FIR IDE: make KtScopeProvider thread local

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/KtFirAnalysisSession.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.idea.fir.low.level.api.LowLevelFirApiFacade
 import org.jetbrains.kotlin.idea.frontend.api.*
 import org.jetbrains.kotlin.idea.frontend.api.fir.scopes.KtFirScopeProvider
 import org.jetbrains.kotlin.idea.frontend.api.fir.symbols.KtFirSymbolProvider
+import org.jetbrains.kotlin.idea.frontend.api.fir.utils.*
 import org.jetbrains.kotlin.idea.frontend.api.scopes.KtScopeProvider
 import org.jetbrains.kotlin.idea.frontend.api.symbols.KtFunctionSymbol
 import org.jetbrains.kotlin.idea.frontend.api.symbols.KtSymbol
@@ -60,8 +61,9 @@ private constructor(
 
     private val firScopeStorage = FirScopeRegistry()
 
-    override val scopeProvider: KtScopeProvider =
+    override val scopeProvider: KtScopeProvider by threadLocal {
         KtFirScopeProvider(token, firSymbolBuilder, project, firSession, firResolveState, firScopeStorage)
+    }
 
     init {
         assertIsValid()

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/utils/ThreadLocalDelegate.kt

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.frontend.api.fir.utils
+
+import kotlin.reflect.KProperty
+
+
+@Suppress("EXPERIMENTAL_FEATURE_WARNING")
+internal inline class ThreadLocalValue<V>(private val threadLocal: ThreadLocal<V>) {
+    @Suppress("NOTHING_TO_INLINE")
+    inline operator fun getValue(thisRef: Any?, property: KProperty<*>): V = threadLocal.get()
+}
+
+internal inline fun <T> threadLocal(crossinline init: () -> T): ThreadLocalValue<T> =
+    ThreadLocalValue(ThreadLocal.withInitial { init() })