Trait rustc_const_eval::interpret::Provenance

pub trait Provenance: Copy + Debug {
    const OFFSET_IS_ADDR: bool;
    const ERR_ON_PARTIAL_PTR_OVERWRITE: bool;

    fn fmt(ptr: &Pointer<Self>, f: &mut Formatter<'_>) -> Result<(), Error>;
    fn get_alloc_id(self) -> Option<AllocId>;
}

This trait abstracts over the kind of provenance that is associated with a Pointer. It is mostly opaque; the Machine trait extends it with some more operations that also have access to some global state. We don’t actually care about this Debug bound (we use Provenance::fmt to format the entire pointer), but derive adds some unnecessary bounds.

Required Associated Constants

const OFFSET_IS_ADDR: bool

Says whether the offset field of Pointers with this provenance is the actual physical address. If true, ptr-to-int casts work by simply discarding the provenance. If false`, ptr-to-int casts are not supported. The offset must be relative in that case.

const ERR_ON_PARTIAL_PTR_OVERWRITE: bool

We also use this trait to control whether to abort execution when a pointer is being partially overwritten (this avoids a separate trait in allocation.rs just for this purpose).

Required Methods

fn fmt(ptr: &Pointer<Self>, f: &mut Formatter<'_>) -> Result<(), Error>

Determines how a pointer should be printed.

fn get_alloc_id(self) -> Option<AllocId>

If OFFSET_IS_ADDR == false, provenance must always be able to identify the allocation this ptr points to (i.e., this must return Some). Otherwise this function is best-effort (but must agree with Machine::ptr_get_alloc). (Identifying the offset in that allocation, however, is harder – use Memory::ptr_get_alloc for that.)

Implementors