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LibJS: Ensure function declarations don't leak outside function scopes

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When using VM::set_variable() to put the created ScriptFunction onto a
ScopeObject, we would previously unexpectedly reach the global object as
set_variable() checks each traversed scope for an existing Variable with
the given name - which would cause a leak of the inner function past the
outer function (we even had a test expecting that behaviour!). Now we
first declare functions (as DeclarationKind::Var) before setting them.
This will need some more work to make hoisting across non-lexical scopes
work, but it fixes this specific issue for now.

Fixes #6766.
This commit is contained in:
Linus Groh 2021-05-13 23:58:45 +01:00
parent b221cad659
commit a92dc4e30d
3 changed files with 31 additions and 10 deletions
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14
Userland/Libraries/LibJS/Interpreter.cpp
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@ -1,9 +1,11 @@
/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2021, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/StringBuilder.h>
#include <LibJS/AST.h>
#include <LibJS/Interpreter.h>
@ -80,13 +82,17 @@ const GlobalObject& Interpreter::global_object() const
void Interpreter::enter_scope(const ScopeNode& scope_node, ScopeType scope_type, GlobalObject& global_object)
{
for (auto& declaration : scope_node.functions()) {
auto* function = ScriptFunction::create(global_object, declaration.name(), declaration.body(), declaration.parameters(), declaration.function_length(), current_scope(), declaration.is_strict_mode());
vm().set_variable(declaration.name(), function, global_object);
}
ScopeGuard guard([&] {
for (auto& declaration : scope_node.functions()) {
auto* function = ScriptFunction::create(global_object, declaration.name(), declaration.body(), declaration.parameters(), declaration.function_length(), current_scope(), declaration.is_strict_mode());
vm().set_variable(declaration.name(), function, global_object);
}
});
if (scope_type == ScopeType::Function) {
push_scope({ scope_type, scope_node, false });
for (auto& declaration : scope_node.functions())
current_scope()->put_to_scope(declaration.name(), { js_undefined(), DeclarationKind::Var });
return;
}