[Bug tree-optimization/15881] New: Incorrect error on legal C++

["dalej at apple dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Compile the following on lno-branch with g++ -O2 and watch the crash.
Some analysis follows example:

class QGArray
{
public:
  char *at (unsigned int index) const { return &shd[index]; }
  char *shd;
};
template<class type>
class QMemArray : public QGArray
{
public:
    type& operator[]( int i ) const
 { return (type &)(*(type *)QGArray::at(i*sizeof(type))); }
};
struct QLayoutStruct
{
  bool empty;
};
class QGridLayoutData
{
    int rr;
    int findSize (int QLayoutStruct::*) const;
    QMemArray<QLayoutStruct> rowData;
};
int QGridLayoutData::findSize( int QLayoutStruct::*size ) const
{
    int h = 0;
    int n = 0;
    for ( int r = 0; r < rr; r++ ) {
       h = h + rowData[r].*size;
       if ( !rowData[r].empty )
         n++;
    }
  return n * h;
}


The key 
difficulty is

       h = h + rowData[r].*size;

which is gimplified into

    size.6<D1654>_15 = (int<D2>)size<D1640>_14;
    T.7<D1655>_16 = T.5<D1653>_13 + size.6<D1654>_15;

The code that looks for induction variables tries to analyze
(int<D2>)size<D1640>_14
and winds up trying to do the conversion at compile time through this chain of calls:

interpret_rhs_modify_expr
chrec_convert
convert
ocp_convert
convert_to_integer

which crashes with
3683113.sm.cc:25: error: aggregate value used where an integer was expected

I'm not familiar enough with ptr-to-member to figure out what it ought to be doing, but this isn't it.

-- 
           Summary: Incorrect error on legal C++
           Product: gcc
           Version: lno
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dalej at apple dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc-apple-darwin7.3.0
  GCC host triplet: powerpc-apple-darwin7.3.0
GCC target triplet: powerpc-apple-darwin7.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15881