| // Copyright 2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use super::{ |
| FulfillmentError, |
| FulfillmentErrorCode, |
| MismatchedProjectionTypes, |
| Obligation, |
| ObligationCause, |
| ObligationCauseCode, |
| OutputTypeParameterMismatch, |
| TraitNotObjectSafe, |
| PredicateObligation, |
| SelectionContext, |
| SelectionError, |
| ObjectSafetyViolation, |
| MethodViolationCode, |
| }; |
| |
| use fmt_macros::{Parser, Piece, Position}; |
| use hir::def_id::DefId; |
| use infer::{self, InferCtxt, TypeOrigin}; |
| use ty::{self, ToPredicate, ToPolyTraitRef, Ty, TyCtxt, TypeFoldable}; |
| use ty::error::ExpectedFound; |
| use ty::fast_reject; |
| use ty::fold::TypeFolder; |
| use ty::subst::{self, Subst, TypeSpace}; |
| use util::nodemap::{FnvHashMap, FnvHashSet}; |
| |
| use std::cmp; |
| use std::fmt; |
| use syntax::ast; |
| use syntax::attr::{AttributeMethods, AttrMetaMethods}; |
| use syntax_pos::Span; |
| use errors::DiagnosticBuilder; |
| |
| #[derive(Debug, PartialEq, Eq, Hash)] |
| pub struct TraitErrorKey<'tcx> { |
| span: Span, |
| warning_node_id: Option<ast::NodeId>, |
| predicate: ty::Predicate<'tcx> |
| } |
| |
| impl<'a, 'gcx, 'tcx> TraitErrorKey<'tcx> { |
| fn from_error(infcx: &InferCtxt<'a, 'gcx, 'tcx>, |
| e: &FulfillmentError<'tcx>, |
| warning_node_id: Option<ast::NodeId>) -> Self { |
| let predicate = |
| infcx.resolve_type_vars_if_possible(&e.obligation.predicate); |
| TraitErrorKey { |
| span: e.obligation.cause.span, |
| predicate: infcx.tcx.erase_regions(&predicate), |
| warning_node_id: warning_node_id |
| } |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { |
| pub fn report_fulfillment_errors(&self, errors: &Vec<FulfillmentError<'tcx>>) { |
| for error in errors { |
| self.report_fulfillment_error(error, None); |
| } |
| } |
| |
| pub fn report_fulfillment_errors_as_warnings(&self, |
| errors: &Vec<FulfillmentError<'tcx>>, |
| node_id: ast::NodeId) { |
| for error in errors { |
| self.report_fulfillment_error(error, Some(node_id)); |
| } |
| } |
| |
| fn report_fulfillment_error(&self, |
| error: &FulfillmentError<'tcx>, |
| warning_node_id: Option<ast::NodeId>) { |
| let error_key = TraitErrorKey::from_error(self, error, warning_node_id); |
| debug!("report_fulfillment_errors({:?}) - key={:?}", |
| error, error_key); |
| if !self.reported_trait_errors.borrow_mut().insert(error_key) { |
| debug!("report_fulfillment_errors: skipping duplicate"); |
| return; |
| } |
| match error.code { |
| FulfillmentErrorCode::CodeSelectionError(ref e) => { |
| self.report_selection_error(&error.obligation, e, warning_node_id); |
| } |
| FulfillmentErrorCode::CodeProjectionError(ref e) => { |
| self.report_projection_error(&error.obligation, e, warning_node_id); |
| } |
| FulfillmentErrorCode::CodeAmbiguity => { |
| self.maybe_report_ambiguity(&error.obligation); |
| } |
| } |
| } |
| |
| fn report_projection_error(&self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &MismatchedProjectionTypes<'tcx>, |
| warning_node_id: Option<ast::NodeId>) |
| { |
| let predicate = |
| self.resolve_type_vars_if_possible(&obligation.predicate); |
| |
| if predicate.references_error() { |
| return |
| } |
| if let Some(warning_node_id) = warning_node_id { |
| self.tcx.sess.add_lint( |
| ::lint::builtin::UNSIZED_IN_TUPLE, |
| warning_node_id, |
| obligation.cause.span, |
| format!("type mismatch resolving `{}`: {}", |
| predicate, |
| error.err)); |
| return |
| } |
| self.probe(|_| { |
| let origin = TypeOrigin::Misc(obligation.cause.span); |
| let err_buf; |
| let mut err = &error.err; |
| let mut values = None; |
| |
| // try to find the mismatched types to report the error with. |
| // |
| // this can fail if the problem was higher-ranked, in which |
| // cause I have no idea for a good error message. |
| if let ty::Predicate::Projection(ref data) = predicate { |
| let mut selcx = SelectionContext::new(self); |
