__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