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LibJS: Don't match async \n function as an async function declaration

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davidot 2021-11-30 15:52:51 +01:00 • committed by Linus Groh
parent c2ebaa9d87
commit 5010d4c20c
2 changed files with 27 additions and 5 deletions
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17
Userland/Libraries/LibJS/Parser.cpp
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@ -631,10 +631,15 @@ NonnullRefPtr<Statement> Parser::parse_statement(AllowLabelledFunction allow_lab
return result.release_nonnull(); return result.release_nonnull();
} }
if (match_expression()) { if (match_expression()) {
if (match(TokenType::Function) || (match(TokenType::Async) && next_token().type() == TokenType::Function) || match(TokenType::Class)) if (match(TokenType::Async)) {
auto lookahead_token = next_token();
if (lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator())
syntax_error("Async function declaration not allowed in single-statement context");
} else if (match(TokenType::Function) || match(TokenType::Class)) {
syntax_error(String::formatted("{} declaration not allowed in single-statement context", m_state.current_token.name())); syntax_error(String::formatted("{} declaration not allowed in single-statement context", m_state.current_token.name()));
if (match(TokenType::Let) && next_token().type() == TokenType::BracketOpen) } else if (match(TokenType::Let) && next_token().type() == TokenType::BracketOpen) {
syntax_error(String::formatted("let followed by [ is not allowed in single-statement context")); syntax_error(String::formatted("let followed by [ is not allowed in single-statement context"));
}
auto expr = parse_expression(0); auto expr = parse_expression(0);
consume_or_insert_semicolon(); consume_or_insert_semicolon();
@ -3608,11 +3613,15 @@ bool Parser::match_declaration() const
return try_match_let_declaration(); return try_match_let_declaration();
} }
if (type == TokenType::Async) {
auto lookahead_token = next_token();
return lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator();
}
return type == TokenType::Function return type == TokenType::Function
|| type == TokenType::Class || type == TokenType::Class
|| type == TokenType::Const || type == TokenType::Const
|| type == TokenType::Let || type == TokenType::Let;
|| (type == TokenType::Async && next_token().type() == TokenType::Function);
} }
Token Parser::next_token() const Token Parser::next_token() const

15
Userland/Libraries/LibJS/Tests/syntax/async-await.js
View file

@ -1,8 +1,9 @@
describe("parsing freestanding async functions", () => { describe("parsing freestanding async functions", () => {
test("simple", () => { test("simple", () => {
expect(`async function foo() {}`).toEval(); expect(`async function foo() {}`).toEval();
// Although it does not create an async function it is valid.
expect(`async expect(`async
function foo() {}`).not.toEval(); function foo() {}`).toEval();
}); });
test("await expression", () => { test("await expression", () => {
expect(`async function foo() { await bar(); }`).toEval(); expect(`async function foo() { await bar(); }`).toEval();
@ -167,6 +168,18 @@ describe("non async function declaration usage of async still works", () => {
const evalResult = eval("async >= 2"); const evalResult = eval("async >= 2");
expect(evalResult).toBeTrue(); expect(evalResult).toBeTrue();
}); });
test("async with line ending does not create a function", () => {
expect(() => {
// The ignore is needed otherwise prettier puts a ';' after async.
// prettier-ignore
async
function f() {}
}).toThrowWithMessage(ReferenceError, "'async' is not defined");
expect(`async
function f() { await 3; }`).not.toEval();
});
}); });
describe("await cannot be used in class static init blocks", () => { describe("await cannot be used in class static init blocks", () => {