Fix kapt class structure configuration not resolving MPP deps, KT-33105

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

@@ -325,10 +325,15 @@ class NewMultiplatformIT : BaseGradleIT() {
                         jvm6MainImplementation("com.google.dagger:dagger:2.24")
                         kapt("com.google.dagger:dagger-compiler:2.24")
                         kapt(project(":sample-lib-gradle-kotlin-dsl"))
+                        
+                        // also check incremental Kapt class structure configurations, KT-33105
+                        jvm6MainImplementation(project(":sample-lib-gradle-kotlin-dsl")) 
                     }
                     """.trimIndent()
                 )
             }
+            // also check incremental Kapt class structure configurations, KT-33105
+            projectDir.resolve("gradle.properties").appendText("\nkapt.incremental.apt=true")
 
             // Check Kapt:
             projectDir.resolve("src/jvm6Main/kotlin/Main.kt").appendText(

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/Kapt3KotlinGradleSubplugin.kt

@@ -396,7 +396,13 @@ class Kapt3KotlinGradleSubplugin : KotlinGradleSubplugin<KotlinCompile> {
 
             maybeRegisterTransform(project)
             val classStructure = project.configurations.create("_classStructure${taskName}")
-            project.dependencies.add(classStructure.name, kotlinCompile.classpath)
+
+            // Wrap the `kotlinCompile.classpath` into a file collection, so that, if the classpath is represented by a configuration,
+            // the configuration is not extended (via extendsFrom, which normally happens when one configuration is _added_ into another)
+            // but is instead included as the (lazily) resolved files. This is needed because the class structure configuration doesn't have
+            // the attributes that are potentially needed to resolve dependencies on MPP modules, and the classpath configuration does.
+            project.dependencies.add(classStructure.name, project.files(project.provider { kotlinCompile.classpath }))
+
             kaptTask.classpathStructure = classStructure.incoming.artifactView { viewConfig ->
                 viewConfig.attributes.attribute(artifactType, CLASS_STRUCTURE_ARTIFACT_TYPE)
             }.files