Allow to use Compose on multiple Kotlin versions (#2366)

JS target supports a lower version (1.7.10), because we have a bug in Koltin 1.7.20

Compose 1.2.0 will support:

1.7.20 and 1.7.10 for Android and Desktop
1.7.10 for JS
We will release the new patchset (1.2.1) with 1.7.2X support for JS later

README.md

@@ -4,10 +4,9 @@
 
 # Compose Multiplatform, by JetBrains
 ![](artwork/readme/apps.png)
-Compose Kotlin UI framework port for desktop platforms (macOS, Linux, Windows) and Web, components outside of the core Compose repository
+Compose Kotlin UI framework port for desktop platforms (macOS, Linux, Windows) and Web, components outside of the core [Compose repository](https://android.googlesource.com/platform/frameworks/support).
-at https://android.googlesource.com/platform/frameworks/support.
 
-Preview functionality (check your application UI without building/running it) for desktop platforms is available via IDEA plugin (https://plugins.jetbrains.com/plugin/16541-compose-multiplatform-ide-support).
+Preview functionality (check your application UI without building/running it) for desktop platforms is available via [IDEA plugin](https://plugins.jetbrains.com/plugin/16541-compose-multiplatform-ide-support).
 
 ## Tutorials
 ### Compose for Desktop
@@ -70,6 +69,9 @@ Note that when you use Compose Multiplatform, you setup your project differently
    * [LWJGL integration](experimental/lwjgl-integration) - An example showing how to integrate Compose with [LWJGL](https://www.lwjgl.org)
    * [CLI example](experimental/build_from_cli) - An example showing how to build Compose without Gradle
        
-## Getting latest version of Compose Multiplatform ##
+## Versions ##
 
-See https://github.com/JetBrains/compose-jb/releases/latest for the latest stable release or https://github.com/JetBrains/compose-jb/releases for all stable and dev releases.
+* [The latest stable release](https://github.com/JetBrains/compose-jb/releases/latest)
+* [The latest dev release](https://github.com/JetBrains/compose-jb/releases)
+* [Compatability and versioning overview](VERSIONING.md)
+* [Changelog](CHANGELOG.md)

VERSIONING.md

@@ -21,12 +21,13 @@ Knowing issues on older versions:
 
 ### Kotlin compatibility
 
-Compose version | Kotlin version
+A new version of Kotlin may be not supported immediately after its release. But after some time we will release a version of Compose Multiplatform
---- | ---
+that supports it.
-1.0.0+ | 1.5.31
+Starting from 1.2.0, Compose Multiplatform supports multiple versions of Kotlin.
-1.0.1-rc2+ | 1.6.10
+
-
+Kotlin version | Minimal Compose version | Notes
-
+--- | --- | ---
-### Gradle plugin compatibility
+1.5.31 | 1.0.0
-
+1.6.20 | 1.1.1
-* 1.0.0 works with Gradle 6.7 or later (7.2 is the latest tested version).
+1.7.10 | 1.2.0
+1.7.20 | 1.2.0 | JS is not supported (will be fixed in the next versions)

examples/validateExamples.sh

@@ -25,7 +25,4 @@ runGradle issues package
 runGradle notepad package
 runGradle todoapp-lite package
 runGradle visual-effects package
-runGradle web-compose-bird build
-runGradle web-landing build
-runGradle web-with-react build
 runGradle widgets-gallery package

examples/validateExamplesWithJs.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# Script to build most of the examples, to verify if they can compile.
+# Don't add examples, which don't depend on maven.pkg.jetbrains.space, because they won't be able to compile.
+
+set -euo pipefail
+
+if [ "$#" -ne 2 ]; then
+echo "Specify Compose and Kotlin version. For example: ./validateExamplesWithJs.sh 1.1.1 1.6.10"
+exit 1
+fi
+COMPOSE_VERSION=$1
+KOTLIN_VERSION=$2
+
+
+runGradle() {
+    pushd $1
+    ./gradlew $2 -Pcompose.version=$COMPOSE_VERSION -Pkotlin.version=$KOTLIN_VERSION
+    popd
+}
+
+runGradle web-compose-bird build
+runGradle web-landing build
+runGradle web-with-react build

