[Gradle] Legacy metadata compilation should contain all source sets from

depends on closure of its default source set.

With HMPP it is no longer needed, since each source compiles
independently and sees its parent declarations via klib dependencies

^KT-55730 Verification Pending

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/metadata/KotlinMetadataTargetConfigurator.kt

@@ -72,6 +72,12 @@ class KotlinMetadataTargetConfigurator :
                 if (isCompatibilityMetadataVariantEnabled) {
                     // Force the default 'main' compilation to produce *.kotlin_metadata regardless of the klib feature flag.
                     forceCompilationToKotlinMetadata = true
+                    // Add directly dependsOn sources for Legacy Compatibility Metadata variant
+                    // it isn't necessary for KLib compilations
+                    // see [KotlinCompilationSourceSetInclusion.AddSourcesWithoutDependsOnClosure]
+                    defaultSourceSet.internal.dependsOnClosure.forAll {
+                        source(it)
+                    }
                 } else {
                     // Clear the dependencies of the compilation so that they don't take time resolving during task graph construction:
                     compileDependencyFiles = target.project.files()

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/regressionTests/KT55730CommonMainDependsOnAnotherSourceSet.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2010-2023 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.
+ */
+
+@file:Suppress("FunctionName")
+
+package org.jetbrains.kotlin.gradle.regressionTests
+
+import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
+import org.jetbrains.kotlin.gradle.util.applyMultiplatformPlugin
+import org.jetbrains.kotlin.gradle.util.buildProject
+import org.jetbrains.kotlin.gradle.util.enableCompatibilityMetadataVariant
+import org.jetbrains.kotlin.gradle.util.kotlin
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class KT55730CommonMainDependsOnAnotherSourceSet {
+    @Test
+    fun `legacy metadata compilation should have commonMain with its depends on closure`() {
+        val project = buildProject {
+            enableCompatibilityMetadataVariant()
+            applyMultiplatformPlugin()
+            kotlin {
+                val grandCommonMain = sourceSets.create("grandCommonMain")
+                val commonMain = sourceSets.getByName("commonMain")
+                commonMain.dependsOn(grandCommonMain)
+            }
+        }
+
+        project.evaluate()
+
+        val actualSourceSets = project
+            .multiplatformExtension
+            .metadata()
+            .compilations
+            .getByName("main")
+            .kotlinSourceSets
+            .map { it.name }
+            .toSet()
+
+        assertEquals(setOf("grandCommonMain", "commonMain"), actualSourceSets)
+    }
+}

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

@@ -17,6 +17,7 @@ import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformAndroidPlugin
 import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformJvmPlugin
 import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider
+import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider.PropertyNames.KOTLIN_MPP_ENABLE_COMPATIBILITY_METADATA_VARIANT
 import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider.PropertyNames.KOTLIN_MPP_ENABLE_INTRANSITIVE_METADATA_CONFIGURATION
 import org.jetbrains.kotlin.gradle.plugin.mpp.pm20.KotlinPm20ProjectExtension
 import org.jetbrains.kotlin.gradle.unitTests.kpm.applyKpmPlugin
@@ -116,4 +117,8 @@ fun Project.setMultiplatformAndroidSourceSetLayoutVersion(version: Int) {
 fun Project.enableDependencyVerification(enabled: Boolean = true) {
     gradle.startParameter.dependencyVerificationMode = if (enabled) DependencyVerificationMode.STRICT
     else DependencyVerificationMode.OFF
-}
+}
+
+fun Project.enableCompatibilityMetadataVariant(enabled: Boolean = true) {
+    propertiesExtension.set(KOTLIN_MPP_ENABLE_COMPATIBILITY_METADATA_VARIANT, enabled.toString())
+}