From 73e7aa1d8b1855954261204f7c09c947f77e6199 Mon Sep 17 00:00:00 2001
From: Toru Nagashima <public@mysticatea.dev>
Date: Sun, 8 Dec 2019 20:14:20 +0900
Subject: [PATCH] fix wrong early errors

---
 acorn/src/lval.js               |  27 +----
 test/tests-optional-chaining.js | 173 ++++++++++++++++++++++++++++++++
 2 files changed, 178 insertions(+), 22 deletions(-)

diff --git a/acorn/src/lval.js b/acorn/src/lval.js
index 0449815f9..0825a6e68 100644
--- a/acorn/src/lval.js
+++ b/acorn/src/lval.js
@@ -75,8 +75,8 @@ pp.toAssignable = function(node, isBinding, refDestructuringErrors) {
 
     case "MemberExpression":
       if (isBinding) this.raise(node.start, "Assigning to rvalue")
-      if (this.options.ecmaVersion >= 11) {
-        this.checkOptionalChainingInLVal(node)
+      if (this.options.ecmaVersion >= 11 && (node.optional || node.shortCircuited)) {
+        this.raise(node.start, "Optional chaining cannot appear in left-hand side")
       }
       break
 
@@ -87,25 +87,6 @@ pp.toAssignable = function(node, isBinding, refDestructuringErrors) {
   return node
 }
 
-pp.checkOptionalChainingInLVal = function(node) {
-  while (node) {
-    switch (node.type) {
-    case "CallExpression":
-      if (node.optional) this.raise(node.start, "Optional chaining cannot appear in left-hand side")
-      node = node.callee
-      break
-
-    case "MemberExpression":
-      if (node.optional) this.raise(node.start, "Optional chaining cannot appear in left-hand side")
-      node = node.object
-      break
-
-    default:
-      return
-    }
-  }
-}
-
 // Convert list of expression atoms to binding list.
 
 pp.toAssignableList = function(exprList, isBinding) {
@@ -226,7 +207,9 @@ pp.checkLVal = function(expr, bindingType = BIND_NONE, checkClashes) {
 
   case "MemberExpression":
     if (bindingType) this.raiseRecoverable(expr.start, "Binding member expression")
-    if (this.options.ecmaVersion >= 11) this.checkOptionalChainingInLVal(expr)
+    if (this.options.ecmaVersion >= 11 && (expr.optional || expr.shortCircuited)) {
+      this.raise(expr.start, "Optional chaining cannot appear in left-hand side")
+    }
     break
 
   case "ObjectPattern":
diff --git a/test/tests-optional-chaining.js b/test/tests-optional-chaining.js
index c787230cc..cb1f6cca4 100644
--- a/test/tests-optional-chaining.js
+++ b/test/tests-optional-chaining.js
@@ -888,6 +888,179 @@ test("(obj?.foo)`template`", {
   ],
   "sourceType": "script"
 }, { ecmaVersion: 11 })
+test("(obj?.foo).bar = 0", {
+  "type": "Program",
+  "start": 0,
+  "end": 18,
+  "body": [
+    {
+      "type": "ExpressionStatement",
+      "start": 0,
+      "end": 18,
+      "expression": {
+        "type": "AssignmentExpression",
+        "start": 0,
+        "end": 18,
+        "operator": "=",
+        "left": {
+          "type": "MemberExpression",
+          "start": 0,
+          "end": 14,
+          "object": {
+            "type": "MemberExpression",
+            "start": 1,
+            "end": 9,
+            "object": {
+              "type": "Identifier",
+              "start": 1,
+              "end": 4,
+              "name": "obj"
+            },
+            "property": {
+              "type": "Identifier",
+              "start": 6,
+              "end": 9,
+              "name": "foo"
+            },
+            "computed": false,
+            "optional": true,
+            "shortCircuited": false
+          },
+          "property": {
+            "type": "Identifier",
+            "start": 11,
+            "end": 14,
+            "name": "bar"
+          },
+          "computed": false,
+          "optional": false,
+          "shortCircuited": false
+        },
+        "right": {
+          "type": "Literal",
+          "start": 17,
+          "end": 18,
+          "value": 0,
+          "raw": "0"
+        }
+      }
+    }
+  ],
+  "sourceType": "script"
+}, { ecmaVersion: 11 })
+test("(obj?.foo).bar++", {
+  "type": "Program",
+  "start": 0,
+  "end": 16,
+  "body": [
+    {
+      "type": "ExpressionStatement",
+      "start": 0,
+      "end": 16,
+      "expression": {
+        "type": "UpdateExpression",
+        "start": 0,
+        "end": 16,
+        "operator": "++",
+        "prefix": false,
+        "argument": {
+          "type": "MemberExpression",
+          "start": 0,
+          "end": 14,
+          "object": {
+            "type": "MemberExpression",
+            "start": 1,
+            "end": 9,
+            "object": {
+              "type": "Identifier",
+              "start": 1,
+              "end": 4,
+              "name": "obj"
+            },
+            "property": {
+              "type": "Identifier",
+              "start": 6,
+              "end": 9,
+              "name": "foo"
+            },
+            "computed": false,
+            "optional": true,
+            "shortCircuited": false
+          },
+          "property": {
+            "type": "Identifier",
+            "start": 11,
+            "end": 14,
+            "name": "bar"
+          },
+          "computed": false,
+          "optional": false,
+          "shortCircuited": false
+        }
+      }
+    }
+  ],
+  "sourceType": "script"
+}, { ecmaVersion: 11 })
+test("for ((obj?.foo).bar of []);", {
+  "type": "Program",
+  "start": 0,
+  "end": 27,
+  "body": [
+    {
+      "type": "ForOfStatement",
+      "start": 0,
+      "end": 27,
+      "await": false,
+      "left": {
+        "type": "MemberExpression",
+        "start": 5,
+        "end": 19,
+        "object": {
+          "type": "MemberExpression",
+          "start": 6,
+          "end": 14,
+          "object": {
+            "type": "Identifier",
+            "start": 6,
+            "end": 9,
+            "name": "obj"
+          },
+          "property": {
+            "type": "Identifier",
+            "start": 11,
+            "end": 14,
+            "name": "foo"
+          },
+          "computed": false,
+          "optional": true,
+          "shortCircuited": false
+        },
+        "property": {
+          "type": "Identifier",
+          "start": 16,
+          "end": 19,
+          "name": "bar"
+        },
+        "computed": false,
+        "optional": false,
+        "shortCircuited": false
+      },
+      "right": {
+        "type": "ArrayExpression",
+        "start": 23,
+        "end": 25,
+        "elements": []
+      },
+      "body": {
+        "type": "EmptyStatement",
+        "start": 26,
+        "end": 27
+      }
+    }
+  ],
+  "sourceType": "script"
+}, { ecmaVersion: 11 })
 
 testFail("obj?.foo", "Unexpected token (1:4)", { ecmaVersion: 10 })
 testFail("obj?.[foo]", "Unexpected token (1:4)", { ecmaVersion: 10 })