Fix adaptation for references with default values after varargs

After vararg argument it's possible to pass values only by name, so
 here we modulate this behavior

 #KT-37721 Fixed

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

@@ -2090,6 +2090,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noReflectionForAdaptedCallableReferencesWithSuspendConversion.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("reflectionForVarargAsArray.kt")
             public void testReflectionForVarargAsArray() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/reflectionForVarargAsArray.kt");

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/CallableReferenceResolution.kt

@@ -292,7 +292,7 @@ class CallableReferencesCandidateFactory(
         val expectedArgumentCount = inputOutputTypes.inputTypes.size - unboundReceiverCount
         if (expectedArgumentCount < 0) return null
 
-        val fakeArguments = (0 until expectedArgumentCount).map { FakeKotlinCallArgumentForCallableReference(it) }
+        val fakeArguments = createFakeArgumentsForReference(descriptor, expectedArgumentCount, inputOutputTypes, unboundReceiverCount)
         val argumentMapping =
             callComponents.argumentsToParametersMapper.mapArguments(fakeArguments, externalArgument = null, descriptor = descriptor)
         if (argumentMapping.diagnostics.any { !it.candidateApplicability.isSuccess }) return null
@@ -387,6 +387,36 @@ class CallableReferencesCandidateFactory(
         )
     }
 
+    private fun createFakeArgumentsForReference(
+        descriptor: FunctionDescriptor,
+        expectedArgumentCount: Int,
+        inputOutputTypes: InputOutputTypes,
+        unboundReceiverCount: Int
+    ): List<FakeKotlinCallArgumentForCallableReference> {
+        var afterVararg = false
+        var varargComponentType: UnwrappedType? = null
+        var vararg = false
+        return (0 until expectedArgumentCount).map { index ->
+            val inputType = inputOutputTypes.inputTypes.getOrNull(index + unboundReceiverCount)
+            if (vararg && varargComponentType != inputType) {
+                afterVararg = true
+            }
+
+            val valueParameter = descriptor.valueParameters.getOrNull(index)
+            val name =
+                if (afterVararg && valueParameter?.declaresDefaultValue() == true)
+                    valueParameter.name
+                else
+                    null
+
+            if (valueParameter?.isVararg == true) {
+                varargComponentType = inputType
+                vararg = true
+            }
+            FakeKotlinCallArgumentForCallableReference(index, name)
+        }
+    }
+
     private fun varargParameterTypeByExpectedParameter(
         expectedParameterType: KotlinType,
         substitutedParameter: ValueParameterDescriptor,

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/model/ArgumentsImpl.kt

@@ -22,10 +22,11 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.prepareReceiverRegardingCap
 
 
 class FakeKotlinCallArgumentForCallableReference(
-    val index: Int
+    val index: Int,
+    val name: Name?
 ) : KotlinCallArgument {
     override val isSpread: Boolean get() = false
-    override val argumentName: Name? get() = null
+    override val argumentName: Name? get() = name
 }
 
 class ReceiverExpressionKotlinCallArgument private constructor(

compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt

@@ -0,0 +1,23 @@
+var result = "fail"
+
+fun foo(vararg xs: Int, s1: String = "", s2: String = "OK") {
+    if (xs[0] == 42 && s1 == "good") {
+        result = s2
+    }
+}
+
+fun bar(vararg xs: Int, s: String = "") {}
+
+fun use(fn: (IntArray, String) -> Unit) {
+    fn(intArrayOf(42), "good")
+}
+
+fun test() {
+    use(::foo)
+    use(::bar)
+}
+
+fun box(): String {
+    test()
+    return "OK"
+}

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

@@ -2110,6 +2110,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noReflectionForAdaptedCallableReferencesWithSuspendConversion.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("reflectionForVarargAsArray.kt")
             public void testReflectionForVarargAsArray() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/reflectionForVarargAsArray.kt");

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

@@ -2110,6 +2110,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noReflectionForAdaptedCallableReferencesWithSuspendConversion.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("reflectionForVarargAsArray.kt")
             public void testReflectionForVarargAsArray() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/reflectionForVarargAsArray.kt");

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

@@ -2090,6 +2090,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noReflectionForAdaptedCallableReferencesWithSuspendConversion.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("reflectionForVarargAsArray.kt")
             public void testReflectionForVarargAsArray() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/reflectionForVarargAsArray.kt");

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

@@ -1510,6 +1510,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noNameClashForReferencesToSameFunction.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("simpleDefaultArgument.kt")
             public void testSimpleDefaultArgument() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleDefaultArgument.kt");

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

@@ -1520,6 +1520,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noNameClashForReferencesToSameFunction.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("simpleDefaultArgument.kt")
             public void testSimpleDefaultArgument() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleDefaultArgument.kt");

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

@@ -1520,6 +1520,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/noNameClashForReferencesToSameFunction.kt");
             }
 
+            @TestMetadata("referenceToVarargWithDefaults.kt")
+            public void testReferenceToVarargWithDefaults() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/referenceToVarargWithDefaults.kt");
+            }
+
             @TestMetadata("simpleDefaultArgument.kt")
             public void testSimpleDefaultArgument() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleDefaultArgument.kt");