Re: [dpdk-dev] [PATCH] eal, power: don't use '-' sign with unsigned literals

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Mar 12, 2021 at 09:05:58AM -0800, Tyler Retzlaff wrote:
> On Fri, Mar 12, 2021 at 12:51:46PM +0000, Burakov, Anatoly wrote:
> > On 09-Mar-21 11:44 PM, Tyler Retzlaff wrote:
> > >use ~0ULL instead of -1ULL to avoid contridctory application of '-' sign
> > >to integer literal where the desired type is unsigned.
> > >
> > >Signed-off-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> > >---
> > 
> > Not sure i agree. It's a very common pattern and is widely used and
> > understood. I mean, if anything, seeing `~0` would have me stop and
> > think as i've literally never seen such code before.
> 
> it produces warnings under some compilers. in some enterprises we are
> required to fix certain classes of warnings (not suppress them from the
> command line) as a function of security policies.
> 
> as an alternative would you be more willing to accept something like the
> following? ``(unsigned long long)-1LL'' if you don't like ``~0ULL'' it
> would make explicit what the compiler is already doing.
> 
> the issue is the application of the sign to what is clearly something not
> signed; it get's flagged. so the cast is an explicit expression of intent
> that will not generate the warnings.
> 
> appreciate you're help in finding a solution even if it isn't the
> proposed solution.
> 
What about using ULLONG_MAX and similar defines from limits.h?