[FIR] add support for varargs in delegated constructor calls

Also add support for spread operators as named arguments.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -258,7 +258,9 @@ class Fir2IrVisitor(
                             varargArgumentsExpression.varargElementType.toIrType(),
                             varargArgumentsExpression.arguments.map { arg ->
                                 convertToIrExpression(arg).run {
-                                    if (arg is FirSpreadArgumentExpression) IrSpreadElementImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, this)
+                                    if (arg is FirSpreadArgumentExpression || arg is FirNamedArgumentExpression && arg.isSpread) {
+                                        IrSpreadElementImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, this)
+                                    }
                                     else this
                                 }
                             })

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/FirCallCompletionResultsWriterTransformer.kt

@@ -133,34 +133,8 @@ class FirCallCompletionResultsWriterTransformer(
             }
             else -> {
                 resultType = typeRef.substituteTypeRef(subCandidate)
-                val argumentMapping = subCandidate.argumentMapping
-                val varargParameter = argumentMapping?.values?.firstOrNull { it.isVararg }
                 result.argumentList.transformArguments(this, subCandidate.createArgumentsMapping())
-                with(result.argumentList) call@{
+                subCandidate.handleVarargs(result.argumentList)
-                    if (varargParameter != null) {
-                        // Create a FirVarargArgumentExpression for the vararg arguments
-                        val varargParameterTypeRef = varargParameter.returnTypeRef
-                        val resolvedArrayType = varargParameterTypeRef.substitute(subCandidate)
-                        val resolvedElementType = resolvedArrayType.arrayElementType(session)
-                        var firstIndex = this@call.arguments.size
-                        val newArgumentMapping = mutableMapOf<FirExpression, FirValueParameter>()
-                        val varargArgument = buildVarargArgumentsExpression {
-                            varargElementType = varargParameterTypeRef.withReplacedConeType(resolvedElementType)
-                            this.typeRef = varargParameterTypeRef.withReplacedConeType(resolvedArrayType)
-                            for ((i, arg) in this@call.arguments.withIndex()) {
-                                val valueParameter = argumentMapping[arg] ?: continue
-                                if (valueParameter.isVararg) {
-                                    firstIndex = min(firstIndex, i)
-                                    arguments += arg
-                                } else {
-                                    newArgumentMapping[arg] = valueParameter
-                                }
-                            }
-                        }
-                        newArgumentMapping[varargArgument] = varargParameter
-                        subCandidate.argumentMapping = newArgumentMapping
-                    }
-                }
                 subCandidate.argumentMapping?.let {
                     result.replaceArgumentList(buildResolvedArgumentList(it))
                 }
@@ -180,6 +154,34 @@ class FirCallCompletionResultsWriterTransformer(
         return result.compose()
     }
 
+    private fun Candidate.handleVarargs(argumentList: FirArgumentList) {
+        val argumentMapping = this.argumentMapping
+        val varargParameter = argumentMapping?.values?.firstOrNull { it.isVararg }
+        if (varargParameter != null) {
+            // Create a FirVarargArgumentExpression for the vararg arguments
+            val varargParameterTypeRef = varargParameter.returnTypeRef
+            val resolvedArrayType = varargParameterTypeRef.substitute(this)
+            val resolvedElementType = resolvedArrayType.arrayElementType(session)
+            var firstIndex = argumentList.arguments.size
+            val newArgumentMapping = mutableMapOf<FirExpression, FirValueParameter>()
+            val varargArgument = buildVarargArgumentsExpression {
+                varargElementType = varargParameterTypeRef.withReplacedConeType(resolvedElementType)
+                this.typeRef = varargParameterTypeRef.withReplacedConeType(resolvedArrayType)
+                for ((i, arg) in argumentList.arguments.withIndex()) {
+                    val valueParameter = argumentMapping[arg] ?: continue
+                    if (valueParameter.isVararg) {
+                        firstIndex = min(firstIndex, i)
+                        arguments += arg
+                    } else {
+                        newArgumentMapping[arg] = valueParameter
+                    }
+                }
+            }
+            newArgumentMapping[varargArgument] = varargParameter
+            this.argumentMapping = newArgumentMapping
+        }
+    }
+
     private fun <D : FirExpression> D.replaceTypeRefWithSubstituted(
         calleeReference: FirNamedReferenceWithCandidate,
         typeRef: FirResolvedTypeRef,
@@ -291,6 +293,7 @@ class FirCallCompletionResultsWriterTransformer(
         val subCandidate = calleeReference.candidate
 
         delegatedConstructorCall.argumentList.transformArguments(this, calleeReference.candidate.createArgumentsMapping())
+        subCandidate.handleVarargs(delegatedConstructorCall.argumentList)
         subCandidate.argumentMapping?.let {
             delegatedConstructorCall.replaceArgumentList(buildResolvedArgumentList(it))
         }

compiler/testData/codegen/box/innerNested/superConstructorCall/objectExtendsClassVararg.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 open class SomeClass(val some: Double, val other: Int, vararg val args: String) {
     fun result() = args[1]
 }

compiler/testData/codegen/box/mixedNamedPosition/varargs.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
-// IGNORE_BACKEND_FIR: JVM_IR
 
 fun foo1(
     vararg p1: Int,

compiler/testData/codegen/box/privateConstructors/withVarargs.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // See also KT-6299
 public open class Outer private constructor(val s: String, vararg i: Int) {
     class Inner: Outer("xyz")

compiler/testData/codegen/box/secondaryConstructors/varargs.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun join(x: Array<out String>): String {
     var result = ""
     for (i in x) {

compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun booleanVararg(vararg xs: Boolean) {
     if (xs.size != 1 && xs[0] != true) throw AssertionError()
 }

compiler/testData/codegen/box/vararg/varargInFunParam.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun box(): String {
     if (test1() != "") return "fail 1"
     if (test1(1) != "1") return "fail 2"