I don't know if this is the right solution, but it does fix an issue accessing std::ios::openmode caused by the ios typedef being defined before ios_base is fully specified.
The assert is being triggered because the window is already being removed in open_windows. It does not really matter if it returns false anyway, as long as the window is removed one way or another.
This is useful because these types are created at static init time, and giving them a constexpr constructor and trivial destructor lets them be created during constant initialization, which helps to prevent static init ordering issues.
Rationale:
1. Per standard, fstream::open takes 2 arguments.
If platforms add a third, they're out of spec.
2. The only platform I could find that takes a file
mask specifically as the third argument is IRIX,
which Panda hasn't targeted in forever.
3. The mask being requested isn't even particularly
interesting - falling back to a platform default
is best.
4. When USE_PANDAFILESTREAM is defined, pfstream
is implemented as PandaFileStream, which doesn't
have a three-argument open() and breaks immediately.
5. makepanda doesn't ever define HAVE_OPEN_MASK
6. It's been broken for so long that, if it were
important to anybody, it would have been fixed by now.
This was a regression in 0bb81a43c9e4fffb37cc2234c1b0fbae42020ceb which was not keeping an edge case in mind if a weak pointer is locked during object destruction. This issue was fixed by 525a05ea2b1d00a1db901f883f1755943aeff33c, but that is not enough since it causes CharacterJointEffect::get_character() to return null now, so we need a separate method to check if a CharacterJointEffect belongs to a given character. This is more efficient, too.
Fixes#330
This came up in #330; the Character destructor caused something to call lock() on a weak pointer to that character, which would induce a ref() and unref() pair, but since the refcount was 0, this would call the destructor and thereby create infinite recursion.
I considered instead calling mark_deleted() inside unref() so that the callbacks get to run before the object is actually deleted, and was_deleted() will become true as soon as unref() reaches 0. However, this would require grabbing the lock in unref() to be fully thread-safe, since we would need to bring the refcount to 0 and mark the object as deleted in one atomic operation, so this would be an unacceptable general performance penalty.
Instead, WeakPointerTo::lock() now atomically increments the reference count if it is not already zero, and returns null otherwise. This should be safe because the object cannot be deleted while the WeakReferenceList lock is held.
This lets one drop the reference to AICharacter after adding it to a flock or AIWorld without crashes.
Also replace the silly and inefficient custom-rolled linked list implementation of AICharPool with a vector, and add additional safety checks.
Fixes#318
This makes it possible to include it multiple times in a single
translation unit, and/or multiple times in a single dynamic
library (and without excess code bloat, too).
