Hi, I just found weird behaviour in our JetPack Co...

# compose-web

[Tomáš Hubálek]

Hi, I just found weird behaviour in our JetPack Compose for Web. project Here is scenario:

File FileA.kt

package mypackage

import org.jetbrains.compose.web.css.px

val a = 96.px

File MyTest.kt

package mypackage 

val b = a

class StyleSheetTest {

    @Test
    fun testA() {
        val result: CSSCalcValue<CSSUnitLength> = 100.vw - 2 * a
        assertEquals("calc(100vw - 192px)", result.toString())
    }

    @Test
    fun testB() {
        val result: CSSCalcValue<CSSUnitLength> = 100.vw - 2 * b
        assertEquals("calc(100vw - 192px)", result.toString())
    }
}

testB fails with TypeError: Cannot read properties of undefined (reading 'value')

@Akif Abasov [JB] any idea what is wrong? Is that compiler bug or some edge case optimalization in Kotlin JS IR compiler?

[Akif Abasov [JB]]

At first sight it could be problem with initialisation order. And it looks like problem of Kotlin JS/IR.

[Akif Abasov [JB]]

something like val b = a executed before val a = 96.px

[Akif Abasov [JB]]

you can check it with println(b) in test. It will print undefined if i’m right.

[Tomáš Hubálek]

Also changing of FileA.kt to

val a
get() = 96.px

helps.

[Akif Abasov [JB]]

So it definitely is initialisation order problem.

[Akif Abasov [JB]]

And this is common Kotlin/JS problem. Can’t help with it 😞

[Tomáš Hubálek]

It is. println(b) really prints undefined

[Tomáš Hubálek]

No problem when I can workaround.

[Tomáš Hubálek]

I just wanted to make sure what's wrong.

[Norbi]

No problem when I can workaround.

Nice catch, please report an issue if you have some time...

[Tomáš Hubálek]

@Norbi where to report? My understanding is that it is Kotlin IR/JS feature.

[Norbi]

it is Kotlin IR/JS feature

It seems to be a bug, not a feature.

[Tomáš Hubálek]

@Akif Abasov [JB] is that bug that I should report to Kotlin/JS team? Or is that just a weird feature?

[Akif Abasov [JB]]

I’m not sure if it is feature. It most likely that it’s just designed that way for now. But i’m sure that there should be compile time check for such problems. Because compiler knows an order and it could check if it’s wrong (and in this case it even could be fixed by compiler). So… it isn’t bug, but huge usability problem for me.

[ephemient]

if FileA and MyTest circularly depend on each other, then I don't think there's anything the Kotlin compiler can do. but if the dependency is only one way, this seems like a bug

[Tomáš Hubálek]

Ok, I'll report it and let Kotlin JS team to evaluate whether it is bug or feature.

[hfhbd]

Does it work with LazyPropertyInit? https://youtrack.jetbrains.com/issue/KT-43222

[Tomáš Hubálek]

I'll check but I didn't work on build scripts so it may take me some time.

[louiscad]

FYI, the place to report Kotlin issues is simply kotl.in/issue