[Bug c++/103811] New: [c++20] ICE when a lambda is used as a template argument of another lambda's function parameter

[iamsupermouse at mail dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103811

            Bug ID: 103811
           Summary: [c++20] ICE when a lambda is used as a template
                    argument of another lambda's function parameter
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iamsupermouse at mail dot ru
  Target Milestone: ---

Following code causes an ICE (segfault):

    template <auto> struct A {};
    int main() {[](A<[]{}>){};}

Tested on https://godbolt.org/ , GCC trunk 12.0.0 20211222.

The same thing happens if I move the nested lambda to A's default argument:

    template <auto = []{}> struct A {};
    int main() {[](A<>){};}

MSVC also ICEs on the second snippet, but not on the first.