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.
Warner
    
    
More information about the freebsd-current
mailing list