[FIR] Change type of argumentMapping properties and parameters from Map

to LinkedHashMap, to signify that the order is important and we don't
assume that mutableMapOf() will always return a LinkedHashMap.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/CallAndReferenceGenerator.kt

@@ -456,7 +456,7 @@ class CallAndReferenceGenerator(
     }
 
     private fun IrMemberAccessExpression<*>.applyArgumentsWithReorderingIfNeeded(
-        argumentMapping: Map<FirExpression, FirValueParameter>,
+        argumentMapping: LinkedHashMap<FirExpression, FirValueParameter>,
         valueParameters: List<FirValueParameter>,
         annotationMode: Boolean
     ): IrExpression {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/Candidate.kt

@@ -102,7 +102,7 @@ class Candidate(
     var usesSAM: Boolean = false
     var usesSuspendConversion: Boolean = false
 
-    var argumentMapping: Map<FirExpression, FirValueParameter>? = null
+    var argumentMapping: LinkedHashMap<FirExpression, FirValueParameter>? = null
     var numDefaults: Int = 0
     lateinit var typeArgumentMapping: TypeArgumentMapping
     val postponedAtoms = mutableListOf<PostponedResolvedAtom>()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirArgumentsToParametersMapper.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.name.Name
 import java.util.*
 import kotlin.collections.ArrayList
+import kotlin.collections.LinkedHashMap
 import kotlin.collections.component1
 import kotlin.collections.component2
 import kotlin.collections.set
@@ -29,13 +30,11 @@ data class ArgumentMapping(
     //      fun foo(a: Int, b: Int) {}
     //      foo(b = bar(), a = qux())
     // parameterToCallArgumentMap.values() should be [ 'bar()', 'foo()' ]
-    // TODO: Consider changing this (and other similar declarations like Candidate.argumentMapping) to LinkedHashMap to signify that
-    // order is important. Right now we're assuming that mutableMapOf() will always return a LinkedHashMap.
-    val parameterToCallArgumentMap: Map<FirValueParameter, ResolvedCallArgument>,
+    val parameterToCallArgumentMap: LinkedHashMap<FirValueParameter, ResolvedCallArgument>,
     val diagnostics: List<ResolutionDiagnostic>
 ) {
-    fun toArgumentToParameterMapping(): Map<FirExpression, FirValueParameter> {
-        val argumentToParameterMapping = mutableMapOf<FirExpression, FirValueParameter>()
+    fun toArgumentToParameterMapping(): LinkedHashMap<FirExpression, FirValueParameter> {
+        val argumentToParameterMapping = linkedMapOf<FirExpression, FirValueParameter>()
         parameterToCallArgumentMap.forEach { (valueParameter, resolvedArgument) ->
             when (resolvedArgument) {
                 is ResolvedCallArgument.SimpleArgument -> argumentToParameterMapping[resolvedArgument.callArgument] = valueParameter
@@ -52,7 +51,7 @@ data class ArgumentMapping(
     }
 }
 
-private val EmptyArgumentMapping = ArgumentMapping(emptyMap(), emptyList())
+private val EmptyArgumentMapping = ArgumentMapping(linkedMapOf(), emptyList())
 
 fun BodyResolveComponents.mapArguments(
     arguments: List<FirExpression>,
@@ -108,7 +107,7 @@ private class FirCallArgumentsProcessor(
     private var nameToParameter: Map<Name, FirValueParameter>? = null
     var diagnostics: MutableList<ResolutionDiagnostic>? = null
         private set
-    val result: MutableMap<FirValueParameter, ResolvedCallArgument> = LinkedHashMap()
+    val result: LinkedHashMap<FirValueParameter, ResolvedCallArgument> = LinkedHashMap(function.valueParameters.size)
 
