[Insight-developers] itkSetClampMacro -- warnings for unsigned int values?

[Bill Lorensen]

Perhaps a new macro:
itkSetClampUnsignedMacro

On Mon, Jul 18, 2011 at 12:43 PM, David Cole <david.cole at kitware.com> wrote:
> On Mon, Jul 18, 2011 at 12:30 PM, Williams, Norman K
> <norman-k-williams at uiowa.edu> wrote:
>> I'm trying the change out, to see what happens. It looks like it does
>> silence that warning, as it's valid to ask if an unsigned value is greater
>> than or equal than zero.
>
> Sure it's valid, but it's still always true. In other words: may as
> well not have an "if" for such an expression... I'm surprised the
> compiler doesn't give a "conditional expression always true" warning.
>
>>
>>
>> I'm more concerned that itkSetClampMacro is used on types where that
>> comparison causes problem. It should not cause a problem with any POD
>> type, but I'm not sure whether its use is limited to POD.
>>
>> On 7/18/11 11:03 AM, "David Cole" <david.cole at kitware.com> wrote:
>>
>>>On Mon, Jul 18, 2011 at 11:43 AM, Williams, Norman K
>>><norman-k-williams at uiowa.edu> wrote:
>>>> This throws compiler warnings:
>>>>
>>>>  itkSetClampMacro(MaxLevel, unsigned int, 0, NumericTraits<unsigned
>>>> int>::max() );
>>>>
>>>> Specifically, it uses the expression _arg < 0, which is always false.
>>>>
>>>>
>>>> This is only seen in the '-Wall -Wextra' world.
>>>>
>>>> Possible solution -- change itkMacro.h and replace
>>>>
>>>> _arg < min
>>>>
>>>> with
>>>>
>>>> !(_arg >= min)
>>>>
>>>
>>>Won't this just change the warning to "this condition is always true"
>>>..... ?
>>>
>>>
>>>> This is a niggling point but eliminating specious and spurious warnings
>>>> will make it easier to see the real warnings.
>>>>
>>>> I imagine that once a compiler optimizes the code in that macro, the end
>>>> result will be nearly the same.
>>>> --
>>>> Kent Williams norman-k-williams at uiowa.edu
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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>>
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