csharp_prefer_simple_default_expression has faulty heuristic

Version Used:

VS Enterprise 2017 15.3.4

Steps to Reproduce:

1. Add csharp_prefer_simple_default_expression to your .editorconfig with a value of true:error
2. Add the statement object i = default(int) to your code.

Expected Behavior:

No error should be triggered, since the target type (object) is more general than the type specified to default.

Actual Behavior:

An error is triggered, suggesting the statement be simplified to:

object i = default;

Which obviously has different semantics.

This problem is particularly pertinent to the declaration of dependency or bindable properties:

public static readonly BindableProperty SomeProperty = BindableProperty.Create(
    nameof(Some),
    typeof(Me),
    defaultValue: default(int));

This triggers the rule when it should not, since defaultValue is of type object.

Here is a repro: EditorConfigRepro.zip

[jcouv]

I’ll go ahead and close since it was fixed already. @kentcb Feel free to re-open if you still run into this with 15.5 (or later). Thanks

[CyrusNajmabadi]

15.5p3:

Available when valid:

But not when invalid: