diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0307.md | 6 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/messages.ftl | 4 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/autoderef.rs | 37 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/wfcheck.rs | 27 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/method/probe.rs | 97 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/traits/query.rs | 12 |
6 files changed, 136 insertions, 47 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0307.md b/compiler/rustc_error_codes/src/error_codes/E0307.md index 0d29d56ea1a..b9c0493e8d6 100644 --- a/compiler/rustc_error_codes/src/error_codes/E0307.md +++ b/compiler/rustc_error_codes/src/error_codes/E0307.md @@ -65,8 +65,10 @@ impl Trait for Foo { ``` The nightly feature [Arbitrary self types][AST] extends the accepted -set of receiver types to also include any type that can dereference to -`Self`: +set of receiver types to also include any type that implements the +`Receiver` trait and can follow its chain of `Target` types to `Self`. +There's a blanket implementation of `Receiver` for `T: Deref`, so any +type which dereferences to `Self` can be used. ``` #![feature(arbitrary_self_types)] diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl index 32498d9c5ab..25feb95d5df 100644 --- a/compiler/rustc_hir_analysis/messages.ftl +++ b/compiler/rustc_hir_analysis/messages.ftl @@ -241,10 +241,10 @@ hir_analysis_invalid_generic_receiver_ty_help = use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`) hir_analysis_invalid_receiver_ty = invalid `self` parameter type: `{$receiver_ty}` - .note = type of `self` must be `Self` or a type that dereferences to it + .note = type of `self` must be `Self` or some type implementing `Receiver` hir_analysis_invalid_receiver_ty_help = - consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`) + consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>` hir_analysis_invalid_union_field = field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union diff --git a/compiler/rustc_hir_analysis/src/autoderef.rs b/compiler/rustc_hir_analysis/src/autoderef.rs index 5a66c31a0cc..d8e9227a87c 100644 --- a/compiler/rustc_hir_analysis/src/autoderef.rs +++ b/compiler/rustc_hir_analysis/src/autoderef.rs @@ -18,7 +18,6 @@ pub enum AutoderefKind { /// A type which must dispatch to a `Deref` implementation. Overloaded, } - struct AutoderefSnapshot<'tcx> { at_start: bool, reached_recursion_limit: bool, @@ -27,6 +26,10 @@ struct AutoderefSnapshot<'tcx> { obligations: PredicateObligations<'tcx>, } +/// Recursively dereference a type, considering both built-in +/// dereferences (`*`) and the `Deref` trait. +/// Although called `Autoderef` it can be configured to use the +/// `Receiver` trait instead of the `Deref` trait. pub struct Autoderef<'a, 'tcx> { // Meta infos: infcx: &'a InferCtxt<'tcx>, @@ -39,6 +42,7 @@ pub struct Autoderef<'a, 'tcx> { // Configurations: include_raw_pointers: bool, + use_receiver_trait: bool, silence_errors: bool, } @@ -69,6 +73,10 @@ impl<'a, 'tcx> Iterator for Autoderef<'a, 'tcx> { } // Otherwise, deref if type is derefable: + // NOTE: in the case of self.use_receiver_trait = true, you might think it would + // be better to skip this clause and use the Overloaded case only, since &T + // and &mut T implement Receiver. But built-in derefs apply equally to Receiver + // and Deref, and this has benefits for const and the emitted MIR. let (kind, new_ty) = if let Some(ty) = self.state.cur_ty.builtin_deref(self.include_raw_pointers) { debug_assert_eq!