[Bug c++/66440] New: Diagnostic on "'foo' was not declared in this scope" offers an invalid suggestion

["unmobile at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66440

            Bug ID: 66440
           Summary: Diagnostic on "'foo' was not declared in this scope"
                    offers an invalid suggestion
           Product: gcc
           Version: 5.1.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: unmobile at gmail dot com
  Target Milestone: ---

Created attachment 35706
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35706&action=edit
Test input

When I try to compile the attached source with g++ 5.1.1, I get a suggestion to
use C::f. However, an explicit qualified call to C::f with the given template
and function arguments would be invalid, as shown in the later statement.
Perhaps the compiler should evaluate the candidates before enumerating them for
the user, and either drop them or distinguish that they wouldn't actually
match?