| //! Error Reporting Code for the inference engine |
| //! |
| //! Because of the way inference, and in particular region inference, |
| //! works, it often happens that errors are not detected until far after |
| //! the relevant line of code has been type-checked. Therefore, there is |
| //! an elaborate system to track why a particular constraint in the |
| //! inference graph arose so that we can explain to the user what gave |
| //! rise to a particular error. |
| //! |
| //! The basis of the system are the "origin" types. An "origin" is the |
| //! reason that a constraint or inference variable arose. There are |
| //! different "origin" enums for different kinds of constraints/variables |
| //! (e.g., `TypeOrigin`, `RegionVariableOrigin`). An origin always has |
| //! a span, but also more information so that we can generate a meaningful |
| //! error message. |
| //! |
| //! Having a catalog of all the different reasons an error can arise is |
| //! also useful for other reasons, like cross-referencing FAQs etc, though |
| //! we are not really taking advantage of this yet. |
| //! |
| //! # Region Inference |
| //! |
| //! Region inference is particularly tricky because it always succeeds "in |
| //! the moment" and simply registers a constraint. Then, at the end, we |
| //! can compute the full graph and report errors, so we need to be able to |
| //! store and later report what gave rise to the conflicting constraints. |
| //! |
| //! # Subtype Trace |
| //! |
| //! Determining whether `T1 <: T2` often involves a number of subtypes and |
| //! subconstraints along the way. A "TypeTrace" is an extended version |
| //! of an origin that traces the types and other values that were being |
| //! compared. It is not necessarily comprehensive (in fact, at the time of |
| //! this writing it only tracks the root values being compared) but I'd |
| //! like to extend it to include significant "waypoints". For example, if |
| //! you are comparing `(T1, T2) <: (T3, T4)`, and the problem is that `T2 |
| //! <: T4` fails, I'd like the trace to include enough information to say |
| //! "in the 2nd element of the tuple". Similarly, failures when comparing |
| //! arguments or return types in fn types should be able to cite the |
| //! specific position, etc. |
| //! |
| //! # Reality vs plan |
| //! |
| //! Of course, there is still a LOT of code in typeck that has yet to be |
| //! ported to this system, and which relies on string concatenation at the |
| //! time of error detection. |
| |
| use super::lexical_region_resolve::RegionResolutionError; |
| use super::region_constraints::GenericKind; |
| use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs}; |
| |
| use crate::hir; |
| use crate::hir::def_id::DefId; |
| use crate::hir::Node; |
| use crate::infer::{self, SuppressRegionErrors}; |
| use crate::infer::opaque_types; |
| use crate::middle::region; |
| use crate::traits::{ |
| IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, |
| }; |
| use crate::ty::error::TypeError; |
| use crate::ty::{self, subst::{Subst, SubstsRef}, Region, Ty, TyCtxt, TypeFoldable}; |
| |
| use errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString}; |
| use rustc_error_codes::*; |
| use rustc_target::spec::abi; |
| use syntax_pos::{Pos, Span}; |
| use std::{cmp, fmt}; |
| |
| mod note; |
| |
| mod need_type_info; |
| |
| pub mod nice_region_error; |
| |
| impl<'tcx> TyCtxt<'tcx> { |
| pub fn note_and_explain_region( |
| self, |
| region_scope_tree: ®ion::ScopeTree, |
| err: &mut DiagnosticBuilder<'_>, |
| prefix: &str, |
| region: ty::Region<'tcx>, |
| suffix: &str, |
| ) { |
| let (description, span) = match *region { |
| ty::ReScope(scope) => { |
| let new_string; |
| let unknown_scope = || { |
| format!( |
| "{}unknown scope: {:?}{}. Please report a bug.", |
| prefix, scope, suffix |
| ) |
| }; |
| let span = scope.span(self, region_scope_tree); |
| let tag = match self.hir().find(scope.hir_id(region_scope_tree)) { |