     private enum class State {
         POSITION_ARGUMENTS,

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

@@ -207,8 +207,12 @@ class FirCallCompletionResultsWriterTransformer(
         withFirArrayOfCallTransformer {
             annotationCall.argumentList.transformArguments(this, expectedArgumentsTypeMapping)
             var index = 0
-            subCandidate.argumentMapping = subCandidate.argumentMapping?.mapKeys { (_, _) ->
-                annotationCall.argumentList.arguments[index++]
+            subCandidate.argumentMapping = subCandidate.argumentMapping?.let {
+                LinkedHashMap<FirExpression, FirValueParameter>(it.size).let { newMapping ->
+                    subCandidate.argumentMapping?.mapKeysTo(newMapping) { (_, _) ->
+                        annotationCall.argumentList.arguments[index++]
+                    }
+                }
             }
         }
         if (!calleeReference.isError) {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/BodyResolveUtils.kt

@@ -37,8 +37,8 @@ internal inline var FirExpression.resultType: FirTypeRef
 internal fun remapArgumentsWithVararg(
     varargParameter: FirValueParameter,
     varargArrayType: ConeKotlinType,
-    argumentMapping: Map<FirExpression, FirValueParameter>
-): Map<FirExpression, FirValueParameter> {
+    argumentMapping: LinkedHashMap<FirExpression, FirValueParameter>
+): LinkedHashMap<FirExpression, FirValueParameter> {
     // Create a FirVarargArgumentExpression for the vararg arguments.
     // The order of arguments in the mapping must be preserved for FIR2IR, hence we have to find where the vararg arguments end.
     // FIR2IR uses the mapping order to determine if arguments need to be reordered.
@@ -46,7 +46,7 @@ internal fun remapArgumentsWithVararg(
     val varargElementType = varargArrayType.arrayElementType()
     val argumentList = argumentMapping.keys.toList()
     var indexAfterVarargs = argumentList.size
-    val newArgumentMapping = mutableMapOf<FirExpression, FirValueParameter>()
+    val newArgumentMapping = linkedMapOf<FirExpression, FirValueParameter>()
     val varargArgument = buildVarargArgumentsExpression {
         this.varargElementType = varargParameterTypeRef.withReplacedConeType(varargElementType)
         this.typeRef = varargParameterTypeRef.withReplacedConeType(varargArrayType)

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirArgumentUtil.kt

@@ -22,7 +22,7 @@ fun buildBinaryArgumentList(left: FirExpression, right: FirExpression): FirArgum
 fun buildArraySetArgumentList(rValue: FirExpression, indexes: List<FirExpression>): FirArgumentList =
     FirArraySetArgumentList(rValue, indexes)
 
-fun buildResolvedArgumentList(mapping: Map<FirExpression, FirValueParameter>): FirArgumentList =
+fun buildResolvedArgumentList(mapping: LinkedHashMap<FirExpression, FirValueParameter>): FirArgumentList =
     FirResolvedArgumentList(mapping)
 
 object FirEmptyArgumentList : FirAbstractArgumentList() {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirExpressionUtil.kt

@@ -40,7 +40,7 @@ inline val FirCall.arguments: List<FirExpression> get() = argumentList.arguments
 
 inline val FirCall.argument: FirExpression get() = argumentList.arguments.first()
 
-inline val FirCall.argumentMapping: Map<FirExpression, FirValueParameter>?
+inline val FirCall.argumentMapping: LinkedHashMap<FirExpression, FirValueParameter>?
     get() = (argumentList as? FirResolvedArgumentList)?.mapping
 
 fun FirExpression.toResolvedCallableReference(): FirResolvedNamedReference? {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirResolvedArgumentList.kt

@@ -11,7 +11,7 @@ import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.visitors.FirVisitor
 
 class FirResolvedArgumentList internal constructor(
-    val mapping: Map<FirExpression, FirValueParameter>
+    val mapping: LinkedHashMap<FirExpression, FirValueParameter>
 ) : FirAbstractArgumentList() {
     override val arguments: List<FirExpression>
         get() = mapping.keys.toList()