Strange pimpl problem - const correctness not respected by compiler

=?iso-8859-1?Q?Daniel_Lidstr=F6m?= <>
Tue, 14 Oct 2008 16:47:29 +0200
(I accidentally posted a first version to


I have a strange problem with my pimpl implementation. What happens is that
const correctness is not respected by the compiler. Among two methods, one
const and one non-const, the non-const version ends up being called on a
object. Let me go straight to the code:

#include <iostream>

struct Geometry {};

class LineData
   class LineDataImpl;
   LineDataImpl& mImpl;



   const Geometry& GetGeometry() const;
   /* */ Geometry& GetGeometry() /* */;

class LineData::LineDataImpl
   Geometry mGeometry;


   const Geometry& GetGeometry() const
      std::cout << "Calling const overload" << std::endl;
      return mGeometry;

   Geometry& GetGeometry()
      std::cout << "Calling non-const overload" << std::endl;
      return mGeometry;

   : mImpl(*(new LineDataImpl))
{ }

const Geometry& LineData::GetGeometry() const
   return mImpl.GetGeometry();

Geometry& LineData::GetGeometry()
   return mImpl.GetGeometry();

int main()
   const LineData lineData;
   const Geometry& geometry = lineData.GetGeometry();

   return 0;

This sample shows that despite my intentions of being const correct, the
compiler ends up calling the non-const overload. What is going on here?
I'm using Visual Studio 2008, SP1.

Thanks in advance!

Daniel Lidstr?m

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