Working Around a Swift “nonmutating” Crash
Nataliya Patsovska (via Florent Pillet):
We recently found a mysterious bug in our framework Flow present only when building with Xcode 10:
-Mutating an object on the same line it was created on would cause BAD_ACCESS crash.
-Splitting the line into 2 lines would work fine.
Of course that was a workaround, not the fix.
[…]
Turns out we were using the “nonmutating” keyword in a protocol extension and the compiler decided it is safe to deallocate the object implementing the protocol too early.
Moving the setter to the class somehow worked[…]
See also: Mutating And Nonmutating Functions.
Previously: Exploring Swift Array’s Implementation.
Update (2018-10-15): Joe Groff notes the bug page and a potential fix.
