Are unsigned types fully supported on JS? I was tr...

# javascript

[Marc]

Are unsigned types fully supported on JS? I was trying to use them but I ran into a strange error:

fun main() {
    ubyteArrayOf(
        *listOf(ubyteArrayOf())[0]
    )
}

results in:

Unhandled JavaScript exception: listOf(...).get_c1px32_k$(...).slice is not a function

https://pl.kotl.in/nEyBqjkBZ

The same code works just fine when replacing ubyteArrayOf with byteArrayOf or running it on JVM instead.

[Edoardo Luppi]

A UByteArray is just a Int8Array under the hood, just treated differently at runtime.
This works:

fun main() {
  val array = listOf(UByteArray(16) { 0u })[0]
  ubyteArrayOf(*array)
}

So to me it's a compiler bug.

[Marc]

Ah, alright. Then I will just rewrite the code like that. Thanks!

[Edoardo Luppi]

Yup, could you also open an issue? Or do you want me to do it?

[Marc]

I don't have an account on the bug tracker, so I would appreciate if you could do it. Thanks!

[Edoardo Luppi]

Np.

[Edoardo Luppi]

There is a missing .storage call with your example.
This is what gets generated when you extract the expression:

listOf(new UByteArray(tmp$ret$0)).get_c1px32_k$(0).storage_1

[Edoardo Luppi]

So yeah this is clearly a bug.

[Marc]

Weird that it works if you extract the variable. I noticed this bug in my code when adding one destructuring thingy in a bigger UByteArray initialisation, and I think it even deleted bytes and made the array shorter? I tried to get a minimal example going, and there I could only observe this crash...

[Marc]

Nevermind, this replicates it:

fun main() {
    println(
        ubyteArrayOf(
            *UByteArray(16) { 0u },
            *listOf(ubyteArrayOf())[0],
        ).joinToString(prefix = "[", postfix = "]")
    )
}

The array is just empty when doing this. Without the extra array it throws the same issue as before.

[Edoardo Luppi]

This is enough as a reproducer I think:

ubyteArrayOf(*listOf(ubyteArrayOf())[0])

[Marc]

Right, it's probably the same issue.