Fix child default toolchain configuration overwrites parent one

Caused by configure actions ordering - parent are applied first.

^KT-55004 Fixed

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

@@ -14,6 +14,7 @@ import org.gradle.util.GradleVersion
 import org.jetbrains.kotlin.gradle.testbase.*
 import org.junit.jupiter.api.DisplayName
 import java.io.File
+import kotlin.io.path.appendText
 
 @JvmGradlePluginTests
 @DisplayName("Kotlin Java Toolchain support")
@@ -659,6 +660,37 @@ class KotlinJavaToolchainTest : KGPBaseTest() {
         }
     }
 
+    @DisplayName("KT-55004: Should use non-default toolchain for parent project")
+    @GradleTest
+    internal fun toolchainFromParentProject(gradleVersion: GradleVersion) {
+        project(
+            projectName = "multiproject".fullProjectName,
+            gradleVersion = gradleVersion,
+            buildOptions = defaultBuildOptions.copy(logLevel = LogLevel.DEBUG)
+        ) {
+            //language=Groovy
+            buildGradle.appendText(
+                """
+                |
+                |allprojects {
+                |    tasks.withType(org.jetbrains.kotlin.gradle.tasks.UsesKotlinJavaToolchain.class)
+                |         .configureEach {
+                |              kotlinJavaToolchain.jdk.use(
+                |                  "${getJdk11Path()}",
+                |                  JavaVersion.VERSION_11
+                |              )
+                |         }
+                |}
+                """.trimMargin()
+            )
+
+            build(":lib:compileKotlin") {
+                assertOutputDoesNotContain("-jvm-target 1.8")
+                assertOutputContains("-jvm-target 11")
+            }
+        }
+    }
+
     private fun BuildResult.assertJdkHomeIsUsingJdk(
         javaexecPath: String
     ) = assertOutputContains("[KOTLIN] Kotlin compilation 'jdkHome' argument: $javaexecPath")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/multiproject/build.gradle

@@ -0,0 +1,3 @@
+plugins {
+    id "org.jetbrains.kotlin.jvm" apply false
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/multiproject/lib/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+    id("org.jetbrains.kotlin.jvm")
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/multiproject/lib/src/main/kotlin/main.kt

@@ -0,0 +1,3 @@
+fun main() {
+    println("I know what you've done last summer...")
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-java-toolchain/multiproject/settings.gradle

@@ -0,0 +1 @@
+include ":lib"

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/dsl/ToolchainDsl.kt

@@ -13,6 +13,7 @@ import org.gradle.api.plugins.PluginContainer
 import org.gradle.api.tasks.TaskContainer
 import org.gradle.jvm.toolchain.JavaToolchainService
 import org.gradle.jvm.toolchain.JavaToolchainSpec
+import org.jetbrains.kotlin.gradle.tasks.DefaultKotlinJavaToolchain
 import org.jetbrains.kotlin.gradle.tasks.UsesKotlinJavaToolchain
 import org.jetbrains.kotlin.gradle.tasks.withType
 import org.jetbrains.kotlin.gradle.utils.newInstance
@@ -62,7 +63,8 @@ internal abstract class DefaultToolchainSupport @Inject constructor(
             tasks
                 .withType<UsesKotlinJavaToolchain>()
                 .configureEach {
-                    it.kotlinJavaToolchain.toolchain.use(javaLauncher)
+                    (it.kotlinJavaToolchain.toolchain as DefaultKotlinJavaToolchain.DefaultJavaToolchainSetter)
+                        .useAsConvention(javaLauncher)
                 }
         }
     }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/tasks/DefaultKotlinJavaToolchain.kt

@@ -164,22 +164,29 @@ internal abstract class DefaultKotlinJavaToolchain @Inject constructor(
         }
     }
 
-    private class DefaultJavaToolchainSetter(
+    internal class DefaultJavaToolchainSetter(
         private val providedJvm: Property<Jvm>
     ) : KotlinJavaToolchain.JavaToolchainSetter {
+
+        internal fun useAsConvention(
+            javaLauncher: Provider<JavaLauncher>
+        ) {
+            providedJvm.convention(javaLauncher.map(::mapToJvm))
+        }
+
         override fun use(
             javaLauncher: Provider<JavaLauncher>
         ) {
-            providedJvm.set(
-                javaLauncher.map { launcher ->
-                    val metadata = launcher.metadata
-                    val javaVersion = JavaVersion.toVersion(metadata.languageVersion.asInt())
-                    Jvm.discovered(
-                        metadata.installationPath.asFile,
-                        null,
-                        javaVersion
-                    )
-                }
+            providedJvm.set(javaLauncher.map(::mapToJvm))
+        }
+
+        private fun mapToJvm(javaLauncher: JavaLauncher): Jvm {
+            val metadata = javaLauncher.metadata
+            val javaVersion = JavaVersion.toVersion(metadata.languageVersion.asInt())
+            return Jvm.discovered(
+                metadata.installationPath.asFile,
+                null,
+                javaVersion
             )
         }
     }