| Some(Node::Block(_)) => "block", |
| Some(Node::Expr(expr)) => match expr.kind { |
| hir::ExprKind::Call(..) => "call", |
| hir::ExprKind::MethodCall(..) => "method call", |
| hir::ExprKind::Match(.., hir::MatchSource::IfLetDesugar { .. }) => "if let", |
| hir::ExprKind::Match(.., hir::MatchSource::WhileLetDesugar) => "while let", |
| hir::ExprKind::Match(.., hir::MatchSource::ForLoopDesugar) => "for", |
| hir::ExprKind::Match(..) => "match", |
| _ => "expression", |
| }, |
| Some(Node::Stmt(_)) => "statement", |
| Some(Node::Item(it)) => Self::item_scope_tag(&it), |
| Some(Node::TraitItem(it)) => Self::trait_item_scope_tag(&it), |
| Some(Node::ImplItem(it)) => Self::impl_item_scope_tag(&it), |
| Some(_) | None => { |
| err.span_note(span, &unknown_scope()); |
| return; |
| } |
| }; |
| let scope_decorated_tag = match scope.data { |
| region::ScopeData::Node => tag, |
| region::ScopeData::CallSite => "scope of call-site for function", |
| region::ScopeData::Arguments => "scope of function body", |
| region::ScopeData::Destruction => { |
| new_string = format!("destruction scope surrounding {}", tag); |
| &new_string[..] |
| } |
| region::ScopeData::Remainder(first_statement_index) => { |
| new_string = format!( |
| "block suffix following statement {}", |
| first_statement_index.index() |
| ); |
| &new_string[..] |
| } |
| }; |
| self.explain_span(scope_decorated_tag, span) |
| } |
| |
| ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReStatic => { |
| self.msg_span_from_free_region(region) |
| } |
| |
| ty::ReEmpty => ("the empty lifetime".to_owned(), None), |
| |
| ty::RePlaceholder(_) => (format!("any other region"), None), |
| |
| // FIXME(#13998) RePlaceholder should probably print like |
| // ReFree rather than dumping Debug output on the user. |
| // |
| // We shouldn't really be having unification failures with ReVar |
| // and ReLateBound though. |
| ty::ReVar(_) | ty::ReLateBound(..) | ty::ReErased => { |
| (format!("lifetime {:?}", region), None) |
| } |
| |
| // We shouldn't encounter an error message with ReClosureBound. |
| ty::ReClosureBound(..) => { |
| bug!("encountered unexpected ReClosureBound: {:?}", region,); |
| } |
| }; |
| |
| TyCtxt::emit_msg_span(err, prefix, description, span, suffix); |
| } |
| |
| pub fn note_and_explain_free_region( |
| self, |
| err: &mut DiagnosticBuilder<'_>, |
| prefix: &str, |
| region: ty::Region<'tcx>, |
| suffix: &str, |
| ) { |
| let (description, span) = self.msg_span_from_free_region(region); |
| |
| TyCtxt::emit_msg_span(err, prefix, description, span, suffix); |
| } |
| |
| fn msg_span_from_free_region(self, region: ty::Region<'tcx>) -> (String, Option<Span>) { |
| match *region { |
| ty::ReEarlyBound(_) | ty::ReFree(_) => { |
| self.msg_span_from_early_bound_and_free_regions(region) |
| } |
| ty::ReStatic => ("the static lifetime".to_owned(), None), |
| ty::ReEmpty => ("an empty lifetime".to_owned(), None), |
| _ => bug!("{:?}", region), |
| } |
| } |
| |
| fn msg_span_from_early_bound_and_free_regions( |
| self, |
| region: ty::Region<'tcx>, |
| ) -> (String, Option<Span>) { |
| let cm = self.sess.source_map(); |
| |
| let scope = region.free_region_binding_scope(self); |
| let node = self.hir().as_local_hir_id(scope).unwrap_or(hir::DUMMY_HIR_ID); |
| let tag = match self.hir().find(node) { |
| Some(Node::Block(_)) | Some(Node::Expr(_)) => "body", |
| Some(Node::Item(it)) => Self::item_scope_tag(&it), |
| Some(Node::TraitItem(it)) => Self::trait_item_scope_tag(&it), |
| Some(Node::ImplItem(it)) => Self::impl_item_scope_tag(&it), |
| _ => unreachable!(), |
| }; |
| let (prefix, span) = match *region { |
| ty::ReEarlyBound(ref br) => { |
| let mut sp = cm.def_span(self.hir().span(node)); |
| if let Some(param) = self.hir() |
| .get_generics(scope) |
| .and_then(|generics| generics.get_named(br.name)) |
| { |
| sp = param.span; |
| } |
| (format!("the lifetime `{}` as defined on", br.name), sp) |
| } |
| ty::ReFree(ty::FreeRegion { |
