From c2d2702cf93f372f7d8e1359111daafeed9fd695 Mon Sep 17 00:00:00 2001
From: Daniel Tschinder <daniel@tschinder.de>
Date: Sun, 25 Sep 2016 01:08:53 +0200
Subject: [PATCH] Fix destructuring evaluation with call expressions (#4552)

* Fix destructuring evaluation with call expressions

Do not optimize destructions with callExpressions, as the call
might change the value of a variable that we are assigning to.

Fixes #4054

* Also deopt on member expressions

members expressions might be getters who have side effects
---
 .../src/index.js                                         | 6 ++++++
 .../destructuring/array-unpack-optimisation/actual.js    | 3 +++
 .../destructuring/array-unpack-optimisation/expected.js  | 9 +++++++++
 3 files changed, 18 insertions(+)

diff --git a/packages/babel-plugin-transform-es2015-destructuring/src/index.js b/packages/babel-plugin-transform-es2015-destructuring/src/index.js
index 95533c4618..0a80489ac9 100644
--- a/packages/babel-plugin-transform-es2015-destructuring/src/index.js
+++ b/packages/babel-plugin-transform-es2015-destructuring/src/index.js
@@ -221,6 +221,12 @@ export default function ({ types: t }) {
       for (let elem of (arr.elements: Array)) {
         // deopt on spread elements
         if (t.isSpreadElement(elem)) return false;
+
+        // deopt call expressions as they might change values of LHS variables
+        if (t.isCallExpression(elem)) return false;
+
+        // deopt on member expressions as they may be getter/setters and have side-effects
+        if (t.isMemberExpression(elem)) return false;
       }
 
       // deopt on reference to left side identifiers
diff --git a/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/actual.js b/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/actual.js
index 0d02d7f7ba..87493c5fd5 100644
--- a/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/actual.js
+++ b/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/actual.js
@@ -8,3 +8,6 @@ var [[a, b]] = [[1, 2, 3]];
 var [a, b] = [a, b];
 [a[0], a[1]] = [a[1], a[0]];
 var [a, b] = [...foo, bar];
+var [a, b] = [foo(), bar];
+var [a, b] = [clazz.foo(), bar];
+var [a, b] = [clazz.foo, bar];
diff --git a/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/expected.js b/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/expected.js
index e6b45f91cb..e26edabdaf 100644
--- a/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/expected.js
+++ b/packages/babel-plugin-transform-es2015-destructuring/test/fixtures/destructuring/array-unpack-optimisation/expected.js
@@ -25,3 +25,12 @@ var _ref5 = [].concat(babelHelpers.toConsumableArray(foo), [bar]);
 
 var a = _ref5[0];
 var b = _ref5[1];
+var _ref6 = [foo(), bar];
+var a = _ref6[0];
+var b = _ref6[1];
+var _ref7 = [clazz.foo(), bar];
+var a = _ref7[0];
+var b = _ref7[1];
+var _ref8 = [clazz.foo, bar];
+var a = _ref8[0];
+var b = _ref8[1];