v8/test/message/fail/let-lexical-declaration-in-single-statement.js

// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

with ({}) let a = [];
Raise SyntaxError on let [ starting an ExpressionStatement ES2017 forbids the sequence of tokens "let [" in in expression statements [1]. This CL makes ParserBase report those instances as SyntaxError. It also adds a customised error message for that, because the standard "Unexpected token" is not applicable: "let" itself is not forbidden in those context, only the sequence of "let [". [1] https://tc39.github.io/ecma262/#sec-expression-statement BUG=v8:5686 Review-Url: https://codereview.chromium.org/2694003002 Cr-Commit-Position: refs/heads/master@{#43258} 2017-02-16 17:37:21 +00:00			`// Copyright 2017 the V8 project authors. All rights reserved.`
			`// Use of this source code is governed by a BSD-style license that can be`
			`// found in the LICENSE file.`

Report unexpected lexical decl also without destructuring https://codereview.chromium.org/2694003002/ introduced "SyntaxError: Lexical declaration cannot appear in a single-statement context" for the case when let + desctructuring from a list happen. As was pointed out in https://codereview.chromium.org/2694003002/#msg18, the case without destructuring would also benefit from a better message: if a single statement is expected and "let identifier = ..." is seen, the error is indeed again that the lexical declaration is not a statement. However, the current error is "Unexpected identifier", because the parser tries to accept "let" as an identifier in an expression statement, and then gives up seeing the other identifier after "let". This CL ensures that the parser recognises the error properly and reports accordingly. It also renames the existing test, which contains destructuring, and adds the one with a non-destructuring lexical declaration. BUG=v8:5686 Review-Url: https://codereview.chromium.org/2697193007 Cr-Commit-Position: refs/heads/master@{#43275} 2017-02-17 10:57:32 +00:00			`with ({}) let a = [];`