This is mostly a development helper, to move all undefined symbols
in shared libraries to link time rather than load time.
At the same time, set --no-allow-shlib-undefined and -z,defs to
further enforce the rule.
This will allow us to use the GC to manage the lifetime of objects
that are not C++ objects, such as Swift objects. In the future we
could expand this cursed FFI to other languages as well.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
Instead, smuggle it in as a `void*` private data and let Javascript
aware code cast out that pointer to a VM&.
In order to make this split, rename JS::Cell to JS::CellImpl. Once we
have a LibGC, this will become GC::Cell. CellImpl then has no specific
knowledge of the VM& and Realm&. That knowledge is instead put into
JS::Cell, which inherits from CellImpl. JS::Cell is responsible for
JavaScript's realm initialization, as well as converting of the void*
private data to what it knows should be the VM&.
This is really just a type alias for NonnullGCPtr<T>, but it provides
a way to have non-owning non-visited NonnullGCPtr<T> without getting
yelled at by the Clang plugin for catching GC errors.
GC-allocated objects should never have JS::SafeFunction/JS::Handle
fields.
For now the plugin only emits warnings here, as there are many cases
of this occurring in the codebase that aren't trivial to fix. It is also
behind a CMake flag since it is a _very_ loud warning.
Now that the lambda capture plugin isn't full of false-positives, we can
make the jump and start halting builds for these errors. It also allows
these plugins to be useful in CI.
Instead of being opt-out with NOESCAPE, it is now opt-in with ESCAPING.
Opt-out is ideal, but unfortunately this was extremely noisy when
compiling the entire codebase. Escaping functions are rarer than non-
escaping ones, so let's just go with that for now.
This also allows us to gradually add heuristics for detecting missing
ESCAPING annotations and emitting them as errors. It also nicely matches
the spelling that Swift uses (@escaping), which is where this idea
originally came from.
This is a more general and robust replacement of the LibJSGCVerifier.
We want to add more generic static analysis, and this new plugin will
be built in a way that integrates into the rest of the system.
