[Bug c++/126828] [16/17 Regression] ICE with template type alias with NTTP and constexpr capture default reference inside a template function

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126828

Drea Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|needs-reduction             |needs-bisection
            Summary|[16/17 Regression] internal |[16/17 Regression] ICE with
                   |compiler error related to   |template type alias with
                   |the Eigen library           |NTTP and constexpr capture
                   |                            |default reference inside a
                   |                            |template function
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2026-08-12
             Status|UNCONFIRMED                 |NEW

--- Comment #4 from Drea Pinski <pinskia at gcc dot gnu.org> ---
Reduced down to:
```
template <int> class a{};
template <int b> using c = a<b>;
template <int> void d() {
  constexpr unsigned blocksize = 8;
  [&] {
    c<blocksize> g;
  };
}
```