I believe it's not stable because it gives std::boxed::Box special treatment in the language. They'd rather find a solution that could work equally well for sma

I believe it's not stable because it gives std::boxed::Box special treatment in the language. They'd rather find a solution that could work equally well for smart pointers defined outside of std. Box patterns are likely to be superseded by one of these: https://github.com/rust-lang/rust/issues/42640 https://github.com/rust-lang/rust/issues/42640 https://github.com/rust-lang/rust/issues/87121 https://github.com/rust-lang/rust/issues/87121