Inaccurate error message when attempting to use a property as a ref

[svick]

Version Used: current main on SharpLab (eb3ccc5)

Steps to Reproduce:

Compile the following code:

ref int y = ref C.P;

class C
{
    public static int P { get; set; }
}

Actual Behavior:

error CS0206: A property or indexer may not be passed as an out or ref parameter

Expected Behavior:

An error message that does not talk about ref parameters, since no method with a ref parameter is involved.

[ArcadeMode]

I will attempt to clarify this by instead showing CS8145: Auto-implemented properties cannot return by reference when attempting to use ref with property access.

After taking a close look at the code and spec regarding ref/out I concluded my initial suggestion made little sense - especially given the more recent language feature which support ref properties (like this). So clarifying the message that this error does not encompass all properties and not just parameters seems more logical. My proposed change is now to update the error message to An indexer or auto-implemented property may not be used as an out or ref value.

[svick]

@ArcadeMode You can have a ref-returning indexer and a property that is not auto-implemented and also not ref-returning produces CS0206, so I think that's not accurate either.

[ArcadeMode]

@svick Thanks for the feedback. I think the ref-returning aspect should then be highlighted (without the auto-property part). e.g. a non ref-returning property or indexer may not be used as an out or ref value

[svick]

@ArcadeMode Yeah, that sounds good to me.

[cston]

Fixed in #64764.