| let (data, _) = self.replace_late_bound_regions_with_fresh_var( |
| obligation.cause.span, |
| infer::LateBoundRegionConversionTime::HigherRankedType, |
| data); |
| let normalized = super::normalize_projection_type( |
| &mut selcx, |
| data.projection_ty, |
| obligation.cause.clone(), |
| 0 |
| ); |
| let origin = TypeOrigin::Misc(obligation.cause.span); |
| if let Err(error) = self.eq_types( |
| false, origin, |
| data.ty, normalized.value |
| ) { |
| values = Some(infer::ValuePairs::Types(ExpectedFound { |
| expected: normalized.value, |
| found: data.ty, |
| })); |
| err_buf = error; |
| err = &err_buf; |
| } |
| } |
| |
| let mut diag = struct_span_err!( |
| self.tcx.sess, origin.span(), E0271, |
| "type mismatch resolving `{}`", predicate |
| ); |
| self.note_type_err(&mut diag, origin, values, err); |
| self.note_obligation_cause(&mut diag, obligation); |
| diag.emit(); |
| }); |
| } |
| |
| fn impl_substs(&self, |
| did: DefId, |
| obligation: PredicateObligation<'tcx>) |
| -> subst::Substs<'tcx> { |
| let tcx = self.tcx; |
| |
| let ity = tcx.lookup_item_type(did); |
| let (tps, rps, _) = |
| (ity.generics.types.get_slice(TypeSpace), |
| ity.generics.regions.get_slice(TypeSpace), |
| ity.ty); |
| |
| let rps = self.region_vars_for_defs(obligation.cause.span, rps); |
| let mut substs = subst::Substs::new( |
| subst::VecPerParamSpace::empty(), |
| subst::VecPerParamSpace::new(rps, Vec::new(), Vec::new())); |
| self.type_vars_for_defs(obligation.cause.span, |
| TypeSpace, |
| &mut substs, |
| tps); |
| substs |
| } |
| |
| fn fuzzy_match_tys(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> bool { |
| /// returns the fuzzy category of a given type, or None |
| /// if the type can be equated to any type. |
| fn type_category<'tcx>(t: Ty<'tcx>) -> Option<u32> { |
| match t.sty { |
| ty::TyBool => Some(0), |
| ty::TyChar => Some(1), |
| ty::TyStr => Some(2), |
| ty::TyInt(..) | ty::TyUint(..) | |
| ty::TyInfer(ty::IntVar(..)) => Some(3), |
| ty::TyFloat(..) | ty::TyInfer(ty::FloatVar(..)) => Some(4), |
| ty::TyEnum(..) => Some(5), |
| ty::TyStruct(..) => Some(6), |
| ty::TyBox(..) | ty::TyRef(..) | ty::TyRawPtr(..) => Some(7), |
| ty::TyArray(..) | ty::TySlice(..) => Some(8), |
| ty::TyFnDef(..) | ty::TyFnPtr(..) => Some(9), |
| ty::TyTrait(..) => Some(10), |
| ty::TyClosure(..) => Some(11), |
| ty::TyTuple(..) => Some(12), |
| ty::TyProjection(..) => Some(13), |
| ty::TyParam(..) => Some(14), |
| ty::TyInfer(..) | ty::TyError => None |
| } |
| } |
| |
| match (type_category(a), type_category(b)) { |
| (Some(cat_a), Some(cat_b)) => match (&a.sty, &b.sty) { |
| (&ty::TyStruct(def_a, _), &ty::TyStruct(def_b, _)) | |
| (&ty::TyEnum(def_a, _), &ty::TyEnum(def_b, _)) => |
| def_a == def_b, |
| _ => cat_a == cat_b |
| }, |
| // infer and error can be equated to all types |
| _ => true |
| } |
| } |
| |
| fn impl_similar_to(&self, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| obligation: &PredicateObligation<'tcx>) |
| -> Option<DefId> |
| { |
| let tcx = self.tcx; |
| |
| let trait_ref = tcx.erase_late_bound_regions(&trait_ref); |
| let trait_self_ty = trait_ref.self_ty(); |
| |
| let mut self_match_impls = vec![]; |
| let mut fuzzy_match_impls = vec![]; |
| |
| self.tcx.lookup_trait_def(trait_ref.def_id) |
| .for_each_relevant_impl(self.tcx, trait_self_ty, |def_id| { |
| let impl_trait_ref = tcx |
| .impl_trait_ref(def_id) |
| .unwrap() |
| .subst(tcx, &self.impl_substs(def_id, obligation.clone())); |
| |
| let impl_self_ty = impl_trait_ref.self_ty(); |
| |
| if let Ok(..) = self.can_equate(&trait_self_ty, &impl_self_ty) { |
| self_match_impls.push(def_id); |
| |
| if trait_ref.substs.types.get_slice(TypeSpace).iter() |
| .zip(impl_trait_ref.substs.types.get_slice(TypeSpace)) |
| .all(|(u,v)| self.fuzzy_match_tys(u, v)) |
| { |
| fuzzy_match_impls.push(def_id); |
| } |
| } |
| }); |
| |
