Fix determining Verilator revision when within git submodules without tags.

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

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

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_*

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)