[Bug c++/124515] New: ICE on invalid code

[rippey.e at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124515

            Bug ID: 124515
           Summary: ICE on invalid code
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rippey.e at gmail dot com
  Target Milestone: ---

Created attachment 63936
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63936&action=edit
Results of "-freportbug"

Tested on:

g++ (GCC) 16.0.1 20260315 (experimental)

This was also tried on:

g++-15 (15.2.0-4ubuntu4)
g++-14 (14.3.0-8ubuntu1)
g++-13 (13.4.0-4ubuntu1)
g++-12 (12.5.0-6ubuntu1)
g++-11 (11.5.0-7ubuntu1.1)

All of which say something similar to:

note: ‘requires’ only available with ‘-std=c++20’ or ‘-fconcepts’

And then they fail with similar errors to trunk when given '-std=c++20'.