From 1d9c5c2c6b5e177732a5617dec49ea8ade057c4b Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Mon, 3 Nov 2025 18:36:20 -0500
Subject: [PATCH] Fix determining Verilator revision when within git submodules
 without tags.

---
 Changes         |  1 +
 Makefile.in     |  2 +-
 src/Makefile.in |  1 +
 src/config_rev  | 58 +++++++++++++++++++++++++++++--------------------
 4 files changed, 38 insertions(+), 24 deletions(-)

diff --git a/Changes b/Changes
index c2394d2fe..e1dcfea15 100644
--- a/Changes
+++ b/Changes
@@ -16,6 +16,7 @@ Verilator 5.043 devel
 * Optimize away calls to empty functions (#6626). [Geza Lore]
 * Fix `--timing` with `--x-initial-edge` (#6603) (#6631). [Krzysztof Bieganski, Antmicro Ltd.]
 * Fix merging of impure assignments in gate optimization (#6629) (#6630). [Geza Lore]
+* Fix determining Verilator revision when within git submodules without tags.
 
 
 Verilator 5.042 2025-11-02
diff --git a/Makefile.in b/Makefile.in
index a1ec1d163..7a8aaf79a 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -781,7 +781,7 @@ clean mostlyclean distclean maintainer-clean::
 
 distclean maintainer-clean::
 	rm -f *.info* *.1 $(INFOS) $(INFOS_OLD) $(VL_INST_MAN_FILES)
-	rm -f Makefile config.status config.cache config.log TAGS
+	rm -f Makefile config.status config.cache config.log configure~ TAGS
 	rm -f verilator_bin* verilator_coverage_bin*
 	rm -f bin/verilator_bin* bin/verilator_coverage_bin*
 	rm -f include/verilated.mk include/verilated_config.h
diff --git a/src/Makefile.in b/src/Makefile.in
index 1fb95ab68..41742f8b0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -108,6 +108,7 @@ clang-format:
 
 maintainer-copy::
 clean mostlyclean distclean maintainer-clean::
+	-rm -f config_rev.h
 	-rm -rf obj_* *.log *.dmp *.vpd core
 	-rm -f *.o *.d *_gen_*
 	-rm -f *__gen* obj_*
diff --git a/src/config_rev b/src/config_rev
index 2b32b57d6..8c36d2197 100755
--- a/src/config_rev
+++ b/src/config_rev
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 # mypy: disallow-untyped-defs
-# pylint: disable=C0103,C0114
+# pylint: disable=C0103,C0114,C0116
 ######################################################################
 #
 # Copyright 2005-2025 by Wilson Snyder. This program is free software; you
@@ -17,32 +17,44 @@ import os
 import re
 import sys
 
+from datetime import datetime, timezone
+
+
+def get_rev() -> str:
+    if 'VERILATOR_SRC_VERSION' in os.environ:
+        # e.g. Ubuntu package build
+        return os.environ['VERILATOR_SRC_VERSION']
+
+    data = os.popen('git describe --always').read()
+
+    result = "vUNKNOWN"
+
+    m = re.search(r'^(v[0-9].*)', data)
+    if m:
+        # e.g. in a complate verilator checkout with tags
+        result = m.group(1)
+        result = re.sub('_', '.', result)
+    else:
+        # e.g. in a sparse submodule checkout without tags
+        m = re.search(r'^([a-f0-9]+)$', data)
+        if m:
+            result = "vUNKNOWN-" + datetime.now(timezone.utc).strftime("%Y%m%d") + "-" + m.group(1)
+
+    data = os.popen('git status').read()
+    if (re.search('Changed but not updated', data, flags=re.IGNORECASE)
+            or re.search('Changes to be committed', data, flags=re.IGNORECASE)
+            or re.search('Changes not staged', data, flags=re.IGNORECASE)):
+        result += " (mod)"
+
+    return result
+
+
 parser = argparse.ArgumentParser()
 parser.add_argument('directory')
 Args = parser.parse_args()
 
 os.chdir(Args.directory)
 
-if 'VERILATOR_SRC_VERSION' in os.environ:
-    rev = os.environ['VERILATOR_SRC_VERSION']
-else:
-    rev = 'UNKNOWN_REV'
-
-data = os.popen('git describe').read()
-
-match = re.search(r'^(v[0-9].*)', data)
-if match:
-    rev = match.group(1)
-rev = re.sub('_', '.', rev)
-
-data = os.popen('git status').read()
-if (re.search('Changed but not updated', data, flags=re.IGNORECASE)
-        or re.search('Changes to be committed', data, flags=re.IGNORECASE)
-        or re.search('Changes not staged', data, flags=re.IGNORECASE)):
-    rev += " (mod)"
-
+rev = get_rev()
+print("config_rev using " + rev, file=sys.stderr)
 print("static const char* const DTVERSION_rev = \"" + rev + "\";")
-
-# Warn after the print, so at least the header has good contents
-if re.search('UNKNOWN', rev):
-    print("%Warning: No git revision found in config_rev.py", file=sys.stderr)