gradle-plugins/buildSrc/src/main/kotlin/BuildProperties.kt

@@ -15,10 +15,6 @@ object BuildProperties {
     fun composeVersion(project: Project): String =
         System.getenv("COMPOSE_GRADLE_PLUGIN_COMPOSE_VERSION")
             ?: project.findProperty("compose.version") as String
-    fun composeCompilerVersion(project: Project): String =
-        project.findProperty("compose.compiler.version") as String
-    fun composeCompilerCompatibleKotlinVersion(project: Project): String =
-        project.findProperty("compose.compiler.compatible.kotlin.version") as String
     fun testsAndroidxCompilerVersion(project: Project): String =
         project.findProperty("compose.tests.androidx.compiler.version") as String
     fun testsAndroidxCompilerCompatibleVersion(project: Project): String =

gradle-plugins/compose/build.gradle.kts

@@ -29,7 +29,6 @@ val buildConfig = tasks.register("buildConfig", GenerateBuildConfig::class.java)
     classFqName.set("org.jetbrains.compose.ComposeBuildConfig")
     generatedOutputDir.set(buildConfigDir)
     fieldsToGenerate.put("composeVersion", BuildProperties.composeVersion(project))
-    fieldsToGenerate.put("composeCompilerVersion", BuildProperties.composeCompilerVersion(project))
     fieldsToGenerate.put("composeGradlePluginVersion", BuildProperties.deployVersion(project))
 }
 tasks.named("compileKotlin") {

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/ComposeCompilerCompatability.kt

@@ -0,0 +1,19 @@
+package org.jetbrains.compose
+
+import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformType
+
+internal object ComposeCompilerCompatability {
+    fun compilerVersionFor(kotlinVersion: String): ComposeCompilerVersion? = when (kotlinVersion) {
+        "1.7.10" -> ComposeCompilerVersion("1.3.0-alpha01")
+        "1.7.20" -> ComposeCompilerVersion(
+            "1.3.2-alpha01",
+            unsupportedPlatforms = setOf(KotlinPlatformType.js)
+        )
+        else -> null
+    }
+}
+
+internal data class ComposeCompilerVersion(
+    val version: String,
+    val unsupportedPlatforms: Set<KotlinPlatformType> = emptySet()
+)

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/ComposeCompilerKotlinSupportPlugin.kt

@@ -13,13 +13,18 @@ import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
 
 class ComposeCompilerKotlinSupportPlugin : KotlinCompilerPluginSupportPlugin {
-    private var composeCompilerArtifactProvider = ComposeCompilerArtifactProvider { null }
+    private lateinit var composeCompilerArtifactProvider: ComposeCompilerArtifactProvider
 
     override fun apply(target: Project) {
         super.apply(target)
         target.plugins.withType(ComposePlugin::class.java) {
             val composeExt = target.extensions.getByType(ComposeExtension::class.java)
-            composeCompilerArtifactProvider = ComposeCompilerArtifactProvider { composeExt.kotlinCompilerPlugin.orNull }
+
+            composeCompilerArtifactProvider = ComposeCompilerArtifactProvider(
+                kotlinVersion = target.getKotlinPluginVersion()
+            ) {
+                composeExt.kotlinCompilerPlugin.orNull
+            }
         }
     }
 
@@ -52,6 +57,7 @@ class ComposeCompilerKotlinSupportPlugin : KotlinCompilerPluginSupportPlugin {
 
     override fun applyToCompilation(kotlinCompilation: KotlinCompilation<*>): Provider<List<SubpluginOption>> {
         val target = kotlinCompilation.target
+        composeCompilerArtifactProvider.checkTargetSupported(target)
         return target.project.provider {
             platformPluginOptions[target.platformType] ?: emptyList()
         }

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/internal/ComposeCompilerArtifactProvider.kt

@@ -5,25 +5,59 @@
 
 package org.jetbrains.compose.internal
 
-import org.jetbrains.compose.ComposeBuildConfig
+import org.jetbrains.compose.ComposeCompilerCompatability
+import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformType
+import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.plugin.SubpluginArtifact
 
