| pub mod on_unimplemented; |
| pub mod suggestions; |
| |
| use super::{ |
| ConstEvalFailure, EvaluationResult, FulfillmentError, FulfillmentErrorCode, |
| MismatchedProjectionTypes, Obligation, ObligationCause, ObligationCauseCode, |
| OnUnimplementedDirective, OnUnimplementedNote, OutputTypeParameterMismatch, Overflow, |
| PredicateObligation, SelectionContext, SelectionError, TraitNotObjectSafe, |
| }; |
| |
| use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCode}; |
| use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
| use crate::infer::{self, InferCtxt, TyCtxtInferExt}; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LOCAL_CRATE}; |
| use rustc_hir::{Node, QPath, TyKind, WhereBoundPredicate, WherePredicate}; |
| use rustc_middle::mir::interpret::ErrorHandled; |
| use rustc_middle::ty::error::ExpectedFound; |
| use rustc_middle::ty::fast_reject; |
| use rustc_middle::ty::fold::TypeFolder; |
| use rustc_middle::ty::SubtypePredicate; |
| use rustc_middle::ty::{ |
| self, AdtKind, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness, |
| }; |
| use rustc_session::DiagnosticMessageId; |
| use rustc_span::{BytePos, ExpnKind, Span, DUMMY_SP}; |
| use std::fmt; |
| |
| use crate::traits::query::evaluate_obligation::InferCtxtExt as _; |
| use crate::traits::query::normalize::AtExt as _; |
| use on_unimplemented::InferCtxtExt as _; |
| use suggestions::InferCtxtExt as _; |
| |
| pub use rustc_infer::traits::error_reporting::*; |
| |
| pub trait InferCtxtExt<'tcx> { |
| fn report_fulfillment_errors( |
| &self, |
| errors: &[FulfillmentError<'tcx>], |
| body_id: Option<hir::BodyId>, |
| fallback_has_occurred: bool, |
| ); |
| |
| fn report_overflow_error<T>( |
| &self, |
| obligation: &Obligation<'tcx, T>, |
| suggest_increasing_limit: bool, |
| ) -> ! |
| where |
| T: fmt::Display + TypeFoldable<'tcx>; |
| |
| fn report_overflow_error_cycle(&self, cycle: &[PredicateObligation<'tcx>]) -> !; |
| |
| fn report_selection_error( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &SelectionError<'tcx>, |
| fallback_has_occurred: bool, |
| points_at_arg: bool, |
| ); |
| |
| /// Given some node representing a fn-like thing in the HIR map, |
| /// returns a span and `ArgKind` information that describes the |
| /// arguments it expects. This can be supplied to |
| /// `report_arg_count_mismatch`. |
| fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)>; |
| |
| /// Reports an error when the number of arguments needed by a |
| /// trait match doesn't match the number that the expression |
| /// provides. |
| fn report_arg_count_mismatch( |
| &self, |
| span: Span, |
| found_span: Option<Span>, |
| expected_args: Vec<ArgKind>, |
| found_args: Vec<ArgKind>, |
| is_closure: bool, |
| ) -> DiagnosticBuilder<'tcx>; |
| } |
| |
| impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { |
| fn report_fulfillment_errors( |
| &self, |
| errors: &[FulfillmentError<'tcx>], |
| body_id: Option<hir::BodyId>, |
| fallback_has_occurred: bool, |
| ) { |
| #[derive(Debug)] |
| struct ErrorDescriptor<'tcx> { |
| predicate: ty::Predicate<'tcx>, |
| index: Option<usize>, // None if this is an old error |
| } |
| |
| let mut error_map: FxHashMap<_, Vec<_>> = self |
| .reported_trait_errors |
| .borrow() |
| .iter() |
| .map(|(&span, predicates)| { |
| ( |
| span, |
| predicates |
| .iter() |
| .map(|&predicate| ErrorDescriptor { predicate, index: None }) |
| .collect(), |
| ) |
| }) |
| .collect(); |
| |
| for (index, error) in errors.iter().enumerate() { |
| // We want to ignore desugarings here: spans are equivalent even |
| // if one is the result of a desugaring and the other is not. |
| let mut span = error.obligation.cause.span; |
| let expn_data = span.ctxt().outer_expn_data(); |
| if let ExpnKind::Desugaring(_) = expn_data.kind { |
| span = expn_data.call_site; |
| } |
| |
| error_map.entry(span).or_default().push(ErrorDescriptor { |
| predicate: error.obligation.predicate, |
| index: Some(index), |
| }); |
| |
| self.reported_trait_errors |
| .borrow_mut() |
| .entry(span) |
| .or_default() |
| .push(error.obligation.predicate.clone()); |
| } |
| |
| // We do this in 2 passes because we want to display errors in order, though |
| // maybe it *is* better to sort errors by span or something. |
| let mut is_suppressed = vec![false; errors.len()]; |
| for (_, error_set) in error_map.iter() { |
| // We want to suppress "duplicate" errors with the same span. |
| for error in error_set { |
| if let Some(index) = error.index { |
| // Suppress errors that are either: |
| // 1) strictly implied by another error. |
| // 2) implied by an error with a smaller index. |
| for error2 in error_set { |
| if error2.index.map_or(false, |index2| is_suppressed[index2]) { |
| // Avoid errors being suppressed by already-suppressed |
| // errors, to prevent all errors from being suppressed |
| // at once. |
| continue; |
| } |
| |
| if self.error_implies(&error2.predicate, &error.predicate) |
| && !(error2.index >= error.index |
| && self.error_implies(&error.predicate, &error2.predicate)) |
| { |
| info!("skipping {:?} (implied by {:?})", error, error2); |
| is_suppressed[index] = true; |
| break; |
| } |
| } |
| } |
| } |
| } |
| |
| for (error, suppressed) in errors.iter().zip(is_suppressed) { |
| if !suppressed { |
| self.report_fulfillment_error(error, body_id, fallback_has_occurred); |
| } |
| } |
| } |
| |
| /// 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. |
| fn report_overflow_error<T>( |
| &self, |
| obligation: &Obligation<'tcx, T>, |
| suggest_increasing_limit: bool, |
| ) -> ! |
| where |
| T: fmt::Display + TypeFoldable<'tcx>, |
| { |
| let predicate = self.resolve_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_code( |
| &mut err, |
| &obligation.predicate, |
| &obligation.cause.code, |
| &mut vec![], |
| ); |
| |
| 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). |
| fn report_overflow_error_cycle(&self, cycle: &[PredicateObligation<'tcx>]) -> ! { |
| let cycle = self.resolve_vars_if_possible(&cycle.to_owned()); |
| assert!(!cycle.is_empty()); |
| |
| debug!("report_overflow_error_cycle: cycle={:?}", cycle); |
| |
| self.report_overflow_error(&cycle[0], false); |
| } |
| |
| fn report_selection_error( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &SelectionError<'tcx>, |
| fallback_has_occurred: bool, |
| points_at_arg: bool, |
| ) { |
| let tcx = self.tcx; |
| let span = obligation.cause.span; |
| |
| let mut err = match *error { |
