Implicitly-typed lambda parameters have RefKind.None

[jcouv]

Fixes #64985

The parameters of an anonymous function in the form of a lambda_expression can be explicitly or implicitly typed. In an explicitly typed parameter list, the type of each parameter is explicitly stated. In an implicitly typed parameter list, the types of the parameters are inferred from the context in which the anonymous function occurs—specifically, when the anonymous function is converted to a compatible delegate type or expression tree type, that type provides the parameter types (§10.7).

The parameter list of an anonymous function in the form of an anonymous_method_expression is optional. If given, the parameters shall be explicitly typed. If not, the anonymous function is convertible to a delegate with any parameter list not containing out parameters.

[333fred]

I don't agree with the original bug here. Is the syntax illegal? Yes. However, the user's experience is likely to be better if we respect the ref that was written in source, as cascaded errors (such as lambda applicability or ref mismatches) are more likely to be lined up with the ref that the user actually specified. I don't think we should change our behavior here.

[cston]

WorkItem(64985, "#64985")

Is this test affected by the change? #Resolved

[jcouv]

Removed