-internal class ComposeCompilerArtifactProvider(private val customPluginString: () -> String?) {
+private const val KOTLIN_COMPATABILITY_LINK =
+    "https://github.com/JetBrains/compose-jb/blob/master/VERSIONING.md#kotlin-compatibility"
+
+internal class ComposeCompilerArtifactProvider(
+    private val kotlinVersion: String,
+    customPluginString: () -> String?
+) {
+    fun checkTargetSupported(target: KotlinTarget) {
+        require(!unsupportedPlatforms.contains(target.platformType)) {
+            "This version of Compose Multiplatform doesn't support Kotlin " +
+                "$kotlinVersion for ${target.platformType} target. " +
+                "Please see $KOTLIN_COMPATABILITY_LINK " +
+                "to know the latest supported version of Kotlin."
+        }
+    }
+
+    private var unsupportedPlatforms: Set<KotlinPlatformType> = emptySet()
+
     val compilerArtifact: SubpluginArtifact
-        get() {
+
+    init {
         val customPlugin = customPluginString()
         val customCoordinates = customPlugin?.split(":")
-            return when (customCoordinates?.size) {
+        when (customCoordinates?.size) {
-                null -> DefaultCompiler.pluginArtifact
+            null -> {
+                val version = requireNotNull(
+                    ComposeCompilerCompatability.compilerVersionFor(kotlinVersion)
+                ) {
+                    "This version of Compose Multiplatform doesn't support Kotlin " +
+                        "$kotlinVersion. " +
+                        "Please see $KOTLIN_COMPATABILITY_LINK " +
+                        "to know the latest supported version of Kotlin."
+                }
+
+                compilerArtifact = DefaultCompiler.pluginArtifact(
+                    version = version.version
+                )
+                unsupportedPlatforms = version.unsupportedPlatforms
+            }
             1 -> {
                 val customVersion = customCoordinates[0]
                 check(customVersion.isNotBlank()) { "'compose.kotlinCompilerPlugin' cannot be blank!" }
-                    DefaultCompiler.pluginArtifact.copy(version = customVersion)
+                compilerArtifact = DefaultCompiler.pluginArtifact(version = customVersion)
             }
-                3 -> DefaultCompiler.pluginArtifact.copy(
+            3 -> compilerArtifact = DefaultCompiler.pluginArtifact(
+                version = customCoordinates[2],
                 groupId = customCoordinates[0],
                 artifactId = customCoordinates[1],
-                    version = customCoordinates[2]
             )
             else -> error("""
                         Illegal format of 'compose.kotlinCompilerPlugin' property.
@@ -47,10 +81,13 @@ internal class ComposeCompilerArtifactProvider(private val customPluginString: (
         const val GROUP_ID = "org.jetbrains.compose.compiler"
         const val ARTIFACT_ID = "compiler"
         const val HOSTED_ARTIFACT_ID = "compiler-hosted"
-        const val VERSION = ComposeBuildConfig.composeCompilerVersion
 
-        val pluginArtifact: SubpluginArtifact
+        fun pluginArtifact(
-            get() = SubpluginArtifact(groupId = GROUP_ID, artifactId = ARTIFACT_ID, version = VERSION)
+            version: String,
+            groupId: String = GROUP_ID,
+            artifactId: String = ARTIFACT_ID,
+        ): SubpluginArtifact =
+            SubpluginArtifact(groupId = groupId, artifactId = artifactId, version = version)
     }
 }
 

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/tests/integration/GradlePluginTest.kt

@@ -22,7 +22,14 @@ import org.junit.jupiter.api.Test
 class GradlePluginTest : GradlePluginTestBase() {
     @Test
     fun jsMppIsNotBroken() =
-        with(testProject(TestProjects.jsMpp)) {
+        with(
+            testProject(
+                TestProjects.jsMpp,
+                testEnvironment = defaultTestEnvironment.copy(
+                    kotlinVersion = TestProperties.composeJsCompilerCompatibleKotlinVersion
+                )
+            )
+        ) {
             gradle(":compileKotlinJs").build().checks { check ->
                 check.taskOutcome(":compileKotlinJs", TaskOutcome.SUCCESS)
             }

