JVM IR: Always produce stubs for interface methods in inline classes

This matches the behavior of the JVM backend, with the exception of
@JvmDefault methods, which are currently broken on the JVM backend.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
 
@@ -116,6 +116,17 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
         }
     }
 
+    private fun createBridgeBody(source: IrSimpleFunction, target: IrSimpleFunction) {
+        source.body = context.createIrBuilder(source.symbol, source.startOffset, source.endOffset).run {
+            irExprBody(irCall(target).apply {
+                passTypeArgumentsFrom(source)
+                for ((parameter, newParameter) in source.explicitParameters.zip(target.explicitParameters)) {
+                    putArgument(newParameter, irGet(parameter))
+                }
+            })
+        }
+    }
+
     private fun transformSimpleFunctionFlat(function: IrSimpleFunction, replacement: IrSimpleFunction): List<IrDeclaration> {
         replacement.valueParameters.forEach { it.transformChildrenVoid() }
         replacement.body = function.body?.transform(this, null)?.patchDeclarationParents(replacement)
@@ -125,16 +136,15 @@ private class JvmInlineClassLowering(private val context: JvmBackendContext) : F
         if (function.overriddenSymbols.isEmpty() || replacement.dispatchReceiverParameter != null)
             return listOf(replacement)
 
-        // Replace the function body with a wrapper
-        context.createIrBuilder(function.symbol, function.startOffset, function.endOffset).run {
-            val call = irCall(replacement).apply {
-                passTypeArgumentsFrom(function)
-                for ((parameter, newParameter) in function.explicitParameters.zip(replacement.explicitParameters)) {
-                    putArgument(newParameter, irGet(parameter))
-                }
-            }
+        // Update the overridden symbols to point to their inline class replacements
+        function.overriddenSymbols = replacement.overriddenSymbols
 
-            function.body = irExprBody(call)
+        // Replace the function body with a wrapper
+        if (!function.isFakeOverride || !function.parentAsClass.isInline) {
+            createBridgeBody(function, replacement)
+        } else {
+            // Fake overrides redirect from the replacement to the original function, which is in turn replaced during interfacePhase.
+            createBridgeBody(replacement, function)
         }
 
         return listOf(replacement, function)

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/inlineclasses/InlineClassAbi.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
 
@@ -101,7 +101,7 @@ private val IrFunction.fullValueParameterList: List<IrValueParameter>
     get() = listOfNotNull(extensionReceiverParameter) + valueParameters
 
 internal val IrFunction.hasMangledParameters: Boolean
-    get() = dispatchReceiverParameter?.type?.getClass()?.isInline == true ||
+    get() = dispatchReceiverParameter != null && parentAsClass.isInline ||
             fullValueParameterList.any { it.type.requiresMangling } ||
             (this is IrConstructor && constructedClass.isInline)
 

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/inlineclasses/MemoizedInlineClassReplacements.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
 
@@ -39,27 +39,26 @@ class MemoizedInlineClassReplacements {
     val getReplacementFunction: (IrFunction) -> IrSimpleFunction? =
         storageManager.createMemoizedFunctionWithNullableValues {
             when {
-                !it.hasMangledParameters ||
-                        it.isSyntheticInlineClassMember ||
-                        it.origin == IrDeclarationOrigin.LOCAL_FUNCTION_FOR_LAMBDA ||
+                // Don't mangle anonymous or synthetic functions
+                it.origin == IrDeclarationOrigin.LOCAL_FUNCTION_FOR_LAMBDA ||
                         it.origin == IrDeclarationOrigin.DELEGATED_PROPERTY_ACCESSOR ||
-                        it.origin.isSynthetic -> null
-                it.hasMethodReplacement -> createMethodReplacement(it)
-                it.hasStaticReplacement -> createStaticReplacement(it)
-                else -> null
+                        it.origin == JvmLoweredDeclarationOrigin.STATIC_INLINE_CLASS_REPLACEMENT ||
+                        it.origin.isSynthetic ||
+                        it.isInlineClassFieldGetter -> null
+
+                // Mangle all functions in the body of an inline class
+                it.parent.safeAs<IrClass>()?.isInline == true ->
+                    createStaticReplacement(it)
+
+                // Otherwise, mangle functions with mangled parameters, while ignoring constructors
+                it is IrSimpleFunction && it.hasMangledParameters ->
+                    if (it.dispatchReceiverParameter != null) createMethodReplacement(it) else createStaticReplacement(it)
+
+                else ->
+                    null
             }
         }
 
