Function rustc_typeck::collect::is_param

fn is_param(tcx: TyCtxt<'_>, ast_ty: &Ty<'_>, param_id: HirId) -> bool

Tests whether this is the AST for a reference to the type parameter with ID param_id. We use this so as to avoid running ast_ty_to_ty, because we want to avoid triggering an all-out conversion of the type to avoid inducing unnecessary cycles.