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/tests/integration/KotlinCompatabilityTest.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2020-2022 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+
+package org.jetbrains.compose.test.tests.integration
+
+import org.gradle.testkit.runner.TaskOutcome
+import org.gradle.testkit.runner.UnexpectedBuildFailure
+import org.jetbrains.compose.test.utils.GradlePluginTestBase
+import org.jetbrains.compose.test.utils.TestProjects
+import org.jetbrains.compose.test.utils.checks
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+
+class KotlinCompatabilityTest : GradlePluginTestBase() {
+    @Test
+    fun testKotlinMpp_1_7_10() = testMpp("1.7.10")
+
+    @Test
+    fun testKotlinJsMpp_1_7_10() = testJsMpp("1.7.10")
+
+    @Test
+    fun testKotlinMpp_1_7_20() = testMpp("1.7.20")
+
+    @Test
+    fun testKotlinJsMpp_1_7_20() {
+        assertThrows<UnexpectedBuildFailure> {
+            testJsMpp("1.7.20")
+        }
+    }
+
+    private fun testMpp(kotlinVersion: String) = with(
+        testProject(
+            TestProjects.mpp,
+            testEnvironment = defaultTestEnvironment.copy(kotlinVersion = kotlinVersion)
+        )
+    ) {
+        val logLine = "Kotlin MPP app is running!"
+        gradle("run").build().checks { check ->
+            check.taskOutcome(":run", TaskOutcome.SUCCESS)
+            check.logContains(logLine)
+        }
+    }
+
+    private fun testJsMpp(kotlinVersion: String) = with(
+        testProject(
+            TestProjects.jsMpp,
+            testEnvironment = defaultTestEnvironment.copy(kotlinVersion = kotlinVersion)
+        )
+    ) {
+        gradle(":compileKotlinJs").build().checks { check ->
+            check.taskOutcome(":compileKotlinJs", TaskOutcome.SUCCESS)
+        }
+    }
+}

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/tests/unit/ComposeCompilerArtifactProviderTest.kt

@@ -18,7 +18,7 @@ internal class ComposeCompilerArtifactProviderTest {
     fun defaultCompilerArtifact() {
         assertArtifactEquals(
             Expected.jbCompiler,
-            Actual.compiler(null)
+            Actual.compiler(null, TestProperties.composeCompilerCompatibleKotlinVersion)
         )
     }
 
@@ -26,7 +26,7 @@ internal class ComposeCompilerArtifactProviderTest {
     fun defaultCompilerHostedArtifact() {
         assertArtifactEquals(
             Expected.jbCompilerHosted,
-            Actual.compilerHosted(null)
+            Actual.compilerHosted(null, TestProperties.composeCompilerCompatibleKotlinVersion)
         )
     }
 
@@ -34,7 +34,7 @@ internal class ComposeCompilerArtifactProviderTest {
     fun customVersion() {
         assertArtifactEquals(
             Expected.jbCompiler.copy(version = "10.20.30"),
-            Actual.compiler("10.20.30")
+            Actual.compiler("10.20.30", TestProperties.composeCompilerCompatibleKotlinVersion)
         )
     }
 
@@ -42,7 +42,10 @@ internal class ComposeCompilerArtifactProviderTest {
     fun customCompiler() {
         assertArtifactEquals(
             Expected.googleCompiler.copy(version = "1.3.1"),
-            Actual.compiler("androidx.compose.compiler:compiler:1.3.1")
+            Actual.compiler(
+                "androidx.compose.compiler:compiler:1.3.1",
+                TestProperties.androidxCompilerCompatibleKotlinVersion
+            )
         )
     }
 
@@ -51,7 +54,10 @@ internal class ComposeCompilerArtifactProviderTest {
         // check that we don't replace artifactId for non-jb compiler
         assertArtifactEquals(
             Expected.googleCompiler.copy(version = "1.3.1"),
-            Actual.compilerHosted("androidx.compose.compiler:compiler:1.3.1")
+            Actual.compilerHosted(
+                "androidx.compose.compiler:compiler:1.3.1",
+                TestProperties.composeCompilerCompatibleKotlinVersion
+            )
         )
     }
 
@@ -64,7 +70,7 @@ internal class ComposeCompilerArtifactProviderTest {
 
     private fun testIllegalCompiler(pluginString: String?) {
         try {
-            Actual.compiler(pluginString)
+            Actual.compiler(pluginString, "")
         } catch (e: Exception) {
             return
         }
@@ -73,11 +79,11 @@ internal class ComposeCompilerArtifactProviderTest {
     }
 
     object Actual {
-        fun compiler(pluginString: String?) =
+        fun compiler(pluginString: String?, kotlinVersion: String) =
-            ComposeCompilerArtifactProvider { pluginString }.compilerArtifact
+            ComposeCompilerArtifactProvider(kotlinVersion) { pluginString }.compilerArtifact
 
-        fun compilerHosted(pluginString: String?) =
+        fun compilerHosted(pluginString: String?, kotlinVersion: String) =
-            ComposeCompilerArtifactProvider { pluginString }.compilerHostedArtifact
+            ComposeCompilerArtifactProvider(kotlinVersion) { pluginString }.compilerHostedArtifact
     }
 
     object Expected {

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/utils/GradlePluginTestBase.kt

@@ -17,7 +17,7 @@ abstract class GradlePluginTestBase {
 
     val defaultAndroidxCompilerEnvironment: TestEnvironment
         get() = defaultTestEnvironment.copy(
-            kotlinVersion = TestKotlinVersion.AndroidxCompatible,
+            kotlinVersion = TestKotlinVersions.AndroidxCompatible,
             composeCompilerArtifact = "androidx.compose.compiler:compiler:${TestProperties.androidxCompilerVersion}"
         )
 

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/utils/TestKotlinVersions.kt

@@ -5,8 +5,7 @@
 
 package org.jetbrains.compose.test.utils
 
-@Suppress("EnumEntryName")
+object TestKotlinVersions {
-enum class TestKotlinVersion(val versionString: String) {
+    val Default = TestProperties.composeCompilerCompatibleKotlinVersion
-    Default(TestProperties.composeCompilerCompatibleKotlinVersion),
+    val AndroidxCompatible =  TestProperties.androidxCompilerCompatibleKotlinVersion
-    AndroidxCompatible(TestProperties.androidxCompilerCompatibleKotlinVersion)
 }

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/utils/TestProject.kt

@@ -11,7 +11,7 @@ import java.io.File
 
 data class TestEnvironment(
     val workingDir: File,
-    val kotlinVersion: TestKotlinVersion = TestKotlinVersion.Default,
+    val kotlinVersion: String = TestKotlinVersions.Default,
     val composeGradlePluginVersion: String = TestProperties.composeGradlePluginVersion,
     val composeCompilerArtifact: String? = null
 )
@@ -41,7 +41,7 @@ class TestProject(
                 val origContent = orig.readText()
                 var newContent = origContent
                     .replace("COMPOSE_GRADLE_PLUGIN_VERSION_PLACEHOLDER", testEnvironment.composeGradlePluginVersion)
-                    .replace("KOTLIN_VERSION_PLACEHOLDER", testEnvironment.kotlinVersion.versionString)
+                    .replace("KOTLIN_VERSION_PLACEHOLDER", testEnvironment.kotlinVersion)
                 if (testEnvironment.composeCompilerArtifact != null) {
                     newContent = newContent.replace("COMPOSE_COMPILER_ARTIFACT_PLACEHOLDER", testEnvironment.composeCompilerArtifact)
                 }

gradle-plugins/compose/src/test/kotlin/org/jetbrains/compose/test/utils/TestProperties.kt

@@ -7,10 +7,13 @@ package org.jetbrains.compose.test.utils
 
 object TestProperties {
     val composeCompilerVersion: String
-        get() = notNullSystemProperty("compose.compiler.version")
+        get() = notNullSystemProperty("compose.tests.compiler.version")
 
     val composeCompilerCompatibleKotlinVersion: String
-        get() = notNullSystemProperty("compose.compiler.compatible.kotlin.version")
+        get() = notNullSystemProperty("compose.tests.compiler.compatible.kotlin.version")
+
+    val composeJsCompilerCompatibleKotlinVersion: String
+        get() = notNullSystemProperty("compose.tests.js.compiler.compatible.kotlin.version")
 
     val androidxCompilerVersion: String
         get() = notNullSystemProperty("compose.tests.androidx.compiler.version")

gradle-plugins/gradle.properties

@@ -1,13 +1,16 @@
 org.gradle.parallel=true
 kotlin.code.style=official
 
-# __LATEST_COMPOSE_RELEASE_VERSION__
 # Default version of Compose Libraries used by Gradle plugin
 compose.version=1.2.0-beta02
-# Default version of Compose Compiler used by Gradle plugin
+# The latest version of Compose Compiler used by Gradle plugin. Used only in tests.
-compose.compiler.version=1.3.2-alpha01
+compose.tests.compiler.version=1.3.2-alpha01
-# Default version of Kotlin compatible with compose.compiler.version
+# The latest version of Kotlin compatible with compose.tests.compiler.version. Used only in tests.
-compose.compiler.compatible.kotlin.version=1.7.20
+compose.tests.compiler.compatible.kotlin.version=1.7.20
+# The latest version of Kotlin compatible with compose.tests.compiler.version for JS target. Used only on CI.
+compose.tests.js.compiler.compatible.kotlin.version=1.7.10
+# Version of Compose Compiler published by Google.
+# Used to check if our plugin is compatible with it.
 # https://developer.android.com/jetpack/androidx/releases/compose-kotlin
 compose.tests.androidx.compiler.version=1.3.1
 compose.tests.androidx.compiler.compatible.kotlin.version=1.7.10

tutorials/checker/build.gradle.kts

@@ -70,7 +70,7 @@ fun maybeFail(tutorial: String, message: String) {
 }
 
 @OptIn(ExperimentalStdlibApi::class)
-fun checkDirs(dirs: List<String>, template: String, buildCmd: String = "build") {
+fun checkDirs(dirs: List<String>, template: String, buildCmd: String, kotlinVersion: String?) {
   val snippets = findSnippets(dirs)
   snippets.forEachIndexed { index, snippet ->
     println("process snippet $index at ${snippet.file}:${snippet.lineNumber} with $template")
@@ -86,7 +86,7 @@ fun checkDirs(dirs: List<String>, template: String, buildCmd: String = "build")
 
         add(buildCmd)
 
-        project.findProperty("kotlin.version")?.also {
+        kotlinVersion?.also {
             add("-Pkotlin.version=$it")
         }
         project.findProperty("compose.version")?.also {
@@ -110,7 +110,7 @@ fun checkDirs(dirs: List<String>, template: String, buildCmd: String = "build")
 // NOTICE: currently we use a bit hacky approach, when "```kotlin" marks code that shall be checked, while "``` kotlin"
 // with whitespace marks code that shall not be checked.
 tasks.register("check") {
-  val checks = CheckSpec.createCheckSpecs(
+  val checks = createCheckSpecs(
     checkTargets = (project.property("CHECK_TARGET")?.toString() ?: "all").toLowerCase()
   )
 
@@ -129,29 +129,36 @@ tasks.register("check") {
       checkDirs(
         dirs = subdirs.map { "${check.dir}/$it" },
         template = check.template,
-        buildCmd = check.gradleCmd
+        buildCmd = check.gradleCmd,
+        kotlinVersion = check.kotlinVersion
       )
     }
   }
 }
 
-data class CheckSpec(
-  val gradleCmd: String,
-  val dir: String,
-  val template: String
-) {
 
-  companion object {
+fun createCheckSpecs(checkTargets: String = "all"): List<CheckSpec> {
-    fun desktop() = CheckSpec(gradleCmd = "build", dir = ".", template = "desktop-template")
+  fun desktop() = CheckSpec(
-    fun web() = CheckSpec(gradleCmd = "compileKotlinJs", dir = "Web", template = "web-template")
+    gradleCmd = "build", dir = ".", template = "desktop-template",
+    kotlinVersion = project.findProperty("kotlin.version")?.toString()
+  )
+  fun web() = CheckSpec(
+    gradleCmd = "compileKotlinJs", dir = "Web", template = "web-template",
+    kotlinVersion = project.findProperty("kotlin.js.version")?.toString() ?:
+      project.findProperty("kotlin.version")?.toString()
+  )
   fun all() = listOf(desktop(), web())
 
-    fun createCheckSpecs(checkTargets: String = "all"): List<CheckSpec> {
   return when (checkTargets) {
     "web" -> listOf(web())
     "desktop" -> listOf(desktop())
     else -> all()
   }
-    }
-  }
 }
+
+data class CheckSpec(
+  val gradleCmd: String,
+  val dir: String,
+  val template: String,
+  val kotlinVersion: String?
+)