Defer storage destruction during Godot->Rust call - #1671
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API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-1671 |
For `RefCounted` objects, user code can drop the last ref to itself mid-call (e.g. a signal handler nulling the emitter), which previously freed the storage under the active instance. Now the storage counts "claims" on itself (Godot's + 1 per call on the stack), and is freed by whoever releases the last one.
The weighed alternatives and cost tables belong in the design notes, not in rustdoc. Keep the conclusion and the one non-obvious constraint.
The claim keeps the storage alive, but the Godot object itself cannot be kept: neither free() nor the last reference drop is vetoable. Godot then dereferences a dangling `this` after the callback returns, e.g. in Object::_notification_forward(). Reuse the claim counter to detect the situation and report it, instead of letting it stay silent. Manually managed classes are excluded, since free() during a call on the object is an established pattern.
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For
RefCountedobjects, user code can drop the last ref to itself mid-call (e.g. a signal handler nulling the emitter), which previously freed the storage under the active instance.I did not go the route of GDScript to add a strong-ref to every Godot->Rust call, for multiple reasons:
NOTIFICATION_PREDELETE)Instead, the storage now counts "claims" on itself (Godot's + 1 per call on the stack), and is freed by whoever releases the last one. This is a bit more complex but retains the benefits of the old version.
Fixes #1666, now covered via itest
signal_emitter_destroyed_during_own_call.