Kapt+JVM_IR: do not generate SuspendFunction supertypes

#KT-54380 Fixed

compiler/ir/backend.jvm/codegen/src/org/jetbrains/kotlin/backend/jvm/codegen/ClassCodegen.kt

@@ -110,7 +110,7 @@ class ClassCodegen private constructor(
     private val classOrigin = irClass.descriptorOrigin
 
     private val visitor = state.factory.newVisitor(classOrigin, type, irClass.fileParent.loadSourceFilesInfo()).apply {
-        val signature = typeMapper.mapClassSignature(irClass, type)
+        val signature = typeMapper.mapClassSignature(irClass, type, context.state.classBuilderMode.generateBodies)
         // Ensure that the backend only produces class names that would be valid in the frontend for JVM.
         if (context.state.classBuilderMode.generateBodies && signature.hasInvalidName()) {
             throw IllegalStateException("Generating class with invalid name '${type.className}': ${irClass.dump()}")

compiler/ir/backend.jvm/codegen/src/org/jetbrains/kotlin/backend/jvm/codegen/irCodegenUtils.kt

@@ -218,7 +218,7 @@ private val KOTLIN_MARKER_INTERFACES: Map<FqName, String> = run {
     kotlinMarkerInterfaces
 }
 
-internal fun IrTypeMapper.mapClassSignature(irClass: IrClass, type: Type): JvmClassSignature {
+internal fun IrTypeMapper.mapClassSignature(irClass: IrClass, type: Type, generateBodies: Boolean): JvmClassSignature {
     val sw = BothSignatureWriter(BothSignatureWriter.Mode.CLASS)
     writeFormalTypeParameters(irClass.typeParameters, sw)
 
@@ -234,7 +234,11 @@ internal fun IrTypeMapper.mapClassSignature(irClass: IrClass, type: Type): JvmCl
     sw.writeSuperclassEnd()
 
     val kotlinMarkerInterfaces = LinkedHashSet<String>()
-    if (irClass.superTypes.any { it.isSuspendFunction() || it.isKSuspendFunction() }) {
+    if (generateBodies && irClass.superTypes.any { it.isSuspendFunction() || it.isKSuspendFunction() }) {
+        // Do not generate this class in the kapt3 mode (generateBodies=false), because kapt3 transforms supertypes correctly in the
+        // "correctErrorTypes" mode only when the number of supertypes between PSI and bytecode is equal. Otherwise it tries to "correct"
+        // the FunctionN type and fails, because that type doesn't need an import in the Kotlin source (kotlin.FunctionN), but needs one
+        // in the Java source (kotlin.jvm.functions.FunctionN), and kapt3 doesn't perform any Kotlin->Java name lookup.
         kotlinMarkerInterfaces.add("kotlin/coroutines/jvm/internal/SuspendFunction")
     }
 

plugins/kapt3/kapt3-compiler/src/org/jetbrains/kotlin/kapt3/stubs/ClassFileToSourceStubConverter.kt

@@ -539,6 +539,12 @@ class ClassFileToSourceStubConverter(val kaptContext: KaptContextForStubGenerati
         val sameSuperClassCount = (superClass == null) == (defaultSuperTypes.superClass == null)
         val sameSuperInterfaceCount = superInterfaces.size == defaultSuperTypes.interfaces.size
 
+        // Note: if the number of supertypes is different, it might mean either that one of them is unresolved, or that backend generated
+        // additional supertypes which were not present in the PSI.
+        // In the former case, the subsequent code behaves as expected, trying to recover the types from the PSI.
+        // In the latter case, ideally we shouldn't do anything, but most of the time invoking error type correction is harmless because
+        // it will be a no-op. However, it might lead to problems for non-trivial types such as `kotlin.FunctionN` which are mapped to
+        // `kotlin.jvm.functions.FunctionN`, because the Java source requires a new import, unlike the Kotlin source.
         if (sameSuperClassCount && sameSuperInterfaceCount) {
             return defaultSuperTypes
         }

plugins/kapt3/kapt3-compiler/testData/converter/suspendFunctionSupertype.kt

@@ -0,0 +1,3 @@
+// CORRECT_ERROR_TYPES
+
+interface SomeInterface : suspend (List<String>, Boolean) -> List<Int>

plugins/kapt3/kapt3-compiler/testData/converter/suspendFunctionSupertype.txt

@@ -0,0 +1,3 @@
+@kotlin.Metadata()
+public abstract interface SomeInterface extends kotlin.jvm.functions.Function3<java.util.List<? extends java.lang.String>, java.lang.Boolean, kotlin.coroutines.Continuation<? super java.util.List<? extends java.lang.Integer>>, java.lang.Object> {
+}

plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/ClassFileToSourceStubConverterTestGenerated.java

@@ -619,6 +619,12 @@ public class ClassFileToSourceStubConverterTestGenerated extends AbstractClassFi
         runTest("plugins/kapt3/kapt3-compiler/testData/converter/suspendErrorTypes.kt");
     }
 
+    @Test
+    @TestMetadata("suspendFunctionSupertype.kt")
+    public void testSuspendFunctionSupertype() throws Exception {
+        runTest("plugins/kapt3/kapt3-compiler/testData/converter/suspendFunctionSupertype.kt");
+    }
+
     @Test
     @TestMetadata("topLevel.kt")
     public void testTopLevel() throws Exception {

plugins/kapt3/kapt3-compiler/tests-gen/org/jetbrains/kotlin/kapt3/test/runners/IrClassFileToSourceStubConverterTestGenerated.java

@@ -619,6 +619,12 @@ public class IrClassFileToSourceStubConverterTestGenerated extends AbstractIrCla
         runTest("plugins/kapt3/kapt3-compiler/testData/converter/suspendErrorTypes.kt");
     }
 
+    @Test
+    @TestMetadata("suspendFunctionSupertype.kt")
+    public void testSuspendFunctionSupertype() throws Exception {
+        runTest("plugins/kapt3/kapt3-compiler/testData/converter/suspendFunctionSupertype.kt");
+    }
+
     @Test
     @TestMetadata("topLevel.kt")
     public void testTopLevel() throws Exception {