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<P> </P><!--SP:rahul1.jain--><!--rahul1.jain:EP-->
<P>Hi all,</P>
<P> </P>
<P>This is regarding 14.5.6.2 Partial ordering of function template.</P>
<P> </P>
<P>Test case - 1</P>
<P>struct A { };</P>
<P>template<class T> struct B {</P>
<P>template<class R> int operator*(R&); // #1</P>
<P>};</P>
<P>template<class T, class R> int operator*(T&, R&); // #2</P>
<P> </P>
<P>// The declaration of B::operator* is transformed into the equivalent of</P>
<P>// template<class R> int operator*(B<A>&, R&); // #1a</P>
<P> </P>
<P>int main() {</P>
<P>A a;</P>
<P>B<A> b;</P>
<P>b * a; // calls #1a</P>
<P>}</P>
<P> </P>
<P>The above test case works fine as per standards as #1a is more specialized than #2.</P>
<P> </P>
<P>However when we tweak the test case in this way:</P>
<P> </P>
<P>struct A{};</P>
<P>template<class T> struct B<BR>{<BR> template<class R> int operator*(R&); // #1<BR>};</P>
<P>template <class T> int operator*(T&, A&); // #2</P>
<P>// The declaration of B::operator* is transformed into the equivalent of<BR>// template<class R> int operator*(B<A>&, R&); // #1a</P>
<P><BR>int main()<BR>{<BR> A a;<BR> B<A> b;<BR> b*a;<BR>}<BR></P>
<P>clang throws an error saying:</P>
<P>error: use of overloaded operator '*' is ambiguous (with operand types 'B<A>' and 'A')</P>
<P> </P>
<P>How is partial ordering done in this case? How is the specialization decided for the below mentioned</P>
<P>operator overloading declarations?</P>
<P> </P>
<P>template<class R> int operator*(B<A>&, R&); // #1a</P>
<P>template <class T> int operator*(T&, A&); // #2</P>
<P> </P>
<P>It would be great if someone could explain whether this behavior is correct and more importantly</P>
<P>how clang does partial ordering and judge specialization between two function template overloads?</P>
<P> </P>
<P>Thanks,</P>
<P>Rahul</P>
<P> </P>
<P> </P>
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