| let impl_def_id = if self_match_impls.len() == 1 { |
| self_match_impls[0] |
| } else if fuzzy_match_impls.len() == 1 { |
| fuzzy_match_impls[0] |
| } else { |
| return None |
| }; |
| |
| if tcx.has_attr(impl_def_id, "rustc_on_unimplemented") { |
| Some(impl_def_id) |
| } else { |
| None |
| } |
| } |
| |
| fn on_unimplemented_note(&self, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| obligation: &PredicateObligation<'tcx>) -> Option<String> { |
| let def_id = self.impl_similar_to(trait_ref, obligation) |
| .unwrap_or(trait_ref.def_id()); |
| let trait_ref = trait_ref.skip_binder(); |
| |
| let span = obligation.cause.span; |
| let mut report = None; |
| for item in self.tcx.get_attrs(def_id).iter() { |
| if item.check_name("rustc_on_unimplemented") { |
| let err_sp = item.meta().span.substitute_dummy(span); |
| let def = self.tcx.lookup_trait_def(trait_ref.def_id); |
| let trait_str = def.trait_ref.to_string(); |
| if let Some(ref istring) = item.value_str() { |
| let mut generic_map = def.generics.types.iter_enumerated() |
| .map(|(param, i, gen)| { |
| (gen.name.as_str().to_string(), |
| trait_ref.substs.types.get(param, i) |
| .to_string()) |
| }).collect::<FnvHashMap<String, String>>(); |
| generic_map.insert("Self".to_string(), |
| trait_ref.self_ty().to_string()); |
| let parser = Parser::new(&istring); |
| let mut errored = false; |
| let err: String = parser.filter_map(|p| { |
| match p { |
| Piece::String(s) => Some(s), |
| Piece::NextArgument(a) => match a.position { |
| Position::ArgumentNamed(s) => match generic_map.get(s) { |
| Some(val) => Some(val), |
| None => { |
| span_err!(self.tcx.sess, err_sp, E0272, |
| "the #[rustc_on_unimplemented] \ |
| attribute on \ |
| trait definition for {} refers to \ |
| non-existent type parameter {}", |
| trait_str, s); |
| errored = true; |
| None |
| } |
| }, |
| _ => { |
| span_err!(self.tcx.sess, err_sp, E0273, |
| "the #[rustc_on_unimplemented] attribute \ |
| on trait definition for {} must have \ |
| named format arguments, eg \ |
| `#[rustc_on_unimplemented = \ |
| \"foo {{T}}\"]`", trait_str); |
| errored = true; |
| None |
| } |
| } |
| } |
| }).collect(); |
| // Report only if the format string checks out |
| if !errored { |
| report = Some(err); |
| } |
| } else { |
| span_err!(self.tcx.sess, err_sp, E0274, |
| "the #[rustc_on_unimplemented] attribute on \ |
| trait definition for {} must have a value, \ |
| eg `#[rustc_on_unimplemented = \"foo\"]`", |
| trait_str); |
| } |
| break; |
| } |
| } |
| report |
| } |
| |
| fn find_similar_impl_candidates(&self, |
| trait_ref: ty::PolyTraitRef<'tcx>) |
| -> Vec<ty::TraitRef<'tcx>> |
| { |
| let simp = fast_reject::simplify_type(self.tcx, |
| trait_ref.skip_binder().self_ty(), |
| true); |
| let mut impl_candidates = Vec::new(); |
| let trait_def = self.tcx.lookup_trait_def(trait_ref.def_id()); |
| |
| match simp { |
| Some(simp) => trait_def.for_each_impl(self.tcx, |def_id| { |
| let imp = self.tcx.impl_trait_ref(def_id).unwrap(); |
| let imp_simp = fast_reject::simplify_type(self.tcx, |
| imp.self_ty(), |
| true); |
| if let Some(imp_simp) = imp_simp { |
| if simp != imp_simp { |
| return; |
| } |
| } |
| impl_candidates.push(imp); |
| }), |
| None => trait_def.for_each_impl(self.tcx, |def_id| { |
| impl_candidates.push( |
| self.tcx.impl_trait_ref(def_id).unwrap()); |
| }) |
| }; |
| impl_candidates |
| } |
| |
| fn report_similar_impl_candidates(&self, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| err: &mut DiagnosticBuilder) |
| { |
| let simp = fast_reject::simplify_type(self.tcx, |
| trait_ref.skip_binder().self_ty(), |
| true); |
| let mut impl_candidates = Vec::new(); |
| let trait_def = self.tcx.lookup_trait_def(trait_ref.def_id()); |
| |
| match simp { |
| Some(simp) => trait_def.for_each_impl(self.tcx, |def_id| { |
| let imp = self.tcx.impl_trait_ref(def_id).unwrap(); |
| let imp_simp = fast_reject::simplify_type(self.tcx, |
