From 33b4ef5d52151b1e9d18483c8951758ae56fc1d4 Mon Sep 17 00:00:00 2001
From: Zachary Miller <zachary.john.miller@gmail.com>
Date: Fri, 5 Feb 2016 11:22:46 -0600
Subject: [PATCH] Parenthize "in" in for-loop init, even when init has nested
 for-loop

---
 packages/babel-generator/src/generators/expressions.js        | 2 +-
 packages/babel-generator/src/generators/statements.js         | 4 ++--
 packages/babel-generator/src/index.js                         | 1 +
 .../test/fixtures/edgecase/for-loop-in/actual.js              | 1 +
 .../test/fixtures/edgecase/for-loop-in/expected.js            | 3 +++
 5 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/packages/babel-generator/src/generators/expressions.js b/packages/babel-generator/src/generators/expressions.js
index f82d409f94..08fd212518 100644
--- a/packages/babel-generator/src/generators/expressions.js
+++ b/packages/babel-generator/src/generators/expressions.js
@@ -156,7 +156,7 @@ export function AssignmentPattern(node: Object) {
 export function AssignmentExpression(node: Object, parent: Object) {
   // Somewhere inside a for statement `init` node but doesn't usually
   // needs a paren except for `in` expressions: `for (a in b ? a : b;;)`
-  let parens = this._inForStatementInit && node.operator === "in" &&
+  let parens = this._inForStatementInitCounter && node.operator === "in" &&
                !n.needsParens(node, parent);
 
   if (parens) {
diff --git a/packages/babel-generator/src/generators/statements.js b/packages/babel-generator/src/generators/statements.js
index 7e8a117616..dea6898f71 100644
--- a/packages/babel-generator/src/generators/statements.js
+++ b/packages/babel-generator/src/generators/statements.js
@@ -52,9 +52,9 @@ export function ForStatement(node: Object) {
   this.keyword("for");
   this.push("(");
 
-  this._inForStatementInit = true;
+  this._inForStatementInitCounter++;
   this.print(node.init, node);
-  this._inForStatementInit = false;
+  this._inForStatementInitCounter--;
   this.push(";");
 
   if (node.test) {
diff --git a/packages/babel-generator/src/index.js b/packages/babel-generator/src/index.js
index b5b7305f25..f65d065520 100644
--- a/packages/babel-generator/src/index.js
+++ b/packages/babel-generator/src/index.js
@@ -28,6 +28,7 @@ export class CodeGenerator extends Printer {
     this.format   = format;
     this.opts     = opts;
     this.ast      = ast;
+    this._inForStatementInitCounter = 0;
 
     this.whitespace = new Whitespace(tokens);
     this.map        = new SourceMap(position, opts, code);
diff --git a/packages/babel-generator/test/fixtures/edgecase/for-loop-in/actual.js b/packages/babel-generator/test/fixtures/edgecase/for-loop-in/actual.js
index da5079a95f..9c279089c2 100644
--- a/packages/babel-generator/test/fixtures/edgecase/for-loop-in/actual.js
+++ b/packages/babel-generator/test/fixtures/edgecase/for-loop-in/actual.js
@@ -1 +1,2 @@
 for ((a in b) ? a : b; i;);
+for (function(){for(;;);} && (a in b);;);
diff --git a/packages/babel-generator/test/fixtures/edgecase/for-loop-in/expected.js b/packages/babel-generator/test/fixtures/edgecase/for-loop-in/expected.js
index da5079a95f..2a24aad352 100644
--- a/packages/babel-generator/test/fixtures/edgecase/for-loop-in/expected.js
+++ b/packages/babel-generator/test/fixtures/edgecase/for-loop-in/expected.js
@@ -1 +1,4 @@
 for ((a in b) ? a : b; i;);
+for (function () {
+  for (;;);
+} && (a in b);;);