Struct rustc_trait_selection::infer::canonical::OriginalQueryValues

pub struct OriginalQueryValues<'tcx> {
    pub universe_map: SmallVec<[UniverseIndex; 4]>,
    pub var_values: SmallVec<[GenericArg<'tcx>; 8]>,
}

When we canonicalize a value to form a query, we wind up replacing various parts of it with canonical variables. This struct stores those replaced bits to remember for when we process the query result.

Fields

universe_map: SmallVec<[UniverseIndex; 4]>

Map from the universes that appear in the query to the universes in the caller context. For the time being, we only ever put ROOT values into the query, so this map is very simple.

var_values: SmallVec<[GenericArg<'tcx>; 8]>

This is equivalent to CanonicalVarValues, but using a SmallVec yields a significant performance win.