FIX: Non-const Conversion Operators Allowed on const Object

MS-DOS | WINDOWS             | WINDOWS NT

The information in this article applies to:

• The Microsoft C/C++ Compiler (CL.EXE) included with:

      - Microsoft C/C++ version 7.0
      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52
      - Microsoft Visual C++, 32-bit Edition, versions 1.0, 2.0, 2.1, 2.2
  

SYMPTOMS

Visual C++ illegally allows use of non-const member functions with const objects. Because of this, const data could be modified.

Visual C++ correctly generates errors in most situations where non-const member functions are used on const objects, but fails to generate errors in the case of non-const conversion operators.

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

The sample code should generate this error message:

    error C2664: 'x_t::x_t(const struct x_t&)' : cannot convert
         parameter 1 from 'struct x_t*const ' to 'const struct x_t&'

Sample Code to Reproduce Problem

/* Compile options needed: none
*/

  int i;
  operator int() {return i;}

void func(const x_t& x)

    int j = (int)x;     //C2664 should be generated on this line
}