C
C++03 schrieb:
13.3.3 Best Viable Function [over.match.best]
...
Given these definitions, a viable function F1 is defined to be a better function than another viable function F2 if for all arguments i, ICSi(F1) is not a worse conversion sequence than ICSi(F2), and then
— for some argument j, ICSj(F1) is a better conversion sequence than ICSj(F2), or, if not that,
— F1 is a non-template function and F2 is a function template specialization, or, if not that,
— F1 and F2 are function template specializations, and the function template for F1 is more specialized than the template for F2 according to the partial ordering rules described in 14.5.5.2, or, if not that,
— the context is an initialization by user-defined conversion (see 8.5, 13.3.1.5, and 13.3.1.6) and the standard conversion sequence from the return type of F1 to the destination type (i.e., the type of the entity being initialized) is a better conversion sequence than the standard conversion sequence from the return type of F2 to the destination type. [Example:
struct A {
A();
operator int();
operator double();
} a;
int i = a; // a.operator int() followed by no conversion
// is better than a.operator double() followed by
// a conversion to int
float x = a; // ambiguous: both possibilities require conversions,
// and neither is better than the other
—end example]
n3290 schrieb:
13.3.3 Best viable function [over.match.best]
...
Given these definitions, a viable function F1 is defined to be a better function than another viable function F2 if for all arguments i, ICSi(F1) is not a worse conversion sequence than ICSi(F2), and then
— for some argument j, ICSj(F1) is a better conversion sequence than ICSj(F2), or, if not that,
— the context is an initialization by user-defined conversion (see 8.5, 13.3.1.5, and 13.3.1.6) and the standard conversion sequence from the return type of F1 to the destination type (i.e., the type of the entity being initialized) is a better conversion sequence than the standard conversion sequence from the return type of F2 to the destination type. [ Example:
struct A {
A();
operator int();
operator double();
} a;
int i = a; // a.operator int() followed by no conversion
// is better than a.operator double() followed by
// a conversion to int
float x = a; // ambiguous: both possibilities require conversions,
// and neither is better than the other
— F1 is a non-template function and F2 is a function template specialization, or, if not that,
— F1 and F2 are function template specializations, and the function template for F1 is more specialized than the template for F2 according to the partial ordering rules described in 14.5.6.2.
Die Reihenfolge, in der die Alternativen abgearbeitet werden, hat sich offenbar geändert. msvc macht es praktisch so wie im neuen Standard vorgesehen, g++ benutzt (noch) die alten Regeln. Nach den alten Regeln führt allein die Tatsache, dass eine Funktion eine Templatefunktion ist und die andere nicht zur Entscheidung, ein Vergleich der Konvertierungsränge findet gar nicht statt.
Edit: Nachdem klar ist, wonach gesucht werden muss, findet sich auch der zugehörige Report schnell.
