Narrowing delegate relaxation of return type or parameters - if the argument is AddressOf or a lambda with a declared type and the conversion from its return type to the delegate return type is narrowing or if the argument is a regular lambda and the conversion from any of its return expressions to the delegate return type is narrowing, or if the argument is an async lambda and the delegate return type is Task(Of T) and the conversion from any of its return expressions to T is narrowing or if the argument is an iterator lambda and the delegate return type IEnumerator(Of T) or IEnumerable(Of T) and the conversion from any of its yield operands to T is narrowing. The delegate relaxation levels are as follows:Įrror delegate relaxation level - if the AddressOf or lambda cannot be converted to the delegate type. If the worst (lowest) delegate relaxation level in N is worse than the lowest delegate relaxation level in M, then eliminate N from the set. Next, if one or more arguments are AddressOf or lambda expressions, then calculate the delegate relaxation levels for each such argument as below. Next, eliminate all members from the set that are inaccessible or not applicable (Section Applicability To Argument List) to the argument list If type inference fails for a method, then that method is eliminated from the set.
If type inference succeeds for a method, then the inferred type arguments are used for that particular method. The steps are:įirst, if no type arguments have been supplied, apply type inference to any methods which have type parameters. If only one member remains in the set, then that member is the most applicable member. If, after applying a particular step, no members remain in the set, then a compile-time error occurs. Given a method group, the most applicable method in the group for an argument list is determined using the following steps. Overload resolution does not take into account the expected return type of the method.Īlso note that because of the named parameter syntax, the ordering of the actual and formal parameters may not be the same. If neither method's parameters are narrower than the other, then there is no way for to determine which method is closer to the arguments.
Barring that, one method is closer than another if all of its parameter types are narrower than (or the same as) the parameter types of the other method. If there is a method whose parameter types match the argument types, then that method is obviously the closest. In practice, the rules for determining overload resolution are intended to find the overload that is "closest" to the actual arguments supplied.
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