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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/102975] Local alias diagnosed as unused when used in failing constraint
Date: Sun, 31 Oct 2021 05:01:25 +0000	[thread overview]
Message-ID: <bug-102975-4-xpy3cUp2ji@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102975-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102975

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, this is interesting:
template<class> concept Never = false;
template<class T> concept C = Never<typename T::type>;
void f() {
  struct X {
   // using type = int;
  };
  static_assert(not C<X>);
}

is able to compile. I don't know enough about C++ concepts to say if this is
valid or not but it looks like the type is really unused in the above case ...
This is different from "constexpr bool" which requires the type to be defined
...

  reply	other threads:[~2021-10-31  5:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-27 22:04 [Bug c++/102975] New: " johelegp at gmail dot com
2021-10-31  5:01 ` pinskia at gcc dot gnu.org [this message]
2021-10-31 14:58 ` [Bug c++/102975] " ppalka at gcc dot gnu.org
2021-10-31 15:01 ` ppalka at gcc dot gnu.org
2021-10-31 15:02 ` johelegp at gmail dot com
2021-11-02 13:15 ` ppalka at gcc dot gnu.org

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