| imp.self_ty(), |
| true); |
| if let Some(imp_simp) = imp_simp { |
| if simp != imp_simp { |
| return; |
| } |
| } |
| impl_candidates.push(imp); |
| }), |
| None => trait_def.for_each_impl(self.tcx, |def_id| { |
| impl_candidates.push( |
| self.tcx.impl_trait_ref(def_id).unwrap()); |
| }) |
| }; |
| |
| if impl_candidates.is_empty() { |
| return; |
| } |
| |
| err.help(&format!("the following implementations were found:")); |
| |
| let end = cmp::min(4, impl_candidates.len()); |
| for candidate in &impl_candidates[0..end] { |
| err.help(&format!(" {:?}", candidate)); |
| } |
| if impl_candidates.len() > 4 { |
| err.help(&format!("and {} others", impl_candidates.len()-4)); |
| } |
| } |
| |
| /// Reports that an overflow has occurred and halts compilation. We |
| /// halt compilation unconditionally because it is important that |
| /// overflows never be masked -- they basically represent computations |
| /// whose result could not be truly determined and thus we can't say |
| /// if the program type checks or not -- and they are unusual |
| /// occurrences in any case. |
| pub fn report_overflow_error<T>(&self, |
| obligation: &Obligation<'tcx, T>, |
| suggest_increasing_limit: bool) -> ! |
| where T: fmt::Display + TypeFoldable<'tcx> |
| { |
| let predicate = |
| self.resolve_type_vars_if_possible(&obligation.predicate); |
| let mut err = struct_span_err!(self.tcx.sess, obligation.cause.span, E0275, |
| "overflow evaluating the requirement `{}`", |
| predicate); |
| |
| if suggest_increasing_limit { |
| self.suggest_new_overflow_limit(&mut err); |
| } |
| |
| self.note_obligation_cause(&mut err, obligation); |
| |
| err.emit(); |
| self.tcx.sess.abort_if_errors(); |
| bug!(); |
| } |
| |
| /// Reports that a cycle was detected which led to overflow and halts |
| /// compilation. This is equivalent to `report_overflow_error` except |
| /// that we can give a more helpful error message (and, in particular, |
| /// we do not suggest increasing the overflow limit, which is not |
| /// going to help). |
| pub fn report_overflow_error_cycle(&self, cycle: &[PredicateObligation<'tcx>]) -> ! { |
| let cycle = self.resolve_type_vars_if_possible(&cycle.to_owned()); |
| assert!(cycle.len() > 0); |
| |
| debug!("report_overflow_error_cycle: cycle={:?}", cycle); |
| |
| self.report_overflow_error(&cycle[0], false); |
| } |
| |
| pub fn report_selection_error(&self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &SelectionError<'tcx>, |
| warning_node_id: Option<ast::NodeId>) |
| { |
| let span = obligation.cause.span; |
| let mut err = match *error { |
| SelectionError::Unimplemented => { |
| if let ObligationCauseCode::CompareImplMethodObligation = obligation.cause.code { |
| span_err!( |
| self.tcx.sess, span, E0276, |
| "the requirement `{}` appears on the impl \ |
| method but not on the corresponding trait method", |
| obligation.predicate); |
| return; |
| } else { |
| match obligation.predicate { |
| ty::Predicate::Trait(ref trait_predicate) => { |
| let trait_predicate = |
| self.resolve_type_vars_if_possible(trait_predicate); |
| |
| if self.tcx.sess.has_errors() && trait_predicate.references_error() { |
| return; |
| } else { |
| let trait_ref = trait_predicate.to_poly_trait_ref(); |
| |
| if let Some(warning_node_id) = warning_node_id { |
| self.tcx.sess.add_lint( |
| ::lint::builtin::UNSIZED_IN_TUPLE, |
| warning_node_id, |
| obligation.cause.span, |
| format!("the trait bound `{}` is not satisfied", |
| trait_ref.to_predicate())); |
| return; |
| } |
| |
| let mut err = struct_span_err!( |
| self.tcx.sess, span, E0277, |
| "the trait bound `{}` is not satisfied", |
| trait_ref.to_predicate()); |
| |
| // Try to report a help message |
| |
| if !trait_ref.has_infer_types() && |
| self.predicate_can_apply(trait_ref) { |
| // If a where-clause may be useful, remind the |
| // user that they can add it. |
