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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
View file

@ -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();

4
Userland/Libraries/LibJS/Tests/builtins/Proxy/Proxy.handler-setPrototypeOf.js
View file

@ -6,9 +6,9 @@ describe("[[SetPrototypeOf]] trap normal behavior", () => {
let p = new Proxy(o, { setPrototypeOf: null });
expect(Object.setPrototypeOf(p, proto)).toBe(p);
let p = new Proxy(o, { setPrototypeOf: undefined });
p = new Proxy(o, { setPrototypeOf: undefined });
expect(Object.setPrototypeOf(p, proto)).toBe(p);
let p = new Proxy(o, {});
p = new Proxy(o, {});
expect(Object.setPrototypeOf(p, proto)).toBe(p);
});

30
Userland/Libraries/LibJS/Tests/duplicated-variable-declarations.js Normal file
View file

@ -0,0 +1,30 @@
describe("duplicated variable declarations should throw", () => {
test("given two declarations in the same statement", () => {
expect("let a, a;").not.toEval();
expect("const a, a;").not.toEval();
expect("var a, a;").toEval();
});
test("fail to parse if repeated over multiple statements", () => {
expect("let a; var a;").not.toEval();
expect("let b, a; var c, a;").not.toEval();
expect("const a; var a;").not.toEval();
expect("const b, a; var c, a;").not.toEval();
});
test.skip("should fail to parse even if variable first declared with var", () => {
expect.skip("var a; let a;").toEval();
expect.skip("var a; let b, a;").toEval();
expect.skip("var a; const a;").toEval();
expect.skip("var a; const b, a;").toEval();
});
test.skip("special cases with for loops", () => {
expect("for (var a;;) { let a; }").toEval();
expect("for (let a;;) { let a; }").toEval();
expect("for (var a;;) { var a; }").toEval();
expect("for (let a;;) { var a; }").not.toEval();
});
});

4
Userland/Libraries/LibJS/Tests/iterators/string-iterator.js
View file

@ -15,12 +15,12 @@ test("basic functionality", () => {
});
test("casts |this| to string", () => {
const it = String.prototype[Symbol.iterator].call(45);
let it = String.prototype[Symbol.iterator].call(45);
expect(it.next()).toEqual({ value: "4", done: false });
expect(it.next()).toEqual({ value: "5", done: false });
expect(it.next()).toEqual({ value: undefined, done: true });
const it = String.prototype[Symbol.iterator].call(false);
it = String.prototype[Symbol.iterator].call(false);
expect(it.next()).toEqual({ value: "f", done: false });
expect(it.next()).toEqual({ value: "a", done: false });
expect(it.next()).toEqual({ value: "l", done: false });