Copyright (c) 2019 The NetBSD Foundation, Inc.
All rights reserved.
This code is derived from software contributed to The NetBSD Foundation
by Christos Zoulas
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
.Dd October 17, 2013 .Dt __FPTRCAST 3 .Os .Sh NAME .Nm __FPTRCAST .Nd function pointer cast .Sh SYNOPSIS n sys/cdefs.h .Ft ftype .Fn __FPTRCAST ftype fname .Sh DESCRIPTION The .Fn __FPTRCAST macro can be used to silence warnings produced by certain compilers when converting from one function pointer type to another. The .Fa ftype argument is the function pointer type to which to cast the function pointer in .Fa fname .
p This cast should be used sparingly and it is typically used in the following situations: l -bullet -offset indent -compact t We know that the function prototypes don't match at all, but we don't care because we point it to a function that does not take arguments and returns an error. t We only care about the first few arguments and we don't care about the rest. t We don't care about the return value, we ignore it anyway. .El .Sh IMPLEMENTATION NOTES This macro is implemented by using an intermediate .Em void * cast. .Sh SEE ALSO .Xr cc 1 , .Xr cdefs 3 .Sh CAVEATS Use of this macro can hide valid errors, and its usage is not recommended unless there is a well-thought reason for a cast. As a general guideline, don't use this macro inside other macros because it will hide cases where the user of the original macro accidentally used an incorrect function pointer.
p Use of this macro is non-portable; this is part of the implementation namespace and should only be used in .Nx code.