Function resolve_var 

fn resolve_var<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
    infcx: &InferCtxt<'tcx>,
    value: T,
) -> T

Resolve inference variables to concrete values after unification. The method was renamed resolve_vars_if_possible → deeply_resolve_ignoring_regions in nightly 2026-09-11.