| SelectionError::Unimplemented => { |
| if let ObligationCauseCode::CompareImplMethodObligation { |
| item_name, |
| impl_item_def_id, |
| trait_item_def_id, |
| } |
| | ObligationCauseCode::CompareImplTypeObligation { |
| item_name, |
| impl_item_def_id, |
| trait_item_def_id, |
| } = obligation.cause.code |
| { |
| self.report_extra_impl_obligation( |
| span, |
| item_name, |
| impl_item_def_id, |
| trait_item_def_id, |
| &format!("`{}`", obligation.predicate), |
| ) |
| .emit(); |
| return; |
| } |
| match obligation.predicate { |
| ty::Predicate::Trait(ref trait_predicate, _) => { |
| let trait_predicate = self.resolve_vars_if_possible(trait_predicate); |
| |
| if self.tcx.sess.has_errors() && trait_predicate.references_error() { |
| return; |
| } |
| let trait_ref = trait_predicate.to_poly_trait_ref(); |
| let (post_message, pre_message, type_def) = self |
| .get_parent_trait_ref(&obligation.cause.code) |
| .map(|(t, s)| { |
| ( |
| format!(" in `{}`", t), |
| format!("within `{}`, ", t), |
| s.map(|s| (format!("within this `{}`", t), s)), |
| ) |
| }) |
| .unwrap_or_default(); |
| |
| let OnUnimplementedNote { message, label, note, enclosing_scope } = |
| self.on_unimplemented_note(trait_ref, obligation); |
| let have_alt_message = message.is_some() || label.is_some(); |
| let is_try = self |
| .tcx |
| .sess |
| .source_map() |
| .span_to_snippet(span) |
| .map(|s| &s == "?") |
| .unwrap_or(false); |
| let is_from = format!("{}", trait_ref.print_only_trait_path()) |
| .starts_with("std::convert::From<"); |
| let (message, note) = if is_try && is_from { |
| ( |
| Some(format!( |
| "`?` couldn't convert the error to `{}`", |
| trait_ref.self_ty(), |
| )), |
| Some( |
| "the question mark operation (`?`) implicitly performs a \ |
| conversion on the error value using the `From` trait" |
| .to_owned(), |
| ), |
| ) |
| } else { |
| (message, note) |
| }; |
| |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0277, |
| "{}", |
| message.unwrap_or_else(|| format!( |
| "the trait bound `{}` is not satisfied{}", |
| trait_ref.without_const().to_predicate(), |
| post_message, |
| )) |
| ); |
| |
| let explanation = |
| if obligation.cause.code == ObligationCauseCode::MainFunctionType { |
| "consider using `()`, or a `Result`".to_owned() |
| } else { |
| format!( |
| "{}the trait `{}` is not implemented for `{}`", |
| pre_message, |
| trait_ref.print_only_trait_path(), |
| trait_ref.self_ty(), |
| ) |
| }; |
| |
| if self.suggest_add_reference_to_arg( |
| &obligation, |
| &mut err, |
| &trait_ref, |
| points_at_arg, |
| have_alt_message, |
| ) { |
| self.note_obligation_cause(&mut err, obligation); |
| err.emit(); |
| return; |
| } |
| if let Some(ref s) = label { |
| // If it has a custom `#[rustc_on_unimplemented]` |
| // error message, let's display it as the label! |
| err.span_label(span, s.as_str()); |
| err.help(&explanation); |
| } else { |
| err.span_label(span, explanation); |
| } |
| if let Some((msg, span)) = type_def { |
| err.span_label(span, &msg); |
| } |
| if let Some(ref s) = note { |
| // If it has a custom `#[rustc_on_unimplemented]` note, let's display it |
| err.note(s.as_str()); |
| } |
| if let Some(ref s) = enclosing_scope { |
| let enclosing_scope_span = tcx.def_span( |
| tcx.hir() |
| .opt_local_def_id(obligation.cause.body_id) |
| .unwrap_or_else(|| { |
| tcx.hir().body_owner_def_id(hir::BodyId { |
| hir_id: obligation.cause.body_id, |
| }) |
| }), |
| ); |
| |
| err.span_label(enclosing_scope_span, s.as_str()); |
| } |
| |
| self.suggest_borrow_on_unsized_slice(&obligation.cause.code, &mut err); |
| self.suggest_fn_call(&obligation, &mut err, &trait_ref, points_at_arg); |
| self.suggest_remove_reference(&obligation, &mut err, &trait_ref); |
| self.suggest_semicolon_removal(&obligation, &mut err, span, &trait_ref); |
| self.note_version_mismatch(&mut err, &trait_ref); |
| if self.suggest_impl_trait(&mut err, span, &obligation, &trait_ref) { |
| err.emit(); |
| return; |
| } |
| |
| // Try to report a help message |
| if !trait_ref.has_infer_types_or_consts() |
| && self.predicate_can_apply(obligation.param_env, 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. |
| self.suggest_restricting_param_bound( |
| &mut err, |
| &trait_ref, |
| obligation.cause.body_id, |
| ); |
| } else { |
| if !have_alt_message { |
| // Can't show anything else useful, try to find similar impls. |
| let impl_candidates = self.find_similar_impl_candidates(trait_ref); |
| self.report_similar_impl_candidates(impl_candidates, &mut err); |
| } |
| self.suggest_change_mut( |
| &obligation, |
| &mut err, |
| &trait_ref, |
| points_at_arg, |
| ); |
| } |
| |
| // If this error is due to `!: Trait` not implemented but `(): Trait` is |
| // implemented, and fallback has occurred, then it could be due to a |
| // variable that used to fallback to `()` now falling back to `!`. Issue a |
| // note informing about the change in behaviour. |
| if trait_predicate.skip_binder().self_ty().is_never() |
| && fallback_has_occurred |
| { |
| let predicate = trait_predicate.map_bound(|mut trait_pred| { |
| trait_pred.trait_ref.substs = self.tcx.mk_substs_trait( |
| self.tcx.mk_unit(), |
| &trait_pred.trait_ref.substs[1..], |
| ); |
| trait_pred |
| }); |
| let unit_obligation = Obligation { |
| predicate: ty::Predicate::Trait( |
| predicate, |
| hir::Constness::NotConst, |
| ), |
| ..obligation.clone() |
| }; |
| if self.predicate_may_hold(&unit_obligation) { |
| err.note( |
| "the trait is implemented for `()`. \ |
| Possibly this error has been caused by changes to \ |
| Rust's type-inference algorithm (see issue #48950 \ |
| <https://github.com/rust-lang/rust/issues/48950> \ |
| for more information). Consider whether you meant to use \ |
| the type `()` here instead.", |
| ); |
| } |
| } |
| |
| err |
| } |
| |
| ty::Predicate::Subtype(ref predicate) => { |
| // Errors for Subtype predicates show up as |
| // `FulfillmentErrorCode::CodeSubtypeError`, |
| // not selection error. |
| span_bug!(span, "subtype requirement gave wrong error: `{:?}`", predicate) |
| } |
| |
| ty::Predicate::RegionOutlives(ref predicate) => { |
| let predicate = self.resolve_vars_if_possible(predicate); |
| let err = self |
| .region_outlives_predicate(&obligation.cause, &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_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); |
| report_object_safety_error(self.tcx, span, trait_def_id, violations) |
| } |
| |
| ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => { |
| let found_kind = self.closure_kind(closure_substs).unwrap(); |
| let closure_span = |
| self.tcx.sess.source_map().guess_head_span( |
| self.tcx.hir().span_if_local(closure_def_id).unwrap(), |
| ); |
| let hir_id = self.tcx.hir().as_local_hir_id(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_label( |
| closure_span, |
| format!("this closure implements `{}`, not `{}`", found_kind, kind), |
| ); |
| err.span_label( |
| obligation.cause.span, |
| format!("the requirement to implement `{}` derives from here", kind), |
| ); |
| |
| // Additional context information explaining why the closure only implements |
| // a particular trait. |
| if let Some(tables) = self.in_progress_tables { |
| let tables = tables.borrow(); |
| match (found_kind, tables.closure_kind_origins().get(hir_id)) { |
| (ty::ClosureKind::FnOnce, Some((span, name))) => { |
| err.span_label( |
| *span, |
| format!( |
| "closure is `FnOnce` because it moves the \ |
| variable `{}` out of its environment", |
| name |
| ), |
| ); |
| } |
| (ty::ClosureKind::FnMut, Some((span, name))) => { |
| err.span_label( |
| *span, |
| format!( |
| "closure is `FnMut` because it mutates the \ |
| variable `{}` here", |
| name |
| ), |
| ); |
| } |
| _ => {} |
| } |
| } |
| |
| 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::ConstEvaluatable(..) => { |
| // Errors for `ConstEvaluatable` predicates show up as |
| // `SelectionError::ConstEvalFailure`, |
| // not `Unimplemented`. |
| span_bug!( |
| span, |
| "const-evaluatable requirement gave wrong error: `{:?}`", |
| obligation |
| ) |
| } |
| } |
| } |
| |
| OutputTypeParameterMismatch(ref found_trait_ref, ref expected_trait_ref, _) => { |
| let found_trait_ref = self.resolve_vars_if_possible(&*found_trait_ref); |
| let expected_trait_ref = self.resolve_vars_if_possible(&*expected_trait_ref); |
| |
| if expected_trait_ref.self_ty().references_error() { |
| return; |
| } |
| |
| let found_trait_ty = found_trait_ref.self_ty(); |
| |
| let found_did = match found_trait_ty.kind { |
| ty::Closure(did, _) | ty::Foreign(did) | ty::FnDef(did, _) => Some(did), |
| ty::Adt(def, _) => Some(def.did), |
| _ => None, |
| }; |
| |
| let found_span = found_did |
| .and_then(|did| self.tcx.hir().span_if_local(did)) |
| .map(|sp| self.tcx.sess.source_map().guess_head_span(sp)); // the sp could be an fn def |
| |
| if self.reported_closure_mismatch.borrow().contains(&(span, found_span)) { |
| // We check closures twice, with obligations flowing in different directions, |
| // but we want to complain about them only once. |
| return; |
| } |
| |
| self.reported_closure_mismatch.borrow_mut().insert((span, found_span)); |
| |
| let found = match found_trait_ref.skip_binder().substs.type_at(1).kind { |
| ty::Tuple(ref tys) => vec![ArgKind::empty(); tys.len()], |
| _ => vec![ArgKind::empty()], |
| }; |
| |
| let expected_ty = expected_trait_ref.skip_binder().substs.type_at(1); |
| let expected = match expected_ty.kind { |
| ty::Tuple(ref tys) => tys |
| .iter() |
| .map(|t| ArgKind::from_expected_ty(t.expect_ty(), Some(span))) |
| .collect(), |
| _ => vec![ArgKind::Arg("_".to_owned(), expected_ty.to_string())], |
| }; |
| |
| if found.len() == expected.len() { |
| self.report_closure_arg_mismatch( |
| span, |
| found_span, |
| found_trait_ref, |
| expected_trait_ref, |
| ) |
| } else { |
| let (closure_span, found) = found_did |
| .and_then(|did| { |
| let node = self.tcx.hir().get_if_local(did)?; |
| let (found_span, found) = self.get_fn_like_arguments(node)?; |
| Some((Some(found_span), found)) |
| }) |
| .unwrap_or((found_span, found)); |
| |
| self.report_arg_count_mismatch( |
| span, |
| closure_span, |
| expected, |
| found, |
| found_trait_ty.is_closure(), |
| ) |
| } |
| } |
| |
| TraitNotObjectSafe(did) => { |
| let violations = self.tcx.object_safety_violations(did); |
| report_object_safety_error(self.tcx, span, did, violations) |
| } |
| |
| ConstEvalFailure(ErrorHandled::TooGeneric) => { |
| // In this instance, we have a const expression containing an unevaluated |
| // generic parameter. We have no idea whether this expression is valid or |
| // not (e.g. it might result in an error), but we don't want to just assume |
| // that it's okay, because that might result in post-monomorphisation time |
| // errors. The onus is really on the caller to provide values that it can |
| // prove are well-formed. |
| let mut err = self |
| .tcx |
| .sess |
| .struct_span_err(span, "constant expression depends on a generic parameter"); |
| // FIXME(const_generics): we should suggest to the user how they can resolve this |
| // issue. However, this is currently not actually possible |
| // (see https://github.com/rust-lang/rust/issues/66962#issuecomment-575907083). |
| err.note("this may fail depending on what value the parameter takes"); |
| err |
| } |
| |
| // Already reported in the query. |
| ConstEvalFailure(ErrorHandled::Reported) => { |
| self.tcx.sess.delay_span_bug(span, "constant in type had an ignored error"); |
| return; |
| } |
| |
| Overflow => { |
| bug!("overflow should be handled before the `report_selection_error` path"); |
| } |
| }; |
| |
| self.note_obligation_cause(&mut err, obligation); |
| self.point_at_returns_when_relevant(&mut err, &obligation); |
| |
| err.emit(); |
| } |
| |
| /// Given some node representing a fn-like thing in the HIR map, |
| /// returns a span and `ArgKind` information that describes the |
| /// arguments it expects. This can be supplied to |
| /// `report_arg_count_mismatch`. |
| fn get_fn_like_arguments(&self, node: Node<'_>) -> Option<(Span, Vec<ArgKind>)> { |
| let sm = self.tcx.sess.source_map(); |
| let hir = self.tcx.hir(); |
| Some(match node { |
| Node::Expr(&hir::Expr { |
| kind: hir::ExprKind::Closure(_, ref _decl, id, span, _), |
| .. |
| }) => ( |
| sm.guess_head_span(span), |
| hir.body(id) |
| .params |
| .iter() |
| .map(|arg| { |
| if let hir::Pat { kind: hir::PatKind::Tuple(ref args, _), span, .. } = |
| *arg.pat |
| { |
| Some(ArgKind::Tuple( |
| Some(span), |
| args.iter() |
| .map(|pat| { |
| sm.span_to_snippet(pat.span) |
| .ok() |
| .map(|snippet| (snippet, "_".to_owned())) |
| }) |
| .collect::<Option<Vec<_>>>()?, |
| )) |
| } else { |
| let name = sm.span_to_snippet(arg.pat.span).ok()?; |
| Some(ArgKind::Arg(name, "_".to_owned())) |
| } |
| }) |
| .collect::<Option<Vec<ArgKind>>>()?, |
| ), |
| Node::Item(&hir::Item { span, kind: hir::ItemKind::Fn(ref sig, ..), .. }) |