| bound_region: ty::BoundRegion::BrNamed(_, name), |
| .. |
| }) => { |
| let mut sp = cm.def_span(self.hir().span(node)); |
| if let Some(param) = self.hir() |
| .get_generics(scope) |
| .and_then(|generics| generics.get_named(name)) |
| { |
| sp = param.span; |
| } |
| (format!("the lifetime `{}` as defined on", name), sp) |
| } |
| ty::ReFree(ref fr) => match fr.bound_region { |
| ty::BrAnon(idx) => ( |
| format!("the anonymous lifetime #{} defined on", idx + 1), |
| self.hir().span(node), |
| ), |
| _ => ( |
| format!("the lifetime `{}` as defined on", region), |
| cm.def_span(self.hir().span(node)), |
| ), |
| }, |
| _ => bug!(), |
| }; |
| let (msg, opt_span) = self.explain_span(tag, span); |
| (format!("{} {}", prefix, msg), opt_span) |
| } |
| |
| fn emit_msg_span( |
| err: &mut DiagnosticBuilder<'_>, |
| prefix: &str, |
| description: String, |
| span: Option<Span>, |
| suffix: &str, |
| ) { |
| let message = format!("{}{}{}", prefix, description, suffix); |
| |
| if let Some(span) = span { |
| err.span_note(span, &message); |
| } else { |
| err.note(&message); |
| } |
| } |
| |
| fn item_scope_tag(item: &hir::Item) -> &'static str { |
| match item.kind { |
| hir::ItemKind::Impl(..) => "impl", |
| hir::ItemKind::Struct(..) => "struct", |
| hir::ItemKind::Union(..) => "union", |
| hir::ItemKind::Enum(..) => "enum", |
| hir::ItemKind::Trait(..) => "trait", |
| hir::ItemKind::Fn(..) => "function body", |
| _ => "item", |
| } |
| } |
| |
| fn trait_item_scope_tag(item: &hir::TraitItem) -> &'static str { |
| match item.kind { |
| hir::TraitItemKind::Method(..) => "method body", |
| hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(..) => "associated item", |
| } |
| } |
| |
| fn impl_item_scope_tag(item: &hir::ImplItem) -> &'static str { |
| match item.kind { |
| hir::ImplItemKind::Method(..) => "method body", |
| hir::ImplItemKind::Const(..) |
| | hir::ImplItemKind::OpaqueTy(..) |
| | hir::ImplItemKind::TyAlias(..) => "associated item", |
| } |
| } |
| |
| fn explain_span(self, heading: &str, span: Span) -> (String, Option<Span>) { |
| let lo = self.sess.source_map().lookup_char_pos(span.lo()); |
| ( |
| format!("the {} at {}:{}", heading, lo.line, lo.col.to_usize() + 1), |
| Some(span), |
| ) |
| } |
| } |
| |
| impl<'a, 'tcx> InferCtxt<'a, 'tcx> { |
| pub fn report_region_errors( |
| &self, |
| region_scope_tree: ®ion::ScopeTree, |
| errors: &Vec<RegionResolutionError<'tcx>>, |
| suppress: SuppressRegionErrors, |
| ) { |
| debug!( |
| "report_region_errors(): {} errors to start, suppress = {:?}", |
| errors.len(), |
| suppress |
| ); |
| |
| if suppress.suppressed() { |
| return; |
| } |
| |
| // try to pre-process the errors, which will group some of them |
| // together into a `ProcessedErrors` group: |
| let errors = self.process_errors(errors); |
| |
| debug!( |
| "report_region_errors: {} errors after preprocessing", |
| errors.len() |
| ); |
| |
| for error in errors { |
| debug!("report_region_errors: error = {:?}", error); |
| |
| if !self.try_report_nice_region_error(&error) { |
| match error.clone() { |
| // These errors could indicate all manner of different |
| // problems with many different solutions. Rather |
| // than generate a "one size fits all" error, what we |
| // attempt to do is go through a number of specific |
| // scenarios and try to find the best way to present |
| // the error. If all of these fails, we fall back to a rather |
| // general bit of code that displays the error information |
| RegionResolutionError::ConcreteFailure(origin, sub, sup) => { |
| if sub.is_placeholder() || sup.is_placeholder() { |
| self.report_placeholder_failure(region_scope_tree, origin, sub, sup) |
| .emit(); |
| } else { |
| self.report_concrete_failure(region_scope_tree, origin, sub, sup) |
| .emit(); |
| } |
| } |
| |
| RegionResolutionError::GenericBoundFailure(origin, param_ty, sub) => { |
| self.report_generic_bound_failure( |
| region_scope_tree, |
| origin.span(), |
| Some(origin), |
| param_ty, |
| sub, |
| ); |
| } |
| |
| RegionResolutionError::SubSupConflict( |
| _, |
| var_origin, |
| sub_origin, |
| sub_r, |
| sup_origin, |
| sup_r, |
| ) => { |
| if sub_r.is_placeholder() { |
| self.report_placeholder_failure( |
| region_scope_tree, |
| sub_origin, |
| sub_r, |
| sup_r, |
| ) |
| .emit(); |
| } else if sup_r.is_placeholder() { |
| self.report_placeholder_failure( |
| region_scope_tree, |
| sup_origin, |
| sub_r, |
| sup_r, |
| ) |
| .emit(); |
| } else { |
| self.report_sub_sup_conflict( |
| region_scope_tree, |
| var_origin, |
| sub_origin, |
| sub_r, |
| sup_origin, |
| sup_r, |
| ); |
| } |
| } |
| |
| RegionResolutionError::MemberConstraintFailure { |
| opaque_type_def_id, |
| hidden_ty, |
| member_region, |
| span: _, |
| choice_regions: _, |
| } => { |
| let hidden_ty = self.resolve_vars_if_possible(&hidden_ty); |
| opaque_types::unexpected_hidden_region_diagnostic( |
| self.tcx, |
| Some(region_scope_tree), |
| opaque_type_def_id, |
| hidden_ty, |
| member_region, |
| ).emit(); |
| } |
| } |
| } |
| } |
| } |
| |
| // This method goes through all the errors and try to group certain types |
| // of error together, for the purpose of suggesting explicit lifetime |
| // parameters to the user. This is done so that we can have a more |
| // complete view of what lifetimes should be the same. |
| // If the return value is an empty vector, it means that processing |
| // failed (so the return value of this method should not be used). |
| // |
| // The method also attempts to weed out messages that seem like |
| // duplicates that will be unhelpful to the end-user. But |
| // obviously it never weeds out ALL errors. |
| fn process_errors( |
| &self, |
| errors: &Vec<RegionResolutionError<'tcx>>, |
| ) -> Vec<RegionResolutionError<'tcx>> { |
| debug!("process_errors()"); |
| |
| // We want to avoid reporting generic-bound failures if we can |
| // avoid it: these have a very high rate of being unhelpful in |
| // practice. This is because they are basically secondary |
| // checks that test the state of the region graph after the |
| // rest of inference is done, and the other kinds of errors |
| // indicate that the region constraint graph is internally |
| // inconsistent, so these test results are likely to be |
| // meaningless. |
| // |
| // Therefore, we filter them out of the list unless they are |
| // the only thing in the list. |
| |
| let is_bound_failure = |e: &RegionResolutionError<'tcx>| match *e { |
| RegionResolutionError::GenericBoundFailure(..) => true, |
| RegionResolutionError::ConcreteFailure(..) |
| | RegionResolutionError::SubSupConflict(..) |
| | RegionResolutionError::MemberConstraintFailure { .. } => false, |
| }; |
| |
| let mut errors = if errors.iter().all(|e| is_bound_failure(e)) { |
| errors.clone() |
| } else { |
| errors |
| .iter() |
| .filter(|&e| !is_bound_failure(e)) |
| .cloned() |
| .collect() |
| }; |
| |
| // sort the errors by span, for better error message stability. |
| errors.sort_by_key(|u| match *u { |
| RegionResolutionError::ConcreteFailure(ref sro, _, _) => sro.span(), |
| RegionResolutionError::GenericBoundFailure(ref sro, _, _) => sro.span(), |
| RegionResolutionError::SubSupConflict(_, ref rvo, _, _, _, _) => rvo.span(), |
| RegionResolutionError::MemberConstraintFailure { span, .. } => span, |
| }); |
| errors |
| } |
| |
| /// Adds a note if the types come from similarly named crates |
| fn check_and_note_conflicting_crates( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| terr: &TypeError<'tcx>, |
| ) { |
| use hir::def_id::CrateNum; |
| use hir::map::DisambiguatedDefPathData; |
| use ty::print::Printer; |
| use ty::subst::GenericArg; |
| |
| struct AbsolutePathPrinter<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| struct NonTrivialPath; |
| |
| impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> { |
| type Error = NonTrivialPath; |
| |
| type Path = Vec<String>; |
| type Region = !; |
| type Type = !; |
