Nullability specifiers not supported in %subclass methods

[jacobcxdev]

What are the steps to reproduce this issue?

- (instancetype _Nonnull)initWithCoder:(NSCoder *)coder {
    …
}

What happens?

https://paste.mod.gg/ejizatesay.rb

What were you expecting to happen?

Successful compilation.

Any logs, error output, etc?

https://paste.mod.gg/ejizatesay.rb

Any other comments?

…

What versions of software are you using?

Operating System: macOS 10.15.4

Toolchain Version: …

SDK Version: 13.4