Q242190: BUG: Full Koenig Lookup Works Only for Operators

Article: Q242190
Product(s): Microsoft C Compiler
Version(s): winnt:5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbCPPonly kbLangCPP kbVC kbVC500 kbVC500bug kbVC600 kbVC600bug
Last Modified: 03-MAY-2001

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The information in this article applies to:

- The C/C++ Compiler (CL.EXE), included with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

Argument-dependent name lookup, also known as Koenig lookup, works only for
operators and not regular functions in a namespace.

CAUSE
=====

The compiler does not fully support argument-dependent name lookup as specified
in the C++ Standard. Please refer to the C++ Standard, section 3.4.2, for
information on argument-dependent name lookup.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

MORE INFORMATION
================

Steps to Reproduce Behavior:

The following code example demonstrates the error:

  //test.cpp
  // compiler option needed:/GX  
  #include <iostream>
  namespace N1 {
  	struct T1 {
  	};
  	void g(T1) {
  	}
   	T1 operator+( T1 x, T1 y) {
  		std::cout<< "In N1::+" <<std::endl;
  		return y;
  	}
  }

  int main() {
  	N1::T1 t1 ,t2;
  	g(t1);	// error C2065: 'g' : undeclared identifier
  	t1 + t2; // works fine calls N1::operator+
  	return 0;
  }

Additional query words:

======================================================================
Keywords          : kbCompiler kbCPPonly kbLangCPP kbVC kbVC500 kbVC500bug kbVC600 kbVC600bug 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:5.0,6.0
Issue type        : kbbug

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