pub fn fully_resolve<'tcx, T>(
    infcx: &InferCtxt<'tcx>,
    value: T,
) -> Result<T, FixupError>where
    T: TypeFoldable<TyCtxt<'tcx>>,Expand description
Full type resolution replaces all type and region variables with
their concrete results. If any variable cannot be replaced (never unified, etc)
then an Err result is returned.