Handle ref returning receivers in dynamic calls

[jjonescz]

Fixes #68063.

[AlekseyTs]

case BoundKind.Call:

Are we missing handling for other interesting scenarios? For example, I do not see explicit case for fields. We probably could run into a sequence (for example if we need to reorder arguments for a call), etc.
It looks like the purpose of this method is to determine whether we can take a reference to the receiver without storing the value in a temp. It feels fragile to have a helper that is used only for the purpose of dynamic rewrite, especially taking future language changes into account. Scenarios involving dynamic rewrite are easy to miss during testing. Therefore, I think we should either switch to a different existing helper, which is used more often (Binder.HasHome?), or we could try always pass value type receiver by reference and let emit layer to figure out if it needs a temp for that (it looks like that shouldn't change semantics of the operation). #Closed

[jjonescz]

Are we missing handling for other interesting scenarios?

Good catch, thanks.

we could try always pass value type receiver by reference and let emit layer to figure out if it needs a temp for that

That seems like it would work except it's hitting the following assert which I'm not sure how to easily change (apart from removing it).

roslyn/src/Compilers/CSharp/Portable/CodeGen/EmitExpression.cs

Line 722 in a5724a2

Debug.Assert(argument.Type.IsDynamic(), "passing args byref should not clone them into temps");

It would also change IL (introducing temp for rvalue struct receivers), so I'm exploring the first option instead (using Binder.HasHome).

[AlekseyTs]

Done with review pass (commit 1)

[AlekseyTs]

_factory.Compilation.IsPeVerifyCompatEnabled

I think we don't need to depend on this setting here. The most permissive value is probably going to be the closest match with the previous behavior. #Closed

[AlekseyTs]

Or, at least, with intent.

[AlekseyTs]

System.Console.Write(GetS().X);

It looks like this line isn't meaningful. It is guaranteed to produce the same output regardless of what the previous line is doing. #Closed

[AlekseyTs]

Done with review pass (commit 4)

Substantial changes

[AlekseyTs]

LGTM (commit 5)