The `arguments` object should only have the *arguments* as numeric
properties, not the *parameters*.
Given this function:
function foo(a, b) {
return arguments.length;
}
Calling foo() with no arguments now correctly returns 0 instead of 2.
This was a standalone function previously (get_method()), but instead of
passing a Value to it, we can just make it a method.
Also add spec step comments and fix the receiver value by using GetV().
Like Get(), but with any value instead of an object - it's calling
ToObject() for us and passes the value to [[Get]]() as the receiver.
This will be used in GetMethod() (and a couple of other places, which
can be updated over time).
I also tried something new here: adding the three steps from the spec as
inline comments :^)
If we define a property with just a setter/getter (not both) we must:
- take the previous getter/setter if defined on the actual object
- overwrite the other to nullptr if it is from a prototype
Negative numeric properties are not a thing (and we even VERIFY()'d this
in the constructor). It still allows using types with a negative range
for now as we have various places using int for example (without
actually needing the negative range, but that's a different story).
u32 is the internal type of `m_number` already, so this now allows us to
leverage the full u32 range for numeric properties.
Requires a bunch of find-and-replace updates across LibJS, but
constructing a PropertyName from a nullptr Symbol* should not be
possible - let's enforce this at the compiler level instead of using
VERIFY() (and already dereference Symbol pointers at the call site).
Our Reference class now has the same fields as the spec:
- Base (a non-nullish value, an environment record, or `unresolvable`)
- Referenced Name (the name of the binding)
- Strict (whether the reference originated in strict mode code)
- ThisValue (if non-empty, the reference represents a `super` keyword)
The main difference from before is that we now resolve the environment
record that a reference interacts with. Previously we simply resolved
to either "local variable" or "global variable".
The associated abstract operations are still largely non-conforming,
since we don't yet implement proper variable bindings. But this patch
should at least fix a handful of test262 cases. :^)
There's one minor regression: some TypeError message strings get
a little worse due to doing a RequireObjectCoercible earlier in the
evaluation of MemberExpression.
At the moment these environments are always the same as the lexical
ones, so this didn't cause any trouble. Once we start separating them
we have to make sure both environments are protected.
This matches what ECMAScript calls it. Also make it a JS::Function*
instead of a generic Value, since it will always either be a function
object or null.
This is true for environments created by `with` statements, and false
for other (global) object environments.
Also add the WithBaseObject abstract operation while we're here.
We had a cached shape for environment records to make instantiating
them fast. Now that environment records don't inherit from JS::Object,
we can just get rid of this. :^)
Previously, EnvironmentRecord was a JS::Object. This was done because
GlobalObject inherited from EnvironmentRecord. Now that this is no
longer the case, we can simplify things by making EnvironmentRecord
inherit from Cell directly.
This also removes the need for environment records to have a shape,
which was awkward. This will be removed in the following patch.
Our environment records are currently weird in that they inherit from
Object, but don't have a connection to the global object.
I'd like to remove this inheritance, and the first step is giving them
their own pointer to the global object.
This patch adds the concept of variable bindings to the various
environment record classes. The bindings are not yet hooked up to
anything, this is just fleshing out all the operations.
Most of this is following the spec exactly, but in a few cases we are
missing the requisite abstract operations to do the exact right thing.
I've added FIXME's in those cases where I noticed it.
