Merge pull request #3245 from babel/assig-parenth

Revert #3217 and add tests

packages/babel-generator/src/generators/expressions.js

@@ -155,10 +155,8 @@ 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;;)`
-  // and for `ObjectPattern`: `({ f } = { f: 2 };`
   let parens = this._inForStatementInit && node.operator === "in" &&
-               !n.needsParens(node, parent) ||
-               t.isObjectPattern(node.left);
+               !n.needsParens(node, parent);
 
   if (parens) {
     this.push("(");

packages/babel-generator/src/node/parentheses.js

@@ -66,7 +66,7 @@ export function Binary(node: Object, parent: Object): boolean {
     return true;
   }
 
-  if (t.isBinary(parent) && !t.isAssignmentExpression(parent)) {
+  if (t.isBinary(parent)) {
     let parentOp  = parent.operator;
     let parentPos = PRECEDENCE[parentOp];
 
@@ -216,7 +216,7 @@ export function ConditionalExpression(node: Object, parent: Object): boolean {
     return true;
   }
 
-  if (t.isBinary(parent) && !t.isAssignmentExpression(parent)) {
+  if (t.isBinary(parent)) {
     return true;
   }
 

packages/babel-generator/test/fixtures/parentheses/assignment-expression/actual.js

@@ -0,0 +1,3 @@
+1 + (a = 2);
+1 + (a += 2);
+a = a || (a = {});

packages/babel-generator/test/fixtures/parentheses/assignment-expression/expected.js

@@ -0,0 +1,3 @@
+1 + (a = 2);
+1 + (a += 2);
+a = a || (a = {});

packages/babel-types/src/definitions/core.js

@@ -42,7 +42,7 @@ defineType("AssignmentExpression", {
   },
   builder: ["operator", "left", "right"],
   visitor: ["left", "right"],
-  aliases: ["Binary", "Expression"]
+  aliases: ["Expression"]
 });
 
 defineType("BinaryExpression", {