| | Node::ImplItem(&hir::ImplItem { |
| span, |
| kind: hir::ImplItemKind::Fn(ref sig, _), |
| .. |
| }) |
| | Node::TraitItem(&hir::TraitItem { |
| span, |
| kind: hir::TraitItemKind::Fn(ref sig, _), |
| .. |
| }) => ( |
| sm.guess_head_span(span), |
| sig.decl |
| .inputs |
| .iter() |
| .map(|arg| match arg.clone().kind { |
| hir::TyKind::Tup(ref tys) => ArgKind::Tuple( |
| Some(arg.span), |
| vec![("_".to_owned(), "_".to_owned()); tys.len()], |
| ), |
| _ => ArgKind::empty(), |
| }) |
| .collect::<Vec<ArgKind>>(), |
| ), |
| Node::Ctor(ref variant_data) => { |
| let span = variant_data.ctor_hir_id().map(|id| hir.span(id)).unwrap_or(DUMMY_SP); |
| let span = sm.guess_head_span(span); |
| (span, vec![ArgKind::empty(); variant_data.fields().len()]) |
| } |
| _ => panic!("non-FnLike node found: {:?}", node), |
| }) |
| } |
| |
| /// Reports an error when the number of arguments needed by a |
| /// trait match doesn't match the number that the expression |
| /// provides. |
| fn report_arg_count_mismatch( |
| &self, |
| span: Span, |
| found_span: Option<Span>, |
| expected_args: Vec<ArgKind>, |
| found_args: Vec<ArgKind>, |
| is_closure: bool, |
| ) -> DiagnosticBuilder<'tcx> { |
| let kind = if is_closure { "closure" } else { "function" }; |
| |
| let args_str = |arguments: &[ArgKind], other: &[ArgKind]| { |
| let arg_length = arguments.len(); |
| let distinct = match &other[..] { |
| &[ArgKind::Tuple(..)] => true, |
| _ => false, |
| }; |
| match (arg_length, arguments.get(0)) { |
| (1, Some(&ArgKind::Tuple(_, ref fields))) => { |
| format!("a single {}-tuple as argument", fields.len()) |
| } |
| _ => format!( |
| "{} {}argument{}", |
| arg_length, |
| if distinct && arg_length > 1 { "distinct " } else { "" }, |
| pluralize!(arg_length) |
| ), |
| } |
| }; |
| |
| let expected_str = args_str(&expected_args, &found_args); |
| let found_str = args_str(&found_args, &expected_args); |
| |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0593, |
| "{} is expected to take {}, but it takes {}", |
| kind, |
| expected_str, |
| found_str, |
| ); |
| |
| err.span_label(span, format!("expected {} that takes {}", kind, expected_str)); |
| |
| if let Some(found_span) = found_span { |
| err.span_label(found_span, format!("takes {}", found_str)); |
| |
| // move |_| { ... } |
| // ^^^^^^^^-- def_span |
| // |
| // move |_| { ... } |
| // ^^^^^-- prefix |
| let prefix_span = self.tcx.sess.source_map().span_until_non_whitespace(found_span); |
| // move |_| { ... } |
| // ^^^-- pipe_span |
| let pipe_span = |
| if let Some(span) = found_span.trim_start(prefix_span) { span } else { found_span }; |
| |
| // Suggest to take and ignore the arguments with expected_args_length `_`s if |
| // found arguments is empty (assume the user just wants to ignore args in this case). |
| // For example, if `expected_args_length` is 2, suggest `|_, _|`. |
| if found_args.is_empty() && is_closure { |
| let underscores = vec!["_"; expected_args.len()].join(", "); |
| err.span_suggestion_verbose( |
| pipe_span, |
| &format!( |
| "consider changing the closure to take and ignore the expected argument{}", |
| pluralize!(expected_args.len()) |
| ), |
| format!("|{}|", underscores), |
| Applicability::MachineApplicable, |
| ); |
| } |
| |
| if let &[ArgKind::Tuple(_, ref fields)] = &found_args[..] { |
| if fields.len() == expected_args.len() { |
| let sugg = fields |
| .iter() |
| .map(|(name, _)| name.to_owned()) |
| .collect::<Vec<String>>() |
| .join(", "); |
| err.span_suggestion_verbose( |
| found_span, |
| "change the closure to take multiple arguments instead of a single tuple", |
| format!("|{}|", sugg), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| if let &[ArgKind::Tuple(_, ref fields)] = &expected_args[..] { |
| if fields.len() == found_args.len() && is_closure { |
| let sugg = format!( |
| "|({}){}|", |
| found_args |
| .iter() |
| .map(|arg| match arg { |
| ArgKind::Arg(name, _) => name.to_owned(), |
| _ => "_".to_owned(), |
| }) |
| .collect::<Vec<String>>() |
| .join(", "), |
| // add type annotations if available |
| if found_args.iter().any(|arg| match arg { |
| ArgKind::Arg(_, ty) => ty != "_", |
| _ => false, |
| }) { |
| format!( |
| ": ({})", |
| fields |
| .iter() |
| .map(|(_, ty)| ty.to_owned()) |
| .collect::<Vec<String>>() |
| .join(", ") |
| ) |
| } else { |
| String::new() |
| }, |
| ); |
| err.span_suggestion_verbose( |
| found_span, |
| "change the closure to accept a tuple instead of individual arguments", |
| sugg, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| err |
| } |
| } |
| |
| trait InferCtxtPrivExt<'tcx> { |
| // returns if `cond` not occurring implies that `error` does not occur - i.e., that |
| // `error` occurring implies that `cond` occurs. |
| fn error_implies(&self, cond: &ty::Predicate<'tcx>, error: &ty::Predicate<'tcx>) -> bool; |
| |
| fn report_fulfillment_error( |
| &self, |
| error: &FulfillmentError<'tcx>, |
| body_id: Option<hir::BodyId>, |
| fallback_has_occurred: bool, |
| ); |
| |
| fn report_projection_error( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &MismatchedProjectionTypes<'tcx>, |
| ); |
| |
| fn fuzzy_match_tys(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> bool; |
| |
| fn describe_generator(&self, body_id: hir::BodyId) -> Option<&'static str>; |
| |
| fn find_similar_impl_candidates( |
| &self, |
| trait_ref: ty::PolyTraitRef<'tcx>, |
| ) -> Vec<ty::TraitRef<'tcx>>; |
| |
| fn report_similar_impl_candidates( |
| &self, |
| impl_candidates: Vec<ty::TraitRef<'tcx>>, |
| err: &mut DiagnosticBuilder<'_>, |
| ); |
| |
| /// Gets the parent trait chain start |
| fn get_parent_trait_ref( |
| &self, |
| code: &ObligationCauseCode<'tcx>, |
| ) -> Option<(String, Option<Span>)>; |
| |
| /// If the `Self` type of the unsatisfied trait `trait_ref` implements a trait |
| /// with the same path as `trait_ref`, a help message about |
| /// a probable version mismatch is added to `err` |
| fn note_version_mismatch( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| trait_ref: &ty::PolyTraitRef<'tcx>, |
| ); |
| |
| fn mk_obligation_for_def_id( |
| &self, |
| def_id: DefId, |
| output_ty: Ty<'tcx>, |
| cause: ObligationCause<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> PredicateObligation<'tcx>; |
| |
| fn maybe_report_ambiguity( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| body_id: Option<hir::BodyId>, |
| ); |
| |
| fn predicate_can_apply( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| pred: ty::PolyTraitRef<'tcx>, |
