On Thu, Aug 20, 2020 at 11:36 PM jim x via Std-Discussion <std-discussion@lists.isocpp.org> wrote:
Hi,  everyone. please consider the below code:

template<typename T>
void func(){
struct Test{};
void show(...){
int main(){
There is no any rule in [temp.dep.type] to specify the local class
declared within function template may be considered as dependent type.
So, I think the name lookup for `show` should be bound at the point it
is used. The second phase name lookup shouldn't occur due to `show` is
not a dependent-name, at least according to the definition of
dependent-name in section [temp.dep]. However, current implementations
all consider `show` as a dependent-name which will be found by ADL in
the context of instantiation, that is, The local class `Test` is
viewed as dependent-type. If I don't misunderstand the section
[temp.dep.type], how would `Test` be a dependent-type? For such a
local class, Is it  a case  missed in the section [temp.dep.type].
Thanks for discussing such an example.
Std-Discussion mailing list

I agree that the current wording does not make "Test" a dependent type in your example. GCC/Clang/MSVC violate [temp.res]/10 by failing to give an undeclared-identifier error for "show".

But maybe that's intentional, and it's the wording that needs to be changed. If nested classes in class templates are dependent, why not also local classes in function templates?