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kotlinlang

Is there a way how to prevent/forbid upcasting? In my test lib I have this method:
```fun &lt;T&gt; assertEqualsRecursive(actual: T, expected: T, vararg ignoringFields: String) {```
I would like to ensure that the objects passed are exactly of the same type, so that the compiler doesn't attempt any silent upcasting.

There is no officially supported way.

Workaround 1: use the internal annotation `OnlyInputTypes` :
```fun <@OnlyInputTypes T> assertEqualsRecursive(actual: T, expected: T, vararg ignoringFields: String) {```
Since it's internal, there's a bit of setup required to use it.

Workaround 2: split your usage into two different functions. For example,
```assertThat(actual)
    .equalsRecursive(expected, "foo", "bar")```
This way, the type is bound on the first function call. No upcasting can happen on the second function call.

Thanks. I guess in my specific situation workaround 2 could be actually considered the proper solution :slightly_smiling_face: