[Bug c++/64826] Better diagnostics for when ADL/overloading doesn't apply as desired

[b.r.longbons at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64826

--- Comment #1 from Ben Longbons <b.r.longbons at gmail dot com> ---
Created attachment 34597
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34597&action=edit
test set 2, regressions on namespace merging (I don't understand this)