| type DynExistential = !; |
| type Const = !; |
| |
| fn tcx<'a>(&'a self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn print_region( |
| self, |
| _region: ty::Region<'_>, |
| ) -> Result<Self::Region, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| |
| fn print_type( |
| self, |
| _ty: Ty<'tcx>, |
| ) -> Result<Self::Type, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| |
| fn print_dyn_existential( |
| self, |
| _predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, |
| ) -> Result<Self::DynExistential, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| |
| fn print_const( |
| self, |
| _ct: &'tcx ty::Const<'tcx>, |
| ) -> Result<Self::Const, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| |
| fn path_crate( |
| self, |
| cnum: CrateNum, |
| ) -> Result<Self::Path, Self::Error> { |
| Ok(vec![self.tcx.original_crate_name(cnum).to_string()]) |
| } |
| fn path_qualified( |
| self, |
| _self_ty: Ty<'tcx>, |
| _trait_ref: Option<ty::TraitRef<'tcx>>, |
| ) -> Result<Self::Path, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| |
| fn path_append_impl( |
| self, |
| _print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, |
| _disambiguated_data: &DisambiguatedDefPathData, |
| _self_ty: Ty<'tcx>, |
| _trait_ref: Option<ty::TraitRef<'tcx>>, |
| ) -> Result<Self::Path, Self::Error> { |
| Err(NonTrivialPath) |
| } |
| fn path_append( |
| self, |
| print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, |
| disambiguated_data: &DisambiguatedDefPathData, |
| ) -> Result<Self::Path, Self::Error> { |
| let mut path = print_prefix(self)?; |
| path.push(disambiguated_data.data.as_symbol().to_string()); |
| Ok(path) |
| } |
| fn path_generic_args( |
| self, |
| print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, |
| _args: &[GenericArg<'tcx>], |
| ) -> Result<Self::Path, Self::Error> { |
| print_prefix(self) |
| } |
| } |
| |
| let report_path_match = |err: &mut DiagnosticBuilder<'_>, did1: DefId, did2: DefId| { |
| // Only external crates, if either is from a local |
| // module we could have false positives |
| if !(did1.is_local() || did2.is_local()) && did1.krate != did2.krate { |
| let abs_path = |def_id| { |
| AbsolutePathPrinter { tcx: self.tcx } |
| .print_def_path(def_id, &[]) |
| }; |
| |
| // We compare strings because DefPath can be different |
| // for imported and non-imported crates |
| let same_path = || -> Result<_, NonTrivialPath> { |
| Ok( |
| self.tcx.def_path_str(did1) == self.tcx.def_path_str(did2) || |
| abs_path(did1)? == abs_path(did2)? |
| ) |
| }; |
| if same_path().unwrap_or(false) { |
| let crate_name = self.tcx.crate_name(did1.krate); |
| err.note(&format!( |
| "perhaps two different versions of crate `{}` are being used?", |
| crate_name |
| )); |
| } |
| } |
| }; |
| match *terr { |
| TypeError::Sorts(ref exp_found) => { |
| // if they are both "path types", there's a chance of ambiguity |
| // due to different versions of the same crate |
| if let (&ty::Adt(exp_adt, _), &ty::Adt(found_adt, _)) |
| = (&exp_found.expected.kind, &exp_found.found.kind) |
| { |
| report_path_match(err, exp_adt.did, found_adt.did); |
| } |
| } |
| TypeError::Traits(ref exp_found) => { |
| report_path_match(err, exp_found.expected, exp_found.found); |
| } |
| _ => (), // FIXME(#22750) handle traits and stuff |
| } |
| } |
| |
| fn note_error_origin( |
| &self, |
| err: &mut DiagnosticBuilder<'tcx>, |
| cause: &ObligationCause<'tcx>, |
| exp_found: Option<ty::error::ExpectedFound<Ty<'tcx>>>, |
| ) { |
| match cause.code { |
| ObligationCauseCode::MatchExpressionArmPattern { span, ty } => { |
| if ty.is_suggestable() { // don't show type `_` |
| err.span_label(span, format!("this match expression has type `{}`", ty)); |
| } |
| if let Some(ty::error::ExpectedFound { found, .. }) = exp_found { |
| if ty.is_box() && ty.boxed_ty() == found { |
| if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) { |
| err.span_suggestion( |
| span, |
