commit c94a5688fb1228a862b2d4a3f1239cdc0e3349e5
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Nov 2 12:14:01 2017 +0100
<array_length.h>: New array_length and array_end macros
diff --git a/include/array_length.h b/include/array_length.h
new file mode 100644
index 0000000000000000..cb4a8b2a56bca3ad
--- /dev/null
+++ b/include/array_length.h
@@ -0,0 +1,36 @@
+/* The array_length and array_end macros.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _ARRAY_LENGTH_H
+#define _ARRAY_LENGTH_H
+
+/* array_length (VAR) is the number of elements in the array VAR. VAR
+ must evaluate to an array, not a pointer. */
+#define array_length(var) \
+ __extension__ ({ \
+ _Static_assert (!__builtin_types_compatible_p \
+ (__typeof (var), __typeof (&(var)[0])), \
+ "argument must be an array"); \
+ sizeof (var) / sizeof ((var)[0]); \
+ })
+
+/* array_end (VAR) is a pointer one past the end of the array VAR.
+ VAR must evaluate to an array, not a pointer. */
+#define array_end(var) (&(var)[array_length (var)])
+
+#endif /* _ARRAY_LENGTH_H */