Re: Type punned-pointers

[Ulrich Lauther]

Henrik Goldman <henrik_goldman@mail.tele.dk> wrote:

: > FD_SET is probably a macro. I would take a look at the expanded code, 
: > which
: > might try to do some illegal pointer assignment.
: >

: Yes, I've been thinking the same thing. Here is a piece of header from 
: /usr/include/sys/_fd_macros.h:


the problem will possibly vanish if you disable strict-aliasing.

>From the manual:

`-fstrict-aliasing'
  Allows the compiler to assume the strictest aliasing rules
  applicable to the language being compiled.  For C (and C++), this
  activates optimizations based on the type of expressions.  In
  particular, an object of one type is assumed never to
  reside at the same address as an object of a different type, unless the
  types are almost the same.  For example, an `unsigned int' can
  alias an `int', but not a `void*' or a `double'.  A character type
  may alias any other type.

        -lauther

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