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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,136 @@ | ||
| use rustc::traits; | ||
| use rustc::ty::subst::SubstsRef; | ||
| use rustc::ty::{self, Instance, TyCtxt, TypeFoldable}; | ||
| use rustc_hir::def_id::DefId; | ||
| 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, | ||
| } | ||
| } |
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