JVM_IR: keep the $default suffix for stubs for @JvmName functions

Technically a backwards compatibility problem, as the new backend
*consistently* renamed `f$default` on `f` with `@JvmName("g")` to
`g` instead of `g$default`, so it all worked out. However, this
breaks when encountering libraries compiled with the non-IR backend.

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/IrUtils.kt

@@ -85,8 +85,10 @@ val IrType.erasedUpperBound: IrClass
 
 
 fun IrDeclaration.getJvmNameFromAnnotation(): String? {
-    val const = getAnnotation(DescriptorUtils.JVM_NAME)?.getValueArgument(0) as? IrConst<*>
-    return const?.value as? String
+    // TODO lower @JvmName?
+    val const = getAnnotation(DescriptorUtils.JVM_NAME)?.getValueArgument(0) as? IrConst<*> ?: return null
+    val value = const.value as? String ?: return null
+    return if (origin == IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER) "$value\$default" else value
 }
 
 val IrFunction.propertyIfAccessor: IrDeclaration

compiler/testData/codegen/box/jvmName/functionWithDefault.kt

@@ -0,0 +1,11 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+
+@JvmName("bar")
+fun foo(x: String = (object {}).javaClass.enclosingMethod.name) = x
+
+fun box(): String {
+    val f = foo()
+    if (f != "bar\$default") return "Fail: $f"
+    return "OK"
+}

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

@@ -15091,6 +15091,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/jvmName/functionName.kt");
         }
 
+        @TestMetadata("functionWithDefault.kt")
+        public void testFunctionWithDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/jvmName/functionWithDefault.kt");
+        }
+
         @TestMetadata("loadJvmName.kt")
         public void testLoadJvmName() throws Exception {
             runTest("compiler/testData/codegen/box/jvmName/loadJvmName.kt");

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

@@ -15091,6 +15091,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/jvmName/functionName.kt");
         }
 
+        @TestMetadata("functionWithDefault.kt")
+        public void testFunctionWithDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/jvmName/functionWithDefault.kt");
+        }
+
         @TestMetadata("loadJvmName.kt")
         public void testLoadJvmName() throws Exception {
             runTest("compiler/testData/codegen/box/jvmName/loadJvmName.kt");

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

@@ -13976,6 +13976,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/jvmName/functionName.kt");
         }
 
+        @TestMetadata("functionWithDefault.kt")
+        public void testFunctionWithDefault() throws Exception {
+            runTest("compiler/testData/codegen/box/jvmName/functionWithDefault.kt");
+        }
+
         @TestMetadata("loadJvmName.kt")
         public void testLoadJvmName() throws Exception {
             runTest("compiler/testData/codegen/box/jvmName/loadJvmName.kt");