From 6545bf638b8977832c87a7a7ab69682606b25bc6 Mon Sep 17 00:00:00 2001
From: tbreisacher <tbreisacher@google.com>
Date: Fri, 10 Nov 2017 13:39:41 -0800
Subject: [PATCH] Return false for yield nodes passed to
 evaluatesToLocalValue()

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=175329600
---
 .../google/javascript/jscomp/NodeUtil.java    |  1 +
 .../javascript/jscomp/NodeUtilTest.java       | 29 ++++++++++++++++---
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/com/google/javascript/jscomp/NodeUtil.java b/src/com/google/javascript/jscomp/NodeUtil.java
index e6cc9ab0790..1c3c88d6141 100644
--- a/src/com/google/javascript/jscomp/NodeUtil.java
+++ b/src/com/google/javascript/jscomp/NodeUtil.java
@@ -4704,6 +4704,7 @@ static boolean evaluatesToLocalValue(Node value, Predicate<Node> locals) {
       case CAST:
         return evaluatesToLocalValue(value.getFirstChild(), locals);
       case SPREAD:
+      case YIELD:
       case AWAIT:
         // TODO(johnlenz): we can do better for await if we use type information.  That is,
         // if we know the promise being awaited on is a immutable value type (string, etc)
diff --git a/test/com/google/javascript/jscomp/NodeUtilTest.java b/test/com/google/javascript/jscomp/NodeUtilTest.java
index 6b5628517ae..40db889c7b0 100644
--- a/test/com/google/javascript/jscomp/NodeUtilTest.java
+++ b/test/com/google/javascript/jscomp/NodeUtilTest.java
@@ -73,18 +73,30 @@ private static Node getNode(String js) {
     return var.getFirstChild();
   }
 
+  private static Node getYieldNode(String js) {
+    return checkNotNull(getYieldNode(parse(js)));
+  }
+
+  private static Node getYieldNode(Node root) {
+    return getNode(root, Token.YIELD);
+  }
+
   private static Node getAwaitNode(String js) {
     return checkNotNull(getAwaitNode(parse(js)));
   }
 
   private static Node getAwaitNode(Node root) {
+    return getNode(root, Token.AWAIT);
+  }
+
+  private static Node getNode(Node root, Token token) {
     for (Node n : root.children()) {
-      if (n.isAwait()) {
+      if (n.getToken() == token) {
         return n;
       }
-      Node awaitNode = getAwaitNode(n);
-      if (awaitNode != null) {
-        return awaitNode;
+      Node potentialMatch = getNode(n, token);
+      if (potentialMatch != null) {
+        return potentialMatch;
       }
     }
     return null;
@@ -1628,6 +1640,15 @@ public void testLocalValueAwait() {
     assertFalse(NodeUtil.evaluatesToLocalValue(expr));
   }
 
+  public void testLocalValueYield() {
+    Node expr;
+    expr = getYieldNode("function *f() { yield; }");
+    assertFalse(NodeUtil.evaluatesToLocalValue(expr));
+
+    expr = getYieldNode("function *f() { yield 'something'; }");
+    assertFalse(NodeUtil.evaluatesToLocalValue(expr));
+  }
+
   public void testCallSideEffects() {
     Node callExpr = getNode("new x().method()");
     assertTrue(NodeUtil.functionCallHasSideEffects(callExpr));