lib: tests: Add 16-cast.

* lib/tests/scaffold/16-cast.c: Add file.
* build-aux/check-mescc.sh (mes_tests): Add it.

build-aux/check-mescc.sh

@@ -46,6 +46,7 @@ lib/tests/scaffold/13-if-neq.c
 lib/tests/scaffold/14-if-goto.c
 lib/tests/scaffold/15-if-not-f.c
 lib/tests/scaffold/16-if-t.c
+lib/tests/scaffold/16-cast.c
 lib/tests/scaffold/17-compare-char.c
 lib/tests/scaffold/17-compare-ge.c
 lib/tests/scaffold/17-compare-gt.c

lib/tests/scaffold/16-cast.c

@@ -0,0 +1,32 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2023 Ekaitz Zarraga <ekaitz@elenq.tech>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes 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 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes 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 GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include<stdio.h>
+int
+main ()
+{
+  char r = -1;
+  unsigned s = r;
+  unsigned t = (unsigned char)r;
+  if (s != -1)
+    return 2;
+  if (t != 255)
+    return 1;
+  return 0;
+}