When launched with the new --enable-idl-tracing option, we now log
every call to web platform APIs declared via IDL, along with the
arguments passed.
This can be very helpful when trying to figure out what a site is
doing, especially if it's not doing what you'd expect.
On macOS, it's not trivial to get a Mach task port for your children.
This implementation registers the chrome process as a well-known
service with launchd based on its pid, and lets each child process
send over a reference to its mach_task_self() back to the chrome.
We'll need this Mach task port right to get process statistics.
C++ classes that inherit from JS::Cell and are leaf classes should have
their own type-specific allocator. We also do this for non-leaf classes
that are constructable from JS.
To do this, JSON messages are passed to communicate information about
each class the Clang tool comes across. This is the only message we have
to worry about for now, but in the future if we want to transmit
different kinds of information, we can make this message format more
generic.
This allows each Clang process to send JSON messages to the
orchestrating Python process, which aggregates the message and can do
something with them all at the end. This is required because we run
Clang multithreaded to speed up the tool execution.
I did try to add a second frontend tool that accepts all the files at
once, but it was _extremely_ slow, so this is the next best thing.
For example, consider the following code snippet:
Vector<Function<void()>> m_callbacks;
void add_callback(Function<void()> callback)
{
m_callbacks.append(move(callback));
}
// Somewhere else...
void do_something()
{
int a = 10;
add_callback([&a] {
dbgln("a is {}", a);
});
} // Oops, "a" is now destroyed, but the callback in m_callbacks
// has a reference to it!
We now statically detect the capture of "a" in the lambda above and flag
it as incorrect. Note that capturing the value implicitly with a capture
list of `[&]` would also be detected.
Of course, many functions that accept Function<...> don't store them
anywhere, instead immediately invoking them inside of the function. To
avoid a warning in this case, the parameter can be annotated with
NOESCAPE to indicate that capturing stack variables is fine:
void do_something_now(NOESCAPE Function<...> callback)
{
callback(...)
}
Lastly, there are situations where the callback does generally escape,
but where the caller knows that it won't escape long enough to cause any
issues. For example, consider this fake example from LibWeb:
void do_something()
{
bool is_done = false;
HTML::queue_global_task([&] {
do_some_work();
is_done = true;
});
HTML::main_thread_event_loop().spin_until([&] {
return is_done;
});
}
In this case, we know that the lambda passed to queue_global_task will
be executed before the function returns, and will not persist
afterwards. To avoid this warning, annotate the type of the capture
with IGNORE_USE_IN_ESCAPING_LAMBDA:
void do_something()
{
IGNORE_USE_IN_ESCAPING_LAMBDA bool is_done = false;
// ...
}
As defined in: https://w3c.github.io/pointerevents
With the exception of the getCoalescedEvents and getPredictedEvents
APIs.
There are still many other parts of that spec (such as the event
handlers) left to implement, but this does get us at least some of the
way.
Previously, parsing would continue if a parameter wasn't given a name
and malformed code would be generated, leading to hard to diagnose
compiler errors.
These allow us to binary search the code point compositions based on
the first code point being combined, which makes the search close to
O(log N) instead of O(N).
Previously we would only warn about missing calls to visit inside
visit_edges implementations, now we warn as well when there's no
visit_edges implementation at all.
This lets us avoid false positives when a GCPtr-wrapped member is only
a weak reference which is automatically updated by the GC when the
member's gc state is updated.
clang doesn't make all `Base::visit_edges()` calls CXXMemberCallExprs
This would lead to false positives like in HeapFunction,
where the matcher would fail to match and report a warning.
Also previously the matcher would succeed
if the visited class is missing the call to `Base::visit_edges()`
but an included class has a correct method.
The new matcher checks the current class for `visit_edges`-overrides
and matches all `visit_edges`-memberExprs inside,
checking those for starting with `Base::`.
This seems to get rid of the false positives
and should be more correct detecting missing calls.
When building, clang would throw errors about dangling references.
Extracting `template_args` to a variable before the loop and
indexing into that seems to fix the errors.
Since we're parsing segment headers for random-access jbig2 inputs
already, just always do that and get the image dimensions from the
PageInformation segment data. Not all that much more code, and it
makes this script much more pleasant to use.
