$NetBSD: __UNCONST.3,v 1.7 2013/10/17 20:43:49 wiz Exp $
Copyright (c) 2010 The NetBSD Foundation, Inc.
All rights reserved.
This code is derived from software contributed to The NetBSD Foundation
by Jukka Ruohonen.
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 __UNCONST 3 .Os .Sh NAME .Nm __UNCONST .Nd compile time cast-away macro .Sh SYNOPSIS n sys/cdefs.h .Ft void .Fn __UNCONST x .Ft void .Fn __UNVOLATILE x .Sh DESCRIPTION The .Fn __UNCONST macro can be used to omit warnings produced by certain compilers when operating with pointers declared with the .Em const type qualifier in a context without such qualifier. Examples include passing a pointer declared with the .Em const qualifier to a function without such qualifier, and variable assignment from a .Em const pointer to a non-const pointer. In the same vein, the .Fn __UNVOLATILE macro can be used to exclude warnings related to the .Em volatile type qualifier. .Sh IMPLEMENTATION NOTES These macros are implemented by explicitly using .Em unsigned long instead of .Em intptr_t , a signed type guaranteed to hold a pointer. .Sh SEE ALSO .Xr cc 1 , .Xr cdefs 3 .Sh CAVEATS As both macros may hide valid errors, their usage is not recommended unless there is a well-thought reason for a cast. A typical use case for .Fn __UNCONST involve an .Tn API that does not follow the so-called ``const correctness'' even if it would be appropriate. Valid use cases of .Fn __UNVOLATILE include passing a .Em volatile pointer to .Xr memset 3 .
Copyright (c) 2010 The NetBSD Foundation, Inc.
All rights reserved.
This code is derived from software contributed to The NetBSD Foundation
by Jukka Ruohonen.
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 __UNCONST 3 .Os .Sh NAME .Nm __UNCONST .Nd compile time cast-away macro .Sh SYNOPSIS n sys/cdefs.h .Ft void .Fn __UNCONST x .Ft void .Fn __UNVOLATILE x .Sh DESCRIPTION The .Fn __UNCONST macro can be used to omit warnings produced by certain compilers when operating with pointers declared with the .Em const type qualifier in a context without such qualifier. Examples include passing a pointer declared with the .Em const qualifier to a function without such qualifier, and variable assignment from a .Em const pointer to a non-const pointer. In the same vein, the .Fn __UNVOLATILE macro can be used to exclude warnings related to the .Em volatile type qualifier. .Sh IMPLEMENTATION NOTES These macros are implemented by explicitly using .Em unsigned long instead of .Em intptr_t , a signed type guaranteed to hold a pointer. .Sh SEE ALSO .Xr cc 1 , .Xr cdefs 3 .Sh CAVEATS As both macros may hide valid errors, their usage is not recommended unless there is a well-thought reason for a cast. A typical use case for .Fn __UNCONST involve an .Tn API that does not follow the so-called ``const correctness'' even if it would be appropriate. Valid use cases of .Fn __UNVOLATILE include passing a .Em volatile pointer to .Xr memset 3 .
p Use of this macro is non-portable; this is part of the implementation namespace and should only be used in .Nx code.