| "consider dereferencing the boxed value", |
| format!("*{}", snippet), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| } |
| ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { |
| source, |
| ref prior_arms, |
| last_ty, |
| discrim_hir_id, |
| .. |
| }) => match source { |
| hir::MatchSource::IfLetDesugar { .. } => { |
| let msg = "`if let` arms have incompatible types"; |
| err.span_label(cause.span, msg); |
| } |
| hir::MatchSource::TryDesugar => { |
| if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found { |
| let discrim_expr = self.tcx.hir().expect_expr(discrim_hir_id); |
| let discrim_ty = if let hir::ExprKind::Call(_, args) = &discrim_expr.kind { |
| let arg_expr = args.first().expect("try desugaring call w/out arg"); |
| self.in_progress_tables.and_then(|tables| { |
| tables.borrow().expr_ty_opt(arg_expr) |
| }) |
| } else { |
| bug!("try desugaring w/out call expr as discriminant"); |
| }; |
| |
| match discrim_ty { |
| Some(ty) if expected == ty => { |
| let source_map = self.tcx.sess.source_map(); |
| err.span_suggestion( |
| source_map.end_point(cause.span), |
| "try removing this `?`", |
| "".to_string(), |
| Applicability::MachineApplicable, |
| ); |
| }, |
| _ => {}, |
| } |
| } |
| } |
| _ => { |
| // `last_ty` can be `!`, `expected` will have better info when present. |
| let t = self.resolve_vars_if_possible(&match exp_found { |
| Some(ty::error::ExpectedFound { expected, .. }) => expected, |
| _ => last_ty, |
| }); |
| let msg = "`match` arms have incompatible types"; |
| err.span_label(cause.span, msg); |
| if prior_arms.len() <= 4 { |
| for sp in prior_arms { |
| err.span_label( *sp, format!("this is found to be of type `{}`", t)); |
| } |
| } else if let Some(sp) = prior_arms.last() { |
| err.span_label( |
| *sp, |
| format!("this and all prior arms are found to be of type `{}`", t), |
| ); |
| } |
| } |
| }, |
| ObligationCauseCode::IfExpression(box IfExpressionCause { then, outer, semicolon }) => { |
| err.span_label(then, "expected because of this"); |
| outer.map(|sp| err.span_label(sp, "if and else have incompatible types")); |
| if let Some(sp) = semicolon { |
| err.span_suggestion_short( |
| sp, |
| "consider removing this semicolon", |
| String::new(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| _ => (), |
| } |
| } |
| |
| /// Given that `other_ty` is the same as a type argument for `name` in `sub`, populate `value` |
| /// highlighting `name` and every type argument that isn't at `pos` (which is `other_ty`), and |
| /// populate `other_value` with `other_ty`. |
| /// |
| /// ```text |
| /// Foo<Bar<Qux>> |
| /// ^^^^--------^ this is highlighted |
| /// | | |
| /// | this type argument is exactly the same as the other type, not highlighted |
| /// this is highlighted |
| /// Bar<Qux> |
| /// -------- this type is the same as a type argument in the other type, not highlighted |
| /// ``` |
| fn highlight_outer( |
| &self, |
| value: &mut DiagnosticStyledString, |
| other_value: &mut DiagnosticStyledString, |
| name: String, |
| sub: ty::subst::SubstsRef<'tcx>, |
| pos: usize, |
| other_ty: Ty<'tcx>, |
| ) { |
| // `value` and `other_value` hold two incomplete type representation for display. |
| // `name` is the path of both types being compared. `sub` |
| value.push_highlighted(name); |
| let len = sub.len(); |
| if len > 0 { |
| value.push_highlighted("<"); |
| } |
| |
| // Output the lifetimes for the first type |
| let lifetimes = sub.regions() |
| .map(|lifetime| { |
| let s = lifetime.to_string(); |
| if s.is_empty() { |
| "'_".to_string() |
| } else { |
| s |
| } |
| }) |
| .collect::<Vec<_>>() |
| .join(", "); |
| if !lifetimes.is_empty() { |
| if sub.regions().count() < len { |
| value.push_normal(lifetimes + &", "); |
| } else { |
| value.push_normal(lifetimes); |
| } |
| } |
| |
| // Highlight all the type arguments that aren't at `pos` and compare the type argument at |
| // `pos` and `other_ty`. |
| for (i, type_arg) in sub.types().enumerate() { |
| if i == pos { |
