Merge pull request #3324 from zjmiller/master

Parenthize "in" in for-loop init, even when init has nested for-loop

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) {

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) {

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);

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);;);

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);;);