From: Nathan Myers <ncm@cygnus.com>
To: egcs@cygnus.com
Subject: Re: Bug in egcs ?
Date: Thu, 23 Apr 1998 21:12:00 -0000 [thread overview]
Message-ID: <353FD1A1.2F66831A@cygnus.com> (raw)
In-Reply-To: <353F3C9D.EDC7B0D8.cygnus.egcs@cern.ch>
Laurent Deniau wrote:
> egcs doesn't complain on the following code:
>
> template <typename T>
> struct Object {
> Object&
> operator = (Object<T> const& e) {
> const_cast<T>(_e) = e;
> return *this;
> }
> T _e;
> };
>
> According to the CD2, we should have write :
>
> const_cast<T&>(_e) = e;
>
> in order to get reference to _e.
This code is wrong in any case.
No cast is needed, generally, to call T::operator= on a
const right-operand. (auto_ptr<> is a special case.)
In this case, the expression _e already has type T&, because
_e is itself not const, so the const_cast has no effect anyway.
I don't see how the compiler could be instrumented to detect
errors like this.
It might be reasonable for the compiler to warn about calling operator=
with an rvalue left-operand, and perhaps to warn about a cast that has
no effect.
Nathan Myers
ncm@cantrip.org
next parent reply other threads:[~1998-04-23 21:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <353F3C9D.EDC7B0D8.cygnus.egcs@cern.ch>
1998-04-23 21:12 ` Nathan Myers [this message]
1998-04-24 6:54 ` Gabriel Dos Reis
1998-04-23 6:05 Laurent Deniau
[not found] <52lnxmz6px.fsf.cygnus.egcs@ace.funcom.com>
1997-12-15 15:07 ` Bug in egcs? Jason Merrill
1997-12-16 0:36 ` Marius Kjeldahl
1997-12-16 12:25 ` Jason Merrill
1997-12-16 12:25 ` Marius Kjeldahl
-- strict thread matches above, loose matches on Subject: below --
1997-12-15 12:34 Marius Kjeldahl
1997-12-15 13:47 ` H.J. Lu
1997-12-15 13:58 ` H.J. Lu
1997-12-15 16:57 ` Jani Hakala
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