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LibJS: Allow let
and const
to create locals in global code
This is actually safe everywhere but in the topmost program scope. For web compatibility reasons, we have to flush all top-level bindings to the environment, in case a subsequent separate <script> program comes looking for them.
This commit is contained in:
parent
0aa8cb7dac
commit
9d21d88374
Notes:
sideshowbarker
2024-07-17 03:00:02 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/LadybirdBrowser/ladybird/commit/9d21d88374 Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/165
@ -351,12 +351,24 @@ public:
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continue;
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if (!identifier_group.captured_by_nested_function && !identifier_group.used_inside_with_statement) {
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auto function_scope = last_function_scope();
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if (!function_scope || m_screwed_by_eval_in_scope_chain) {
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if (m_screwed_by_eval_in_scope_chain)
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continue;
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auto local_scope = last_function_scope();
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if (!local_scope) {
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// NOTE: If there is no function scope, we are in a *descendant* of the global program scope.
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// While we cannot make `let` and `const` into locals in the topmost program scope,
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// as that would break expected web behavior where subsequent <script> elements should see
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// lexical bindings created by earlier <script> elements, we *can* promote them in descendant scopes.
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// Of course, global `var` bindings can never be made into locals, as they get hoisted to the topmost program scope.
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if (identifier_group.declaration_kind == DeclarationKind::Var)
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continue;
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// Add these locals to the top-level scope. (We only produce one executable for the entire program
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// scope, so that's where the locals have to be stored.)
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local_scope = m_top_level_scope;
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}
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auto local_variable_index = function_scope->m_node->add_local_variable(identifier_group_name);
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auto local_variable_index = local_scope->m_node->add_local_variable(identifier_group_name);
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for (auto& identifier : identifier_group.identifiers)
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identifier->set_local_variable_index(local_variable_index);
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}
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@ -421,7 +433,7 @@ public:
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return m_scope_level != ScopeLevel::ScriptTopLevel;
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}
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void register_identifier(NonnullRefPtr<Identifier> id)
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void register_identifier(NonnullRefPtr<Identifier> id, Optional<DeclarationKind> declaration_kind = {})
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{
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if (auto maybe_identifier_group = m_identifier_groups.get(id->string()); maybe_identifier_group.has_value()) {
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maybe_identifier_group.value().identifiers.append(id);
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@ -429,6 +441,7 @@ public:
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m_identifier_groups.set(id->string(), IdentifierGroup {
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.captured_by_nested_function = false,
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.identifiers = { id },
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.declaration_kind = declaration_kind,
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});
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}
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}
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@ -495,6 +508,7 @@ private:
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bool used_inside_scope_with_eval { false };
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bool might_be_variable_in_lexical_scope_in_named_function_assignment { false };
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Vector<NonnullRefPtr<Identifier>> identifiers;
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Optional<DeclarationKind> declaration_kind;
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};
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HashMap<DeprecatedFlyString, IdentifierGroup> m_identifier_groups;
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@ -3273,24 +3287,24 @@ RefPtr<BindingPattern const> Parser::parse_binding_pattern(Parser::AllowDuplicat
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return pattern;
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}
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RefPtr<Identifier const> Parser::parse_lexical_binding()
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RefPtr<Identifier const> Parser::parse_lexical_binding(Optional<DeclarationKind> declaration_kind)
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{
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auto binding_start = push_start();
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if (match_identifier()) {
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume_identifier().DeprecatedFlyString_value());
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume_identifier().DeprecatedFlyString_value(), declaration_kind);
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}
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if (!m_state.in_generator_function_context && match(TokenType::Yield)) {
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if (m_state.strict_mode)
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syntax_error("Identifier must not be a reserved word in strict mode ('yield')");
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume().DeprecatedFlyString_value());
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume().DeprecatedFlyString_value(), declaration_kind);
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}
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if (!m_state.await_expression_is_valid && match(TokenType::Async)) {
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if (m_program_type == Program::Type::Module)
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syntax_error("Identifier must not be a reserved word in modules ('async')");
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume().DeprecatedFlyString_value());
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return create_identifier_and_register_in_current_scope({ m_source_code, binding_start.position(), position() }, consume().DeprecatedFlyString_value(), declaration_kind);
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}
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return {};
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@ -3329,7 +3343,7 @@ NonnullRefPtr<VariableDeclaration const> Parser::parse_variable_declaration(IsFo
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}
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target = pattern.release_nonnull();
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} else if (auto lexical_binding = parse_lexical_binding()) {
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} else if (auto lexical_binding = parse_lexical_binding(declaration_kind)) {
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check_identifier_name_for_assignment_validity(lexical_binding->string());
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if ((declaration_kind == DeclarationKind::Let || declaration_kind == DeclarationKind::Const) && lexical_binding->string() == "let"sv)
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syntax_error("Lexical binding may not be called 'let'");
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@ -5145,11 +5159,11 @@ Parser::ForbiddenTokens Parser::ForbiddenTokens::forbid(std::initializer_list<To
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template NonnullRefPtr<FunctionExpression> Parser::parse_function_node(u16, Optional<Position> const&);
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template NonnullRefPtr<FunctionDeclaration> Parser::parse_function_node(u16, Optional<Position> const&);
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NonnullRefPtr<Identifier const> Parser::create_identifier_and_register_in_current_scope(SourceRange range, DeprecatedFlyString string)
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NonnullRefPtr<Identifier const> Parser::create_identifier_and_register_in_current_scope(SourceRange range, DeprecatedFlyString string, Optional<DeclarationKind> declaration_kind)
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{
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auto id = create_ast_node<Identifier const>(range, string);
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if (m_state.current_scope_pusher)
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m_state.current_scope_pusher->register_identifier(const_cast<Identifier&>(*id));
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m_state.current_scope_pusher->register_identifier(const_cast<Identifier&>(*id), declaration_kind);
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return id;
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}
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@ -96,7 +96,7 @@ public:
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};
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NonnullRefPtr<VariableDeclaration const> parse_variable_declaration(IsForLoopVariableDeclaration is_for_loop_variable_declaration = IsForLoopVariableDeclaration::No);
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RefPtr<Identifier const> parse_lexical_binding();
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[[nodiscard]] RefPtr<Identifier const> parse_lexical_binding(Optional<DeclarationKind> = {});
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NonnullRefPtr<UsingDeclaration const> parse_using_declaration(IsForLoopVariableDeclaration is_for_loop_variable_declaration = IsForLoopVariableDeclaration::No);
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NonnullRefPtr<Statement const> parse_for_statement();
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@ -347,7 +347,7 @@ private:
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}
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};
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NonnullRefPtr<Identifier const> create_identifier_and_register_in_current_scope(SourceRange range, DeprecatedFlyString string);
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[[nodiscard]] NonnullRefPtr<Identifier const> create_identifier_and_register_in_current_scope(SourceRange range, DeprecatedFlyString string, Optional<DeclarationKind> = {});
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NonnullRefPtr<SourceCode const> m_source_code;
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Vector<Position> m_rule_starts;
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