[vtkusers] error: ISO C++ says that these are ambiguous, even though the worst conversion for the first is better than the worst conversion for the second

[Martin Costabel]

Martin Baumann wrote:
> Hi,
> 
> I have a problem compiling VTK4.2 on a Suse 10 system.
> I get the following errors:
[]
> /home/martin/local/src/VTK/VTK4.2/IO/vtkBMPReader.cxx: In function ‘void 
> vtkBMPReaderUpdate2(vtkBMPReader*, vtkImageData*, OT*) [with OT = double]’:
> /home/martin/local/src/VTK/VTK4.2/IO/vtkBMPReader.cxx:545: instantiated 
> from here
> /home/martin/local/src/VTK/VTK4.2/IO/vtkBMPReader.cxx:507: error: ISO 
> C++ says that these are ambiguous, even though the worst conversion for 
> the first is better than the worst conversion for the second:
> /usr/include/c++/4.0.2/bits/postypes.h:175: note: candidate 1: 
> std::fpos<_StateT> std::fpos<_StateT>::operator+(std::streamoff) const 
> [with _StateT = mbstate_t]
> /home/martin/local/src/VTK/VTK4.2/IO/vtkBMPReader.cxx:507: note: 
> candidate 2: operator+(std::streamoff, long int) <built-in>

This comes from increased anality of recent gcc compiler versions. It 
has been fixed on CVS. From the cvs log for this file:

revision 1.45
date: 2003-10-19 14:38:03 +0000;  author: dgobbi;  state: Exp;  lines: +5 -5
ERR: C++ ambiguity compile error: typecast operands of '+' to same type

% cvs diff -r1.44 -r1.45 IO/vtkBMPReader.cxx
Index: IO/vtkBMPReader.cxx
===================================================================
RCS file: /cvsroot/VTK/VTK/IO/vtkBMPReader.cxx,v
retrieving revision 1.44
retrieving revision 1.45
diff -u -b -w -r1.44 -r1.45
--- IO/vtkBMPReader.cxx 10 Sep 2003 19:41:56 -0000      1.44
+++ IO/vtkBMPReader.cxx 19 Oct 2003 14:38:03 -0000      1.45
@@ -3,8 +3,8 @@
    Program:   Visualization Toolkit
    Module:    $RCSfile: vtkBMPReader.cxx,v $
    Language:  C++
-  Date:      $Date: 2003/09/10 19:41:56 $
-  Version:   $Revision: 1.44 $
+  Date:      $Date: 2003/10/19 14:38:03 $
+  Version:   $Revision: 1.45 $

    Copyright (c) 1993-2002 Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
@@ -23,7 +23,7 @@
  #include "vtkObjectFactory.h"
  #include "vtkPointData.h"

-vtkCxxRevisionMacro(vtkBMPReader, "$Revision: 1.44 $");
+vtkCxxRevisionMacro(vtkBMPReader, "$Revision: 1.45 $");
  vtkStandardNewMacro(vtkBMPReader);

  #ifdef read
@@ -504,11 +504,11 @@
          outPtr0 += outIncr[0];
          }
        // move to the next row in the file and data
-      self->GetFile()->seekg(self->GetFile()->tellg() + streamSkip0, 
ios::beg);
+ 
self->GetFile()->seekg(static_cast<long>(self->GetFile()->tellg()) + 
streamSkip0, ios::beg);
        outPtr1 += outIncr[1];
        }
      // move to the next image in the file and data
-    self->GetFile()->seekg(self->GetFile()->tellg() + streamSkip1, 
ios::beg);
+    self->GetFile()->seekg(static_cast<long>(self->GetFile()->tellg()) 
+ streamSkip1, ios::beg);
      outPtr2 += outIncr[2];
      }

-- 
Martin