__FPTRCAST(3) - NetBSD Manual Pages

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__FPTRCAST(3)           NetBSD Library Functions Manual          __FPTRCAST(3)


NAME

     __FPTRCAST -- function pointer cast


SYNOPSIS

     #include <sys/cdefs.h>

     ftype
     __FPTRCAST(ftype, fname);


DESCRIPTION

     The __FPTRCAST() macro can be used to silence warnings produced by cer-
     tain compilers when converting from one function pointer type to another.
     The ftype argument is the function pointer type to which to cast the
     function pointer in fname.

     This cast should be used sparingly and it is typically used in the fol-
     lowing situations:
           ·   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.
           ·   We only care about the first few arguments and we don't care
               about the rest.
           ·   We don't care about the return value, we ignore it anyway.


IMPLEMENTATION NOTES

     This macro is implemented by using an intermediate void * cast.


SEE ALSO

     cc(1), cdefs(3)


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 guide-
     line, don't use this macro inside other macros because it will hide cases
     where the user of the original macro accidentally used an incorrect func-
     tion pointer.

     Use of this macro is non-portable; this is part of the implementation
     namespace and should only be used in NetBSD code.

NetBSD 10.1                    October 17, 2013                    NetBSD 10.1