a/Grid/Makefile.am
+++ b/Grid/Makefile.am
@@ -21,6 +21,28 @@ if BUILD_HDF5
   extra_headers+=serialisation/Hdf5Type.h
 endif
 
+all: version-cache
+
+version-cache:
+	if [ `git status --porcelain | wc -l` -gt 0 ]; then\
+		a="uncommited changes";\
+	else\
+		a="no uncommitted changes";\
+	fi;\
+	echo "`git log -n 1 --format=format:"#define GITHASH \\"%H:%d $$a\\"%n" HEAD`" > vertmp;\
+	if [ -e version-cache ]; then\
+		d=`diff vertmp version-cache`;\
+		[ "${d}" != "" ] && mv vertmp version-cache;\
+	else\
+		mv vertmp version-cache;\
+	fi;\
+	rm -f vertmp
+
+Version.h:
+	echo "`git log -n 1 --format=format:"#define GITHASH \\"%H:%d $$a\\"%n" HEAD`" > Version.h
+
+.PHONY: version-cache
+
 #
 # Libraries
 #
@@ -30,8 +52,8 @@ include Eigen.inc
 lib_LIBRARIES = libGrid.a
 
 CCFILES += $(extra_sources)
-HFILES  += $(extra_headers)
+HFILES  += $(extra_headers) Config.h Version.h
 
 libGrid_a_SOURCES              = $(CCFILES)
 libGrid_adir                   = $(includedir)/Grid
-nobase_dist_pkginclude_HEADERS = $(HFILES) $(eigen_files) $(eigen_unsupp_files) Config.h
+nobase_dist_pkginclude_HEADERS = $(HFILES) $(eigen_files) $(eigen_unsupp_files)
diff --git a/Grid/util/Init.cc b/Grid/util/Init.cc
index 5d93cb64..aed62ed3 100644
--- a/Grid/util/Init.cc
+++ b/Grid/util/Init.cc
@@ -49,7 +49,6 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
 #include <Grid/Grid.h>
 
 #include <Grid/util/CompilerCompatible.h>
-#include <version.h>
 
 
 #include <fenv.h>
diff --git a/Grid/util/version.cc b/Grid/util/version.cc
index 19759274..c9507137 100644
--- a/Grid/util/version.cc
+++ b/Grid/util/version.cc
@@ -1,5 +1,5 @@
 #include <iostream>
-#include <version.h>
+#include "Version.h"
 namespace Grid {
   void printHash(){
 #ifdef GITHASH
diff --git a/Makefile.am b/Makefile.am
index 1901305b..09ec3029 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,11 +5,6 @@ include $(top_srcdir)/doxygen.inc
 
 bin_SCRIPTS=grid-config
 
-BUILT_SOURCES = version.h
-
-version.h:
-	if [ `git status --porcelain | wc -l` -gt 0 ]; then a="uncommited changes"; else a="no uncommitted changes"; fi; echo "`git log -n 1 --format=format:"#define GITHASH \\"%H:%d $$a\\"%n" HEAD`" > $(srcdir)/Grid/version.h
-
 .PHONY: bench check tests doxygen-run doxygen-doc $(DX_PS_GOAL) $(DX_PDF_GOAL)
 
 tests-local: all