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LibJS: Disallow duplicated variable declarations

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davidot 2021-07-12 01:29:47 +02:00 • committed by Andreas Kling
parent 5cc518f07a
commit 40b8689f9b
4 changed files with 62 additions and 4 deletions
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28
Userland/Libraries/LibJS/Parser.cpp
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@ -1955,6 +1955,7 @@ NonnullRefPtr<VariableDeclaration> Parser::parse_variable_declaration(bool for_l
for (;;) {
Variant<NonnullRefPtr<Identifier>, NonnullRefPtr<BindingPattern>, Empty> target { Empty() };
if (match_identifier()) {
auto identifier_start = push_start();
auto name = consume_identifier().value();
target = create_ast_node<Identifier>(
{ m_state.current_token.filename(), rule_start.position(), position() },
@ -1962,6 +1963,33 @@ NonnullRefPtr<VariableDeclaration> Parser::parse_variable_declaration(bool for_l
check_identifier_name_for_assignment_validity(name);
if ((declaration_kind == DeclarationKind::Let || declaration_kind == DeclarationKind::Const) && name == "let"sv)
syntax_error("Lexical binding may not be called 'let'");
// Check we do not have duplicates
auto check_declarations = [&](VariableDeclarator const& declarator) {
declarator.target().visit([&](NonnullRefPtr<Identifier> const& identifier) {
if (identifier->string() == name)
syntax_error(String::formatted("Identifier '{}' has already been declared", name), identifier_start.position()); },
[&](auto const&) {});
};
// In any previous let scope
if (!m_state.let_scopes.is_empty()) {
for (auto& decls : m_state.let_scopes.last()) {
for (auto& decl : decls.declarations()) {
check_declarations(decl);
}
}
}
// or this declaration
if (declaration_kind == DeclarationKind::Let || declaration_kind == DeclarationKind::Const) {
// FIXME: We should check the var_scopes here as well however this has edges cases with for loops.
// See duplicated-variable-declarations.js.
for (auto& declaration : declarations) {
check_declarations(declaration);
}
}
} else if (auto pattern = parse_binding_pattern()) {
target = pattern.release_nonnull();