| ) -> bool; |
| |
| fn note_obligation_cause( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| obligation: &PredicateObligation<'tcx>, |
| ); |
| |
| fn suggest_unsized_bound_if_applicable( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| obligation: &PredicateObligation<'tcx>, |
| ); |
| |
| fn is_recursive_obligation( |
| &self, |
| obligated_types: &mut Vec<&ty::TyS<'tcx>>, |
| cause_code: &ObligationCauseCode<'tcx>, |
| ) -> bool; |
| } |
| |
| impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> { |
| // returns if `cond` not occurring implies that `error` does not occur - i.e., that |
| // `error` occurring implies that `cond` occurs. |
| fn error_implies(&self, cond: &ty::Predicate<'tcx>, error: &ty::Predicate<'tcx>) -> bool { |
| if cond == error { |
| return true; |
| } |
| |
| let (cond, error) = match (cond, error) { |
| (&ty::Predicate::Trait(..), &ty::Predicate::Trait(ref error, _)) => (cond, error), |
| _ => { |
| // FIXME: make this work in other cases too. |
| return false; |
| } |
| }; |
| |
| for implication in super::elaborate_predicates(self.tcx, vec![*cond]) { |
| if let ty::Predicate::Trait(implication, _) = implication { |
| let error = error.to_poly_trait_ref(); |
| let implication = implication.to_poly_trait_ref(); |
| // FIXME: I'm just not taking associated types at all here. |
| // Eventually I'll need to implement param-env-aware |
| // `Γ₁ ⊦ φ₁ => Γ₂ ⊦ φ₂` logic. |
| let param_env = ty::ParamEnv::empty(); |
| if self.can_sub(param_env, error, implication).is_ok() { |
| debug!("error_implies: {:?} -> {:?} -> {:?}", cond, error, implication); |
| return true; |
| } |
| } |
| } |
| |
| false |
| } |
| |
| fn report_fulfillment_error( |
| &self, |
| error: &FulfillmentError<'tcx>, |
| body_id: Option<hir::BodyId>, |
| fallback_has_occurred: bool, |
| ) { |
| debug!("report_fulfillment_error({:?})", error); |
| match error.code { |
| FulfillmentErrorCode::CodeSelectionError(ref selection_error) => { |
| self.report_selection_error( |
| &error.obligation, |
| selection_error, |
| fallback_has_occurred, |
| error.points_at_arg_span, |
| ); |
| } |
| FulfillmentErrorCode::CodeProjectionError(ref e) => { |
| self.report_projection_error(&error.obligation, e); |
| } |
| FulfillmentErrorCode::CodeAmbiguity => { |
| self.maybe_report_ambiguity(&error.obligation, body_id); |
| } |
| FulfillmentErrorCode::CodeSubtypeError(ref expected_found, ref err) => { |
| self.report_mismatched_types( |
| &error.obligation.cause, |
| expected_found.expected, |
| expected_found.found, |
| err.clone(), |
| ) |
| .emit(); |
| } |
| } |
| } |
| |
| fn report_projection_error( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| error: &MismatchedProjectionTypes<'tcx>, |
| ) { |
| let predicate = self.resolve_vars_if_possible(&obligation.predicate); |
| |
| if predicate.references_error() { |
| return; |
| } |
| |
| self.probe(|_| { |
| 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_bound_vars_with_fresh_vars( |
| obligation.cause.span, |
| infer::LateBoundRegionConversionTime::HigherRankedType, |
| data, |
| ); |
| let mut obligations = vec![]; |
| let normalized_ty = super::normalize_projection_type( |
| &mut selcx, |
| obligation.param_env, |
| data.projection_ty, |
| obligation.cause.clone(), |
| 0, |
| &mut obligations, |
| ); |
| |
| debug!( |
| "report_projection_error obligation.cause={:?} obligation.param_env={:?}", |
| obligation.cause, obligation.param_env |
| ); |
| |
| debug!( |
| "report_projection_error normalized_ty={:?} data.ty={:?}", |
| normalized_ty, data.ty |
| ); |
| |
| let is_normalized_ty_expected = match &obligation.cause.code { |
| ObligationCauseCode::ItemObligation(_) |
| | ObligationCauseCode::BindingObligation(_, _) |
| | ObligationCauseCode::ObjectCastObligation(_) => false, |
| _ => true, |
| }; |
| |
| if let Err(error) = self.at(&obligation.cause, obligation.param_env).eq_exp( |
| is_normalized_ty_expected, |
| normalized_ty, |
| data.ty, |
| ) { |
| values = Some(infer::ValuePairs::Types(ExpectedFound::new( |
| is_normalized_ty_expected, |
| normalized_ty, |
| data.ty, |
| ))); |
| |
| err_buf = error; |
| err = &err_buf; |
| } |
| } |
| |
| let msg = format!("type mismatch resolving `{}`", predicate); |
| let error_id = (DiagnosticMessageId::ErrorId(271), Some(obligation.cause.span), msg); |
| let fresh = self.tcx.sess.one_time_diagnostics.borrow_mut().insert(error_id); |
| if fresh { |
| let mut diag = struct_span_err!( |
| self.tcx.sess, |
| obligation.cause.span, |
| E0271, |
| "type mismatch resolving `{}`", |
| predicate |
| ); |
| self.note_type_err(&mut diag, &obligation.cause, None, values, err); |
| self.note_obligation_cause(&mut diag, obligation); |
| diag.emit(); |
| } |
| }); |
| } |
| |
| 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(t: Ty<'_>) -> Option<u32> { |
| match t.kind { |
| ty::Bool => Some(0), |
| ty::Char => Some(1), |
| ty::Str => Some(2), |
| ty::Int(..) | ty::Uint(..) | ty::Infer(ty::IntVar(..)) => Some(3), |
| ty::Float(..) | ty::Infer(ty::FloatVar(..)) => Some(4), |
| ty::Ref(..) | ty::RawPtr(..) => Some(5), |
| ty::Array(..) | ty::Slice(..) => Some(6), |
| ty::FnDef(..) | ty::FnPtr(..) => Some(7), |
| ty::Dynamic(..) => Some(8), |
| ty::Closure(..) => Some(9), |
| ty::Tuple(..) => Some(10), |
| ty::Projection(..) => Some(11), |
| ty::Param(..) => Some(12), |
| ty::Opaque(..) => Some(13), |
| ty::Never => Some(14), |
| ty::Adt(adt, ..) => match adt.adt_kind() { |
| AdtKind::Struct => Some(15), |
| AdtKind::Union => Some(16), |
| AdtKind::Enum => Some(17), |
| }, |
| ty::Generator(..) => Some(18), |
| ty::Foreign(..) => Some(19), |
| ty::GeneratorWitness(..) => Some(20), |
| ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error => None, |
| ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"), |
| } |
| } |
| |
| match (type_category(a), type_category(b)) { |
| (Some(cat_a), Some(cat_b)) => match (&a.kind, &b.kind) { |
| (&ty::Adt(def_a, _), &ty::Adt(def_b, _)) => def_a == def_b, |
| _ => cat_a == cat_b, |
| }, |
| // infer and error can be equated to all types |
| _ => true, |
| } |
| } |
| |
| fn describe_generator(&self, body_id: hir::BodyId) -> Option<&'static str> { |
| self.tcx.hir().body(body_id).generator_kind.map(|gen_kind| match gen_kind { |
| hir::GeneratorKind::Gen => "a generator", |
| hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) => "an async block", |
| hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Fn) => "an async function", |
| hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Closure) => "an async closure", |
| }) |
| } |
| |
| 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 all_impls = self.tcx.all_impls(trait_ref.def_id()); |
| |
| match simp { |
| Some(simp) => all_impls |
| .iter() |
| .filter_map(|&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 None; |
| } |
| } |
| |
| Some(imp) |
| }) |
| .collect(), |
| None => { |
| all_impls.iter().map(|&def_id| self.tcx.impl_trait_ref(def_id).unwrap()).collect() |
| } |
| } |
| } |
| |
| fn report_similar_impl_candidates( |
| &self, |
| impl_candidates: Vec<ty::TraitRef<'tcx>>, |
| err: &mut DiagnosticBuilder<'_>, |
| ) { |
| if impl_candidates.is_empty() { |
| return; |
| } |
| |
| let len = impl_candidates.len(); |
| let end = if impl_candidates.len() <= 5 { impl_candidates.len() } else { 4 }; |
| |
| let normalize = |candidate| { |
| self.tcx.infer_ctxt().enter(|ref infcx| { |
| let normalized = infcx |
| .at(&ObligationCause::dummy(), ty::ParamEnv::empty()) |
| .normalize(candidate) |
| .ok(); |
| match normalized { |
| Some(normalized) => format!("\n {:?}", normalized.value), |
| None => format!("\n {:?}", candidate), |
| } |
| }) |
| }; |
| |
| // Sort impl candidates so that ordering is consistent for UI tests. |
| let mut normalized_impl_candidates = |
| impl_candidates.iter().map(normalize).collect::<Vec<String>>(); |
| |
| // Sort before taking the `..end` range, |
| // because the ordering of `impl_candidates` may not be deterministic: |
| // https://github.com/rust-lang/rust/pull/57475#issuecomment-455519507 |
| normalized_impl_candidates.sort(); |
| |
| err.help(&format!( |
| "the following implementations were found:{}{}", |
| normalized_impl_candidates[..end].join(""), |
| if len > 5 { format!("\nand {} others", len - 4) } else { String::new() } |
| )); |
| } |
| |
| /// Gets the parent trait chain start |
| fn get_parent_trait_ref( |
| &self, |
| code: &ObligationCauseCode<'tcx>, |
| ) -> Option<(String, Option<Span>)> { |
| match code { |
| &ObligationCauseCode::BuiltinDerivedObligation(ref data) => { |
| let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref); |
| match self.get_parent_trait_ref(&data.parent_code) { |
| Some(t) => Some(t), |
| None => { |
| let ty = parent_trait_ref.skip_binder().self_ty(); |
| let span = |
| TyCategory::from_ty(ty).map(|(_, def_id)| self.tcx.def_span(def_id)); |
| Some((ty.to_string(), span)) |
| } |
| } |
| } |
| _ => None, |
| } |
| } |
| |
| /// If the `Self` type of the unsatisfied trait `trait_ref` implements a trait |
| /// with the same path as `trait_ref`, a help message about |
| /// a probable version mismatch is added to `err` |
| fn note_version_mismatch( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| trait_ref: &ty::PolyTraitRef<'tcx>, |
| ) { |
| let get_trait_impl = |trait_def_id| { |
| let mut trait_impl = None; |
| self.tcx.for_each_relevant_impl(trait_def_id, trait_ref.self_ty(), |impl_def_id| { |
| if trait_impl.is_none() { |
| trait_impl = Some(impl_def_id); |
| } |
| }); |
| trait_impl |
| }; |
| let required_trait_path = self.tcx.def_path_str(trait_ref.def_id()); |
| let all_traits = self.tcx.all_traits(LOCAL_CRATE); |
| let traits_with_same_path: std::collections::BTreeSet<_> = all_traits |
| .iter() |
| .filter(|trait_def_id| **trait_def_id != trait_ref.def_id()) |
| .filter(|trait_def_id| self.tcx.def_path_str(**trait_def_id) == required_trait_path) |
| .collect(); |
| for trait_with_same_path in traits_with_same_path { |
| if let Some(impl_def_id) = get_trait_impl(*trait_with_same_path) { |
| let impl_span = self.tcx.def_span(impl_def_id); |
| err.span_help(impl_span, "trait impl with same name found"); |
| let trait_crate = self.tcx.crate_name(trait_with_same_path.krate); |
| let crate_msg = format!( |
| "perhaps two different versions of crate `{}` are being used?", |
| trait_crate |
| ); |
| err.note(&crate_msg); |
| } |
| } |
| } |
| |
| fn mk_obligation_for_def_id( |
| &self, |
| def_id: DefId, |
| output_ty: Ty<'tcx>, |
| cause: ObligationCause<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> PredicateObligation<'tcx> { |
| let new_trait_ref = |
| ty::TraitRef { def_id, substs: self.tcx.mk_substs_trait(output_ty, &[]) }; |
| Obligation::new(cause, param_env, new_trait_ref.without_const().to_predicate()) |
| } |
| |
| fn maybe_report_ambiguity( |
| &self, |
| obligation: &PredicateObligation<'tcx>, |
| body_id: Option<hir::BodyId>, |
| ) { |
| // 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_vars_if_possible(&obligation.predicate); |
| let span = obligation.cause.span; |
| |
| debug!( |
| "maybe_report_ambiguity(predicate={:?}, obligation={:?} body_id={:?}, code={:?})", |
| predicate, obligation, body_id, obligation.cause.code, |
| ); |
| |
| // 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; |
| } |
| |
| let mut err = match predicate { |
| ty::Predicate::Trait(ref data, _) => { |
| let trait_ref = data.to_poly_trait_ref(); |
| let self_ty = trait_ref.self_ty(); |
| debug!("self_ty {:?} {:?} trait_ref {:?}", self_ty, self_ty.kind, trait_ref); |
| |
| if predicate.references_error() { |
| return; |
| } |
| // 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. We used to check for `self.tcx.sess.has_errors()` to |
| // avoid inundating the user with unnecessary errors, but we now |
| // check upstream for type errors and don't add the obligations to |
| // begin with in those cases. |
| if self |
| .tcx |
| .lang_items() |
| .sized_trait() |
| .map_or(false, |sized_id| sized_id == trait_ref.def_id()) |
| { |
| self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0282).emit(); |
| return; |
| } |
| let mut err = self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0283); |
| err.note(&format!("cannot satisfy `{}`", predicate)); |
| if let ObligationCauseCode::ItemObligation(def_id) = obligation.cause.code { |
| self.suggest_fully_qualified_path(&mut err, def_id, span, trait_ref.def_id()); |
| } else if let ( |
| Ok(ref snippet), |
| ObligationCauseCode::BindingObligation(ref def_id, _), |
| ) = |
| (self.tcx.sess.source_map().span_to_snippet(span), &obligation.cause.code) |
| { |
| let generics = self.tcx.generics_of(*def_id); |
| if !generics.params.is_empty() && !snippet.ends_with('>') { |
| // FIXME: To avoid spurious suggestions in functions where type arguments |
| // where already supplied, we check the snippet to make sure it doesn't |
