[Bug c++/13384] New: error: non-lvalue in assignment - message a little misleading for C++

[Bug c++/13384] New: error: non-lvalue in assignment - message a little misleading for C++

[gianni at mariani dot ws]

The code below :

struct C
{
    int a;

    C()
      : a(1)
    {
    }
};

template<typename T> void func()
{
    T() = T();
}

int main()
{
    func<C>();
    func<int>();
}

Produces the error message

"error: non-lvalue in assignment"

As you can see, the first instantiation (func<C>) is quite happy to call assign
on an rvalue.  The second (func<int>) uses the built-in operator= which does not
allow assignment to non-lvalue.  While the message is accurate, it would be IMHO
better if the message was:

"error: non-lvalue in built-in assignment" (suggestions welcome)

This message geneaology is probably from the C compiler and is a little
misleading for C++.

-- 
           Summary: error: non-lvalue in assignment - message a little
                    misleading for C++
           Product: gcc
           Version: 3.3.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gianni at mariani dot ws
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13384

[Bug c++/13384] error: non-lvalue in assignment - message a little misleading for C++

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-11 17:05 -------
I can confirm the behavior, though I'm not sure whether we really 
need to change the error message. Gaby -- you're the diagnostics 
maintainer, so it's your call. 
 
W. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gdr at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |diagnostic
   Last reconfirmed|0000-00-00 00:00:00         |2003-12-11 17:05:26
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13384

[Bug c++/13384] error: non-lvalue in assignment - message a little misleading for C++

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-13 06:43 -------
Icc 6.0 produces:
pr13384.cc(15): error: expression must be a modifiable lvalue
      T() = T();
      ^
          detected during instantiation of "void func<T>() [with T=int]" 

compilation aborted for pr13384.cc (code 2)

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13384

[Bug c++/13384] error: non-lvalue in assignment - message a little misleading for C++

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-29 13:32 -------
But note C++ has a definition of lvalue and rvalues so the message is still correct in the C++ sense.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2004-06-13 09:42:53         |2005-01-29 13:32:04
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13384