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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/96088] Range insertion into unordered_map is less
 effective than a loop with insertion
Date: Thu, 09 Jul 2020 14:46:17 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D96088

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #3)
> > Adding hash<string>::operator()(string_view) is an interesting idea for=
 the
> > standard though.
>=20
> Indeed. If we want to, I think it is possible to add some overloads for w=
hen
> the argument is exactly const char* or string_view, which should remain
> conforming and provide a significant part of the benefits.

It would probably have to be:

  template<typename T>
    requires same_as<T, basic_string_view<Char,Traits>>
    size_t
    operator()(T) const;

otherwise it can introduce ambiguities for things convertible to both string
and string_view. But that annoyance aside, it seems worth exploring.=