This PR does not fix the main issue with our current implementation:
The specification requires that we first check the JSON string for
validity with an ECMA-404 compliant parser, and then evaluate it as if
it was javascript code, of which we do neither at the moment.
Specifically, we now cast to a u32 instead of an i32, as well as use
the validity check required by the specification. The current
constructor is still quite far from the specification, as we directly
set the indexed properties' length instead of going through the Array's
overriden DefineOwnProperty. (and as a result the checks imposed by the
ArraySetLength abstract operation)
This is not exactly compliant with the specification, but our current
bound function implementation isn't either, so its not currently
possible to implement it the way the specification requires.
This patch adds a new ArgumentsObject class to represent what the spec
calls "Arguments Exotic Objects"
These are constructed by the new CreateMappedArgumentsObject when the
`arguments` identifier is resolved in a callee context.
The implementation is incomplete and doesn't yet support mapping of
the parameter variables to the indexed properties of `arguments`.
This includes checking that the target is a constructor, not just a
function, as well as switching the order of the list creation and
argument validation to match the specification, to ensure correct
exception throwing order.
This patch implements the IsSimpleParameterList static semantics for
ordinary function objects.
We now also create an unmapped arguments object for callee contexts
with non-simple parameter lists, instead of only doing it in strict
mode. Covered by test262.
This makes the implicit run-time assertion in PropertyName::to_string()
into an explicit compile-time requirement, removes a wasteful FlyString
-> PropertyName -> FlyString construction from NativeFunction::create()
and allows setting the function name to a null string for anonymous
native functions.
The unsigned shift right implementation was already doing this, but
the spec requires a mod32 of rhs before the shift for the signed shift
right implementation as well. Caught by UBSAN and oss-fuzz.
If the value we get after fmod in Value::to_u32 is negative, UBSAN
complains that -N is out of bounds for u32. An extra static cast to i64
makes it stop complaining. An alternative implementation could add 2^32
if the fmod'd value is negative. Caught by UBSAN and oss-fuzz.
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
