Strange warning in C++11 range based for loop

[Ian Lance Taylor]

Marc Glisse <marc.glisse@inria.fr> writes:

> On Tue, 30 Aug 2011, Ian Lance Taylor wrote:
>
>> Jonathan Wakely <jwakely.gcc@gmail.com> writes:
>>
>>> You could file an enhancement request in Bugzilla requesting that the
>>> warning is disabled for the variable in the for-range-declaration.
>>
>> Personally I think this is the way to go.  The variable is implicitly
>> used, and the warning should reflect that.
>
> If C++ had allowed for(int:range) in addition to for(int i:range),
> like you can abstain from naming function arguments, the warning would
> have made more sense. As it is, I agree the warning should go,
> although I don't know why you say the variable is implicitly used.

The variable is implicitly used in the generated code: each element of
the iterable is assigned to it in turn.  Those assignments are likely
later discarded as dead, but there is still an implicit use.

Ian