| // |
| // don't display an on-unimplemented note, as |
| // these notes will often be of the form |
| // "the type `T` can't be frobnicated" |
| // which is somewhat confusing. |
| err.help(&format!("consider adding a `where {}` bound", |
| trait_ref.to_predicate())); |
| } else if let Some(s) = self.on_unimplemented_note(trait_ref, |
| obligation) { |
| // If it has a custom "#[rustc_on_unimplemented]" |
| // error message, let's display it! |
| err.note(&s); |
| } else { |
| // If we can't show anything useful, try to find |
| // similar impls. |
| let impl_candidates = |
| self.find_similar_impl_candidates(trait_ref); |
| if impl_candidates.len() > 0 { |
| self.report_similar_impl_candidates(trait_ref, &mut err); |
| } |
| } |
| err |
| } |
| } |
| |
| ty::Predicate::Equate(ref predicate) => { |
| let predicate = self.resolve_type_vars_if_possible(predicate); |
| let err = self.equality_predicate(span, |
| &predicate).err().unwrap(); |
| struct_span_err!(self.tcx.sess, span, E0278, |
| "the requirement `{}` is not satisfied (`{}`)", |
| predicate, err) |
| } |
| |
| ty::Predicate::RegionOutlives(ref predicate) => { |
| let predicate = self.resolve_type_vars_if_possible(predicate); |
| let err = self.region_outlives_predicate(span, |
| &predicate).err().unwrap(); |
| struct_span_err!(self.tcx.sess, span, E0279, |
| "the requirement `{}` is not satisfied (`{}`)", |
| predicate, err) |
| } |
| |
| ty::Predicate::Projection(..) | ty::Predicate::TypeOutlives(..) => { |
| let predicate = |
| self.resolve_type_vars_if_possible(&obligation.predicate); |
| struct_span_err!(self.tcx.sess, span, E0280, |
| "the requirement `{}` is not satisfied", |
| predicate) |
| } |
| |
| ty::Predicate::ObjectSafe(trait_def_id) => { |
| let violations = self.tcx.object_safety_violations(trait_def_id); |
| let err = self.tcx.report_object_safety_error(span, |
| trait_def_id, |
| warning_node_id, |
| violations); |
| if let Some(err) = err { |
| err |
| } else { |
| return; |
| } |
| } |
| |
| ty::Predicate::ClosureKind(closure_def_id, kind) => { |
| let found_kind = self.closure_kind(closure_def_id).unwrap(); |
| let closure_span = self.tcx.map.span_if_local(closure_def_id).unwrap(); |
| let mut err = struct_span_err!( |
| self.tcx.sess, closure_span, E0525, |
| "expected a closure that implements the `{}` trait, \ |
| but this closure only implements `{}`", |
| kind, |
| found_kind); |
| err.span_note( |
| obligation.cause.span, |
| &format!("the requirement to implement \ |
| `{}` derives from here", kind)); |
| err.emit(); |
| return; |
| } |
| |
| ty::Predicate::WellFormed(ty) => { |
| // WF predicates cannot themselves make |
| // errors. They can only block due to |
| // ambiguity; otherwise, they always |
| // degenerate into other obligations |
| // (which may fail). |
| span_bug!(span, "WF predicate not satisfied for {:?}", ty); |
| } |
| |
| ty::Predicate::Rfc1592(ref data) => { |
| span_bug!( |
| obligation.cause.span, |
| "RFC1592 predicate not satisfied for {:?}", |
| data); |
| } |
| } |
| } |
| } |
| |
| OutputTypeParameterMismatch(ref expected_trait_ref, ref actual_trait_ref, ref e) => { |
| let expected_trait_ref = self.resolve_type_vars_if_possible(&*expected_trait_ref); |
| let actual_trait_ref = self.resolve_type_vars_if_possible(&*actual_trait_ref); |
| if actual_trait_ref.self_ty().references_error() { |
| return; |
| } |
| struct_span_err!(self.tcx.sess, span, E0281, |
| "type mismatch: the type `{}` implements the trait `{}`, \ |
| but the trait `{}` is required ({})", |
| expected_trait_ref.self_ty(), |
| expected_trait_ref, |
| actual_trait_ref, |
| e) |
| } |
| |
| TraitNotObjectSafe(did) => { |
| let violations = self.tcx.object_safety_violations(did); |
| let err = self.tcx.report_object_safety_error(span, did, |
| warning_node_id, |
| violations); |
| if let Some(err) = err { |
| err |
| } else { |
| return; |
