1.\" Copyright (c) 2003 Hiten M. Pandya 2.\" 3.\" All rights reserved. 4.\" 5.\" This program is free software. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd September 5, 2008 30.Dt CTASSERT 9 31.Os 32.Sh NAME 33.Nm CTASSERT 34.Nd compile time assertion macro 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/systm.h 38.Fn CTASSERT expression 39.Sh DESCRIPTION 40The 41.Fn CTASSERT 42macro evaluates 43.Fa expression 44at compile time and causes a compiler error if it is false. 45.Pp 46The 47.Fn CTASSERT 48macro is useful for asserting the size or alignment of important 49data structures and variables during compilation, which would 50otherwise cause the code to fail at run time. 51.Sh IMPLEMENTATION NOTES 52The 53.Fn CTASSERT 54macro should not be used in a header file. 55It is implemented using a dummy typedef, with a name (based on line number) 56that may conflict with a 57.Fn CTASSERT 58in a source file including that header. 59.Sh EXAMPLES 60Assert that the size of the 61.Vt uuid 62structure is 16 bytes. 63.Pp 64.Dl "CTASSERT(sizeof(struct uuid) == 16);" 65.Sh SEE ALSO 66.Xr KASSERT 9 67.Sh AUTHORS 68This manual page was written by 69.An Hiten M. Pandya 70.Aq hmp@FreeBSD.org . 71