We were allowing this dangerous kind of thing:
RefPtr<Base> base;
RefPtr<Derived> derived = base;
This patch changes the {Nonnull,}RefPtr constructors so this is no
longer possible.
To downcast one of these pointers, there is now static_ptr_cast<T>:
RefPtr<Derived> derived = static_ptr_cast<Derived>(base);
Fixing this exposed a ton of cowboy-downcasts in various places,
which we're now forced to fix. :^)
The generic swap() is not able to swap a NonnullRefPtr with itself,
due to its use of a temporary and NonnullRefPtr asserting when trying
to move() from an already move()'d instance.
Given the following situation:
struct Object : public RefCounted<Object> {
RefPtr<Object> parent;
}
NonnullRefPtr<Object> object = get_some_object();
object = *object->parent;
We would previously crash if 'object' was the only strongly referencing
pointer to 'parent'. This happened because NonnullRefPtr would unref
the outgoing pointee before reffing the incoming pointee.
This patch fixes that by implementing NonnullRefPtr assignments using
pointer swaps, just like RefPtr already did.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
Since NonnullRefPtr and NonnullOwnPtr cannot be null, it is pointless
to convert them to a bool, since it would always be true.
This patch makes it an error to null-check one of these pointers.
Use AK::exchange() to switch out the internal storage. Also mark these
functions with [[nodiscard]] to provoke an compile-time error if they
are called without using the return value.
This gives us much better error messages when you try to use them.
Without this change, it would complain about the absence of functions
named ref() and deref() on RefPtr itself. With it, we instead get a
"hey, this function is deleted" error.
Change operator=(T&) to operator=T(const T&) also, to keep assigning
a const T& to a NonnullRefPtr working.
Clang loses the typestate when passing NonnullRefPtr's via lambda captures.
This is unfortunate, but not much we can do about it. Allowing ptr() makes
it possible to use captured NonnullRefPtrs as you'd expect.
Add an "ElementType" typedef to NonnullOwnPtr and NonnullRefPtr to allow
clients to easily find the pointee type. Then use this to remove a template
argument from NonnullPtrVector. :^)
We shouldn't allow constructing e.g an OwnPtr from a RefPtr, and similar
conversions. Instead just delete those functions so the compiler whines
loudly if you try to use them.
This patch also deletes constructing OwnPtr from a WeakPtr, even though
that *may* be a valid thing to do, it's sufficiently weird that we can
make the client jump through some hoops if he really wants it. :^)
This patch removes copy_ref() from RefPtr and NonnullRefPtr. This means that
it's now okay to simply copy these smart pointers instead:
- RefPtr = RefPtr // Okay!
- RefPtr = NonnullRefPtr // Okay!
- NonnullRefPtr = NonnullRefPtr // Okay!
- NonnullRefPtr = RefPtr // Not okay, since RefPtr can be null.
- Delete the default constructor instead of just making it private.
It's never valid to create an empty NonnullRefPtr.
- Add copy assignment operators. I originally omitted these to force use
of .copy_ref() at call sites, but the hassle/gain ratio is minuscule.
- Allow calling all the assignment operators in all consumable states.
This codifies that it's okay to overwrite a moved-from NonnullRefPtr.
