From 222e7a2da345f01980d9261c40c5d50eced4f9ab Mon Sep 17 00:00:00 2001
From: =?utf8?q?Daniel=20Gr=C3=B6ber?= <dxld@darkboxed.org>
Date: Thu, 30 Dec 2021 18:45:15 +0100
Subject: [PATCH] Make GIT_REV logic work in release tarballs

Currently GIT_REV doesn't get set properly when building a release
tarball. To fix this we arrange for .gitcommit to contain the (short)
commit hash in tarballs generated with git-archive(1) using export-subst in
gitattributes. This way the correct commit hash is (reproducibly) included
in the release tarballs while not burdening the maintainers with updating
it in the git repo.

Please note this even works on Github and similar forges as they use
git-archive for generating tarballs so this works out quite nicely.
---
 .gitattributes |  1 +
 .gitcommit     |  1 +
 Makefile       | 11 +++++++++++
 3 files changed, 13 insertions(+)
 create mode 100644 .gitcommit

diff --git a/.gitattributes b/.gitattributes
index f85ae06c9..5e568606e 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1 +1,2 @@
 *.v linguist-language=Verilog
+/.gitcommit export-subst
diff --git a/.gitcommit b/.gitcommit
new file mode 100644
index 000000000..46b7856fb
--- /dev/null
+++ b/.gitcommit
@@ -0,0 +1 @@
+$Format:%h$
diff --git a/Makefile b/Makefile
index 34aeb9dc4..d081161be 100644
--- a/Makefile
+++ b/Makefile
@@ -130,7 +130,18 @@ LDLIBS += -lrt
 endif
 
 YOSYS_VER := 0.17+41
+
+# Note: We arrange for .gitcommit to contain the (short) commit hash in
+# tarballs generated with git-archive(1) using .gitattributes. The git repo
+# will have this file in its unexpanded form tough, in which case we fall
+# back to calling git directly.
+TARBALL_GIT_REV := $(shell cat $(YOSYS_SRC)/.gitcommit)
+ifeq ($(TARBALL_GIT_REV),$$Format:%h$$)
 GIT_REV := $(shell git ls-remote $(YOSYS_SRC) HEAD -q | $(AWK) 'BEGIN {R = "UNKNOWN"}; ($$2 == "HEAD") {R = substr($$1, 1, 9); exit} END {print R}')
+else
+GIT_REV := $(TARBALL_GIT_REV)
+endif
+
 OBJS = kernel/version_$(GIT_REV).o
 
 bumpversion:
-- 
2.30.2