| let values = self.cmp(type_arg, other_ty); |
| value.0.extend((values.0).0); |
| other_value.0.extend((values.1).0); |
| } else { |
| value.push_highlighted(type_arg.to_string()); |
| } |
| |
| if len > 0 && i != len - 1 { |
| value.push_normal(", "); |
| } |
| } |
| if len > 0 { |
| value.push_highlighted(">"); |
| } |
| } |
| |
| /// If `other_ty` is the same as a type argument present in `sub`, highlight `path` in `t1_out`, |
| /// as that is the difference to the other type. |
| /// |
| /// For the following code: |
| /// |
| /// ```norun |
| /// let x: Foo<Bar<Qux>> = foo::<Bar<Qux>>(); |
| /// ``` |
| /// |
| /// The type error output will behave in the following way: |
| /// |
| /// ```text |
| /// Foo<Bar<Qux>> |
| /// ^^^^--------^ this is highlighted |
| /// | | |
| /// | this type argument is exactly the same as the other type, not highlighted |
| /// this is highlighted |
| /// Bar<Qux> |
| /// -------- this type is the same as a type argument in the other type, not highlighted |
| /// ``` |
| fn cmp_type_arg( |
| &self, |
| mut t1_out: &mut DiagnosticStyledString, |
| mut t2_out: &mut DiagnosticStyledString, |
| path: String, |
| sub: ty::subst::SubstsRef<'tcx>, |
| other_path: String, |
| other_ty: Ty<'tcx>, |
| ) -> Option<()> { |
| for (i, ta) in sub.types().enumerate() { |
| if ta == other_ty { |
| self.highlight_outer(&mut t1_out, &mut t2_out, path, sub, i, &other_ty); |
| return Some(()); |
| } |
| if let &ty::Adt(def, _) = &ta.kind { |
| let path_ = self.tcx.def_path_str(def.did.clone()); |
| if path_ == other_path { |
| self.highlight_outer(&mut t1_out, &mut t2_out, path, sub, i, &other_ty); |
| return Some(()); |
| } |
| } |
| } |
| None |
| } |
| |
| /// Adds a `,` to the type representation only if it is appropriate. |
| fn push_comma( |
| &self, |
| value: &mut DiagnosticStyledString, |
| other_value: &mut DiagnosticStyledString, |
| len: usize, |
| pos: usize, |
| ) { |
| if len > 0 && pos != len - 1 { |
| value.push_normal(", "); |
| other_value.push_normal(", "); |
| } |
| } |
| |
| /// For generic types with parameters with defaults, remove the parameters corresponding to |
| /// the defaults. This repeats a lot of the logic found in `ty::print::pretty`. |
| fn strip_generic_default_params( |
| &self, |
| def_id: DefId, |
| substs: ty::subst::SubstsRef<'tcx>, |
| ) -> SubstsRef<'tcx> { |
| let generics = self.tcx.generics_of(def_id); |
| let mut num_supplied_defaults = 0; |
| let mut type_params = generics.params.iter().rev().filter_map(|param| match param.kind { |
| ty::GenericParamDefKind::Lifetime => None, |
| ty::GenericParamDefKind::Type { has_default, .. } => Some((param.def_id, has_default)), |
| ty::GenericParamDefKind::Const => None, // FIXME(const_generics:defaults) |
| }).peekable(); |
| let has_default = { |
| let has_default = type_params.peek().map(|(_, has_default)| has_default); |
| *has_default.unwrap_or(&false) |
| }; |
| if has_default { |
| let types = substs.types().rev(); |
| for ((def_id, has_default), actual) in type_params.zip(types) { |
| if !has_default { |
| break; |
| } |
| if self.tcx.type_of(def_id).subst(self.tcx, substs) != actual { |
| break; |
| } |
| num_supplied_defaults += 1; |
| } |
| } |
| let len = generics.params.len(); |
| let mut generics = generics.clone(); |
| generics.params.truncate(len - num_supplied_defaults); |
| substs.truncate_to(self.tcx, &generics) |
| } |
| |
| /// Given two `fn` signatures highlight only sub-parts that are different. |
| fn cmp_fn_sig( |
| &self, |
| sig1: &ty::PolyFnSig<'tcx>, |
| sig2: &ty::PolyFnSig<'tcx>, |
| ) -> (DiagnosticStyledString, DiagnosticStyledString) { |
| let get_lifetimes = |sig| { |
| use crate::hir::def::Namespace; |
| let mut s = String::new(); |
| let (_, (sig, reg)) = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS) |
| .name_all_regions(sig) |
| .unwrap(); |
| let lts: Vec<String> = reg.into_iter().map(|(_, kind)| kind.to_string()).collect(); |
| (if lts.is_empty() { |
