Using additional configuration with `js` block in ...

# eap

[altavir]

Using additional configuration with js block in gradle after js(IR) gives error:

==========
This project currently uses the Kotlin/JS Legacy compiler backend, which has been deprecated and will be removed in a future release.
Please migrate the project to the new IR-based compiler (<https://kotl.in/jsir>) by adding:
- kotlin.js.compiler=ir to your gradle.properties file.
- js(IR) { ... } to your build file.
You can continue to use the deprecated legacy compiler in the current version of the toolchain by specifying it explicitly.
==========

Before it automatically used first provided compiler. I think since LEGACY is deprecated, js should mean IR by default.

[altavir]

This is also a build breaking change.

[Ivan Kubyshkin [JetBrains]]

cc @Ilya Goncharov [JB]

[Ilya Goncharov [JB]]

Is it with kotlin("js") plugin or with kotlin("multiplatform")?

[altavir]

mpp

[Ilya Goncharov [JB]]

It is a bug, and it is bug in reporting as I can see, logic with using existing compiler works like in previous versions

[Ilya Goncharov [JB]]

Thank you for reporting

[altavir]

I think that js block should use IR by default now.

[altavir]

It is a breaking change, but it is a major version after all. It could break things.

[Ilya Goncharov [JB]]

We want to notify all users who rely on previous default behaviour that it is no more option, and after that we’ll change default

[altavir]

Well, I think it will make sense to do things faster in this case. One of the stoppers for Kotlin-JS adoption is this uncertainty with compilers version. I am not sure about the statistics of Legacy backend usage, but it seems like it is rather low. And default is important for the new users. So switching default half a year sooner could mean a lot.

[louiscad]

I second thet, especially since the official stability of Kotlin/JS was "moving fast", I don't really see a point in delaying the default to be IR any longer.

There are no compatibility related reasons to do that, right?

[Ilya Goncharov [JB]]

As for additional configuration of already existing target
https://youtrack.jetbrains.com/issue/KT-55099/K-JS-Second-declaration-of-JS-target-without-compiler-type-report-warning-incorrectly