m4: Allow empty base argument in eval()

ebblake · emaste · commit ac196a584575 · 2025-05-24T12:57:24.000-04:00
POSIX specifies "The second argument, if specified, shall set the radix
for the result; if the argument is blank or unspecified, the default
is 10."  Previously we reported an invalid

PR:		287015
Reviewed by:	emaste
diff --git a/usr.bin/m4/eval.c b/usr.bin/m4/eval.c
@@ -181,7 +181,7 @@ expand_builtin(const char *argv[], int argc, int td)
 		int maxdigits = 0;
 		const char *errstr;
 
-		if (argc > 3) {
+		if (argc > 3 && *argv[3] != '\0') {
 			base = strtonum(argv[3], 2, 36, &errstr);
 			if (errstr) {
 				m4errx(1, "expr: base is %s: %s.",
