Struct rustc_mir::borrow_check::universal_regions::UniversalRegionIndices

pub(in borrow_check::universal_regions) struct UniversalRegionIndices<'tcx> {
    indices: FxHashMap<Region<'tcx>, RegionVid>,
}

Fields

indices: FxHashMap<Region<'tcx>, RegionVid>

For those regions that may appear in the parameter environment ('static and early-bound regions), we maintain a map from the ty::Region to the internal RegionVid we are using. This is used because trait matching and type-checking will feed us region constraints that reference those regions and we need to be able to map them our internal RegionVid. This is basically equivalent to a InternalSubsts, except that it also contains an entry for ReStatic -- it might be nice to just use a substs, and then handle ReStatic another way.

Implementations

impl<'tcx> UniversalRegionIndices<'tcx>

pub(in borrow_check::universal_regions) fn insert_late_bound_region(
    &mut self,
    r: Region<'tcx>,
    vid: RegionVid
)

Initially, the UniversalRegionIndices map contains only the early-bound regions in scope. Once that is all setup, we come in later and instantiate the late-bound regions, and then we insert the ReFree version of those into the map as well. These are used for error reporting.

pub fn to_region_vid(&self, r: Region<'tcx>) -> RegionVid

Converts r into a local inference variable: r can either by a ReVar (i.e., already a reference to an inference variable) or it can be 'static or some early-bound region. This is useful when taking the results from type-checking and trait-matching, which may sometimes reference those regions from the ParamEnv. It is also used during initialization. Relies on the indices map having been fully initialized.

pub fn fold_to_region_vids<T>(&self, tcx: TyCtxt<'tcx>, value: T) -> T where
    T: TypeFoldable<'tcx>, 

Replaces all free regions in value with region vids, as returned by to_region_vid.

Trait Implementations

impl<'tcx> Debug for UniversalRegionIndices<'tcx>

pub fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.