[BUG] Compilation order with explicit mappings

[thomaslhostis]

Describe the bug
When defining two mappers, the first one is defined explicitly and overrides the map function, and the second one uses the first one implicitly, if those two mappers are defined in different files and I modify the second mapper, then I get a compilation error.

To Reproduce
Full example here: https://github.com/thomaslhostis/mappie-compile-issue

Two data classes:

class Range(
    val startsOn: java.time.LocalDate,
    val endsOn: java.time.LocalDate,
)
class RangeResource(
    val startsOn: kotlinx.datetime.LocalDate,
    val endsOn: kotlinx.datetime.LocalDate,
)

First mapper (JavaToKotlinLocalDateMapper.kt):

object JavaToKotlinLocalDateMapper : ObjectMappie<java.time.LocalDate, kotlinx.datetime.LocalDate>() {
    override fun map(from: java.time.LocalDate) = from.toKotlinLocalDate()
}

Second mapper (RangeMapper.kt):

object RangeMapper : ObjectMappie<Range, RangeResource>()

When I modify the file RangeMapper.kt without modifying JavaToKotlinLocalDateMapper.kt, I get a compilation error. If I modify the file JavaToKotlinLocalDateMapper.kt after RangeMapper.kt, I don't get any error.

Expected behavior
Should compile no matter the order of modification of the files.

Kotlin version
2.2.0

Mappie version
1.4.1

Mappie and Kotlin compatibility
Yes

Invocation method
Gradle

[thomaslhostis]

I'd be happy to contribute if you point me the right direction :)

[stefankoppier]

Hi sorry for the late response. I don't have a lot of spare time currently, especially for issues which may require some research/delving in the kotlin compiler. So you're definitely welcome to contribute!

Are you in the kotlinlang Slack workspace? If so, can you message me there so I can point you in the right direction?

[thomaslhostis]

Hi. No problem. I'm not in the kotlinlang Slack workspace, and I'm on vacation right now.

Let me know if you have a few hints and I'll try to have a look if I can find some time. If not, I'll contact you when I go back to work.

Have a nice day.

[stefankoppier]

I suspect it has something to do with incremental compilation of the Kotlin compiler.

I would start with writing a test that reproduces your example. Preferably an unit test in :compiler-plugin, but if it doesn't reproduce the issue, then a Gradle test should. This should allow debugging the cause.

I don't have any hints about the possible cause at this point. Let me know when you start, so I can give more concrete pointers.