(verify, verify_dcl): New file/macros.

diff --git a/lib/verify.h b/lib/verify.h
new file mode 100644 (file)
index 0000000..013ed84
--- /dev/null
+++ b/lib/verify.h
@@ -0,0 +1,43 @@
+/* Compile-time assert-like macros.
+
+   Copyright (C) 2005 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifndef VERIFY_H
+# define VERIFY_H 1
+
+# ifndef verify_dcl
+#  define GL_CONCAT0(x, y) x##y
+#  define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
+
+/* Verify requirement, R, at compile-time, as a declaration.
+   The implementation uses a struct declaration whose name includes the
+   expansion of __LINE__, so there is a small chance that two uses of
+   verify_dcl from different files will end up colliding (for example,
+   f.c includes f.h and verify_dcl is used on the same line in each).  */
+#  define verify_dcl(R) \
+    struct GL_CONCAT (ct_assert_, __LINE__) { char a[(R) ? 1 : -1]; }
+# endif
+
+/* Verify requirement, R, at compile-time, as an expression.
+   Unlike assert, there is no run-time overhead.  Unlike verify_dcl,
+   above, there is no risk of collision, since there is no declared name.
+   This macro may be used in some contexts where the other may not, and
+   vice versa.  Return void.  */
+# undef verify
+# define verify(R) ((void) sizeof (struct { char a[(R) ? 1 : -1]; }))
+
+#endif