https://doc.rust-lang.org/nightly/nightly-rustc/miri/borrow_tracker/stacked_borrows/item/constant.PERM_MASK.html
PERM_MASK in miri::borrow_tracker::stacked_borrows::item - Rust
API documentation for the Rust `PERM_MASK` constant in crate `miri`.
stacked borrowspermmaskmiritracker