| // end with a turbofish. Ideally we would have access to a `PathSegment` |
| // instead. Otherwise we would produce the following output: |
| // |
| // error[E0283]: type annotations needed |
| // --> $DIR/issue-54954.rs:3:24 |
| // | |
| // LL | const ARR_LEN: usize = Tt::const_val::<[i8; 123]>(); |
| // | ^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| // | | |
| // | cannot infer type |
| // | help: consider specifying the type argument |
| // | in the function call: |
| // | `Tt::const_val::<[i8; 123]>::<T>` |
| // ... |
| // LL | const fn const_val<T: Sized>() -> usize { |
| // | --------- - required by this bound in `Tt::const_val` |
| // | |
| // = note: cannot satisfy `_: Tt` |
| |
| err.span_suggestion_verbose( |
| span.shrink_to_hi(), |
| &format!( |
| "consider specifying the type argument{} in the function call", |
| pluralize!(generics.params.len()), |
| ), |
| format!( |
| "::<{}>", |
| generics |
| .params |
| .iter() |
| .map(|p| p.name.to_string()) |
| .collect::<Vec<String>>() |
| .join(", ") |
| ), |
| Applicability::HasPlaceholders, |
| ); |
| } |
| } |
| err |
| } |
| |
| 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() { |
| return; |
| } |
| self.need_type_info_err(body_id, span, ty, ErrorCode::E0282) |
| } |
| |
| ty::Predicate::Subtype(ref data) => { |
| if data.references_error() || self.tcx.sess.has_errors() { |
| // no need to overload user in such cases |
| return; |
| } |
| let &SubtypePredicate { a_is_expected: _, a, b } = data.skip_binder(); |
| // both must be type variables, or the other would've been instantiated |
| assert!(a.is_ty_var() && b.is_ty_var()); |
| self.need_type_info_err(body_id, span, a, ErrorCode::E0282) |
| } |
| ty::Predicate::Projection(ref data) => { |
| let trait_ref = data.to_poly_trait_ref(self.tcx); |
| let self_ty = trait_ref.self_ty(); |
| if predicate.references_error() { |
| return; |
| } |
| let mut err = self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0284); |
| err.note(&format!("cannot satisfy `{}`", predicate)); |
| err |
| } |
| |
| _ => { |
| if self.tcx.sess.has_errors() { |
| return; |
| } |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0284, |
| "type annotations needed: cannot satisfy `{}`", |
| predicate, |
| ); |
| err.span_label(span, &format!("cannot satisfy `{}`", predicate)); |
| err |
| } |
| }; |
| self.note_obligation_cause(&mut err, obligation); |
| err.emit(); |
| } |
| |
| /// Returns `true` if the trait predicate may apply for *some* assignment |
| /// to the type parameters. |
| fn predicate_can_apply( |
| &self, |
| param_env: ty::ParamEnv<'tcx>, |
| pred: ty::PolyTraitRef<'tcx>, |
| ) -> bool { |
| struct ParamToVarFolder<'a, 'tcx> { |
| infcx: &'a InferCtxt<'a, 'tcx>, |
| var_map: FxHashMap<Ty<'tcx>, Ty<'tcx>>, |
| } |
| |
| impl<'a, 'tcx> TypeFolder<'tcx> for ParamToVarFolder<'a, 'tcx> { |
| fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
| self.infcx.tcx |
| } |
| |
| fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { |
| if let ty::Param(ty::ParamTy { name, .. }) = ty.kind { |
| let infcx = self.infcx; |
| self.var_map.entry(ty).or_insert_with(|| { |
| infcx.next_ty_var(TypeVariableOrigin { |
| kind: TypeVariableOriginKind::TypeParameterDefinition(name, None), |
| span: DUMMY_SP, |
| }) |
| }) |
| } 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: Default::default() }); |
| |
| let cleaned_pred = super::project::normalize( |
| &mut selcx, |
| param_env, |
| ObligationCause::dummy(), |
| &cleaned_pred, |
| ) |
| .value; |
| |
| let obligation = Obligation::new( |
| ObligationCause::dummy(), |
| param_env, |
| cleaned_pred.without_const().to_predicate(), |
| ); |
| |
| self.predicate_may_hold(&obligation) |
| }) |
| } |
| |
| fn note_obligation_cause( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| obligation: &PredicateObligation<'tcx>, |
| ) { |
| // First, attempt to add note to this error with an async-await-specific |
| // message, and fall back to regular note otherwise. |
| if !self.maybe_note_obligation_cause_for_async_await(err, obligation) { |
| self.note_obligation_cause_code( |
| err, |
| &obligation.predicate, |
| &obligation.cause.code, |
| &mut vec![], |
| ); |
| self.suggest_unsized_bound_if_applicable(err, obligation); |
| } |
| } |
| |
| fn suggest_unsized_bound_if_applicable( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| obligation: &PredicateObligation<'tcx>, |
| ) { |
| if let ( |
| ty::Predicate::Trait(pred, _), |
| ObligationCauseCode::BindingObligation(item_def_id, span), |
| ) = (&obligation.predicate, &obligation.cause.code) |
| { |
| if let (Some(generics), true) = ( |
| self.tcx.hir().get_if_local(*item_def_id).as_ref().and_then(|n| n.generics()), |
| Some(pred.def_id()) == self.tcx.lang_items().sized_trait(), |
| ) { |
| for param in generics.params { |
| if param.span == *span |
| && !param.bounds.iter().any(|bound| { |
| bound.trait_ref().and_then(|trait_ref| trait_ref.trait_def_id()) |
| == self.tcx.lang_items().sized_trait() |
| }) |
| { |
| let (span, separator) = match param.bounds { |
| [] => (span.shrink_to_hi(), ":"), |
| [.., bound] => (bound.span().shrink_to_hi(), " + "), |
| }; |
| err.span_suggestion_verbose( |
| span, |
| "consider relaxing the implicit `Sized` restriction", |
| format!("{} ?Sized", separator), |
| Applicability::MachineApplicable, |
| ); |
| return; |
| } |
| } |
| } |
| } |
| } |
| |
| fn is_recursive_obligation( |
| &self, |
| obligated_types: &mut Vec<&ty::TyS<'tcx>>, |
| cause_code: &ObligationCauseCode<'tcx>, |
| ) -> bool { |
| if let ObligationCauseCode::BuiltinDerivedObligation(ref data) = cause_code { |
| let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref); |
| |
| if obligated_types.iter().any(|ot| ot == &parent_trait_ref.skip_binder().self_ty()) { |
| return true; |
| } |
| } |
| false |
| } |
| } |
| |
| pub fn recursive_type_with_infinite_size_error( |
| tcx: TyCtxt<'tcx>, |
| type_def_id: DefId, |
| ) -> DiagnosticBuilder<'tcx> { |
| assert!(type_def_id.is_local()); |
| let span = tcx.hir().span_if_local(type_def_id).unwrap(); |
| let span = tcx.sess.source_map().guess_head_span(span); |
| let mut err = struct_span_err!( |
| tcx.sess, |
| span, |
| E0072, |
| "recursive type `{}` has infinite size", |
| tcx.def_path_str(type_def_id) |
| ); |
| err.span_label(span, "recursive type has infinite size"); |
| err.help(&format!( |
| "insert indirection (e.g., a `Box`, `Rc`, or `&`) \ |
| at some point to make `{}` representable", |
