Omit Type for Generic Initialization

[szaliubovskii]

We can initialize generics with initial data, but we still have to specify type of the generic. It would be nice to omit type defenition in that case.

Currently following statements are legal.

int[] array = { 1, 2, 3 };
var array = new[] { 1, 2, 3 };
var list = new List<int> { 1, 2, 3 };
var dictionary = new Dictionary<string, string> { ["key"] = "value" };

With syntax proposed in this topic you'd be able to write:

var list = new List { 1, 2, 3 };           // List<int>
var dictionary = new Dictionary { ["key"] = "value" }; // Dictionary<string,string>

It is simmilar to how type omit works for Generic Methods.

...
public static T GetData<T>(T data) => data;
...

// type is omited in this case
var data = GetData(1);

Relates to #5865 issue.

[Neme12]

belongs to https://github.com/dotnet/csharplang/, please move this

[szaliubovskii]

Sure, will open there and colse this one. Thank you.