From 7480608e795c4979d3832661788f9e629faad671 Mon Sep 17 00:00:00 2001
From: Herman Venter <hermanv@fb.com>
Date: Fri, 20 Jul 2018 18:25:25 -0700
Subject: [PATCH] Provide a way to temporarily disable effects tracking (#2304)

Summary:
Release note: Provide a way to temporarily disable effects tracking

The default error handler constructs a new Error object in order to reuse its logic for obtaining a call stack. Since the object is then thrown a away, it makes no sense to keep tracking its properties and doing so makes debugging more painful.
Pull Request resolved: https://github.com/facebook/prepack/pull/2304

Differential Revision: D8945121

Pulled By: hermanventer

fbshipit-source-id: 68fb8b84c2ef937fcdf3ecaccdff5041779424d5
---
 src/realm.js | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/realm.js b/src/realm.js
index dd641aa27..03147d3a5 100644
--- a/src/realm.js
+++ b/src/realm.js
@@ -854,8 +854,32 @@ export class Realm {
     return [effects, nodeAst, nodeIO];
   }
 
+  // Use this to evaluate code for internal purposes, so that the tracked state does not get polluted
+  evaluateWithoutEffects<T>(f: () => T): T {
+    // Save old state and set up undefined state
+    let savedGenerator = this.generator;
+    let savedBindings = this.modifiedBindings;
+    let savedProperties = this.modifiedProperties;
+    let savedCreatedObjects = this.createdObjects;
+    let saved_completion = this.savedCompletion;
+    try {
+      this.generator = undefined;
+      this.modifiedBindings = undefined;
+      this.modifiedProperties = undefined;
+      this.createdObjects = undefined;
+      this.savedCompletion = undefined;
+      return f();
+    } finally {
+      this.generator = savedGenerator;
+      this.modifiedBindings = savedBindings;
+      this.modifiedProperties = savedProperties;
+      this.createdObjects = savedCreatedObjects;
+      this.savedCompletion = saved_completion;
+    }
+  }
+
   evaluateForEffects(f: () => Completion | Value, state: any, generatorName: string): Effects {
-    // Save old state and set up empty state for ast
+    // Save old state and set up empty state
     let [savedBindings, savedProperties] = this.getAndResetModifiedMaps();
     let saved_generator = this.generator;
     let saved_createdObjects = this.createdObjects;
@@ -1764,7 +1788,7 @@ export class Realm {
   // Return value indicates whether the caller should try to recover from the error or not.
   handleError(diagnostic: CompilerDiagnostic): ErrorHandlerResult {
     if (!diagnostic.callStack && this.contextStack.length > 0) {
-      let error = Construct(this, this.intrinsics.Error);
+      let error = this.evaluateWithoutEffects(() => Construct(this, this.intrinsics.Error));
       let stack = error._SafeGetDataPropertyValue("stack");
       if (stack instanceof StringValue) diagnostic.callStack = stack.value;
     }