Add flag for proper array convention with default args calls

compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.codegen.coroutines.CoroutineCodegenUtilKt;
 import org.jetbrains.kotlin.codegen.intrinsics.IntrinsicMethods;
 import org.jetbrains.kotlin.codegen.pseudoInsns.PseudoInsnsKt;
 import org.jetbrains.kotlin.codegen.state.KotlinTypeMapper;
+import org.jetbrains.kotlin.config.LanguageFeature;
 import org.jetbrains.kotlin.descriptors.*;
 import org.jetbrains.kotlin.descriptors.impl.SyntheticFieldDescriptor;
 import org.jetbrains.kotlin.load.java.JvmAbi;
@@ -1534,6 +1535,7 @@ public abstract class StackValue {
 
             CollectionElementReceiver collectionElementReceiver = (CollectionElementReceiver) receiver;
             boolean callDefault = false;
+            boolean properSetterCalls = codegen.getState().getLanguageVersionSettings().supportsFeature(LanguageFeature.ProperArrayConventionSetterWithDefaultCalls);
             if (collectionElementReceiver.isGetter) {
                 //Convention setter/getter could have default parameters at the end of parameter list (in case of setter before last parameter)
                 //We should remove default parameters of getter from stack if they don't match setter ones and regenerate mask for setter
@@ -1561,28 +1563,34 @@ public abstract class StackValue {
                         }
                     }
 
-                    DefaultCallArgs defaultArgs = new DefaultCallArgs(
+                    if (properSetterCalls) {
-                            CodegenUtilKt.unwrapFrontendVersion(resolvedSetCall.getResultingDescriptor()).getValueParameters().size());
+                        DefaultCallArgs defaultArgs = new DefaultCallArgs(
-                    if (!setterDefaults.isEmpty()) {
+                                CodegenUtilKt.unwrapFrontendVersion(resolvedSetCall.getResultingDescriptor()).getValueParameters().size());
-                        ArgumentGenerator setterArgumentGenerator =  new CallBasedArgumentGenerator(
+                        if (!setterDefaults.isEmpty()) {
-                                codegen,
+                            ArgumentGenerator setterArgumentGenerator = new CallBasedArgumentGenerator(
-                                callGenerator,
+                                    codegen,
-                                resolvedSetCall.getResultingDescriptor().getValueParameters(), setter.getValueParameterTypes()
+                                    callGenerator,
-                        );
+                                    resolvedSetCall.getResultingDescriptor().getValueParameters(), setter.getValueParameterTypes()
+                            );
 
-                        int defaultIndex = CollectionsKt.getLastIndex(setterArguments) - 1/*rhs value*/ - setterDefaults.size();
+                            int defaultIndex = CollectionsKt.getLastIndex(setterArguments) - 1/*rhs value*/ - setterDefaults.size();
-                        for (ResolvedValueArgument aDefault : setterDefaults) {
+                            for (ResolvedValueArgument aDefault : setterDefaults) {
-                            defaultArgs.mark(++defaultIndex);
+                                defaultArgs.mark(++defaultIndex);
-                            setterArgumentGenerator.generateDefault(defaultIndex, (DefaultValueArgument)aDefault);
+                                setterArgumentGenerator.generateDefault(defaultIndex, (DefaultValueArgument) aDefault);
+                            }
+                            callDefault = true;
                         }
-                        callDefault = true;
+                        rhsValue.put(v);
+                        codegen.myFrameMap.leaveTemp(lastParameterType);
+                        defaultArgs.generateOnStackIfNeeded(callGenerator, false);
+                    }
+                    else {
+                        rhsValue.put(v);
+                        codegen.myFrameMap.leaveTemp(lastParameterType);
                     }
-                    rhsValue.put(v);
-                    codegen.myFrameMap.leaveTemp(lastParameterType);
-                    defaultArgs.generateOnStackIfNeeded(callGenerator, false);
                 }
             } else {
-                callDefault = genDefaultMaskIfPresent(callGenerator);
+                callDefault = properSetterCalls && genDefaultMaskIfPresent(callGenerator);
             }
 
             callGenerator.genCall(setter, resolvedSetCall, callDefault, codegen);

compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java

@@ -8856,6 +8856,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520.kt");
             }
 
+            @TestMetadata("kt16520_old.kt")
+            public void testKt16520_old() throws Exception {
+                runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520_old.kt");
+            }
+
             @TestMetadata("kt9140.kt")
             public void testKt9140() throws Exception {
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt9140.kt");

compiler/testData/codegen/box/defaultArguments/convention/incWithDefaults.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperArrayConventionSetterWithDefaultCalls
 // IGNORE_BACKEND_FIR: JVM_IR
 var inc: String = ""
 

compiler/testData/codegen/box/defaultArguments/convention/kt16520.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperArrayConventionSetterWithDefaultCalls
 // IGNORE_BACKEND_FIR: JVM_IR
 var result = "fail"
 

compiler/testData/codegen/box/defaultArguments/convention/kt16520_old.kt

@@ -0,0 +1,20 @@
+// !LANGUAGE: -ProperArrayConventionSetterWithDefaultCalls
+// IGNORE_BACKEND: JVM_IR
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM
+var result = "fail"
+
+class A {
+    operator fun set(
+        i1: Int,
+        i2: Int = 1,
+        v: String
+    ) {
+        result = "" + i1 + i2 + v
+    }
+}
+
+fun box(): String {
+    A()[1] = "OK"
+    return if (result != "10OK") "fail: $result" else "OK"
+}

compiler/testData/codegen/box/defaultArguments/convention/plusAssignWithDefaults.kt

@@ -1,3 +1,4 @@
+// !LANGUAGE: +ProperArrayConventionSetterWithDefaultCalls
 // IGNORE_BACKEND_FIR: JVM_IR
 var inc: String = ""
 

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

@@ -10071,6 +10071,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520.kt");
             }
 
+            @TestMetadata("kt16520_old.kt")
+            public void testKt16520_old() throws Exception {
+                runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520_old.kt");
+            }
+
             @TestMetadata("kt9140.kt")
             public void testKt9140() throws Exception {
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt9140.kt");

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

@@ -10071,6 +10071,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520.kt");
             }
 
+            @TestMetadata("kt16520_old.kt")
+            public void testKt16520_old() throws Exception {
+                runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520_old.kt");
+            }
+
             @TestMetadata("kt9140.kt")
             public void testKt9140() throws Exception {
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt9140.kt");

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

@@ -8856,6 +8856,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520.kt");
             }
 
+            @TestMetadata("kt16520_old.kt")
+            public void testKt16520_old() throws Exception {
+                runTest("compiler/testData/codegen/box/defaultArguments/convention/kt16520_old.kt");
+            }
+
             @TestMetadata("kt9140.kt")
             public void testKt9140() throws Exception {
                 runTest("compiler/testData/codegen/box/defaultArguments/convention/kt9140.kt");

compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt

@@ -130,6 +130,7 @@ enum class LanguageFeature(
     ProhibitNonReifiedArraysAsReifiedTypeArguments(KOTLIN_1_5, kind = BUG_FIX),
     ProhibitVarargAsArrayAfterSamArgument(KOTLIN_1_5, kind = BUG_FIX),
     CorrectSourceMappingSyntax(KOTLIN_1_5, kind = UNSTABLE_FEATURE),
+    ProperArrayConventionSetterWithDefaultCalls(KOTLIN_1_5, kind = OTHER),
 
     // Temporarily disabled, see KT-27084/KT-22379
     SoundSmartcastFromLoopConditionForLoopAssignedVariables(sinceVersion = null, kind = BUG_FIX),