c++/7135: Faulty Operator Precedence

[lindahlb@hotmail.com]

>Number:         7135
>Category:       c++
>Synopsis:       Faulty Operator Precedence
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Wed Jun 26 16:36:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Brian Lindahl
>Release:        2.95.3
>Organization:
>Environment:
FreeBSD
>Description:
The source code depicting the problem is attatched as a file.

Lines which show existance of the bug:
cout << a.set(5).get() << a.set(30).get();
cout << a.get();

The output of the compiled program:
5305

The machine code appears to be executeing 'set(5)' first, and then 'set(30)', as it should. However, as indicated by the last output, it executed 'set(5)' last as well as first. It appears to be executing 'set(5)' twice.

The generated code should be of the following:
operator<<(operator<<(cout, a.set(5).get()), a.set(30).get());

I ran over the output and code several times to figure out what order the operations are actually taking place, but I was unable to come up with a logical order that would produce the output, unless 'set(5)' was being executed twice.
>How-To-Repeat:
The file attatched shows how to repeat.
>Fix:
There are two fixes:
1) Adjust the problem lines as so:
cout << a.set(5).get();
cout << a.set(30).get();
cout << a.get();
2) Inline the methods 'set(int)' and 'get()'

Apply either fix and the output of the compiled program is as expected:
53030
>Release-Note:
>Audit-Trail:
>Unformatted: