[Gradle, JS] Check current chosen js compiler for targets in JS and MPP

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinProjectExtension.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerType.*
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinAndroidTarget
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJsSingleTargetPreset
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinWithJavaTarget
+import org.jetbrains.kotlin.gradle.targets.js.calculateJsCompilerType
 import org.jetbrains.kotlin.gradle.targets.js.dsl.KotlinJsTargetDsl
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrSingleTargetPreset
 import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
@@ -115,12 +116,19 @@ open class KotlinJsProjectExtension :
 
     override lateinit var defaultJsCompilerType: KotlinJsCompilerType
 
-    open fun js(
-        compiler: KotlinJsCompilerType = defaultJsCompilerType,
-        body: KotlinJsTargetDsl.() -> Unit = { }
+    private fun jsInternal(
+        compiler: KotlinJsCompilerType? = null,
+        body: KotlinJsTargetDsl.() -> Unit
     ): KotlinJsTargetDsl {
+        if (_target != null) {
+            val previousCompilerType = _target!!.calculateJsCompilerType()
+            check(compiler == null || previousCompilerType == compiler) {
+                "You already registered Kotlin/JS target with another compiler: ${previousCompilerType.lowerName}"
+            }
+        }
+
         if (_target == null) {
-            val target: KotlinJsTargetDsl = when (compiler) {
+            val target: KotlinJsTargetDsl = when (compiler ?: defaultJsCompilerType) {
                 LEGACY -> legacyPreset
                     .also { it.irPreset = null }
                     .createTarget("js")
@@ -151,8 +159,13 @@ open class KotlinJsProjectExtension :
     }
 
     fun js(
+        compiler: KotlinJsCompilerType = defaultJsCompilerType,
         body: KotlinJsTargetDsl.() -> Unit = { }
-    ) = js(compiler = defaultJsCompilerType, body = body)
+    ): KotlinJsTargetDsl = jsInternal(compiler, body)
+
+    fun js(
+        body: KotlinJsTargetDsl.() -> Unit = { }
+    ) = jsInternal(body = body)
 
     fun js() = js { }
 
@@ -161,7 +174,7 @@ open class KotlinJsProjectExtension :
             ConfigureUtil.configure(configure, this)
         }
 
-    fun js(configure: Closure<*>) = js {
+    fun js(configure: Closure<*>) = jsInternal {
         ConfigureUtil.configure(configure, this)
     }
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinTargetContainerWithJsPresetFunctions.kt

@@ -2,10 +2,8 @@ package org.jetbrains.kotlin.gradle.dsl
 
 import groovy.lang.Closure
 import org.gradle.util.ConfigureUtil
-import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerType
-import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerTypeHolder
-import org.jetbrains.kotlin.gradle.plugin.KotlinTargetPreset
-import org.jetbrains.kotlin.gradle.plugin.lowerName
+import org.jetbrains.kotlin.gradle.plugin.*
+import org.jetbrains.kotlin.gradle.targets.js.calculateJsCompilerType
 import org.jetbrains.kotlin.gradle.targets.js.dsl.KotlinJsTargetDsl
 import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
 
@@ -16,17 +14,11 @@ interface KotlinTargetContainerWithJsPresetFunctions :
         name: String = "js",
         compiler: KotlinJsCompilerType = defaultJsCompilerType,
         configure: KotlinJsTargetDsl.() -> Unit = { }
-    ): KotlinJsTargetDsl =
-        configureOrCreate(
-            lowerCamelCaseName(name, if (compiler == KotlinJsCompilerType.BOTH) KotlinJsCompilerType.LEGACY.lowerName else null),
-            presets.getByName(
-                lowerCamelCaseName(
-                    "js",
-                    if (compiler == KotlinJsCompilerType.LEGACY) null else compiler.lowerName
-                )
-            ) as KotlinTargetPreset<KotlinJsTargetDsl>,
-            configure
-        )
+    ): KotlinJsTargetDsl = jsInternal(
+        name,
+        compiler,
+        configure
+    )
 
     fun js(
         name: String,
@@ -44,18 +36,18 @@ interface KotlinTargetContainerWithJsPresetFunctions :
     fun js(
         name: String = "js",
         configure: KotlinJsTargetDsl.() -> Unit = { }
-    ) = js(name = name, compiler = defaultJsCompilerType, configure = configure)
+    ) = jsInternal(name = name, configure = configure)
 
     fun js(
         compiler: KotlinJsCompilerType,
         configure: KotlinJsTargetDsl.() -> Unit = { }
     ) = js(name = "js", compiler = compiler, configure = configure)
 
