Show all extension methods in completion list.

[ijklang]

Is your feature request related to a problem? Please describe.

Many of C# libraries use extension methods to extend functionality of the existing types, and the C# language service can list all of them out, no matter whether the namespace is opened. Users doesn't care about which namespace containing the extension method they want to use.

Describe the solution you'd like

Show all extension methods in completion list, no matter whether the namespace is opened.

Describe alternatives you've considered

Manually find out which namespace containing the extension method, and open it.

[vzarytovskii]

While this is possible, it might be quite heavy on the checker and inforeader, we might put it under flag (though to be honest, I though we already do so in VS).

[baronfel]

In FSAC we've also put this behavior behind a flag for performance purposes: FSharp.externalAutocomplete.

[vzarytovskii]

In FSAC we've also put this behavior behind a flag for performance purposes: FSharp.externalAutocomplete.

We do have it in VS too, not sure if we discover extensions too: