Update to K2

[ZacSweers]

• Change supportsK2 to true by default
• Change disableStandardScript to true by default. This doesn't seem to work yet
• Update kapt class location refs
• Support Kapt4
• Support KSP2

Notes

• KSP1 and Kapt 3 support require setting languageVersion to 1.9

TODO

• Support Kapt4, which runs in FIR
• Support KSP2

[ZacSweers]

I've published 0.5.0-alpha01 with the changes up to this point in the PR

Some notes

• Build against Kotlin 2.0.0-Beta1 and KSP 2.0.0-Beta1-1.0.14.
• To use KSP, you must set KotlinCompilation.languageVersion to 1.9.
• To use Kapt, you must set the languageVersion to 1.9 or set it to 2.0 and set KotlinCompilation.useKapt4 to true. Kapt 4 is still experimental.
• KotlinCompilation.supportsK2 is now true by default
• KotlinCompilation.disableStandardScript is currently now true by default as script support doesn't appear to be supported yet.

[jisungbin]

Thank you for your quick support of the new Kotlin version!

[ZacSweers]

I've published 0.5.0-alpha02 with the changes up to this point in the PR.

• Kotlin 2.0.0-Beta3
• KSP 2.0.0-Beta3-1.0.17
• Merged latest main branch changes
• Implemented initial KSP2 support

Note that KSP 2 and KSP 1 cannot be tested in the same compilation. You would need to do something like I've set up at the build level in this PR to conditionally choose dependencies. There also appears to be a broken dependency in their new Analysis API artifacts (google/ksp#1712), so you'd need to use an exclusion like I've done in this PR. I can publish a new alpha when this is fixed.

In dependencies

ksp-api = { module = "com.google.devtools.ksp:symbol-processing-api", version.ref = "ksp" }
ksp-cli = { module = "com.google.devtools.ksp:symbol-processing-cmdline", version.ref = "ksp" }
ksp-aa-embeddable = { module = "com.google.devtools.ksp:symbol-processing-aa-embeddable", version.ref = "ksp" }
ksp-commonDeps = { module = "com.google.devtools.ksp:symbol-processing-common-deps", version.ref = "ksp" }

In the build

// It's not possible to test both KSP 1 and KSP 2 in the same compilation unit
val testKsp2 = providers.systemProperty("kct.test.useKsp2").getOrElse("false").toBoolean()

tasks.test {
  if (testKsp2) {
    systemProperty("kct.test.useKsp2", testKsp2)
  }
}

dependencies {
  if (testKsp2) {
    testImplementation(libs.ksp.aa.embeddable) {
      exclude(group = "com.google.devtools.ksp", module = "common-deps")
    }
    testImplementation(libs.ksp.commonDeps)
    testImplementation(libs.ksp.cli)
  } else {
    testImplementation(libs.ksp)
  }
}

In tests

val useKSP2 = System.getProperty("kct.test.useKsp2", "false").toBoolean()

KotlinCompilation().apply {
  if (useKSP2) {
    useKsp2()
  } else {
    // Fall back to K1
    languageVersion = "1.9"
  }
}

[ZacSweers]

bug I found: inheritClasspath no longer works for KSP2. Will probably need to do it manually

[ZacSweers]

I'm unable to repro the inheritClasspath issue I'm seeing in another repo, going to dig into the debugger there

[3flex]

Worth an alpha08? It looks like Kotlin 2.0.0 will be based on the same commit as Kotlin 2.0.0-RC3: https://github.com/JetBrains/kotlin/commits/e84e83568cde569ee54980542e37c87507e914bc/

[ZacSweers]

Only if we need one, otherwise will just wait for 2.0.0 to release

[ZacSweers]

KSP broke something in the 1.0.21 release google/ksp#1908

[ZacSweers]

I'm going to publish an alpha08 against the 2.0 finals, but reluctant to publish a non-alpha until there's resolution on the above-linked KSP2 regression. It appears that it only works on linux in 1.0.21. I can't publish yet though because sonatype appears to be down

[ZacSweers]

Published 0.5.0-alpha08 see below

[ZacSweers]

I would actually advise against using 0.5.0-alpha08 due to google/ksp#1917, which I didn't notice before releasing due to inherited extra maven repositories set up on this project that I'll remove.

[3flex]

FWIW detekt updated to alpha07 and now alpha08 with Kotlin 2.0.0 and it seems to be working well with cross platform tests all green, though we don't use KSP at all.

Just mentioning as other non-KSP users may be safe to update.