Generate AC_INIT version number by script

Generate the version number used in Autotools builds
via script instead of manual editing.

This script mimics what the avrdude top-level CMakeLists.txt
does for composing AVRDUDE_FULL_VERSION.

However, unlike the cmake based builds, this does not print the
commit hash in the "avrdude --help" message (yet).

src/GNUmakefile.in

@@ -0,0 +1,15 @@
+# Helps update the version number automatically if using GNU make.
+include Makefile
+
+AUTORECONF ?= autoreconf
+AUTORECONF_OPTS ?= -vis
+
+script_version := $(shell $(top_srcdir)/build-helpers/package-version $(top_srcdir) version-stamp)
+ifneq ($(PACKAGE_VERSION),$(script_version))
+$(info autoconf and script versions do not match: $(PACKAGE_VERSION) vs $(script_version))
+$(info Removing autom4te.cache and related files and re-running autoreconf)
+dummy1 := $(shell rm -rf $(top_srcdir)/autom4te.cache)
+dummy2 := $(shell $(AUTORECONF) $(AUTORECONF_OPTS) $(top_srcdir))
+endif
+
+# vim: syntax=make

src/Makefile.am

@@ -40,6 +40,8 @@ CLEANFILES = \
 	config_gram.h \
 	lexer.c
 
+include build-helpers/package-version.mk
+
 BUILT_SOURCES = $(CLEANFILES)
 
 #SUBDIRS      = doc

src/build-helpers/package-version

@@ -0,0 +1,93 @@
+#!/bin/sh
+# Syntax:
+#   $0 <path-to-top_srcdir> <version-stamp-file>
+#
+# <path-to-top_srcdir> may be relative
+# <version-stamp-file> is relative to the dist top_srcdir
+#
+# Test this script by running
+#     rm -rf autom4te.cache/ && autoreconf -vis . && sed -n "/^# Generated by GNU/p" configure
+#
+# If we run into an error, we cannot abort the "autoreconf" run by
+# exiting with a non-0 error code. (We do exit non-0 in that case
+# anyway for help when testing this script.)
+# The only thing we can do to report an error is to write to stderr
+# which appears as "autoreconf" output, and to write a version number
+# to stdout which indicates an error. The "configure" script can
+# then check whether $PACKAGE_VERSION indicates such an error.
+
+# Parse the command line arguments
+prog="$(basename "$0")"
+top_srcdir="${1-.}"
+test -d "$top_srcdir" || { \
+    echo "$prog: Error: Could not change to top_srcdir '$1'" >&2; \
+    echo "version_error_1" | ${TR-tr} -d '\012'
+    exit 2; \
+}
+version_stamp="${2-version-stamp}"
+
+# echo "$prog: Error: Some error happend." >&2
+# echo "version_error_2" | ${TR-tr} -d '\012'
+# exit 2
+
+# Is this a dist source tree?
+# If so, use the version number from the version_stamp file.
+if test -f "$top_srcdir/$version_stamp"; then
+    cat "$top_srcdir/$version_stamp" | ${TR-tr} -d '\012'
+    exit
+fi
+
+# Is this part of a git checkout or an expanded github snapshot tarball?
+test -f "$top_srcdir/../CMakeLists.txt" || { \
+    echo "$prog: Error: top-level avrdude CMakeLists.txt file not found" >&2; \
+    echo "version_error_3" | ${TR-tr} -d '\012'
+    exit 2; \
+}
+
+if PROJECT_VERSION="$(${SED-sed} -n 's/project(avrdude\s\{1,\}VERSION\s\{1,\}\([0-9\.]\{1,\}\)\s\{1,\}.*/\1/p' "$top_srcdir/../CMakeLists.txt")"; then
+    :
+else
+    echo "$prog: Error: Could not parse top-level avrdude 'CMakeLists.txt'." >&2
+    echo "version_error_4" | ${TR-tr} -d '\012'
+    exit 2
+fi
+
+# If GIT_DIR is set, use it. If not, try "$top_srcdir/../.git".
+test -n "$GIT_DIR" || { \
+    GIT_DIR="$top_srcdir/../.git"; \
+    export GIT_DIR; \
+}
+
+# Working with a git source tree
+if test -d "$GIT_DIR"; then
+    GIT_COMMIT_HASH="$(${GIT-git} log -1 --format=%h)" || { \
+        echo "$prog: Error: Cannot run 'git log' for commit hash" >&2; \
+        echo "version_error_5" | ${TR-tr} -d '\012'; \
+        exit 2; \
+    }
+    GIT_COMMIT_DATE="$(${GIT-git} log -1 --format=%ad --date=format:%Y%m%d)" || { \
+        echo "$prog: Error: Cannot run 'git log' for commit date" >&2; \
+        echo "version_error_6" | ${TR-tr} -d '\012'; \
+        exit 2; \
+    }
+    GIT_TAG_HASH="$(${GIT-git} log -1 --tags --format=%h)" || { \
+        echo "$prog: Error: Cannot run 'git log' for tag hash" >&2; \
+        echo "version_error_7" | ${TR-tr} -d '\012'; \
+        exit 2; \
+    }
+    if test "x$GIT_COMMIT_HASH" = "x$GIT_TAG_HASH"; then
+        echo "${PROJECT_VERSION}" | ${TR-tr} -d '\012'
+        exit
+    else
+        echo "${PROJECT_VERSION}-${GIT_COMMIT_DATE}" | ${TR-tr} -d '\012'
+        exit
+    fi
+else
+    # Building a github release or snapshot tarball
+    echo "${PROJECT_VERSION}-nogit" | ${TR-tr} -d '\012'
+    exit
+fi
+
+# If everything else has failed, call this version "devel"
+echo "devel" | ${TR-tr} -d '\012'
+exit 2

