Function compute_query_response_instantiation_values 

fn compute_query_response_instantiation_values<D, I, T>(
    delegate: &D,
    original_values: &[I::GenericArg],
    response: &Canonical<I, T>,
    span: I::Span,
) -> CanonicalVarValues<I>
where
    D: SolverDelegate<Interner = I>,
    I: Interner,
    T: ResponseT<I>,

This returns the canonical variable values to instantiate the bound variables of the canonical response. This depends on the original_values for the bound variables.