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Re: [c++-concepts] requires expression semantics
- From: Andrew Sutton <andrew dot n dot sutton at gmail dot com>
- To: Jason Merrill <jason at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Gabriel Dos Reis <gdr at axiomatics dot org>
- Date: Thu, 27 Jun 2013 15:56:29 -0500
- Subject: Re: [c++-concepts] requires expression semantics
- References: <CANq5SyvWKM8dm_Qaiu2_UHqXyWU=6tetPrEwhuZH3i+DYd42Xg at mail dot gmail dot com> <51CC7AC4 dot 9070400 at redhat dot com>
> Judging from the implementation, it seems that this relies on the notion of
> "potentially-constant expression" which is no longer part of the standard;
> that notion should only be used for diagnostics that are not required, not
> for things that participate in the type system.
>
> I think it would be better to have a requirement that a particular
> expression instantiate into an actual constant expression.
I was not aware of that. That's probably the right, but I remember
having some troubles getting that to work the way I wanted in the
previous implementation. It seemed like I actually had to evaluate the
expression to determine if it was actually constexpr.
Andrew