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From: Ian Lance Taylor <iant@google.com>
To: Pawel Sikora <pluto@agmk.net>
Cc: gcc-help@gcc.gnu.org
Subject: Re: confusion about string.erase( --string.end() )
References: <8433837.L6u1V86xfQ@pawels>
Date: Tue, 22 Nov 2011 18:18:00 -0000
In-Reply-To: <8433837.L6u1V86xfQ@pawels> (Pawel Sikora's message of "Tue, 22	Nov 2011 16:31:42 +0100")
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Pawel Sikora <pluto@agmk.net> writes:

> afaics the gcc-4.6 accepts following code:
>
> #include <string>
> int main()
> {
>         std::string line( "blabla" );
>         line.erase( --line.end() );
> }
>
> but other compilers reject such code:
>
> msvc8  : error C2105: '--' needs l-value
> comeau : error: expression must be a modifiable lvalue
>
> is it a bug in g++?

I don't think this is a bug.  std::string::end is required to return a
std::string::iterator.  The type of std::string::iterator is
implementation defined.  It so happens that the g++ implementation of
std::string::iterator has an operator-- method.  Apparently this is not
true of the implementations used by MSVC or Comeau.  So it's not a bug,
it's just an implementation difference permitted by the standard.

Ian