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POC++ operator overloading resolution ambiguity
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  1. POC++ operator overloading resolution ambiguity
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    copied!<p>Am trying to move an antique C++ code base from gcc 3.2 to gcc 4.1, as I have run into a few issues. Of all the issues, the following is left me clueless (I guess I spent too much time with Java or I might have forgotten the basics of C++ :-P ).</p> <p>I have a template class</p> <pre><code>template &lt; class T &gt; class XVector &lt; T &gt; { ... template &lt; class T &gt; T XVector &lt; T &gt;::getIncrement () { ... } template &lt; class T &gt; int XVector &lt; T &gt;::getValue (size_t index, T&amp; value) { ... //The problematic line value = (T) (first_value + getIncrement()) * (long) (index - first_index); .... } } </code></pre> <p>This class is based on the STL std::vector. I have a second class TypeValue and its defined as below which can hold one of int, long and their unsigned variants, float, double, std::string. Also overloads almost all possible operators.</p> <pre><code>class TypeValue { union { long* _int_value; double* _real_value; string* _text_value; } _value; TypeValue(); explicit TypeValue(long _long); explicit TypeValue(int _int); explicit TypeValue(unsigned long _ulong); ... //similarly for all the remaining supported types. TypeValue(const TypeValue&amp; ) //Copy constructor virtual TypeValue&amp; operator=(const TypeValue &amp;rhs); TypeValue&amp; operator+ (TypeValue&amp; )const; TypeValue&amp; operator* (TypeValue&amp; )const; ... //For all the basic operators operator long() const; operator int() const; operator unsigned long() const; operator unsigned int() const; ... } </code></pre> <p>And finally I have another class, lets call it the build_breaker, which creates an object as <code>XVector &lt; TypeValue &gt; a_variable;</code>. Now when I compile this on gcc 3.2 this compiles without any problems. But when I try compiling this on gcc 4.1 I get errors saying ambigous overload for <code>operator*</code> in the class <code>XVector</code> and the candidates being</p> <pre> operator*(long int, long int) operator*(int, long int) operator*(long unsigned int, long int) operator*(unsigned int, long int) operator*(double, long int) operator*(float, long int) </pre> <p>If the compiler said it had problems finding a match for T * long, that would have made sense, but, why is it trying to typecast it to native type and then perform the arithmetic operation? Please help me on this.</p> <p>Thanks in advance.</p>
 

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