[PATCH] Use the correct from type in a SCS

[Richard Smith]

On Mon, Jul 14, 2014 at 5:15 AM, Ehsan Akhgari <ehsan.akhgari at gmail.com>
wrote:

> On Sun, Jul 13, 2014 at 9:04 PM, Richard Smith <richard at metafoo.co.uk>
> wrote:
>
>> The problem in PR20218 is visible in its notes:
>>
>> test.cpp(4,3) :  note: candidate constructor [with X = int, Y = void ()]
>>   pair(X&&, Y&&);
>>   ^
>>
>> This deduction is wrong. We should get Y = void (&)(). Presumably the
>> 'deduce an lvalue reference if an rvalue reference to T binds to an lvalue'
>> rule isn't being applied appropriately in the case where the lvalue is an
>> overload set.
>>
>
> Thanks, Richard!  Given the above, and also r212916, do we want to still
> take my patch here?
>

Does it change the diagnostic in this case (from 'no overload [...]' to 'no
known conversion from 'void ()' to 'int'):

template<typename T> void f();
int g(int);
int k = g(f<int>);

If so, please go ahead with that as a testcase.

--
> Ehsan
> <http://ehsanakhgari.org/>
>
>
>
>>
>> On Tue, Jul 8, 2014 at 3:13 PM, Ehsan Akhgari <ehsan.akhgari at gmail.com>
>> wrote:
>>
>>> On Tue, Jul 8, 2014 at 6:05 PM, Richard Smith <richard at metafoo.co.uk>
>>> wrote:
>>>
>>>> On Sun, Jul 6, 2014 at 12:16 PM, Ehsan Akhgari <ehsan.akhgari at gmail.com
>>>> > wrote:
>>>>
>>>>> Hi doug.gregor,
>>>>>
>>>>> If during constructing a standard conversion sequence, we resolve an
>>>>> overload, we need to adjust the from type in the SCS according to the
>>>>> resolved operator.
>>>>>
>>>>> I found this bug when debugging PR20218.  It doesn't completely fix
>>>>> that
>>>>> test case though.
>>>>>
>>>>
>>>> The fix looks correct, but please provide some kind of test case for
>>>> this patch (even if it doesn't solve PR20218's test case).
>>>>
>>>
>>> I tried to do that, but I wasn't able to write a simpler test case
>>> similar to that of PR20218 which would have an observable outcome different
>>> after this patch...  Any ideas how I can write a good test case for this?
>>>
>>> Thanks!
>>> --
>>> Ehsan
>>> <http://ehsanakhgari.org/>
>>>
>>>
>>>>
>>>>
>>>>> http://reviews.llvm.org/D4402
>>>>>
>>>>> Files:
>>>>>   lib/Sema/SemaOverload.cpp
>>>>>
>>>>> Index: lib/Sema/SemaOverload.cpp
>>>>> ===================================================================
>>>>> --- lib/Sema/SemaOverload.cpp
>>>>> +++ lib/Sema/SemaOverload.cpp
>>>>> @@ -1462,6 +1462,7 @@
>>>>>        // We were able to resolve the address of the overloaded
>>>>> function,
>>>>>        // so we can convert to the type of that function.
>>>>>        FromType = Fn->getType();
>>>>> +      SCS.setFromType(FromType);
>>>>>
>>>>>        // we can sometimes resolve &foo<int> regardless of ToType, so
>>>>> check
>>>>>        // if the type matches (identity) or we are converting to bool
>>>>>
>>>>> _______________________________________________
>>>>> cfe-commits mailing list
>>>>> cfe-commits at cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>>>
>>>>>
>>>>
>>>
>>
>
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