decltype((void)T{}) in template Partial Specialization not deduce?


decltype((void)T{}) in template Partial Specialization not deduce?


template<typename T,typename U = void>
struct Test
{
static const int value = 0;
};
template<typename T>
struct Test<T, decltype((void)T{})>
{
static const int value = 2;
};

template<typename T>
struct Test<T*, decltype((void)T{})>
{
static const int value = 1;
};

int main(){
cout<<Test<int*>::value<<endl;
return 0;
}



code on gcc/clang both get error:ambiguous ,but decltype change to void_t is ok.why?





Could this be related? stackoverflow.com/questions/4031228/…
– alter igel
Jun 30 at 1:07





@alterigel I don't think so.change to decltype(T{},void()) error again
– fe263
Jun 30 at 1:13





What are you trying to do here?
– Nicol Bolas
Jun 30 at 1:18





@NicolBolas I think use decltype is deduced context,but compiler don't think so. I want to know why?
– fe263
Jun 30 at 1:38









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