src/build-helpers/package-version.mk

@@ -0,0 +1,26 @@
+BUILD_SCRIPT_DIR = build-helpers
+
+# Check that package version matches git version before creating dist tarballs
+dist-hook: git-version-check git-version-stamp
+distcheck-hook: git-version-check
+
+# Note: We cannot run autoreconf from here, because we would need some way to
+#       restart the whole dist process from the start and there is none.
+EXTRA_DIST += $(top_srcdir)/$(BUILD_SCRIPT_DIR)/package-version
+git-version-check:
+	@cur_ver=`$(top_srcdir)/$(BUILD_SCRIPT_DIR)/package-version $(top_srcdir) version-stamp`; \
+	if test "x$${cur_ver}" = "x$(PACKAGE_VERSION)"; then :; else \
+		echo "ERROR: Recorded PACKAGE_VERSION and current version do not match:"; \
+		echo "         current  version:         $${cur_ver}"; \
+		echo "         recorded PACKAGE_VERSION: $(PACKAGE_VERSION)"; \
+		rm -rf "$(top_srcdir)/autom4te.cache"; \
+		echo "Update PACKAGE_VERSION by running autoreconf(1)."; \
+		exit 1; \
+	fi
+
+# Version stamp files can only exist in tarball source trees.
+#
+# So there is no need to generate them anywhere else or to clean them
+# up anywhere.
+git-version-stamp:
+	echo "$(PACKAGE_VERSION)" > "$(distdir)/version-stamp"

src/configure.ac

@@ -24,7 +24,7 @@
 
 AC_PREREQ(2.60)
 AC_INIT([avrdude],
-        [7.2-20230720],
+        m4_esyscmd([./build-helpers/package-version . version-stamp]),
         [https://github.com/avrdudes/avrdude/issues])
 
 AC_CANONICAL_BUILD
@@ -36,6 +36,21 @@ AM_INIT_AUTOMAKE([foreign])
 AC_CONFIG_HEADERS(ac_cfg.h)
 AC_CONFIG_MACRO_DIR([m4])
 
+# Check that the build-helpers/package-version script has worked properly.
+case "$PACKAGE_VERSION" in
+    devel|version_error_*)
+	AC_MSG_ERROR([
+Autogenerating the package version (${PACKAGE_VERSION}) has failed.
+
+Please file an issue at ${PACKAGE_BUGREPORT}
+
+You can write some version number to the file version-stamp as a
+workaround to allow building avrdude until the filed issue has been
+fixed.
+])
+	;;
+esac
+
 LT_INIT()
 
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
@@ -545,9 +560,23 @@ AC_CONFIG_FILES([
        Makefile
 ])
 
+AC_CONFIG_FILES([
+       GNUmakefile
+])
+dnl TODO: Add GIT_COMMIT_HASH to the AVRDUDE_FULL_VERSION like cmake build does
+dnl # Detect GIT
+dnl AC_ARG_VAR([GIT], [git revision control system])
+dnl AS_VAR_IF([GIT], [], [dnl
+dnl   AC_PATH_PROG([GIT], [git], [no])
+dnl ])
+dnl AM_CONDITIONAL([HAVE_GIT], [test "x$GIT" != xno])
+dnl AS_IF([test -d "../.git/info/exclude"], [dnl
+dnl   GIT_COMMIT_HASH="$(${GIT} --version)"
+dnl ])
+
 # Pass version number into avrdude.conf
-AVRDUDE_FULL_VERSION=$PACKAGE_VERSION
-AC_SUBST(AVRDUDE_FULL_VERSION, $AVRDUDE_FULL_VERSION)
+dnl AVRDUDE_FULL_VERSION="${PACKAGE_VERSION} (${GIT_COMMIT_HASH})"
+AC_SUBST([AVRDUDE_FULL_VERSION], ["$PACKAGE_VERSION"])
 
 # The procedure to create avrdude.conf involves two steps.  First,
 # normal autoconf substitution will be applied, resulting in