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LibJS: Allow escaped 'async' as identifier

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Since 'async' is only special if it occurs before a function it can be
used as escaped identifier in all cases.
This commit is contained in:
davidot 2021-11-26 23:25:10 +01:00 • committed by Linus Groh
parent e751dcea43
commit c57721cf83
2 changed files with 19 additions and 9 deletions
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16
Userland/Libraries/LibJS/Parser.cpp
View file

@ -596,13 +596,15 @@ bool Parser::match_invalid_escaped_keyword() const
if (m_state.current_token.type() != TokenType::EscapedKeyword) if (m_state.current_token.type() != TokenType::EscapedKeyword)
return false; return false;
auto token_value = m_state.current_token.value(); auto token_value = m_state.current_token.value();
if (token_value == "await"sv) { if (token_value == "await"sv)
return m_program_type == Program::Type::Module; return m_program_type == Program::Type::Module || m_state.in_async_function_context;
} if (token_value == "async"sv)
if (m_state.strict_mode) { return false;
if (token_value == "yield"sv)
return m_state.in_generator_function_context;
if (m_state.strict_mode)
return true; return true;
} return token_value != "let"sv;
return token_value != "yield"sv && token_value != "let"sv;
} }
static constexpr AK::Array<StringView, 9> strict_reserved_words = { "implements", "interface", "let", "package", "private", "protected", "public", "static", "yield" }; static constexpr AK::Array<StringView, 9> strict_reserved_words = { "implements", "interface", "let", "package", "private", "protected", "public", "static", "yield" };
@ -1230,7 +1232,7 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
syntax_error("'super' keyword unexpected here"); syntax_error("'super' keyword unexpected here");
return { create_ast_node<SuperExpression>({ m_state.current_token.filename(), rule_start.position(), position() }) }; return { create_ast_node<SuperExpression>({ m_state.current_token.filename(), rule_start.position(), position() }) };
case TokenType::EscapedKeyword: case TokenType::EscapedKeyword:
if (m_state.strict_mode || (m_state.current_token.value() != "let"sv && (m_state.in_generator_function_context || m_state.current_token.value() != "yield"sv) && (m_state.in_async_function_context || m_state.current_token.value() != "await"sv))) if (match_invalid_escaped_keyword())
syntax_error("Keyword must not contain escaped characters"); syntax_error("Keyword must not contain escaped characters");
[[fallthrough]]; [[fallthrough]];
case TokenType::Identifier: { case TokenType::Identifier: {

12
Userland/Libraries/LibJS/Tests/syntax/async-await.js
View file

@ -9,6 +9,10 @@ describe("parsing freestanding async functions", () => {
expect(`async function foo() { await; }`).not.toEval(); expect(`async function foo() { await; }`).not.toEval();
expect(`function foo() { await bar(); }`).not.toEval(); expect(`function foo() { await bar(); }`).not.toEval();
expect(`function foo() { await; }`).toEval(); expect(`function foo() { await; }`).toEval();
expect(`\\u0061sync function foo() { await bar(); }`).not.toEval();
expect(`\\u0061sync function foo() { \\u0061wait bar(); }`).not.toEval();
expect(`async function foo() { \\u0061wait bar(); }`).not.toEval();
}); });
}); });
@ -82,11 +86,15 @@ describe("async arrow functions", () => {
expect("async (b = await) => await b;").not.toEval(); expect("async (b = await) => await b;").not.toEval();
expect("async (b = await 3) => await b;").not.toEval(); expect("async (b = await 3) => await b;").not.toEval();
// Cannot escape the async keyword. // Cannot escape the async keyword and get an async arrow function.
expect("\\u0061sync () => await 3").not.toEval(); expect("\\u0061sync () => await 3").not.toEval();
expect("for (async of => {};;) {}").toEval(); expect("for (async of => {};false;) {}").toEval();
expect("for (async of []) {}").not.toEval(); expect("for (async of []) {}").not.toEval();
expect("for (\\u0061sync of []) {}").toEval();
expect("for (\\u0061sync of => {};false;) {}").not.toEval();
expect("for (\\u0061sync => {};false;) {}").toEval();
}); });
test("async within a for-loop", () => { test("async within a for-loop", () => {