C# overloading with generics: bug or feature?
- by TN
Let's have a following simplified example:
void Foo<T>(IEnumerable<T> collection, params T[] items)
{
// ...
}
void Foo<C, T>(C collection, T item)
where C : ICollection<T>
{
// ...
}
void Main()
{
Foo((IEnumerable<int>)new[] { 1 }, 2);
}
Compiler says:
The type 'System.Collections.Generic.IEnumerable' cannot be used as type parameter 'C' in the generic type or method 'UserQuery.Foo(C, T)'. There is no implicit reference conversion from 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.ICollection'.
If I change Main to:
void Main()
{
Foo<int>((IEnumerable<int>)new[] { 1 }, 2);
}
It will work ok. Why compiler does not choose the right overload?
