https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112594
Bug ID: 112594
Summary: Non-type template parameter created with converting
constructor sometimes has original type
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mital at mitalashok dot co.uk
Target Milestone: ---
The following code complains that `N` (which was declared `n N`) is `3` (of
type `int`) instead of `n(3)`:
<https://godbolt.org/z/rv3777Ycv>
template<typename T>
concept C = true;
struct n {
constexpr n(int) {}
static int i;
};
template<n N>
using get_n_i_type = decltype(N.i);
template<int X>
int f() {
using iii = get_n_i_type<X>;
#if 1 // Change to 0 and this compiles
static_assert(C<iii>);
#endif
return iii{};
}
template int f<3>();
Compiler error given:
<source>: In instantiation of 'int f() [with int X = 3]':
<source>:21:19: required from here
21 | template int f<3>();
| ^
<source>:10:33: error: request for member 'i' in '3', which is of non-class
type 'int'
10 | using get_n_i_type = decltype(N.i);
| ~~^
This compiles fine if Clang and MSVC or if you remove the static_assert or
change `template<int X>` to `template<auto X>`.
