[Bug c++/85809] New: SFINAE code compiles that shouldn't be able to compile.

[viktorzoutman at vzout dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85809

            Bug ID: 85809
           Summary: SFINAE code compiles that shouldn't be able to
                    compile.
           Product: gcc
           Version: 8.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: viktorzoutman at vzout dot com
  Target Milestone: ---

The following SFINAE code shouldn't be able to compile as far as I'm aware.
However it does compile on gcc: https://godbolt.org/g/D5BkWf

The interesting thing is if you comment out line 25 it gives an error as it
should. But line 25 doesn't have anything to do with the incorrect code. As you
can see in the following code example: https://godbolt.org/g/azEvKp