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Stephen Boddy
02aa60b135
Reported: Blender segfaults when clicking Cancel on the "newer
autosave found" recovery popup shown by LoadProject at startup.
Root cause: LoadProject.execute()/invoke() triggered the recovery
popup via bpy.ops.bim.load_autosaved_recovery_popup("INVOKE_DEFAULT",
...) and returned that call's result ({'RUNNING_MODAL'}) as their own
return value, without LoadProject itself ever calling
modal_handler_add(). Blender's window manager takes a RUNNING_MODAL
return as a promise the operator registered its own modal handler;
since it hadn't, the WM's operator bookkeeping was left corrupted -
silently, since this is heap/state corruption rather than an
immediate crash. It only surfaced later, when the real modal operator
(the popup) closed and the WM reconciled its modal stack, which lines
up with the crash occurring specifically on dialog close regardless
of which button was pressed. check_autosave_recovery() now returns a
plain bool and fires the popup fire-and-forget; LoadProject reports
its own honest {"FINISHED"}.
Also hardened, as defense in depth: LoadAutosavedRecoveryPopup's
execute()/cancel() call back into bim.load_project(...), which (with
should_start_fresh_session) calls wm.read_homefile() and tears down
the window manager/screens. Doing that synchronously from inside this
popup's own execute()/cancel() - itself invoked from deep inside
Blender's modal handling for the popup's button click - risks the
same class of use-after-free as the timer bug fixed in the previous
commit. The reload is now deferred by one timer tick so it runs after
the popup's modal handling has fully unwound, and the deferred
callback closes over plain values rather than `self`, since the
operator instance may not survive past cancel()/execute() returning.
This defer-only change was tried and tested first, on the (incorrect)
assumption it was the root cause: it produced a byte-for-byte
identical crash backtrace on retest, which is what pointed at the
RUNNING_MODAL bug above as the actual cause - the defer change alone
was insufficient because the corruption happens when the popup is
first shown, not when it's closed.
Generated with the assistance of an AI coding tool.
(cherry picked from commit d0eca6fa90)