From b159d82cb474d8ff4fc76e843b871a6d808e70bc Mon Sep 17 00:00:00 2001
From: Bogdan Drozdowski <>
Date: Tue, 29 Aug 2023 20:31:55 +0200
Subject: [PATCH] Add params to AM_PROG_LEX

---
 m4/lex.m4          |  15 ++++++-
 t/lex-args.sh      | 104 +++++++++++++++++++++++++++++++++++++++++++++
 t/list-of-tests.mk |   1 +
 3 files changed, 118 insertions(+), 2 deletions(-)
 create mode 100644 t/lex-args.sh

diff --git a/m4/lex.m4 b/m4/lex.m4
index 7b0511526..bc3555773 100644
--- a/m4/lex.m4
+++ b/m4/lex.m4
@@ -10,10 +10,21 @@
 # -----------
 # Autoconf leaves LEX=: if lex or flex can't be found.  Change that to a
 # "missing" invocation, for better error output.
+# Make sure to pass any supported parameters (since Autoconf 2.70).
 AC_DEFUN([AM_PROG_LEX],
-[AC_PREREQ([2.50])dnl
+[AC_PREREQ([2.70])dnl
 AC_REQUIRE([AM_MISSING_HAS_RUN])dnl
-AC_REQUIRE([AC_PROG_LEX])dnl
+m4_define([params], [])dnl
+m4_case([$1],
+  [],         [m4_define([params], [])],
+  [yywrap],   [m4_define([params], [yywrap])],
+  [noyywrap], [m4_define([params], [noyywrap])],
+  [empty],    [m4_define([params], [])],
+  [m4_define([params], [])
+m4_warn([syntax], ['$0': calling AM_PROG_LEX with an unknown argument '$1'.
+You should use one of: 'yywrap', 'noyywrap', 'empty', or an empty value. Using an empty value.])])
+
+AC_PROG_LEX(m4_expand([params]))
 if test "$LEX" = :; then
   LEX=${am_missing_run}flex
 fi])
diff --git a/t/lex-args.sh b/t/lex-args.sh
new file mode 100644
index 000000000..eea1e34f6
--- /dev/null
+++ b/t/lex-args.sh
@@ -0,0 +1,104 @@
+#! /bin/sh
+# Copyright (C) 2023 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# Autoconf new requires AC_PROG_LEX to be called with either 'yywrap'
+# or 'noyywrap' as the parameter (previously, the macro had no parameters).
+# After updating AM_PROG_LEX, check that either the required parameter values
+# are passed down to AC_PROG_LEX, the defaults are used, or a warning is
+# issued (and the default is used).
+# (parts copied from t/lex-clean.sh)
+
+required='cc lex'
+. test-init.sh
+
+expected_errmsg='AC_PROG_LEX without either yywrap or noyywrap'
+
+cp configure.ac configure.bak
+
+cat > Makefile.am << 'END'
+bin_PROGRAMS = foo
+foo_SOURCES = main.c lexer.l
+LDADD = $(LEXLIB)
+END
+
+cat > lexer.l << 'END'
+%{
+#define YY_NO_UNISTD_H 1
+%}
+%%
+"GOOD"   return EOF;
+.
+END
+
+cat > main.c << 'END'
+int main (void) { return yylex (); }
+int yywrap (void) { return 1; }
+END
+
+for failing in '' '([empty])' '([])' '()';
+do
+	echo "============== Testing AM_PROG_LEX with >$failing<"
+
+	cat configure.bak - > configure.ac <<END
+AC_PROG_CC
+AM_PROG_LEX$failing
+AC_OUTPUT
+END
+	# debug:
+	#cat configure.ac
+
+	# aclocal seems required every time (at least, if 'make' would be run)
+	$ACLOCAL
+	# we expect the message, so missing is an error:
+	($AUTOCONF 2>&1 | grep "$expected_errmsg") \
+		|| (cat configure.ac && exit 1)
+	rm -rf autom4te*.cache
+done;
+
+for working in '([noyywrap])' '([yywrap])';
+do
+	echo "============== Testing AM_PROG_LEX with >$working<"
+
+	cat configure.bak - > configure.ac <<END
+AC_PROG_CC
+AM_PROG_LEX$working
+AC_OUTPUT
+END
+	# debug:
+	#cat configure.ac
+
+	$ACLOCAL
+	# we don't expect the message, so it is an error if found:
+	($AUTOCONF 2>&1 | grep "$expected_errmsg") \
+		&& cat configure.ac && exit 2
+	rm -rf autom4te*.cache
+done;
+
+echo "============== Testing AM_PROG_LEX with '([lex-blah])'"
+
+cat configure.bak - > configure.ac << 'END'
+AC_PROG_CC
+AM_PROG_LEX([lex-blah])
+AC_OUTPUT
+END
+
+# debug:
+#cat configure.ac
+
+$ACLOCAL
+($AUTOCONF 2>&1 | grep lex-blah) || (cat configure.ac && exit 3)
+
+:
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index 94781d9b0..3701fb0bb 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -592,6 +592,7 @@ t/lex3.sh \
 t/lex5.sh \
 t/lexcpp.sh \
 t/lexvpath.sh \
+t/lex-args.sh \
 t/lex-subobj-nodep.sh \
 t/lex-header.sh \
 t/lex-lib.sh \
-- 
2.35.1