[Gradle, MPP] Fix 'getCommonizerTarget' for source sets participating in multiple compilations of the same konanTarget

The previous implementation would return a 'SharedCommonizerTarget'
containing just a single leaf target. This would trigger the commonizer.
The new implementation will correctly return just a single
LeafCommonizerTarget instead.

^KT-49735 Verification Pending

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/CommonizerIT.kt

@@ -426,6 +426,16 @@ class CommonizerIT : BaseGradleIT() {
         `test multiple cinterops with test source sets and compilations`(false)
     }
 
+    @Test
+    fun `test KT-49735 two kotlin targets with same konanTarget`() {
+        with(Project("commonize-kt-49735-twoKotlinTargets-oneKonanTarget")) {
+            build(":assemble") {
+                assertTasksExecuted(":compileCommonMainKotlinMetadata")
+                assertSuccessful()
+            }
+        }
+    }
+
     private fun `test multiple cinterops with test source sets and compilations`(testSourceSetsDependingOnMain: Boolean) {
         with(Project("commonizeMultipleCInteropsWithTests", minLogLevel = INFO)) {
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/commonize-kt-49735-twoKotlinTargets-oneKonanTarget/build.gradle.kts

@@ -0,0 +1,27 @@
+import org.jetbrains.kotlin.gradle.plugin.sources.DefaultKotlinSourceSet
+import org.jetbrains.kotlin.konan.target.HostManager
+
+plugins {
+    kotlin("multiplatform")
+}
+
+repositories {
+    mavenCentral()
+    mavenLocal()
+}
+
+kotlin {
+    val platformTargetA = when {
+        HostManager.hostIsMac -> macosX64("platformA")
+        HostManager.hostIsMingw -> mingwX64("platformA")
+        HostManager.hostIsLinux -> linuxX64("platformA")
+        else -> error("Unexpected host: ${HostManager.host}")
+    }
+
+    val platformTargetB = when {
+        HostManager.hostIsMac -> macosX64("platformB")
+        HostManager.hostIsMingw -> mingwX64("platformB")
+        HostManager.hostIsLinux -> linuxX64("platformB")
+        else -> error("Unexpected host: ${HostManager.host}")
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/commonize-kt-49735-twoKotlinTargets-oneKonanTarget/gradle.properties

@@ -0,0 +1,6 @@
+kotlin.code.style=official
+kotlin.mpp.enableGranularSourceSetsMetadata=true
+kotlin.mpp.enableCInteropCommonization=true
+kotlin.native.enableDependencyPropagation=false
+kotlin.mpp.enableIntransitiveMetadataConfiguration=true
+kotlin.mpp.enableCompatibilityMetadataVariant=false

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/commonize-kt-49735-twoKotlinTargets-oneKonanTarget/settings.gradle.kts

@@ -0,0 +1,10 @@
+pluginManagement {
+    repositories {
+        mavenLocal()
+        gradlePluginPortal()
+    }
+    val kotlin_version: String by settings
+    plugins {
+        kotlin("multiplatform").version(kotlin_version)
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/commonize-kt-49735-twoKotlinTargets-oneKonanTarget/src/commonMain/kotlin/CommonMain.kt

@@ -0,0 +1,8 @@
+/*
+ * Copyright 2010-2021 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.
+ */
+
+object CommonMain {
+    fun x(stat: platform.posix.stat) = Unit
+}

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/SourceSetCommonizerTargetTest.kt

@@ -12,6 +12,7 @@ import org.gradle.api.Project
 import org.gradle.api.plugins.ExtraPropertiesExtension
 import org.gradle.testfixtures.ProjectBuilder
 import org.jetbrains.kotlin.commonizer.CommonizerTarget
+import org.jetbrains.kotlin.commonizer.LeafCommonizerTarget
 import org.jetbrains.kotlin.commonizer.SharedCommonizerTarget
 import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
 import org.jetbrains.kotlin.gradle.targets.native.internal.getCommonizerTarget
@@ -83,6 +84,33 @@ class SourceSetCommonizerTargetTest {
         assertEquals(CommonizerTarget(LINUX_X64, MACOS_X64), project.getCommonizerTarget(commonTest))
     }
 
+    @Test
+    fun `nativeMain linuxX64-a linuxX64-b`() {
+        kotlin.linuxX64("linuxA")
+        kotlin.linuxX64("linuxB")
+
+        val commonMain = kotlin.sourceSets.getByName("commonMain")
+        val commonTest = kotlin.sourceSets.getByName("commonTest")
+        val nativeMain = kotlin.sourceSets.create("nativeMain")
+        val linuxAMain = kotlin.sourceSets.getByName("linuxAMain")
+        val linuxBMain = kotlin.sourceSets.getByName("linuxBMain")
+        val linuxATest = kotlin.sourceSets.getByName("linuxATest")
+        val linuxBTest = kotlin.sourceSets.getByName("linuxBTest")
+
+        nativeMain.dependsOn(commonMain)
+        linuxAMain.dependsOn(nativeMain)
+        linuxBMain.dependsOn(nativeMain)
+
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(linuxAMain))
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(linuxATest))
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(linuxBMain))
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(linuxBTest))
+
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(nativeMain))
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(commonMain))
+        assertEquals(LeafCommonizerTarget(LINUX_X64), project.getCommonizerTarget(commonTest))
+    }
+
     @Test
     fun `nativeMain iosMain linux macos iosX64 iosArm64`() {
         kotlin.linuxX64("linux")

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/native/internal/GetCommonizerTargetOfSourceSet.kt

@@ -14,17 +14,18 @@ import org.jetbrains.kotlin.gradle.plugin.mpp.CompilationSourceSetUtil.compilati
 import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinMetadataCompilation
 
 internal fun Project.getCommonizerTarget(sourceSet: KotlinSourceSet): CommonizerTarget? {
-    val compilationTargets = compilationsBySourceSets(this)[sourceSet].orEmpty()
+    val allCompilationLeafTargets = compilationsBySourceSets(this)[sourceSet].orEmpty()
         .filter { compilation -> compilation !is KotlinMetadataCompilation }
         .map { compilation -> getCommonizerTarget(compilation) ?: return null }
+        .allLeaves()
 
     return when {
-        compilationTargets.isEmpty() -> null
-        compilationTargets.size == 1 -> compilationTargets.single()
-        else -> SharedCommonizerTarget(compilationTargets.allLeaves())
+        allCompilationLeafTargets.isEmpty() -> null
+        allCompilationLeafTargets.size == 1 -> allCompilationLeafTargets.single()
+        else -> SharedCommonizerTarget(allCompilationLeafTargets)
     }
 }
 
 internal fun Project.getSharedCommonizerTarget(sourceSet: KotlinSourceSet): SharedCommonizerTarget? {
     return getCommonizerTarget(sourceSet) as? SharedCommonizerTarget
-}
+}