Correction:
The construct gcc complains about is not
if ( a < b ) ...
but
if ( a < b - ( b >> 2 ) ) ...
but still the same applies. The RHS of the > operator can never be
negative or have an overflow on 32 bits.
On Fri, 8 Mar 2019 10:40:06 +1100
Zoltan Kocsi wrote:
> Gcc 8.2.0 (arm-none-eabi) throws a warning on the following construct:
>
> uint32_t a;
> uint16_t b;
>
> if ( a > b ) ...
>
> compaining that a signed integer is compared against an unsigned.
> Of course, it is correct, as 'b' was promoted to int.
>
> But shouldn't it be smart enough to know that (int) b is restricted to
> the range of [0,65535] which it can safely compare against the range
> of [0,0xu]?
>
> Thanks,
>
> Zoltan
