Make collection literal IEnumerable<T> by default

[virzak]

When I want to create a FrozenSet from collection literal, it must be cast to IEnumerable first.

using System.Collections.Frozen;
using System.Collections.Generic;

var fs = ((IEnumerable<int>)[1]).ToFrozenSet();

Should it implement IEnumerable by default?

[yaakov-h]

"must" is a strong word, you could also do:

using System.Collections.Frozen;
var fs = FrozenSet.ToFrozenSet([1]);

[ufcpp]

https://github.com/dotnet/csharplang/blob/main/proposals/collection-expressions-next.md#natural-type
https://github.com/dotnet/csharplang/blob/main/meetings/working-groups/collection-literals/CL-2023-06-26.md#extension-method-lookup