[FIR] Make MemberWithScope a data class

Previously, there was a contract that each callable symbol in the chain
  of `processDirectOverriddenWithBaseScope` will be unique. And if some
  symbol is accessible from multiple scopes, then only last of them will
  be returned as a component of `MemberWithScope`. So there actually was
  no such thing as "pair of two different MemberWithScope with the same
  symbol and different scopes"

After the change of `processDirectOverriddenWithBaseScope` contract (see
  previous commits) each scope returns `MemberWithScope` for some symbol
  with the previous scope in the hierarchy even if it contains the same
  symbol as the current scope

So now scope is actually a part of `MemberWithScope`, which should be
  considered as part of equality. Otherwise, we can skip some part of
  the overridden hierarchy, because we will start to consider symbol as
  visited after its first occurrence (in opposite to the previous behavior,
  when only the last scope was returned)

compiler/fir/analysis-tests/testData/resolveWithStdlib/contracts/fromSource/good/returnsImplies/eqNotEq.kt

@@ -30,4 +30,4 @@ fun test_1(x: String?) {
 fun test_2(x: String?) {
     trickyRequireNotNull(x)
     x.length
-}
+}

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirTypeIntersectionScopeContext.kt

@@ -144,8 +144,13 @@ class FirTypeIntersectionScopeContext(
             return members.map { ResultOfIntersection.SingleMember(it, MemberWithBaseScope(it, scope)) }
         }
 
+        val uniqueSymbols = mutableSetOf<D>()
         val allMembersWithScope = membersByScope.flatMapTo(linkedSetOf()) { (scope, members) ->
-            members.map { MemberWithBaseScope(it, scope) }
+            members.mapNotNull {
+                runIf(uniqueSymbols.add(it)) {
+                    MemberWithBaseScope(it, scope)
+                }
+            }
         }
 
         val result = mutableListOf<ResultOfIntersection<D>>()

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/tower/TowerLevels.kt

@@ -92,26 +92,30 @@ class MemberScopeTowerLevel(
             )
 
         if (scopeWithoutSmartcast == null) {
-            consumeCandidates(output, candidates)
+            consumeCandidates(
+                output,
+                candidatesWithoutSmartcast = candidates,
+                candidatesWithSmartcast = null
+            )
         } else {
-            val isFromSmartCast: MutableMap<MemberWithBaseScope<T>, Boolean> = mutableMapOf()
+            val map: MutableMap<T, MemberFromSmartcastScope<T>> = mutableMapOf()
 
             scopeWithoutSmartcast.collectCandidates(processScopeMembers).let { (isEmpty, originalCandidates) ->
                 empty = empty && isEmpty
                 for (originalCandidate in originalCandidates) {
-                    isFromSmartCast[originalCandidate] = false
+                    map[originalCandidate.member] = MemberFromSmartcastScope(originalCandidate, cameFromSmartcast = false)
                 }
             }
 
             for (candidateFromSmartCast in candidates) {
-                isFromSmartCast[candidateFromSmartCast] = true
+                map[candidateFromSmartCast.member] = MemberFromSmartcastScope(candidateFromSmartCast, cameFromSmartcast = true)
             }
 
             consumeCandidates(
                 output,
                 // all the candidates, both from original type and smart cast
-                candidates = isFromSmartCast.keys,
-                isFromSmartCast,
+                candidatesWithoutSmartcast = null,
+                candidatesWithSmartcast = map
             )
         }
 
@@ -162,6 +166,11 @@ class MemberScopeTowerLevel(
         return if (empty) ProcessResult.SCOPE_EMPTY else ProcessResult.FOUND
     }
 
+    private data class MemberFromSmartcastScope<T : FirCallableSymbol<*>>(
+        val memberWithBaseScope: MemberWithBaseScope<T>,
+        val cameFromSmartcast: Boolean
+    )
+
     private fun <T : FirCallableSymbol<*>> FirTypeScope.collectCandidates(
         processScopeMembers: FirScope.(processor: (T) -> Unit) -> Unit
     ): Pair<Boolean, List<MemberWithBaseScope<T>>> {
@@ -185,16 +194,21 @@ class MemberScopeTowerLevel(
 
     private fun <T : FirCallableSymbol<*>> consumeCandidates(
         output: TowerScopeLevelProcessor<T>,
-        candidates: Collection<MemberWithBaseScope<T>>,
+        candidatesWithoutSmartcast: Collection<MemberWithBaseScope<T>>?,
         // The map is not null only if there's a smart cast type on a dispatch receiver
         // and candidates are present both in smart cast and original types.
         // isFromSmartCast[candidate] == true iff exactly that member is present in smart cast type
-        isFromSmartCast: Map<MemberWithBaseScope<T>, Boolean>? = null
+        candidatesWithSmartcast: Map<T, MemberFromSmartcastScope<T>>?
     ) {
+        val candidates = candidatesWithoutSmartcast
+            ?: candidatesWithSmartcast?.values?.map { it.memberWithBaseScope }
+            ?: error("candidatesWithoutSmartcast or candidatesWithSmartcast should be not null")
+
         for (candidateWithScope in candidates) {
             val (candidate, scope) = candidateWithScope
             if (candidate.hasConsistentExtensionReceiver(givenExtensionReceiverOptions)) {
-                val isFromOriginalTypeInPresenceOfSmartCast = isFromSmartCast != null && !isFromSmartCast.getValue(candidateWithScope)
+                val isFromOriginalTypeInPresenceOfSmartCast = candidatesWithSmartcast != null &&
+                        !candidatesWithSmartcast.getValue(candidateWithScope.member).cameFromSmartcast
 
                 val dispatchReceiverToUse = when {
                     isFromOriginalTypeInPresenceOfSmartCast ->

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirTypeScope.kt

@@ -64,18 +64,7 @@ abstract class FirTypeScope : FirContainingNamesAwareScope() {
     }
 }
 
-class MemberWithBaseScope<out D : FirCallableSymbol<*>>(val member: D, val baseScope: FirTypeScope) {
-    operator fun component1() = member
-    operator fun component2() = baseScope
-
-    override fun equals(other: Any?): Boolean {
-        return other is MemberWithBaseScope<*> && member == other.member
-    }
-
-    override fun hashCode(): Int {
-        return member.hashCode()
-    }
-}
+data class MemberWithBaseScope<out D : FirCallableSymbol<*>>(val member: D, val baseScope: FirTypeScope)
 
 typealias ProcessOverriddenWithBaseScope<D> = FirTypeScope.(D, (D, FirTypeScope) -> ProcessorAction) -> ProcessorAction
 typealias ProcessAllOverridden<D> = FirTypeScope.(D, (D) -> ProcessorAction) -> ProcessorAction