Refactor callableId around pathToLocal and classId properties

#KT-58739 Fixed

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirProviderImpl.kt

@@ -63,18 +63,18 @@ class FirProviderImpl(val session: FirSession, val kotlinScopeProvider: FirKotli
 
         @FirSymbolProviderInternals
         override fun getTopLevelCallableSymbolsTo(destination: MutableList<FirCallableSymbol<*>>, packageFqName: FqName, name: Name) {
-            destination += (state.functionMap[CallableId(packageFqName, null, name)] ?: emptyList())
-            destination += (state.propertyMap[CallableId(packageFqName, null, name)] ?: emptyList())
+            destination += (state.functionMap[CallableId(packageFqName, name)] ?: emptyList())
+            destination += (state.propertyMap[CallableId(packageFqName, name)] ?: emptyList())
         }
 
         @FirSymbolProviderInternals
         override fun getTopLevelFunctionSymbolsTo(destination: MutableList<FirNamedFunctionSymbol>, packageFqName: FqName, name: Name) {
-            destination += (state.functionMap[CallableId(packageFqName, null, name)] ?: emptyList())
+            destination += (state.functionMap[CallableId(packageFqName, name)] ?: emptyList())
         }
 
         @FirSymbolProviderInternals
         override fun getTopLevelPropertySymbolsTo(destination: MutableList<FirPropertySymbol>, packageFqName: FqName, name: Name) {
-            destination += (state.propertyMap[CallableId(packageFqName, null, name)] ?: emptyList())
+            destination += (state.propertyMap[CallableId(packageFqName, name)] ?: emptyList())
         }
 
         override fun getPackage(fqName: FqName): FqName? {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirVariableSymbol.kt

@@ -130,7 +130,7 @@ class FirValueParameterSymbol(name: Name) : FirVariableSymbol<FirValueParameter>
 
 class FirErrorPropertySymbol(
     val diagnostic: ConeDiagnostic
-) : FirVariableSymbol<FirErrorProperty>(CallableId(FqName.ROOT, null, NAME)) {
+) : FirVariableSymbol<FirErrorProperty>(CallableId(FqName.ROOT, NAME)) {
     companion object {
         val NAME: Name = Name.special("<error property>")
     }

core/compiler.common/src/org/jetbrains/kotlin/name/CallableId.kt

@@ -6,18 +6,24 @@
 package org.jetbrains.kotlin.name
 
 // NB: with className == null we are at top level
-data class CallableId(
+class CallableId private constructor(
     val packageName: FqName,
     val className: FqName?,
     val callableName: Name,
-    // Currently, it's only used for debug info
-    private val pathToLocal: FqName? = null
+    val classId: ClassId?,
 ) {
     companion object {
         private val LOCAL_NAME = SpecialNames.LOCAL
         val PACKAGE_FQ_NAME_FOR_LOCAL = FqName.topLevel(LOCAL_NAME)
+
+        private fun calculateClassId(packageName: FqName, className: FqName?): ClassId? =
+            className?.let { ClassId(packageName, it, isLocal = packageName == PACKAGE_FQ_NAME_FOR_LOCAL) }
     }
 
+    // Effectively val (changed in constructors only)
+    // Used only for debug info
+    private var pathToLocal: FqName? = null
+
     /**
      * Return `true` if corresponding declaration is itself local or it is a member of local class
      * Otherwise, returns `false`
@@ -25,34 +31,34 @@ data class CallableId(
     val isLocal: Boolean
         get() = packageName == PACKAGE_FQ_NAME_FOR_LOCAL || classId?.isLocal == true
 
-    var classId: ClassId? = null
-        get() {
-            if (field == null && className != null) {
-                field = ClassId(packageName, className, isLocal = packageName == PACKAGE_FQ_NAME_FOR_LOCAL)
-            }
-            return field
-        }
-        private set
+    constructor(
+        packageName: FqName, className: FqName?, callableName: Name,
+    ) : this(packageName, className, callableName, calculateClassId(packageName, className))
 
-    constructor(classId: ClassId, callableName: Name) : this(classId.packageFqName, classId.relativeClassName, callableName) {
-        this.classId = classId
+    constructor(
+        packageName: FqName, className: FqName?, callableName: Name,
+        // Currently, it's only used for debug info
+        pathToLocal: FqName?
+    ) : this(packageName, className, callableName, calculateClassId(packageName, className)) {
+        this.pathToLocal = pathToLocal
     }
 
-    constructor(packageName: FqName, callableName: Name) : this(packageName, null, callableName)
+    constructor(classId: ClassId, callableName: Name) : this(classId.packageFqName, classId.relativeClassName, callableName, classId)
+
+    constructor(packageName: FqName, callableName: Name) : this(packageName, className = null, callableName, classId = null)
 
     constructor(
         callableName: Name,
         // Currently, it's only used for debug info
-        pathToLocal: FqName? = null
-    ) : this(
-        PACKAGE_FQ_NAME_FOR_LOCAL,
-        className = null,
-        callableName,
-        pathToLocal,
-    )
+        pathToLocal: FqName?
+    ) : this(PACKAGE_FQ_NAME_FOR_LOCAL, className = null, callableName, classId = null) {
+        this.pathToLocal = pathToLocal
+    }
+
+    constructor(callableName: Name) : this(PACKAGE_FQ_NAME_FOR_LOCAL, className = null, callableName, classId = null)
 
     fun asFqNameForDebugInfo(): FqName {
-        if (pathToLocal != null) return pathToLocal.child(callableName)
+        pathToLocal?.child(callableName)?.let { return it }
         return asSingleFqName()
     }
 
@@ -60,6 +66,25 @@ data class CallableId(
         return classId?.asSingleFqName()?.child(callableName) ?: packageName.child(callableName)
     }
 
+    fun copy(callableName: Name): CallableId = CallableId(packageName, className, callableName, classId)
+
+    override fun equals(other: Any?): Boolean {
+        return when {
+            this === other -> true
+            other !is CallableId -> false
+            // classId isn't needed
+            else -> packageName == other.packageName && className == other.className && callableName == other.callableName
+        }
+    }
+
+    override fun hashCode(): Int {
+        var result = 17
+        result = result * 31 + packageName.hashCode()
+        result = result * 31 + className.hashCode()
+        result = result * 31 + callableName.hashCode()
+        return result
+    }
+
     override fun toString(): String {
         return buildString {
             append(packageName.asString().replace('.', '/'))