| use rustc::ty::subst::SubstsRef; |
| use rustc::ty::{self, Instance, TyCtxt, TypeFoldable}; |
| use rustc_hir::def_id::DefId; |
| use rustc_infer::traits; |
| use rustc_target::spec::abi::Abi; |
| |
| use log::debug; |
| |
| pub fn resolve_instance<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| def_id: DefId, |
| substs: SubstsRef<'tcx>, |
| ) -> Option<Instance<'tcx>> { |
| debug!("resolve(def_id={:?}, substs={:?})", def_id, substs); |
| let result = if let Some(trait_def_id) = tcx.trait_of_item(def_id) { |
| debug!(" => associated item, attempting to find impl in param_env {:#?}", param_env); |
| let item = tcx.associated_item(def_id); |
| resolve_associated_item(tcx, &item, param_env, trait_def_id, substs) |
| } else { |
| let ty = tcx.type_of(def_id); |
| let item_type = tcx.subst_and_normalize_erasing_regions(substs, param_env, &ty); |
| |
| let def = match item_type.kind { |
| ty::FnDef(..) |
| if { |
| let f = item_type.fn_sig(tcx); |
| f.abi() == Abi::RustIntrinsic || f.abi() == Abi::PlatformIntrinsic |
| } => |
| { |
| debug!(" => intrinsic"); |
| ty::InstanceDef::Intrinsic(def_id) |
| } |
| _ => { |
| if Some(def_id) == tcx.lang_items().drop_in_place_fn() { |
| let ty = substs.type_at(0); |
| if ty.needs_drop(tcx, param_env.with_reveal_all()) { |
| debug!(" => nontrivial drop glue"); |
| ty::InstanceDef::DropGlue(def_id, Some(ty)) |
| } else { |
| debug!(" => trivial drop glue"); |
| ty::InstanceDef::DropGlue(def_id, None) |
| } |
| } else { |
| debug!(" => free item"); |
| ty::InstanceDef::Item(def_id) |
| } |
| } |
| }; |
| Some(Instance { def: def, substs: substs }) |
| }; |
| debug!("resolve(def_id={:?}, substs={:?}) = {:?}", def_id, substs, result); |
| result |
| } |
| |
| fn resolve_associated_item<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| trait_item: &ty::AssocItem, |
| param_env: ty::ParamEnv<'tcx>, |
| trait_id: DefId, |
| rcvr_substs: SubstsRef<'tcx>, |
| ) -> Option<Instance<'tcx>> { |
| let def_id = trait_item.def_id; |
| debug!( |
| "resolve_associated_item(trait_item={:?}, \ |
| param_env={:?}, \ |
| trait_id={:?}, \ |
| rcvr_substs={:?})", |
| def_id, param_env, trait_id, rcvr_substs |
| ); |
| |
| let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs); |
| let vtbl = tcx.codegen_fulfill_obligation((param_env, ty::Binder::bind(trait_ref))); |
| |
| // Now that we know which impl is being used, we can dispatch to |
| // the actual function: |
| match vtbl { |
| traits::VtableImpl(impl_data) => { |
| let (def_id, substs) = |
| traits::find_associated_item(tcx, param_env, trait_item, rcvr_substs, &impl_data); |
| |
| let resolved_item = tcx.associated_item(def_id); |
| |
| // Since this is a trait item, we need to see if the item is either a trait default item |
| // or a specialization because we can't resolve those unless we can `Reveal::All`. |
| // NOTE: This should be kept in sync with the similar code in |
| // `rustc::traits::project::assemble_candidates_from_impls()`. |
| let eligible = if !resolved_item.defaultness.is_default() { |
| true |
| } else if param_env.reveal == traits::Reveal::All { |
| !trait_ref.needs_subst() |
| } else { |
| false |
| }; |
| |
| if !eligible { |
| return None; |
| } |
| |
| let substs = tcx.erase_regions(&substs); |
| Some(ty::Instance::new(def_id, substs)) |
| } |
| traits::VtableGenerator(generator_data) => Some(Instance { |
| def: ty::InstanceDef::Item(generator_data.generator_def_id), |
| substs: generator_data.substs, |
| }), |
| traits::VtableClosure(closure_data) => { |
| let trait_closure_kind = tcx.fn_trait_kind_from_lang_item(trait_id).unwrap(); |
| Some(Instance::resolve_closure( |
| tcx, |
| closure_data.closure_def_id, |
| closure_data.substs, |
| trait_closure_kind, |
| )) |
| } |
| traits::VtableFnPointer(ref data) => Some(Instance { |
| def: ty::InstanceDef::FnPtrShim(trait_item.def_id, data.fn_ty), |
| substs: rcvr_substs, |
| }), |
| traits::VtableObject(ref data) => { |
| let index = traits::get_vtable_index_of_object_method(tcx, data, def_id); |
| Some(Instance { def: ty::InstanceDef::Virtual(def_id, index), substs: rcvr_substs }) |
| } |
| traits::VtableBuiltin(..) => { |
| if tcx.lang_items().clone_trait().is_some() { |
| Some(Instance { |
| def: ty::InstanceDef::CloneShim(def_id, trait_ref.self_ty()), |
| substs: rcvr_substs, |
| }) |
| } else { |
| None |
| } |
| } |
| traits::VtableAutoImpl(..) | traits::VtableParam(..) | traits::VtableTraitAlias(..) => None, |
| } |
| } |