From 6f97745de2bb63da7876dcbbdc2425b33eaf6084 Mon Sep 17 00:00:00 2001
From: Ilya Chernikov <ilya.chernikov@jetbrains.com>
Date: Fri, 6 Mar 2020 18:19:06 +0100
Subject: [PATCH] Optimize MutableDiagnosticsWithSuppression

avoid modificationTracker and own diagnostics list initialization if
possible
---
 .../MutableDiagnosticsWithSuppression.kt            | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/diagnostics/MutableDiagnosticsWithSuppression.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/diagnostics/MutableDiagnosticsWithSuppression.kt
index 47b3f4934ce..847f53487ec 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/diagnostics/MutableDiagnosticsWithSuppression.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/diagnostics/MutableDiagnosticsWithSuppression.kt
@@ -39,11 +39,16 @@ class MutableDiagnosticsWithSuppression @JvmOverloads constructor(
 
     private fun readonlyView(): DiagnosticsWithSuppression = cache.value!!
 
-    override val modificationTracker = CompositeModificationTracker(delegateDiagnostics.modificationTracker)
+    override val modificationTracker by lazy(LazyThreadSafetyMode.PUBLICATION) {
+        CompositeModificationTracker(delegateDiagnostics.modificationTracker)
+    }
 
-    override fun all(): Collection<Diagnostic> = readonlyView().all()
-    override fun forElement(psiElement: PsiElement) = readonlyView().forElement(psiElement)
-    override fun noSuppression() = readonlyView().noSuppression()
+    override fun all(): Collection<Diagnostic> =
+        if (diagnosticList.isEmpty()) delegateDiagnostics.all() else readonlyView().all()
+    override fun forElement(psiElement: PsiElement) =
+        if (diagnosticList.isEmpty()) delegateDiagnostics.forElement(psiElement) else readonlyView().forElement(psiElement)
+    override fun noSuppression() =
+        if (diagnosticList.isEmpty()) delegateDiagnostics.noSuppression() else readonlyView().noSuppression()
 
     //essential that this list is readonly
     fun getOwnDiagnostics(): List<Diagnostic> {