Default Interface Methods docs are a mess

[MgSam]

There is a ton of confusion out in the community on how to use Default Interface Methods and the awful documentation makes matters worse. Microsoft Learn/MSDN has inherited the last version of the proposal from 2019 - which contains ideas like override that were not actually in the implementation as far as I can tell (the code under Base interface invocations does not compile). Mads' blog post from 4 years ago is similarly bereft of most details about the feature and should either be updated or deleted, IMHO.

In addition to just containing flat-out-wrong information, the docs also don't address the most common pit-of-failure with this feature which is that people expect classes to inherit functionality from the interface.

interface I { void Bark() => "woof"; }
class C : I { public void Greet() => Bark(); } //Error - Bark() is not visible unless `this` is cast to `I` first

Related, the docs should call out the fact that you cannot actually access a DIM from an implementing class unless it is static (this is something I think the language should find a solution for as the workaround is very clunky):

interface I { void Bark() => "woof"; }
class C : I { public void Bark() => ((I)this).Bark(); } //Stack overflow here we come- no way to call a DIM once you've implemented the interface

Can only delegate to DIMs if you use statics.

interface I { void Bark() => I.Bark(); static void Bark() => "woof"; }
class C : I { public void Bark() => I.Bark(); }

We absolutely need accurate docs for DIMs that include the current state of the feature, including the changes made in C# 11 around static members. You guys can't make fundamental type system changes and then not provide accurate documentation. Please fix this!

[CyrusNajmabadi]

@BillWagner Can you transfer this to the docs site. I can't seem to do it on my end. Thanks :)

[richlander]

Feel free to open up an issue at dotnet/docs that is more polite. We expect to discourse on these repos to be more reasonable.

This issue is not actionable as-is.