Bug 1041341 - Part 2: Report a SyntaxError for destructuring rest with trailing comma. r=arai

--HG--
extra : rebase_source : 686eb8d6fb58998255365d53bdfc71b4d5ec50a9

js/src/frontend/Parser.cpp

@@ -8571,6 +8571,8 @@ Parser<ParseHandler>::arrayInitializer(YieldHandling yieldHandling, PossibleErro
                     modifier = TokenStream::None;
                     break;
                 }
+                if (tt == TOK_TRIPLEDOT && possibleError)
+                    possibleError->setPendingDestructuringError(null(), JSMSG_REST_WITH_COMMA);
             }
         }
 

js/src/jit-test/tests/basic/destructuring-rest.js

@@ -12,13 +12,7 @@ assertThrowsInstanceOf(() => new Function('[...!a] = []'), SyntaxError, 'unary e
 assertThrowsInstanceOf(() => new Function('[...a+b] = []'), SyntaxError, 'binary expression');
 assertThrowsInstanceOf(() => new Function('var [...a.x] = []'), SyntaxError, 'lvalue expression in declaration');
 assertThrowsInstanceOf(() => new Function('var [...(b)] = []'), SyntaxError);
-
-// XXX: The way the current parser works, a trailing comma is lost before we
-//      check for destructuring.  See bug 1041341. Once fixed, please update
-//      this assertion.
-assertThrowsInstanceOf(() =>
-	assertThrowsInstanceOf(() => new Function('[...b,] = []'), SyntaxError)
-	, Error);
+assertThrowsInstanceOf(() => new Function('[...b,] = []'), SyntaxError);
 
 assertThrowsInstanceOf(() => {
   try {

js/src/js.msg

@@ -301,6 +301,7 @@ MSG_DEF(JSMSG_RC_AFTER_EXPORT_SPEC_LIST, 0, JSEXN_SYNTAXERR, "missing '}' after
 MSG_DEF(JSMSG_RC_AFTER_IMPORT_SPEC_LIST, 0, JSEXN_SYNTAXERR, "missing '}' after module specifier list")
 MSG_DEF(JSMSG_REDECLARED_CATCH_IDENTIFIER, 1, JSEXN_SYNTAXERR, "redeclaration of identifier '{0}' in catch")
 MSG_DEF(JSMSG_RESERVED_ID,             1, JSEXN_SYNTAXERR, "{0} is a reserved identifier")
+MSG_DEF(JSMSG_REST_WITH_COMMA,         0, JSEXN_SYNTAXERR, "rest element may not have a trailing comma")
 MSG_DEF(JSMSG_REST_WITH_DEFAULT,       0, JSEXN_SYNTAXERR, "rest parameter may not have a default")
 MSG_DEF(JSMSG_SELFHOSTED_TOP_LEVEL_LEXICAL, 1, JSEXN_SYNTAXERR, "self-hosted code cannot contain top-level {0} declarations")
 MSG_DEF(JSMSG_SELFHOSTED_METHOD_CALL,  0, JSEXN_SYNTAXERR, "self-hosted code may not contain direct method calls. Use callFunction() or callContentFunction()")

js/src/tests/ecma_6/Destructuring/rest-with-trailing-comma.js

@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const invalidSyntax = [
+    "[...r, ]",
+    "[a, ...r, ]",
+    "[a = 0, ...r, ]",
+    "[[], ...r, ]",
+    "[[...r,]]",
+    "[[...r,], ]",
+    "[[...r,], a]",
+];
+
+const validSyntax = [
+    "[, ]",
+    "[a, ]",
+    "[[], ]",
+];
+
+const destructuringForms = [
+    a => `${a} = [];`,
+    a => `var ${a} = [];`,
+    a => `let ${a} = [];`,
+    a => `const ${a} = [];`,
+    a => `(${a}) => {};`,
+    a => `(${a} = []) => {};`,
+    a => `function f(${a}) {}`,
+];
+
+for (let invalid of invalidSyntax) {
+    for (let fn of destructuringForms) {
+        assertThrowsInstanceOf(() => Function(fn(invalid)), SyntaxError);
+    }
+}
+
+for (let invalid of validSyntax) {
+    for (let fn of destructuringForms) {
+        Function(fn(invalid));
+    }
+}
+
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);