-    private val IrFunction.hasStaticReplacement: Boolean
-        get() = origin != IrDeclarationOrigin.FAKE_OVERRIDE &&
-                (this is IrSimpleFunction || this is IrConstructor && constructedClass.isInline)
-
-    private val IrFunction.hasMethodReplacement: Boolean
-        get() = dispatchReceiverParameter != null && this is IrSimpleFunction && (parent as? IrClass)?.isInline != true
-
-    private val IrFunction.isSyntheticInlineClassMember: Boolean
-        get() = origin == JvmLoweredDeclarationOrigin.SYNTHETIC_INLINE_CLASS_MEMBER || isInlineClassFieldGetter
-
     /**
      * Get the box function for an inline class. Concretely, this is a synthetic
      * static function named "box-impl" which takes an unboxed value and returns
@@ -150,20 +149,24 @@ class MemoizedInlineClassReplacements {
         buildReplacement(function, JvmLoweredDeclarationOrigin.STATIC_INLINE_CLASS_REPLACEMENT) {
             val newValueParameters = ArrayList<IrValueParameter>()
             for ((index, parameter) in function.explicitParameters.withIndex()) {
-                val name = when (parameter) {
-                    function.dispatchReceiverParameter -> Name.identifier("arg$index")
-                    function.extensionReceiverParameter -> Name.identifier("\$this\$${function.name}")
-                    else -> parameter.name
+                newValueParameters += when (parameter) {
+                    // FAKE_OVERRIDEs have broken dispatch receivers
+                    function.dispatchReceiverParameter ->
+                        function.parentAsClass.thisReceiver!!.copyTo(
+                            this, index = index, name = Name.identifier("arg$index"),
+                            type = function.parentAsClass.defaultType, origin = IrDeclarationOrigin.MOVED_DISPATCH_RECEIVER
+                        )
+                    function.extensionReceiverParameter ->
+                        parameter.copyTo(
+                            this, index = index, name = Name.identifier("\$this\$${function.name}"),
+                            origin = IrDeclarationOrigin.MOVED_EXTENSION_RECEIVER
+                        )
+                    else ->
+                        parameter.copyTo(this, index = index, defaultValue = null).also {
+                            // See comment next to a similar line above.
+                            it.defaultValue = parameter.defaultValue?.patchDeclarationParents(this)
+                        }
                 }
-                val parameterOrigin = when (parameter) {
-                    function.dispatchReceiverParameter -> IrDeclarationOrigin.MOVED_DISPATCH_RECEIVER
-                    function.extensionReceiverParameter -> IrDeclarationOrigin.MOVED_EXTENSION_RECEIVER
-                    else -> parameter.origin
-                }
-                val newParameter = parameter.copyTo(this, index = index, name = name, defaultValue = null, origin = parameterOrigin)
-                newValueParameters += newParameter
-                // See comment next to a similar line above.
-                newParameter.defaultValue = parameter.defaultValue?.patchDeclarationParents(this)
             }
             valueParameters = newValueParameters
         }

compiler/testData/codegen/bytecodeText/inlineClasses/interfaceDefaultImplStubs.kt

@@ -0,0 +1,29 @@
+// !LANGUAGE: +InlineClasses
+// FILE: test.kt
+
+fun box(): String {
+    val b = B(0)
+    return b.f() + b.g()
+}
+
+interface A {
+    fun f() = "O"
+    fun g() = "K"
+}
+
+inline class B(val x: Int) : A
+
+// 1 public static f-impl\(I\)Ljava/lang/String;
+// 1 public f\(\)Ljava/lang/String;
+
+// 1 public static g-impl\(I\)Ljava/lang/String;
+// 1 public g\(\)Ljava/lang/String;
+
+// JVM_TEMPLATES:
+// The JVM backend calls f-impl, g-impl from f, g, respectively, in addition to the call from box.
+// 2 INVOKESTATIC B.g-impl \(I\)Ljava/lang/String;
+// 2 INVOKESTATIC B.f-impl \(I\)Ljava/lang/String;
+
+// JVM_IR_TEMPLATES:
+// 1 INVOKESTATIC B.g-impl \(I\)Ljava/lang/String;
+// 1 INVOKESTATIC B.f-impl \(I\)Ljava/lang/String;

compiler/testData/codegen/bytecodeText/inlineClasses/interfaceJvmDefaultImplStubs.kt

@@ -0,0 +1,36 @@
+// !LANGUAGE: +InlineClasses
+
+// IGNORE_BACKEND: JVM
+// The JVM backend does not generate the g-impl method, but ends up calling it from box.
+
+// !JVM_DEFAULT_MODE: enable
+// JVM_TARGET: 1.8
+// FILE: test.kt
+
+
+fun box(): String {
+    val b = B(0)
+    return b.f() + b.g()
+}
+
+interface A {
+    fun f() = "O"
+    @JvmDefault
+    fun g() = "K"
+}
+
+inline class B(val x: Int) : A
+
+// 1 public static f-impl\(I\)Ljava/lang/String;
+// 1 public f\(\)Ljava/lang/String;
+
+// 1 public static g-impl\(I\)Ljava/lang/String;
+// 0 public g\(\)Ljava/lang/String;
+
+// 1 INVOKESTATIC B.g-impl \(I\)Ljava/lang/String;
+
+// JVM_TEMPLATES:
+// 2 INVOKESTATIC B.f-impl \(I\)Ljava/lang/String;
+
+// JVM_IR_TEMPLATES:
+// 1 INVOKESTATIC B.f-impl \(I\)Ljava/lang/String;

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -2775,6 +2775,16 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/inlineClasses/inlineClassesUnboxingAfterAssertionOperator.kt");
         }
 
+        @TestMetadata("interfaceDefaultImplStubs.kt")
+        public void testInterfaceDefaultImplStubs() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/inlineClasses/interfaceDefaultImplStubs.kt");
+        }
+
+        @TestMetadata("interfaceJvmDefaultImplStubs.kt")
+        public void testInterfaceJvmDefaultImplStubs() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/inlineClasses/interfaceJvmDefaultImplStubs.kt");
+        }
+
         @TestMetadata("isCheckForInlineClass.kt")
         public void testIsCheckForInlineClass() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/inlineClasses/isCheckForInlineClass.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBytecodeTextTestGenerated.java

@@ -2820,6 +2820,16 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/inlineClasses/inlineClassesUnboxingAfterAssertionOperator.kt");
         }
 
+        @TestMetadata("interfaceDefaultImplStubs.kt")
+        public void testInterfaceDefaultImplStubs() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/inlineClasses/interfaceDefaultImplStubs.kt");
+        }
+
+        @TestMetadata("interfaceJvmDefaultImplStubs.kt")
+        public void testInterfaceJvmDefaultImplStubs() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/inlineClasses/interfaceJvmDefaultImplStubs.kt");
+        }
+
         @TestMetadata("isCheckForInlineClass.kt")
         public void testIsCheckForInlineClass() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/inlineClasses/isCheckForInlineClass.kt");