FIX: C2664 When Converting Type Defined Array to Const Array

The information in this article applies to:

• Microsoft C/C++ Compiler (CL.EXE) included with Microsoft Visual C++, 32-bit Edition, version 2.0

SYMPTOMS

The C/C++ compiler incorrectly generates a C2664 error when attempting to implicitly convert from a typedef non-constant array type to a constant array type. The compiler reports an error that indicates a conversion from a constant array type to a non-constant array type. The following error message is reported by the compiler if a non-constant integer array type is used:

   test.cpp(#): error C2664: 'copy' : cannot convert parameter 1 from
               'const int[2]' to 'int[2]'

RESOLUTION

To work around the problem, typedef a constant array type instead of using the keyword 'const' together with the typedef non-constant array type. An example is shown in the Sample Code section in this article.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Microsoft Visual C++, 32-bit Edition, version 4.0.

MORE INFORMATION

Sample Code

/* Compile options needed: none
*/

/* -- test.cpp -- */

typedef       int ARRAY[2];

void copy ( const ARRAY src, ARRAY dest );
void copy1( CONST_ARRAY src, ARRAY dest );

  private:
    ARRAY pts[2];
  public:
    void operator=( const CTest& src );

void CTest :: operator=( const CTest& src )

  for ( int i=0; i<2; i++ )
  {

   copy ( src.pts[i], pts[i] );   // Generates C2664
   copy1( src.pts[i], pts[i] );   // Workaround

  }
}