| } |
| } |
| }; |
| self.note_obligation_cause(&mut err, obligation); |
| err.emit(); |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { |
| pub fn recursive_type_with_infinite_size_error(self, |
| type_def_id: DefId) |
| -> DiagnosticBuilder<'tcx> |
| { |
| assert!(type_def_id.is_local()); |
| let span = self.map.span_if_local(type_def_id).unwrap(); |
| let mut err = struct_span_err!(self.sess, span, E0072, |
| "recursive type `{}` has infinite size", |
| self.item_path_str(type_def_id)); |
| err.help(&format!("insert indirection (e.g., a `Box`, `Rc`, or `&`) \ |
| at some point to make `{}` representable", |
| self.item_path_str(type_def_id))); |
| err |
| } |
| |
| pub fn report_object_safety_error(self, |
| span: Span, |
| trait_def_id: DefId, |
| warning_node_id: Option<ast::NodeId>, |
| violations: Vec<ObjectSafetyViolation>) |
| -> Option<DiagnosticBuilder<'tcx>> |
| { |
| let mut err = match warning_node_id { |
| Some(_) => None, |
| None => { |
| Some(struct_span_err!( |
| self.sess, span, E0038, |
| "the trait `{}` cannot be made into an object", |
| self.item_path_str(trait_def_id))) |
| } |
| }; |
| |
| let mut reported_violations = FnvHashSet(); |
| for violation in violations { |
| if !reported_violations.insert(violation.clone()) { |
| continue; |
| } |
| let buf; |
| let note = match violation { |
| ObjectSafetyViolation::SizedSelf => { |
| "the trait cannot require that `Self : Sized`" |
| } |
| |
| ObjectSafetyViolation::SupertraitSelf => { |
| "the trait cannot use `Self` as a type parameter \ |
| in the supertrait listing" |
| } |
| |
| ObjectSafetyViolation::Method(method, |
| MethodViolationCode::StaticMethod) => { |
| buf = format!("method `{}` has no receiver", |
| method.name); |
| &buf |
| } |
| |
| ObjectSafetyViolation::Method(method, |
| MethodViolationCode::ReferencesSelf) => { |
| buf = format!("method `{}` references the `Self` type \ |
| in its arguments or return type", |
| method.name); |
| &buf |
| } |
| |
| ObjectSafetyViolation::Method(method, |
| MethodViolationCode::Generic) => { |
| buf = format!("method `{}` has generic type parameters", |
| method.name); |
| &buf |
| } |
| }; |
| match (warning_node_id, &mut err) { |
| (Some(node_id), &mut None) => { |
| self.sess.add_lint( |
| ::lint::builtin::OBJECT_UNSAFE_FRAGMENT, |
| node_id, |
| span, |
| note.to_string()); |
| } |
| (None, &mut Some(ref mut err)) => { |
| err.note(note); |
| } |
| _ => unreachable!() |
| } |
| } |
| err |
| } |
| } |
| |
| impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> { |
| fn maybe_report_ambiguity(&self, obligation: &PredicateObligation<'tcx>) { |
| // Unable to successfully determine, probably means |
| // insufficient type information, but could mean |
| // ambiguous impls. The latter *ought* to be a |
| // coherence violation, so we don't report it here. |
| |
| let predicate = self.resolve_type_vars_if_possible(&obligation.predicate); |
| |
| debug!("maybe_report_ambiguity(predicate={:?}, obligation={:?})", |
| predicate, |
| obligation); |
| |
| // Ambiguity errors are often caused as fallout from earlier |
| // errors. So just ignore them if this infcx is tainted. |
| if self.is_tainted_by_errors() { |
| return; |
| } |
| |
| match predicate { |
| ty::Predicate::Trait(ref data) => { |
| let trait_ref = data.to_poly_trait_ref(); |
| let self_ty = trait_ref.self_ty(); |
| let all_types = &trait_ref.substs().types; |
| if all_types.references_error() { |
| } else { |
| // Typically, this ambiguity should only happen if |
| // there are unresolved type inference variables |
| // (otherwise it would suggest a coherence |
| // failure). But given #21974 that is not necessarily |
| // the case -- we can have multiple where clauses that |
| // are only distinguished by a region, which results |
| // in an ambiguity even when all types are fully |
| // known, since we don't dispatch based on region |
