Collection Expression Compile Error after upgrading to SDK 8.0.3.

[oruchreis]

Collection Expression Compile Error after upgrading to SDK 8.0.3.

[cston]

@oruchreis, thanks for reporting this.

The collection expression conversion requires each element in the collection to be implicitly convertible to the iteration type of the target type. Previously, the compiler ignored the strongly-typed GetEnumerator() implementation and assumed the iteration type of a type implementing IEnumerable only is object (rather than (string, uint) in this case) and that all elements were implicitly convertible to object.

Sorry for the inconvenience.

[oruchreis]

@cston But the element item is not (string, uint), it is object in this case, The class is IEnumerable and not IEnumerable<(string, uint)>.

public class IpList : IEnumerable //<<
{ 

The IEnumerator<(string, uint)> GetEnumerator() method is not belong to IEnumerable interface. Shouldn't the compiler not recognise this method as part of IEnumerable? Anyway, this method does not belong to IEnumerable. So the collection expression is applied to a class that implements IEnumerable, not to a class that is IEnumerable<(string, uint).

[cston]

The iteration type used by collection expression conversions is the foreach statement iteration type which prefers the signature of the accessible GetEnumerator() method, if any, over the interface. It was an oversight that the compiler ignored the accessible GetEnumerator() method previously for the conversion and simply relied on the interface.

[jaredpar]

Closing as the new behavior is "By Design".