DefaultFederatedIndexUrls doesn't include https://source.dot.net

[tannergooding]

As per the title, DefaultFederatedIndexUrls doesn't include https://source.dot.net which leads to various URLs going to dead ends.

Can this be added and can it take precedence over referencesource.microsoft.com (which is largely for .NET Framework only)?

[tannergooding]

An additional issue here is that this doesn't look to cover or handle TypeForward and the urls get messed up at times.

For example: https://source.terrafx.dev/#TerraFX.Interop.Windows/um/shellapi/SHELLEXECUTEINFOW.cs,22

If you click on IntPtr the URL generated is: https://source.dot.net/System.Runtime/A.html#d99bf6ad49979009 which takes you to Don't use this page directly, pass #symbolId to get redirected.

Simply inserting #System.Runtime isn't sufficient here either nor is #System.Private.Corelib. Ideally it ultimately takes us to https://source.dot.net/#System.Private.CoreLib/IntPtr.cs,d99bf6ad49979009

[KirillOsenkov]

Yes I think it's time to switch from referencesource to source.dot.net.

I've also recently added an API to look up which assembly a symbol is actually declared in:

SourceBrowser/src/SourceIndexServer/Controllers/SymbolsController.cs

Line 45 in 7e34e7f

[HttpGet("/api/symbolurl")]

So we could call that and if that returns the better URL, use that. This would be equivalent to following type forwarders