xref: /freebsd/share/man/man9/CTASSERT.9 (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
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27.\" $FreeBSD$
28.\"
29.Dd September 5, 2008
30.Os
31.Dt CTASSERT 9
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