Re: c++/7135: Faulty Operator Precedence

["Brian Lindahl" <lindahlb at hotmail dot com>]

The following reply was made to PR c++/7135; it has been noted by GNATS.

From: "Brian Lindahl" <lindahlb@hotmail.com>
To: nathan@gcc.gnu.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, lindahlb@hotmail.com, nobody@gcc.gnu.org, unifex@yuidesigns.net, gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c++/7135: Faulty Operator Precedence
Date: Thu, 27 Jun 2002 11:47:27 -0700

 First of all, I disagree with your analysis. One fact alone should 
 contradict the analysis:
 Inlining the methods changes the compiler output, and thus, the output 
 displayed on the screen.
 
 I believe that, according to C++ semantics, inlining a function should not 
 change compiler output.
 
 I think the problem in my example was the naive expansion of the code from:
 cout << a.set(5).get() << a.set(30).get();
 To:
 operator<<(operator<<(cout, a.set(5).get()), a.set(30).get());
 
 In fact, I should have stated that the code should be equivalent to:
 operator<<(
    operator<<(
       cout,
       A::get(
          &A::set(5, &a)
       )
    ),
    A::get(
       &A::set(30, &a)
    )
 );
 
 (Note the method, set, returns '*this' as a 'const A &')
 
 >     There are 4 sequence points in that, each between
 >     evaluating the parameters to a call, and the call itself.
 >     These sequence points are partially ordered, but not
 >     completely ordered. In particular there is no ordering
 
 As shown above, there are more than 4 sequence points, in evaluating the 
 parameters of the parameters of the call. Furthermore, the existance of 
 parenthesis creates a need, I believe, for complete ordering, not the 
 partial ordering you suggest.
 
 >     completely ordered. In particular there is no ordering
 >     between the a.Wobble (30) call and the a.Wibble (5) call.
 
 Correct, in particular. But because they are contained in different layers 
 of parenthesis, there is a complete ordering in the code.
 
 I hope I understood what you meant correctly,
 -Brian Lindahl
 
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