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LibJS: Don't hoist functions under certain circumstances

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When a lexical declaration with the same name as a function exists,
the function is not hoisted (annex B).
This commit is contained in:
Hendi 2021-07-05 21:45:34 +02:00 • committed by Linus Groh
parent c194afd17c
commit 3411d50737
4 changed files with 45 additions and 8 deletions
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39
Userland/Libraries/LibJS/Parser.cpp
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@ -64,7 +64,24 @@ public:
scope_node->add_variables(m_parser.m_state.let_scopes.last());
scope_node->add_functions(m_parser.m_state.current_scope->function_declarations);
scope_node->add_hoisted_functions(m_parser.m_state.current_scope->hoisted_function_declarations);
for (auto& hoistable_function : m_parser.m_state.current_scope->hoisted_function_declarations) {
if (is_hoistable(hoistable_function)) {
scope_node->add_hoisted_function(hoistable_function.declaration);
}
}
}
static bool is_hoistable(Parser::Scope::HoistableDeclaration& declaration)
{
auto& name = declaration.declaration->name();
// See if we find any conflicting lexical declaration on the way up
for (RefPtr<Parser::Scope> scope = declaration.scope; !scope.is_null(); scope = scope->parent) {
if (scope->lexical_declarations.contains(name)) {
return false;
}
}
return true;
}
Parser& m_parser;
@ -304,7 +321,8 @@ NonnullRefPtr<Declaration> Parser::parse_declaration()
case TokenType::Function: {
auto declaration = parse_function_node<FunctionDeclaration>();
m_state.current_scope->function_declarations.append(declaration);
m_state.current_scope->get_current_function_scope()->hoisted_function_declarations.append(declaration);
auto hoisting_target = m_state.current_scope->get_current_function_scope();
hoisting_target->hoisted_function_declarations.append({ declaration, *m_state.current_scope });
return declaration;
}
case TokenType::Let:
@ -1760,10 +1778,23 @@ NonnullRefPtr<VariableDeclaration> Parser::parse_variable_declaration(bool for_l
consume_or_insert_semicolon();
auto declaration = create_ast_node<VariableDeclaration>({ m_state.current_token.filename(), rule_start.position(), position() }, declaration_kind, move(declarations));
if (declaration_kind == DeclarationKind::Var)
if (declaration_kind == DeclarationKind::Var) {
m_state.var_scopes.last().append(declaration);
else
} else {
m_state.let_scopes.last().append(declaration);
for (auto& declarator : declaration->declarations()) {
declarator.target().visit(
[&](const NonnullRefPtr<Identifier>& id) {
m_state.current_scope->lexical_declarations.set(id->string());
},
[&](const NonnullRefPtr<BindingPattern>& binding) {
binding->for_each_bound_name([&](const auto& name) {
m_state.current_scope->lexical_declarations.set(name);
});
});
}
}
return declaration;
}