-    fun js() = js(name = "js") { }
-    fun js(name: String) = js(name = name) { }
-    fun js(name: String, configure: Closure<*>) = js(name = name) { ConfigureUtil.configure(configure, this) }
+    fun js() = jsInternal(name = "js") { }
+    fun js(name: String) = jsInternal(name = name) { }
+    fun js(name: String, configure: Closure<*>) = jsInternal(name = name) { ConfigureUtil.configure(configure, this) }
     fun js(compiler: KotlinJsCompilerType, configure: Closure<*>) = js(compiler = compiler) { ConfigureUtil.configure(configure, this) }
-    fun js(configure: Closure<*>) = js { ConfigureUtil.configure(configure, this) }
+    fun js(configure: Closure<*>) = jsInternal { ConfigureUtil.configure(configure, this) }
 
     fun js(
         name: String,
@@ -78,4 +70,74 @@ interface KotlinTargetContainerWithJsPresetFunctions :
     ) {
         ConfigureUtil.configure(configure, this)
     }
+}
+
+private fun KotlinTargetContainerWithJsPresetFunctions.jsInternal(
+    name: String = "js",
+    compiler: KotlinJsCompilerType? = null,
+    configure: KotlinJsTargetDsl.() -> Unit
+): KotlinJsTargetDsl {
+    val existingTarget = getExistingTarget(name, compiler)
+
+    val compilerOrDefault = compiler
+        ?: existingTarget?.calculateJsCompilerType()
+        ?: defaultJsCompilerType
+
+    val targetName = getTargetName(name, compilerOrDefault)
+
+    if (existingTarget != null) {
+        val previousCompilerType = existingTarget.calculateJsCompilerType()
+        check(compiler == null || previousCompilerType == compiler) {
+            "You already registered Kotlin/JS target '$targetName' with another compiler: ${previousCompilerType.lowerName}"
+        }
+    }
+
+    return configureOrCreate(
+        targetName,
+        presets.getByName(
+            lowerCamelCaseName(
+                "js",
+                if (compilerOrDefault == KotlinJsCompilerType.LEGACY) null else compilerOrDefault.lowerName
+            )
+        ) as KotlinTargetPreset<KotlinJsTargetDsl>,
+        configure
+    )
+}
+
+// Try to find existing target with exact name
+// and with append suffix Legacy in case when compiler for found target is BOTH,
+// and removed suffix Legacy in case when current compiler is BOTH
+private fun KotlinTargetContainerWithJsPresetFunctions.getExistingTarget(
+    name: String,
+    compiler: KotlinJsCompilerType?
+): KotlinJsTargetDsl? {
+
+    fun getPreviousTarget(
+        targetName: String,
+        currentBoth: Boolean
+    ): KotlinJsTargetDsl? {
+        val singleTarget = targets.findByName(
+            targetName
+        ) as KotlinJsTargetDsl?
+
+        return singleTarget?.let {
+            val previousCompiler = it.calculateJsCompilerType()
+            if (compiler == KotlinJsCompilerType.BOTH && currentBoth || previousCompiler == KotlinJsCompilerType.BOTH && !currentBoth) {
+                it
+            } else null
+        }
+    }
+
+    val targetNameCandidate = getTargetName(name, compiler)
+
+    return targets.findByName(targetNameCandidate) as KotlinJsTargetDsl?
+        ?: getPreviousTarget(targetNameCandidate.removeJsCompilerSuffix(KotlinJsCompilerType.LEGACY), true)
+        ?: getPreviousTarget(lowerCamelCaseName(targetNameCandidate, KotlinJsCompilerType.LEGACY.lowerName), false)
+}
+
+private fun getTargetName(name: String, compiler: KotlinJsCompilerType?): String {
+    return lowerCamelCaseName(
+        name,
+        if (compiler == KotlinJsCompilerType.BOTH) KotlinJsCompilerType.LEGACY.lowerName else null
+    )
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/KotlinJsTargets.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.targets.js
+
+import org.jetbrains.kotlin.gradle.plugin.KotlinJsCompilerType
+import org.jetbrains.kotlin.gradle.targets.js.dsl.KotlinJsTargetDsl
+import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrTarget
+
+fun KotlinJsTargetDsl.calculateJsCompilerType(): KotlinJsCompilerType {
+    return when {
+        this is KotlinJsTarget && this.irTarget == null -> KotlinJsCompilerType.LEGACY
+        this is KotlinJsIrTarget && !this.mixedMode -> KotlinJsCompilerType.IR
+        this is KotlinJsTarget && this.irTarget != null -> KotlinJsCompilerType.BOTH
+        else -> throw IllegalStateException("Unable to find previous Kotlin/JS compiler type for $this")
+    }
+}