GCC 3.3.1, new warnings with <limits>

M. Warner Losh imp at bsdimp.com
Sun Jul 13 11:24:44 PDT 2003

: >     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).

(unsigned int) -1 == 0xffffffff	  (assuming 32-bit int).

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.


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