| // relationships. |
| |
| // This is kind of a hack: it frequently happens that some earlier |
| // error prevents types from being fully inferred, and then we get |
| // a bunch of uninteresting errors saying something like "<generic |
| // #0> doesn't implement Sized". It may even be true that we |
| // could just skip over all checks where the self-ty is an |
| // inference variable, but I was afraid that there might be an |
| // inference variable created, registered as an obligation, and |
| // then never forced by writeback, and hence by skipping here we'd |
| // be ignoring the fact that we don't KNOW the type works |
| // out. Though even that would probably be harmless, given that |
| // we're only talking about builtin traits, which are known to be |
| // inhabited. But in any case I just threw in this check for |
| // has_errors() to be sure that compilation isn't happening |
| // anyway. In that case, why inundate the user. |
| if !self.tcx.sess.has_errors() { |
| if |
| self.tcx.lang_items.sized_trait() |
| .map_or(false, |sized_id| sized_id == trait_ref.def_id()) |
| { |
| self.need_type_info(obligation.cause.span, self_ty); |
| } else { |
| let mut err = struct_span_err!(self.tcx.sess, |
| obligation.cause.span, E0283, |
| "type annotations required: \ |
| cannot resolve `{}`", |
| predicate); |
| self.note_obligation_cause(&mut err, obligation); |
| err.emit(); |
| } |
| } |
| } |
| } |
| |
| ty::Predicate::WellFormed(ty) => { |
| // Same hacky approach as above to avoid deluging user |
| // with error messages. |
| if !ty.references_error() && !self.tcx.sess.has_errors() { |
| self.need_type_info(obligation.cause.span, ty); |
| } |
| } |
| |
| _ => { |
| if !self.tcx.sess.has_errors() { |
| let mut err = struct_span_err!(self.tcx.sess, |
| obligation.cause.span, E0284, |
| "type annotations required: \ |
| cannot resolve `{}`", |
| predicate); |
| self.note_obligation_cause(&mut err, obligation); |
| err.emit(); |
| } |
| } |
| } |
| } |
| |
| /// Returns whether the trait predicate may apply for *some* assignment |
| /// to the type parameters. |
| fn predicate_can_apply(&self, pred: ty::PolyTraitRef<'tcx>) -> bool { |
| struct ParamToVarFolder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
| infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, |
| var_map: FnvHashMap<Ty<'tcx>, Ty<'tcx>> |
| } |
| |
| impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for ParamToVarFolder<'a, 'gcx, 'tcx> { |
| fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { self.infcx.tcx } |
| |
| fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { |
| if let ty::TyParam(..) = ty.sty { |
| let infcx = self.infcx; |
| self.var_map.entry(ty).or_insert_with(|| infcx.next_ty_var()) |
| } else { |
| ty.super_fold_with(self) |
| } |
| } |
| } |
| |
| self.probe(|_| { |
| let mut selcx = SelectionContext::new(self); |
| |
| let cleaned_pred = pred.fold_with(&mut ParamToVarFolder { |
| infcx: self, |
| var_map: FnvHashMap() |
| }); |
| |
| let cleaned_pred = super::project::normalize( |
| &mut selcx, |
| ObligationCause::dummy(), |
| &cleaned_pred |
| ).value; |
| |
| let obligation = Obligation::new( |
| ObligationCause::dummy(), |
| cleaned_pred.to_predicate() |
| ); |
| |
| selcx.evaluate_obligation(&obligation) |
| }) |
| } |
| |
| |
| fn need_type_info(&self, span: Span, ty: Ty<'tcx>) { |
| span_err!(self.tcx.sess, span, E0282, |
| "unable to infer enough type information about `{}`; \ |
| type annotations or generic parameter binding required", |
| ty); |
| } |
| |
| fn note_obligation_cause<T>(&self, |
| err: &mut DiagnosticBuilder, |
| obligation: &Obligation<'tcx, T>) |
| where T: fmt::Display |
| { |
| self.note_obligation_cause_code(err, |
| &obligation.predicate, |
| &obligation.cause.code); |
| } |
| |
| fn note_obligation_cause_code<T>(&self, |
| err: &mut DiagnosticBuilder, |
| predicate: &T, |