| tcx.def_path_str(type_def_id) |
| )); |
| err |
| } |
| |
| /// Summarizes information |
| #[derive(Clone)] |
| pub enum ArgKind { |
| /// An argument of non-tuple type. Parameters are (name, ty) |
| Arg(String, String), |
| |
| /// An argument of tuple type. For a "found" argument, the span is |
| /// the locationo in the source of the pattern. For a "expected" |
| /// argument, it will be None. The vector is a list of (name, ty) |
| /// strings for the components of the tuple. |
| Tuple(Option<Span>, Vec<(String, String)>), |
| } |
| |
| impl ArgKind { |
| fn empty() -> ArgKind { |
| ArgKind::Arg("_".to_owned(), "_".to_owned()) |
| } |
| |
| /// Creates an `ArgKind` from the expected type of an |
| /// argument. It has no name (`_`) and an optional source span. |
| pub fn from_expected_ty(t: Ty<'_>, span: Option<Span>) -> ArgKind { |
| match t.kind { |
| ty::Tuple(ref tys) => ArgKind::Tuple( |
| span, |
| tys.iter().map(|ty| ("_".to_owned(), ty.to_string())).collect::<Vec<_>>(), |
| ), |
| _ => ArgKind::Arg("_".to_owned(), t.to_string()), |
| } |
| } |
| } |
| |
| /// Suggest restricting a type param with a new bound. |
| pub fn suggest_constraining_type_param( |
| tcx: TyCtxt<'_>, |
| generics: &hir::Generics<'_>, |
| err: &mut DiagnosticBuilder<'_>, |
| param_name: &str, |
| constraint: &str, |
| def_id: Option<DefId>, |
| ) -> bool { |
| let param = generics.params.iter().find(|p| p.name.ident().as_str() == param_name); |
| |
| let param = if let Some(param) = param { |
| param |
| } else { |
| return false; |
| }; |
| |
| const MSG_RESTRICT_BOUND_FURTHER: &str = "consider further restricting this bound"; |
| let msg_restrict_type = format!("consider restricting type parameter `{}`", param_name); |
| let msg_restrict_type_further = |
| format!("consider further restricting type parameter `{}`", param_name); |
| |
| if def_id == tcx.lang_items().sized_trait() { |
| // Type parameters are already `Sized` by default. |
| err.span_label(param.span, &format!("this type parameter needs to be `{}`", constraint)); |
| return true; |
| } |
| let mut suggest_restrict = |span| { |
| err.span_suggestion_verbose( |
| span, |
| MSG_RESTRICT_BOUND_FURTHER, |
| format!(" + {}", constraint), |
| Applicability::MachineApplicable, |
| ); |
| }; |
| |
| if param_name.starts_with("impl ") { |
| // If there's an `impl Trait` used in argument position, suggest |
| // restricting it: |
| // |
| // fn foo(t: impl Foo) { ... } |
| // -------- |
| // | |
| // help: consider further restricting this bound with `+ Bar` |
| // |
| // Suggestion for tools in this case is: |
| // |
| // fn foo(t: impl Foo) { ... } |
| // -------- |
| // | |
| // replace with: `impl Foo + Bar` |
| |
| suggest_restrict(param.span.shrink_to_hi()); |
| return true; |
| } |
| |
| if generics.where_clause.predicates.is_empty() |
| // Given `trait Base<T = String>: Super<T>` where `T: Copy`, suggest restricting in the |
| // `where` clause instead of `trait Base<T: Copy = String>: Super<T>`. |
| && !matches!(param.kind, hir::GenericParamKind::Type { default: Some(_), .. }) |
| { |
| if let Some(bounds_span) = param.bounds_span() { |
| // If user has provided some bounds, suggest restricting them: |
| // |
| // fn foo<T: Foo>(t: T) { ... } |
| // --- |
| // | |
| // help: consider further restricting this bound with `+ Bar` |
| // |
| // Suggestion for tools in this case is: |
| // |
| // fn foo<T: Foo>(t: T) { ... } |
| // -- |
| // | |
| // replace with: `T: Bar +` |
| suggest_restrict(bounds_span.shrink_to_hi()); |
| } else { |
| // If user hasn't provided any bounds, suggest adding a new one: |
| // |
| // fn foo<T>(t: T) { ... } |
| // - help: consider restricting this type parameter with `T: Foo` |
| err.span_suggestion_verbose( |
| param.span.shrink_to_hi(), |
| &msg_restrict_type, |
| format!(": {}", constraint), |
| Applicability::MachineApplicable, |
| ); |
| } |
| |
| true |
| } else { |
| // This part is a bit tricky, because using the `where` clause user can |
| // provide zero, one or many bounds for the same type parameter, so we |
| // have following cases to consider: |
| // |
| // 1) When the type parameter has been provided zero bounds |
| // |
| // Message: |
| // fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... } |
| // - help: consider restricting this type parameter with `where X: Bar` |
| // |
| // Suggestion: |
| // fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... } |
| // - insert: `, X: Bar` |
| // |
| // |
| // 2) When the type parameter has been provided one bound |
| // |
| // Message: |
| // fn foo<T>(t: T) where T: Foo { ... } |
| // ^^^^^^ |
| // | |
| // help: consider further restricting this bound with `+ Bar` |
| // |
| // Suggestion: |
| // fn foo<T>(t: T) where T: Foo { ... } |
| // ^^ |
| // | |
| // replace with: `T: Bar +` |
| // |
| // |
| // 3) When the type parameter has been provided many bounds |
| // |
| // Message: |
| // fn foo<T>(t: T) where T: Foo, T: Bar {... } |
| // - help: consider further restricting this type parameter with `where T: Zar` |
| // |
| // Suggestion: |
| // fn foo<T>(t: T) where T: Foo, T: Bar {... } |
| // - insert: `, T: Zar` |
| |
| let mut param_spans = Vec::new(); |
| |
| for predicate in generics.where_clause.predicates { |
| if let WherePredicate::BoundPredicate(WhereBoundPredicate { |
| span, bounded_ty, .. |
| }) = predicate |
| { |
| if let TyKind::Path(QPath::Resolved(_, path)) = &bounded_ty.kind { |
| if let Some(segment) = path.segments.first() { |
| if segment.ident.to_string() == param_name { |
| param_spans.push(span); |
| } |
| } |
| } |
| } |
| } |
| |
| let where_clause_span = generics.where_clause.span_for_predicates_or_empty_place(); |
| // Account for `fn foo<T>(t: T) where T: Foo,` so we don't suggest two trailing commas. |
| let mut trailing_comma = false; |
| if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(where_clause_span) { |
| trailing_comma = snippet.ends_with(","); |
| } |
| let where_clause_span = if trailing_comma { |
| let hi = where_clause_span.hi(); |
| Span::new(hi - BytePos(1), hi, where_clause_span.ctxt()) |
| } else { |
| where_clause_span.shrink_to_hi() |
| }; |
| |
| match ¶m_spans[..] { |
| &[¶m_span] => suggest_restrict(param_span.shrink_to_hi()), |
| _ => { |
| err.span_suggestion_verbose( |
| where_clause_span, |
| &msg_restrict_type_further, |
| format!(", {}: {}", param_name, constraint), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| true |
| } |
| } |