(ty, self.infcx.resolve_vars_if_possible(ty)); @@ -111,7 +119,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> { body_def_id: LocalDefId, span: Span, base_ty: Ty<'tcx>, - ) -> Autoderef<'a, 'tcx> { + ) -> Self { Autoderef { infcx, span, @@ -125,6 +133,7 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> { reached_recursion_limit: false, }, include_raw_pointers: false, + use_receiver_trait: false, silence_errors: false, } } @@ -137,8 +146,13 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> { return None; } - // <ty as Deref> - let trait_ref = ty::TraitRef::new(tcx, tcx.lang_items().deref_trait()?, [ty]); + // <ty as Deref>, or whatever the equivalent trait is that we've been asked to walk. + let (trait_def_id, trait_target_def_id) = if self.use_receiver_trait { + (tcx.lang_items().receiver_trait()?, tcx.lang_items().receiver_target()?) + } else { + (tcx.lang_items().deref_trait()?, tcx.lang_items().deref_target()?) + }; + let trait_ref = ty::TraitRef::new(tcx, trait_def_id, [ty]); let cause = traits::ObligationCause::misc(self.span, self.body_id); let obligation = traits::Obligation::new( tcx, @@ -151,11 +165,8 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> { return None; } - let (normalized_ty, obligations) = self.structurally_normalize(Ty::new_projection( - tcx, - tcx.lang_items().deref_target()?, - [ty], - ))?; + let (normalized_ty, obligations) = + self.structurally_normalize(Ty::new_projection(tcx, trait_target_def_id, [ty]))?; debug!("overloaded_deref_ty({:?}) = ({:?}, {:?})", ty, normalized_ty, obligations); self.state.obligations.extend(obligations); @@ -234,6 +245,14 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> { self } + /// Use `core::ops::Receiver` and `core::ops::Receiver::Target` as + /// the trait and associated type to iterate, instead of + /// `core::ops::Deref` and `core::ops::Deref::Target` + pub fn use_receiver_trait(mut self) -> Self { + self.use_receiver_trait = true; + self + } + pub fn silence_errors(mut self) -> Self { self.silence_errors = true; self diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs index c9773972d9a..57264d0bd2a 100644 --- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs +++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs @@ -1821,13 +1821,18 @@ fn receiver_is_valid<'tcx>( let mut autoderef = Autoderef::new(infcx, wfcx.param_env, wfcx.body_def_id, span, receiver_ty); + // The `arbitrary_self_types` feature allows custom smart pointer + // types to be method receivers, as identified by following the Receiver<Target=T> + // chain. + if arbitrary_self_types_enabled.is_some() { + autoderef = autoderef.use_receiver_trait(); + } + // The `arbitrary_self_types_pointers` feature allows raw pointer receivers like `self: *const Self`. if arbitrary_self_types_enabled == Some(ArbitrarySelfTypesLevel::WithPointers) { autoderef = autoderef.include_raw_pointers(); } - let receiver_trait_def_id = tcx.require_lang_item(LangItem::LegacyReceiver, Some(span)); - // Keep dereferencing `receiver_ty` until we get to `self_ty`. while let Some((potential_self_ty, _)) = autoderef.next() { debug!( @@ -1849,11 +1854,13 @@ fn receiver_is_valid<'tcx>( } // Without `feature(arbitrary_self_types)`, we require that each step in the - // deref chain implement `receiver`. + // deref chain implement `LegacyReceiver`. if arbitrary_self_types_enabled.is_none() { - if !receiver_is_implemented( + let legacy_receiver_trait_def_id = + tcx.require_lang_item(LangItem::LegacyReceiver, Some(span)); + if !legacy_receiver_is_implemented( wfcx, - receiver_trait_def_id, + legacy_receiver_trait_def_id, cause.clone(), potential_self_ty, ) { @@ -1866,7 +1873,7 @@ fn receiver_is_valid<'tcx>( cause.clone(), wfcx.param_env, potential_self_ty, - receiver_trait_def_id, + legacy_receiver_trait_def_id, ); } } @@ -1875,14 +1882,14 @@ fn receiver_is_valid<'tcx>( Err(ReceiverValidityError::DoesNotDeref) } -fn receiver_is_implemented<'tcx>( +fn legacy_receiver_is_implemented<'tcx>( wfcx: &WfCheckingCtxt<'_, 'tcx>, - receiver_trait_def_id: DefId, + legacy_receiver_trait_def_id: DefId, cause: ObligationCause<'tcx>, receiver_ty: Ty<'tcx>, ) -> bool { let tcx = wfcx.tcx(); - let trait_ref = ty::TraitRef::new(tcx, receiver_trait_def_id, [receiver_ty]); + let trait_ref = ty::TraitRef::new(tcx, legacy_receiver_trait_def_id, [receiver_ty]); let obligation = Obligation::new(tcx, cause, wfcx.param_env, trait_ref); @@ -1890,7 +1897,7 @@ fn receiver_is_implemented<'tcx>( true } else { debug!( - "receiver_is_implemented: type `{:?}` does not implement `Receiver` trait", + "receiver_is_implemented: type `{:?}` does not implement `LegacyReceiver` trait", receiver_ty ); false diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs index 039c117c099..91e65af8df9 100644 --- a/compiler/rustc_hir_typeck/src/method/probe.rs +++ b/compiler/rustc_hir_typeck/src/method/probe.rs @@ -366,6 +366,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { autoderefs: 0, from_unsafe_deref: false, unsize: false, + reachable_via_deref: true, }]), opt_bad_ty: None, reached_recursion_limit: false, @@ -516,47 +517,93 @@ fn method_autoderef_steps<'tcx>( let (ref infcx, goal, inference_vars) = tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &goal); let ParamEnvAnd { param_env, value: self_ty } = goal; - let mut autoderef = + // If arbitrary self types is not enabled, we follow the chain of + // `Deref<Target=T>`. If arbitrary self types is enabled, we instead + // follow the chain of `Receiver<Target=T>`, but we also record whether + // such types are reachable by following the (potentially shorter) + // chain of `Deref<Target=T>`. We will use the first list when finding + // potentially relevant function implementations (e.g. relevant impl blocks) + // but the second list when determining types that the receiver may be + // converted to, in order to find out which of those methods might actually + // be callable. + let mut autoderef_via_deref = Autoderef::new(infcx, param_env, hir::def_id::CRATE_DEF_ID, DUMMY_SP, self_ty) .include_raw_pointers() .silence_errors(); - let mut reached_raw_pointer = false; - let mut steps: Vec<_> = autoderef - .by_ref() - .map(|(ty, d)| { - let step = CandidateStep { - self_ty: infcx.make_query_response_ignoring_pending_obligations(inference_vars, ty), - autoderefs: d, - from_unsafe_deref: reached_raw_pointer, - unsize: false, - }; - if let ty::RawPtr(_, _) = ty.kind() { - // all the subsequent steps will be from_unsafe_deref - reached_raw_pointer = true; - } - step - }) - .collect(); - let final_ty = autoderef.final_ty(true); + let mut reached_raw_pointer = false; + let arbitrary_self_types_enabled = + tcx.features().arbitrary_self_types() || tcx.features().arbitrary_self_types_pointers(); + let (mut steps, reached_recursion_limit): (Vec<_>, bool) = if arbitrary_self_types_enabled { + let reachable_via_deref = + autoderef_via_deref.by_ref().map(|_| true).chain(std::iter::repeat(false)); + + let mut autoderef_via_receiver = + Autoderef::new(infcx, param_env, hir::def_id::CRATE_DEF_ID, DUMMY_SP, self_ty) + .include_raw_pointers() + .use_receiver_trait() + .silence_errors(); + let steps = autoderef_via_receiver + .by_ref() + .zip(reachable_via_deref) + .map(|((ty, d), reachable_via_deref)| { + let step = CandidateStep { + self_ty: infcx + .make_query_response_ignoring_pending_obligations(inference_vars, ty), + autoderefs: d, + from_unsafe_deref: reached_raw_pointer, + unsize: false, + reachable_via_deref, + }; + if ty.is_unsafe_ptr() { + // all the subsequent steps