| cause_code: &ObligationCauseCode<'tcx>) |
| where T: fmt::Display |
| { |
| let tcx = self.tcx; |
| match *cause_code { |
| ObligationCauseCode::MiscObligation => { } |
| ObligationCauseCode::SliceOrArrayElem => { |
| err.note("slice and array elements must have `Sized` type"); |
| } |
| ObligationCauseCode::TupleElem => { |
| err.note("tuple elements must have `Sized` type"); |
| } |
| ObligationCauseCode::ProjectionWf(data) => { |
| err.note(&format!("required so that the projection `{}` is well-formed", |
| data)); |
| } |
| ObligationCauseCode::ReferenceOutlivesReferent(ref_ty) => { |
| err.note(&format!("required so that reference `{}` does not outlive its referent", |
| ref_ty)); |
| } |
| ObligationCauseCode::ItemObligation(item_def_id) => { |
| let item_name = tcx.item_path_str(item_def_id); |
| err.note(&format!("required by `{}`", item_name)); |
| } |
| ObligationCauseCode::ObjectCastObligation(object_ty) => { |
| err.note(&format!("required for the cast to the object type `{}`", |
| self.ty_to_string(object_ty))); |
| } |
| ObligationCauseCode::RepeatVec => { |
| err.note("the `Copy` trait is required because the \ |
| repeated element will be copied"); |
| } |
| ObligationCauseCode::VariableType(_) => { |
| err.note("all local variables must have a statically known size"); |
| } |
| ObligationCauseCode::ReturnType => { |
| err.note("the return type of a function must have a \ |
| statically known size"); |
| } |
| ObligationCauseCode::AssignmentLhsSized => { |
| err.note("the left-hand-side of an assignment must have a statically known size"); |
| } |
| ObligationCauseCode::StructInitializerSized => { |
| err.note("structs must have a statically known size to be initialized"); |
| } |
| ObligationCauseCode::ClosureCapture(var_id, _, builtin_bound) => { |
| let def_id = tcx.lang_items.from_builtin_kind(builtin_bound).unwrap(); |
| let trait_name = tcx.item_path_str(def_id); |
| let name = tcx.local_var_name_str(var_id); |
| err.note( |
| &format!("the closure that captures `{}` requires that all captured variables \ |
| implement the trait `{}`", |
| name, |
| trait_name)); |
| } |
| ObligationCauseCode::FieldSized => { |
| err.note("only the last field of a struct or enum variant \ |
| may have a dynamically sized type"); |
| } |
| ObligationCauseCode::ConstSized => { |
| err.note("constant expressions must have a statically known size"); |
| } |
| ObligationCauseCode::SharedStatic => { |
| err.note("shared static variables must have a type that implements `Sync`"); |
| } |
| ObligationCauseCode::BuiltinDerivedObligation(ref data) => { |
| let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref); |
| err.note(&format!("required because it appears within the type `{}`", |
| parent_trait_ref.0.self_ty())); |
| let parent_predicate = parent_trait_ref.to_predicate(); |
| self.note_obligation_cause_code(err, |
| &parent_predicate, |
| &data.parent_code); |
| } |
| ObligationCauseCode::ImplDerivedObligation(ref data) => { |
| let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref); |
| err.note( |
| &format!("required because of the requirements on the impl of `{}` for `{}`", |
| parent_trait_ref, |
| parent_trait_ref.0.self_ty())); |
| let parent_predicate = parent_trait_ref.to_predicate(); |
| self.note_obligation_cause_code(err, |
| &parent_predicate, |
| &data.parent_code); |
| } |
| ObligationCauseCode::CompareImplMethodObligation => { |
| err.note( |
| &format!("the requirement `{}` appears on the impl method \ |
| but not on the corresponding trait method", |
| predicate)); |
| } |
| } |
| } |
| |
| fn suggest_new_overflow_limit(&self, err: &mut DiagnosticBuilder) { |
| let current_limit = self.tcx.sess.recursion_limit.get(); |
| let suggested_limit = current_limit * 2; |
| err.note(&format!( |
| "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate", |
| suggested_limit)); |
| } |
| } |
