[[FIX]] Report "Bad assignment." in destructuring

During destructuring, the return value of the internal
`checkLeftSideAssign` function was discarded, so JSHint would fail to
report invalid assignment targets in that context.

Move the reporting of Error 031 ("Bad assignment.") into the
`checkLeftSideAssign` to enhance consistency. Improve the
implementation of that internal function by making it aware of the rest
operator (the previous implementation considered this form "invalid" but
failed to report that).

src/jshint.js

@@ -1335,6 +1335,9 @@ var JSHINT = (function() {
       if (nativeObject)
         warning("W121", left, nativeObject);
     }
+    if (checkPunctuator(left, "...")) {
+      left = left.right;
+    }
 
     if (left.identifier && !left.isMetaProperty) {
       // reassign also calls modify
@@ -1370,10 +1373,7 @@ var JSHINT = (function() {
       }
 
       return true;
-    } else if (left.isMetaProperty) {
-      error("E031", assignToken);
-      return true;
-    } else if (left.identifier && !isReserved(left)) {
+    } else if (left.identifier && !isReserved(left) && !left.isMetaProperty) {
       if (state.funct["(scope)"].labeltype(left.value) === "exception") {
         warning("W022", left);
       }
@@ -1383,6 +1383,8 @@ var JSHINT = (function() {
 
     if (left === state.syntax["function"]) {
       warning("W023", state.tokens.curr);
+    } else {
+      error("E031", assignToken);
     }
 
     return false;
@@ -1392,9 +1394,7 @@ var JSHINT = (function() {
     var x = infix(s, typeof f === "function" ? f : function(left, that) {
       that.left = left;
 
-      if (!checkLeftSideAssign(left, that, { allowDestructuring: true })) {
-        error("E031", that);
-      }
+      checkLeftSideAssign(left, that, { allowDestructuring: true });
 
       that.right = expression(10);
 
@@ -1427,9 +1427,7 @@ var JSHINT = (function() {
         warning("W016", that, that.id);
       }
 
-      if (!checkLeftSideAssign(left, that)) {
-        error("E031", that);
-      }
+      checkLeftSideAssign(left, that);
 
       that.right = expression(10);
 
@@ -2277,7 +2275,7 @@ var JSHINT = (function() {
 
       error("E030", state.tokens.next, state.tokens.next.value);
     }
-    expression(150);
+    this.right = expression(150);
     return this;
   });
 

tests/unit/parser.js

@@ -1854,6 +1854,7 @@ exports["destructuring globals with syntax error"] = function (test) {
 
   TestRun(test)
     .addError(3, "Expected an identifier and instead saw '1'.")
+    .addError(3, "Bad assignment.")
     .addError(4, "Expected ',' and instead saw ';'.")
     .addError(5, "Expected ']' to match '[' from line 5 and instead saw ';'.")
     .addError(5, "Missing semicolon.")
@@ -1895,6 +1896,8 @@ exports["destructuring globals with syntax error"] = function (test) {
     .addError(4, "Bad assignment.")
     .addError(6, "Do not assign to the exception parameter.")
     .addError(7, "Do not assign to the exception parameter.")
+    .addError(9, "Bad assignment.")
+    .addError(10, "Bad assignment.")
     .test([
       "[ Number.prototype.toString ] = [function(){}];",
       "function a() {",
@@ -1904,6 +1907,9 @@ exports["destructuring globals with syntax error"] = function (test) {
       "    ({e} = {e});",
       "    [e] = [];",
       "  }",
+      "  ({ x: null } = {});",
+      "  ({ y: [...this] } = {});",
+      "  ({ y: [...z] } = {});",
       "}"], {esnext: true, freeze: true});
 
   test.done();