Enum flowistry_pdg::rustc::mir::BorrowKind

pub enum BorrowKind {
    Shared,
    Shallow,
    Mut {
        kind: MutBorrowKind,
    },
}

Variants

Shared

Data must be immutable and is aliasable.

Shallow

The immediately borrowed place must be immutable, but projections from it don’t need to be. For example, a shallow borrow of a.b doesn’t conflict with a mutable borrow of a.b.c.

This is used when lowering matches: when matching on a place we want to ensure that place have the same value from the start of the match until an arm is selected. This prevents this code from compiling:

let mut x = &Some(0);
match *x {
    None => (),
    Some(_) if { x = &None; false } => (),
    Some(_) => (),
}

This can’t be a shared borrow because mutably borrowing (*x as Some).0 should not prevent if let None = x { ... }, for example, because the mutating (*x as Some).0 can’t affect the discriminant of x. We can also report errors with this kind of borrow differently.

Mut

Fields

kind: MutBorrowKind

Data is mutable and not aliasable.