[Bug libstdc++/106669] incorrect definition of viewable_range ("more madness with move-only views")

[h2+bugs at fsfe dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106669

--- Comment #1 from Hannes Hauswedell <h2+bugs at fsfe dot org> ---
This affects GCC 10.4 and GCC 11.3 since move-only views were backported.

The following part of the draft standard also needs changing:

https://eel.is/c++draft/range.all#general-2.1

--->

decay-copy(E) if that expression is well-formed and the decayed type of E
models view.

This will make references to move-only views pick the second option (ref_view).