From 9844671ded497a70cb0f6ed45d8c6c401593e73a Mon Sep 17 00:00:00 2001
From: Dmitriy Novozhilov <dmitriy.novozhilov@jetbrains.com>
Date: Fri, 3 Sep 2021 13:54:37 +0300
Subject: [PATCH] [FIR] Add KDoc about thread safety rules of
 FirDeclarationAttributes

---
 .../kotlin/fir/declarations/FirDeclarationAttributes.kt   | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationAttributes.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationAttributes.kt
index 08db07b21fb..314ce38424f 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationAttributes.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationAttributes.kt
@@ -15,6 +15,14 @@ import kotlin.reflect.KProperty
 
 abstract class FirDeclarationDataKey
 
+/**
+ * Please note that FirDeclarationAttributes itself is thread unsafe, so when you read
+ *   or write some attribute you need to ensure that this operation is safe and there
+ *   won't be any race condition. You can achieve this by
+ * - setting attribute to declaration before it's publication (e.g. in scopes)
+ * - setting attribute in one phase and reading it only in following ones (using `ensureResolve` on symbol)
+ * - resetting attribute under lock over specific attribute value
+ */
 class FirDeclarationAttributes : AttributeArrayOwner<FirDeclarationDataKey, Any> {
     override val typeRegistry: TypeRegistry<FirDeclarationDataKey, Any>
         get() = FirDeclarationDataRegistry