fixed missing errors on assignment pattern in object expression

packages/babel-parser/src/parser/expression.js

@@ -204,7 +204,10 @@ export default class ExpressionParser extends LValParser {
       node.left = this.match(tt.eq)
         ? this.toAssignable(left, undefined, "assignment expression")
         : left;
-      refShorthandDefaultPos.start = 0; // reset because shorthand default was used correctly
+
+      if (refShorthandDefaultPos.start >= node.left.start) {
+        refShorthandDefaultPos.start = 0; // reset because shorthand default was used correctly
+      }
 
       this.checkLVal(left, undefined, undefined, "assignment expression");
 

packages/babel-parser/test/fixtures/core/object/invalid-property-initializer-1/input.js

@@ -0,0 +1,4 @@
+const obj = {
+  bar: x = 123,
+  foo = 123
+};

packages/babel-parser/test/fixtures/core/object/invalid-property-initializer-1/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token (3:6)"
+}

packages/babel-parser/test/fixtures/core/object/invalid-property-initializer/input.js

@@ -0,0 +1,4 @@
+const obj = {
+  foo = 123,
+  bar: x = 123
+};

packages/babel-parser/test/fixtures/core/object/invalid-property-initializer/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token (2:6)"
+}

packages/babel-parser/test/fixtures/core/object/valid-property-initializer/input.js

@@ -0,0 +1,4 @@
+const obj = {
+  foo = 123,
+  bar: x = 123,
+} = { foo: 24, bar: 45 };