https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94819
--- Comment #1 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
A slightly more reduced example:
```c++
#include <utility>
template <typename component_types>
struct alphabet_tuple_base
{
template <typename component_type>
requires std::is_same_v<component_type, component_types>
constexpr alphabet_tuple_base(component_type) {} // commenting out
constexpr works?!
template <typename indirect_component_type>
requires (!std::is_same_v<indirect_component_type, component_types>)
alphabet_tuple_base(indirect_component_type) {};
};
template <typename sequence_alphabet_t>
struct structured_rna : alphabet_tuple_base<sequence_alphabet_t> {
using base_type = alphabet_tuple_base<sequence_alphabet_t>;
using base_type::base_type;
};
struct dna4 {};
struct rna4 {};
structured_rna<rna4> t1{rna4{}}; // commenting out any of these works?!
structured_rna<rna4> t2{dna4{}}; // commenting out any of these works?!
structured_rna<rna4> t3{rna4{}}; // commenting out any of these works?!
```
https://godbolt.org/z/VACou9
