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LibJS: Make Errors fully spec compliant

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The previous handling of the name and message properties specifically
was breaking websites that created their own error types and relied on
the error prototype working correctly - not assuming an JS::Error this
object, that is.

The way it works now, and it is supposed to work, is:

- Error.prototype.name and Error.prototype.message just have initial
  string values and are no longer getters/setters
- When constructing an error with a message, we create a regular
  property on the newly created object, so a lookup of the message
  property will either get it from the object directly or go though the
  prototype chain
- Internal m_name/m_message properties are no longer needed and removed

This makes printing errors slightly more complicated, as we can no
longer rely on the (safe) internal properties, and cannot trust a
property lookup either - get_without_side_effects() is used to solve
this, it's not perfect but something we can revisit later.

I did some refactoring along the way, there was some really old stuff in
there - accessing vm.call_frame().arguments[0] is not something we (have
to) do anymore :^)

Fixes #6245.
This commit is contained in:
Linus Groh 2021-04-12 00:08:28 +02:00 • committed by Andreas Kling
parent 6e9eb0a284
commit da177c6517
18 changed files with 157 additions and 180 deletions
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32
Userland/Utilities/js.cpp
View file

@ -239,18 +239,25 @@ static void print_function(const JS::Object& object, HashTable<JS::Object*>&)
out(" {}", static_cast<const JS::NativeFunction&>(object).name());
}
static void print_date(const JS::Object& date, HashTable<JS::Object*>&)
static void print_date(const JS::Object& object, HashTable<JS::Object*>&)
{
print_type("Date");
out(" \033[34;1m{}\033[0m", static_cast<const JS::Date&>(date).string());
out(" \033[34;1m{}\033[0m", static_cast<const JS::Date&>(object).string());
}
static void print_error(const JS::Object& object, HashTable<JS::Object*>&)
static void print_error(const JS::Object& object, HashTable<JS::Object*>& seen_objects)
{
auto& error = static_cast<const JS::Error&>(object);
print_type(error.name());
if (!error.message().is_empty())
out(" \033[31;1m{}\033[0m", error.message());
auto name = object.get_without_side_effects(vm->names.name).value_or(JS::js_undefined());
auto message = object.get_without_side_effects(vm->names.message).value_or(JS::js_undefined());
if (name.is_accessor() || name.is_native_property() || message.is_accessor() || message.is_native_property()) {
print_value(&object, seen_objects);
} else {
auto name_string = name.to_string_without_side_effects();
auto message_string = message.to_string_without_side_effects();
print_type(name_string);
if (!message_string.is_empty())
out(" \033[31;1m{}\033[0m", message_string);
}
}
static void print_regexp_object(const JS::Object& object, HashTable<JS::Object*>&)
@ -498,9 +505,11 @@ static bool parse_and_run(JS::Interpreter& interpreter, const StringView& source
}
auto handle_exception = [&] {
auto* exception = vm->exception();
vm->clear_exception();
out("Uncaught exception: ");
print(vm->exception()->value());
auto trace = vm->exception()->trace();
print(exception->value());
auto& trace = exception->trace();
if (trace.size() > 1) {
unsigned repetitions = 0;
for (size_t i = 0; i < trace.size(); ++i) {
@ -522,7 +531,6 @@ static bool parse_and_run(JS::Interpreter& interpreter, const StringView& source
repetitions = 0;
}
}
vm->clear_exception();
};
if (vm->exception()) {
@ -532,8 +540,8 @@ static bool parse_and_run(JS::Interpreter& interpreter, const StringView& source
if (s_print_last_result)
print(vm->last_value());
if (vm->exception()) {
return false;
handle_exception();
return false;
}
return true;
}
@ -738,7 +746,7 @@ int main(int argc, char** argv)
OwnPtr<JS::Interpreter> interpreter;
interrupt_interpreter = [&] {
auto error = JS::Error::create(interpreter->global_object(), "Error", "Received SIGINT");
auto error = JS::Error::create(interpreter->global_object(), "Received SIGINT");
vm->throw_exception(interpreter->global_object(), error);
};