c++/3601: GCC 3.0 barfs on overloaded operator==

c++/3601: GCC 3.0 barfs on overloaded operator==

[markus_schoder]

>Number:         3601
>Category:       c++
>Synopsis:       GCC 3.0 barfs on overloaded operator==
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 06 22:06:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Markus Schoder
>Release:        gcc-3.0 gcc-3.0-20010626
>Organization:
>Environment:
Linux i386
>Description:
Compilation of the attached program gives the following error:

eqtempl.cpp: In function `bool g(A)':
eqtempl.cpp:14: choosing `bool operator==(A, void*)' over `operator=='
eqtempl.cpp:14:   because worst conversion for the former is better than worst 
   conversion for the latter

I do not see how there is a conversion involved for bool operator==(A, void*).  0 needs not be "converted" to void* in C++.  However with an explicit conversion to void* it compiles.

It also compiles when -fpermissive is given as an option but this should not be needed.
>How-To-Repeat:
Compile attached program (without linking)
>Fix:
A workaround is to use an explicit cast like:

a == (void*)0

or specify -fpermissive as a command line option.
>Release-Note:
>Audit-Trail:
>Unformatted:
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Re: c++/3601: GCC 3.0 barfs on overloaded operator==

[lerdsuwa]

Synopsis: GCC 3.0 barfs on overloaded operator==

State-Changed-From-To: open->closed
State-Changed-By: lerdsuwa
State-Changed-When: Sat Jul  7 06:19:33 2001
State-Changed-Why:
    Not a bug.  According to the standard Sectio 4.10 (Pointer
    conversions) paragraph 1:
      A null pointer constant is an integral constant expression
      (5.19) rvalue of integer type that evaluates to zero.  A
      null pointer constant can be converted to a pointer type;
      the result is the null pointer value of that type and is
      is distinguishable from every other value of pointer to
      object or pointer to function type. ...
    
    Here 0 is "null pointer constant" and has to be converted
    to "null pointer value" of type "void *".

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=3601&database=gcc