JVM IR: Don't generate bridges for default argument stubs (KT-46389)

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -2130,6 +2130,18 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @Test
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @Test
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @Test
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {

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

@@ -200,8 +200,16 @@ internal class BridgeLowering(val context: JvmBackendContext) : FileLoweringPass
         // Track final overrides and bridges to avoid clashes
         val blacklist = mutableSetOf<Method>()
 
-        // Add the current method to the blacklist if it is concrete or final.
+        // Don't generate bridges for default argument stubs. This is a workaround for a
-        val targetMethod = (irFunction.resolveFakeOverride() ?: irFunction).jvmMethod
+        // frontend bug (KT-36188). Ideally, the frontend should not allow inheriting from
+        // multiple different default argument stubs, but for now we need this special case
+        // to avoid a ClassCastException in the inliner (KT-46389).
+        val targetFunction = irFunction.resolveFakeOverride() ?: irFunction
+        if (targetFunction.origin == IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER) {
+            return
+        }
+        // Add the current method to the blacklist if it is concrete or final
+        val targetMethod = targetFunction.jvmMethod
         if (!irFunction.isFakeOverride || irFunction.modality == Modality.FINAL)
             blacklist += targetMethod
 

compiler/testData/codegen/box/bridges/kt46389.kt

@@ -0,0 +1,23 @@
+// IGNORE_BACKEND: JS, JS_IR
+
+// The code in this test should be prohibited in the frontend, see KT-36188.
+
+// This test fails with an IllegalStateException on the JS(-IR) backend,
+// but the behavior would probably not match the JVM backend even if
+// the test passed. Compare with kt46389_jvmDefault.
+
+interface I {
+    fun h(x: String = "O"): Any
+}
+
+interface I2 : I
+
+open class A {
+    inline fun h(x: String = "K") = x
+}
+
+class B : A(), I2
+
+fun box(): String {
+    return "${(B() as I).h()}${B().h()}"
+}

compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt

@@ -0,0 +1,30 @@
+// IGNORE_BACKEND: JS, JS_IR
+// !JVM_DEFAULT_MODE: all
+// JVM_TARGET: 1.8
+
+// The code in this test should be prohibited in the frontend, see KT-36188.
+
+// Before the fix to kt46389, the IR backend would have added a bridge
+// for `h$default` in `B`, which would have lead both calls to use "K"
+// as the default value. This would arguably be less surprising, but is
+// impossible to match without jvm-default on the JVM(-IR)backend.
+//
+// Meanwhile, the two calls using "K" as the default value is the current
+// behavior on the JS backend, which is why the test is muted for the JS
+// backend.
+
+interface I {
+    fun h(x: String = "O"): Any
+}
+
+interface I2 : I
+
+open class A {
+    fun h(x: String = "K") = x
+}
+
+class B : A(), I2
+
+fun box(): String {
+    return "${(B() as I).h()}${B().h()}"
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/BlackBoxCodegenTestGenerated.java

@@ -2058,6 +2058,18 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @Test
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @Test
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @Test
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -2130,6 +2130,18 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @Test
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @Test
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @Test
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -1808,6 +1808,16 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {
             runTest("compiler/testData/codegen/box/bridges/longChainOneBridge.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java

@@ -1273,6 +1273,16 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {
             runTest("compiler/testData/codegen/box/bridges/longChainOneBridge.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -1273,6 +1273,16 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {
             runTest("compiler/testData/codegen/box/bridges/longChainOneBridge.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -1253,6 +1253,16 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {
             runTest("compiler/testData/codegen/box/bridges/longChainOneBridge.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/wasm/semantics/IrCodegenBoxWasmTestGenerated.java

@@ -1138,6 +1138,16 @@ public class IrCodegenBoxWasmTestGenerated extends AbstractIrCodegenBoxWasmTest
             runTest("compiler/testData/codegen/box/bridges/kt42137.kt");
         }
 
+        @TestMetadata("kt46389.kt")
+        public void testKt46389() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389.kt");
+        }
+
+        @TestMetadata("kt46389_jvmDefault.kt")
+        public void testKt46389_jvmDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/bridges/kt46389_jvmDefault.kt");
+        }
+
         @TestMetadata("longChainOneBridge.kt")
         public void testLongChainOneBridge() throws Exception {
             runTest("compiler/testData/codegen/box/bridges/longChainOneBridge.kt");