GCC 3.3.1, new warnings with <limits>
leimy2k at mac.com
Sun Jul 13 11:38:05 PDT 2003
On Sunday, July 13, 2003, at 1:23PM, M. Warner Losh wrote:
> : > 134 #define __glibcpp_signed(T) ((T)(-1) < 0)
> : #define __glibcpp_signed(T) (!((T)(-1) > 0))
> Why not the simpler:
> #define __glibcpp_signed(T) ((T)(-1) <= 0)
> that way we have an overlap on the range of the two types, so we won't
> get a warning. We know for a fact that -1 != 0 for all known machine
> types (all machines are two's complement, or are required to behave as
> if they are two's complement, per the standard).
You keep saying this... where is this "must behave as two's compliment
> (unsigned int) -1 == 0xffffffff (assuming 32-bit int).
or with a valid one's compliment C99 compliant system
(unsigned int) -1 = 0xfffffffe;
> even on a one's complement's machine, without the standard conversion,
> the 'type punning' conversion of -1 would yield 0xfffffffe, which is
> still > 0.
Correct :). I still don't think C enforces two's compliment.
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