[Bug c++/99511] New: default arguments are allowed for parameters of a requires expression

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99511

            Bug ID: 99511
           Summary: default arguments are allowed for parameters of a
                    requires expression
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

The following code should not be accepted by gcc-10, since default arguments
are not allowed for parameters of a requires expression.

template <typename T>
concept C = requires (T = {}) { true; };

(goldbot: https://godbolt.org/z/fM88qb)