This counter is increased each time a synchronous execution sequence
completes, and will allow us to emulate the abstract operations
AddToKeptObjects & ClearKeptObjects efficiently.
This is very similar to Object::define_native_property, but here the
native functions are exported as standalone JS getter and setter
functions, instead of being transparently called by interactions with
the property.
Some of this stuff is already tested properly in the name and message
prototype tests, so let's focus on covering all error types here as well
instead.
The fact that they *are* subclasses is an implementation detail and
should not be highlighted. The spec calls these NativeErrors, so let's
use that.
Also added a comment explaining *why* they inherit from Error - I was
about to change that :^)
The property name in an object literal can either be a literal or a
computed name, in which case any AssignmentExpression can be used, we
now only parse AssignmentExpression instead of the previous incorrect
behaviour which allowed any Expression (Specifically, comma
expressions).
The addition of an is_generator parameter broke this, as is_strict was
being passed in, causing an assertion.
This is being addressed by changing it to an enum in #7981, but in the
meantime let's just fix these two cases.
20.5.1.1 Error ( message )
When the Error function is called with argument message, the
following steps are taken:
[...]
3b. Let msgDesc be the PropertyDescriptor {
[[Value]]: msg,
[[Writable]]: true,
[[Enumerable]]: false,
[[Configurable]]: true
}.
3c. Perform ! DefinePropertyOrThrow(O, "message", msgDesc).
The FunctionPrototype is correct for ErrorConstructor itself:
20.5.2 Properties of the Error Constructor
The Error constructor:
- has a [[Prototype]] internal slot whose value is
%Function.prototype%.
However, not for all the other "NativeError" constructors:
20.5.6.2 Properties of the NativeError Constructors
Each NativeError constructor:
- has a [[Prototype]] internal slot whose value is %Error%.
Non-RangeError exceptions can be thrown by user implementations of
valueOf (which are called by to_index), and the specification disallows
changing the type of the thrown error.
The second argument (the default constructor) and the return value have
to be constructors (as a result functions), so we can require that
explicitly by using appropriate types.
This patch adds a CallType to the Bytecode::Op::Call instruction,
which can be either Call or Construct. We then generate Construct
calls for the NewExpression AST node.
When executed, these get fed into VM::construct().
This adds a new PushLexicalEnvironment instruction that creates a new
LexicalEnvironment and pushes it on the VM's scope stack.
There is no corresponding PopLexicalEnvironment instruction yet,
so this will behave incorrectly with let/const scopes for example.
This replaces Bytecode::Op::EnterScope with a new NewFunction op that
instantiates a ScriptFunction from a given FunctionNode (AST).
This is then used to instantiate the local functions directly from
bytecode when entering a ScopeNode. :^)
These will be partly handled by the relevant ScopeNode due to
hoisting, same basic idea as function declarations.
VariableDeclaration needs to do some work, but let's stub it out
first and start empty.
EnterUnwindContext pushes an unwind context (exception handler and/or
finalizer) onto a stack.
LeaveUnwindContext pops the unwind context from that stack.
Upon return to the interpreter loop we check whether the VM has an
exception pending. If no unwind context is available we return from the
loop. If an exception handler is available we clear the VM's exception,
put the exception value into the accumulator register, clear the unwind
context's handler and jump to the handler. If no handler is available
but a finalizer is available we save the exception value + metadata (for
later use by ContinuePendingUnwind), clear the VM's exception, pop the
unwind context and jump to the finalizer.
ContinuePendingUnwind checks whether a saved exception is available. If
no saved exception is available it jumps to the resume label. Otherwise
it stores the exception into the VM.
The Jump after LeaveUnwindContext could be integrated into the
LeaveUnwindContext instruction. I've kept them separate for now to make
the bytecode more readable.
> try { 1; throw "x" } catch (e) { 2 } finally { 3 }; 4
1:
[ 0] EnterScope
[ 10] EnterUnwindContext handler:@4 finalizer:@3
[ 38] EnterScope
[ 48] LoadImmediate 1
[ 60] NewString 1 ("x")
[ 70] Throw
<for non-terminated blocks: insert LeaveUnwindContext + Jump @3 here>
2:
[ 0] LoadImmediate 4
3:
[ 0] EnterScope
[ 10] LoadImmediate 3
[ 28] ContinuePendingUnwind resume:@2
4:
[ 0] SetVariable 0 (e)
[ 10] EnterScope
[ 20] LoadImmediate 2
[ 38] LeaveUnwindContext
[ 3c] Jump @3
String Table:
0: e
1: x
