Function instantiate_canonical_state 

pub fn instantiate_canonical_state<D, I, T>(
    delegate: &D,
    span: I::Span,
    param_env: I::ParamEnv,
    orig_values: &mut Vec<I::GenericArg>,
    state: CanonicalState<I, T>,
) -> T
where
    D: SolverDelegate<Interner = I>,
    I: Interner,
    T: TypeFoldable<I>,