will be from_unsafe_deref + reached_raw_pointer = true; + } + step + }) + .collect(); + (steps, autoderef_via_receiver.reached_recursion_limit()) + } else { + let steps = autoderef_via_deref + .by_ref() + .map(|(ty, d)| { + let step = CandidateStep { + self_ty: infcx + .make_query_response_ignoring_pending_obligations(inference_vars, ty), + autoderefs: d, + from_unsafe_deref: reached_raw_pointer, + unsize: false, + reachable_via_deref: true, + }; + if ty.is_unsafe_ptr() { + // all the subsequent steps will be from_unsafe_deref + reached_raw_pointer = true; + } + step + }) + .collect(); + (steps, autoderef_via_deref.reached_recursion_limit()) + }; + let final_ty = autoderef_via_deref.final_ty(true); let opt_bad_ty = match final_ty.kind() { ty::Infer(ty::TyVar(_)) | ty::Error(_) => Some(MethodAutoderefBadTy { reached_raw_pointer, ty: infcx.make_query_response_ignoring_pending_obligations(inference_vars, final_ty), }), ty::Array(elem_ty, _) => { - let dereferences = steps.len() - 1; - + let autoderefs = steps.iter().filter(|s| s.reachable_via_deref).count() - 1; steps.push(CandidateStep { self_ty: infcx.make_query_response_ignoring_pending_obligations( inference_vars, Ty::new_slice(infcx.tcx, *elem_ty), ), - autoderefs: dereferences, + autoderefs, // this could be from an unsafe deref if we had // a *mut/const [T; N] from_unsafe_deref: reached_raw_pointer, unsize: true, + reachable_via_deref: true, // this is always the final type from + // autoderef_via_deref }); None @@ -569,7 +616,7 @@ fn method_autoderef_steps<'tcx>( MethodAutoderefStepsResult { steps: tcx.arena.alloc_from_iter(steps), opt_bad_ty: opt_bad_ty.map(|ty| &*tcx.arena.alloc(ty)), - reached_recursion_limit: autoderef.reached_recursion_limit(), + reached_recursion_limit, } } @@ -1065,6 +1112,10 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> { ) -> Option<PickResult<'tcx>> { self.steps .iter() + // At this point we're considering the types to which the receiver can be converted, + // so we want to follow the `Deref` chain not the `Receiver` chain. Filter out + // steps which can only be reached by following the (longer) `Receiver` chain. + .filter(|step| step.reachable_via_deref) .filter(|step| { debug!("pick_all_method: step={:?}", step); // skip types that are from a type error or that would require dereferencing diff --git a/compiler/rustc_middle/src/traits/query.rs b/compiler/rustc_middle/src/traits/query.rs index eeed5118592..f049da95f29 100644 --- a/compiler/rustc_middle/src/traits/query.rs +++ b/compiler/rustc_middle/src/traits/query.rs @@ -149,11 +149,21 @@ pub struct CandidateStep<'tcx> { /// `foo.by_raw_ptr()` will work and `foo.by_ref()` won't. pub from_unsafe_deref: bool, pub unsize: bool, + /// We will generate CandidateSteps which are reachable via a chain + /// of following `Receiver`. The first 'n' of those will be reachable + /// by following a chain of 'Deref' instead (since there's a blanket + /// implementation of Receiver for Deref). + /// We use the entire set of steps when identifying method candidates + /// (e.g. identifying relevant `impl` blocks) but only those that are + /// reachable via Deref when examining what the receiver type can + /// be converted into by autodereffing. + pub reachable_via_deref: bool, } #[derive(Copy, Clone, Debug, HashStable)] pub struct MethodAutoderefStepsResult<'tcx> { - /// The valid autoderef steps that could be found. + /// The valid autoderef steps that could be found by following a chain + /// of `Receiver<Target=T>` or `Deref<Target=T>` trait implementations. pub steps: &'tcx [CandidateStep<'tcx>], /// If Some(T), a type autoderef reported an error on. pub opt_bad_ty: Option<&'tcx MethodAutoderefBadTy<'tcx>>, |