__UNCONST(3)						   BSD Library Functions Manual 					      __UNCONST(3)

NAME

     __UNCONST -- compile time cast-away macro

SYNOPSIS

     #include <sys/cdefs.h>

     void
     __UNCONST(x);

     void
     __UNVOLATILE(x);

DESCRIPTION

     The __UNCONST() macro can be used to omit warnings produced by certain compilers when operating with pointers declared with the const type
     qualifier in a context without such qualifier.  Examples include passing a pointer declared with the const qualifier to a function without
     such qualifier, and variable assignment from a const pointer to a non-const pointer.  In the same vein, the __UNVOLATILE() macro can be used
     to exclude warnings related to the volatile type qualifier.

IMPLEMENTATION NOTES

     These macros are implemented by explicitly using unsigned long instead of intptr_t, a signed type guaranteed to hold a pointer.

SEE ALSO

     cc(1), cdefs(3)

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 __UNCONST() involve an API that does not follow the so-called ``const correctness'' even if it would be appropriate.  Valid use cases of
     __UNVOLATILE() include passing a volatile pointer to memset(3).

BSD
								 December 16, 2010							       BSD