| String::new() |
| } else { |
| format!("for<{}> ", lts.join(", ")) |
| }, sig) |
| }; |
| |
| let (lt1, sig1) = get_lifetimes(sig1); |
| let (lt2, sig2) = get_lifetimes(sig2); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| let mut values = ( |
| DiagnosticStyledString::normal("".to_string()), |
| DiagnosticStyledString::normal("".to_string()), |
| ); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^^^^ |
| values.0.push(sig1.unsafety.prefix_str(), sig1.unsafety != sig2.unsafety); |
| values.1.push(sig2.unsafety.prefix_str(), sig1.unsafety != sig2.unsafety); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^^^^^^^^ |
| if sig1.abi != abi::Abi::Rust { |
| values.0.push(format!("extern {} ", sig1.abi), sig1.abi != sig2.abi); |
| } |
| if sig2.abi != abi::Abi::Rust { |
| values.1.push(format!("extern {} ", sig2.abi), sig1.abi != sig2.abi); |
| } |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^^^^^^ |
| let lifetime_diff = lt1 != lt2; |
| values.0.push(lt1, lifetime_diff); |
| values.1.push(lt2, lifetime_diff); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^ |
| values.0.push_normal("fn("); |
| values.1.push_normal("fn("); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^^^ |
| let len1 = sig1.inputs().len(); |
| let len2 = sig2.inputs().len(); |
| if len1 == len2 { |
| for (i, (l, r)) in sig1.inputs().iter().zip(sig2.inputs().iter()).enumerate() { |
| let (x1, x2) = self.cmp(l, r); |
| (values.0).0.extend(x1.0); |
| (values.1).0.extend(x2.0); |
| self.push_comma(&mut values.0, &mut values.1, len1, i); |
| } |
| } else { |
| for (i, l) in sig1.inputs().iter().enumerate() { |
| values.0.push_highlighted(l.to_string()); |
| if i != len1 - 1 { |
| values.0.push_highlighted(", "); |
| } |
| } |
| for (i, r) in sig2.inputs().iter().enumerate() { |
| values.1.push_highlighted(r.to_string()); |
| if i != len2 - 1 { |
| values.1.push_highlighted(", "); |
| } |
| } |
| } |
| |
| if sig1.c_variadic { |
| if len1 > 0 { |
| values.0.push_normal(", "); |
| } |
| values.0.push("...", !sig2.c_variadic); |
| } |
| if sig2.c_variadic { |
| if len2 > 0 { |
| values.1.push_normal(", "); |
| } |
| values.1.push("...", !sig1.c_variadic); |
| } |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^ |
| values.0.push_normal(")"); |
| values.1.push_normal(")"); |
| |
| // unsafe extern "C" for<'a> fn(&'a T) -> &'a T |
| // ^^^^^^^^ |
| let output1 = sig1.output(); |
| let output2 = sig2.output(); |
| let (x1, x2) = self.cmp(output1, output2); |
| if !output1.is_unit() { |
| values.0.push_normal(" -> "); |
| (values.0).0.extend(x1.0); |
| } |
| if !output2.is_unit() { |
| values.1.push_normal(" -> "); |
| (values.1).0.extend(x2.0); |
| } |
| values |
| } |
| |
| /// Compares two given types, eliding parts that are the same between them and highlighting |
| /// relevant differences, and return two representation of those types for highlighted printing. |
| fn cmp(&self, t1: Ty<'tcx>, t2: Ty<'tcx>) -> (DiagnosticStyledString, DiagnosticStyledString) { |
| debug!("cmp(t1={}, t1.kind={:?}, t2={}, t2.kind={:?})", t1, t1.kind, t2, t2.kind); |
| |
| // helper functions |
| fn equals<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool { |
| match (&a.kind, &b.kind) { |
| (a, b) if *a == *b => true, |
| (&ty::Int(_), &ty::Infer(ty::InferTy::IntVar(_))) |
| | (&ty::Infer(ty::InferTy::IntVar(_)), &ty::Int(_)) |
| | (&ty::Infer(ty::InferTy::IntVar(_)), &ty::Infer(ty::InferTy::IntVar(_))) |
| | (&ty::Float(_), &ty::Infer(ty::InferTy::FloatVar(_))) |
| | (&ty::Infer(ty::InferTy::FloatVar(_)), &ty::Float(_)) |
| | (&ty::Infer(ty::InferTy::FloatVar(_)), &ty::Infer(ty::InferTy::FloatVar(_))) => { |
| true |
| } |
| _ => false, |
| } |
| } |
| |
| fn push_ty_ref<'tcx>( |
| r: &ty::Region<'tcx>, |
| ty: Ty<'tcx>, |
| mutbl: hir::Mutability, |
| s: &mut DiagnosticStyledString, |
| ) { |
| let mut r = r.to_string(); |
| if r == "'_" { |
| r.clear(); |
| } else { |
| r.push(' '); |
| } |
| s.push_highlighted(format!("&{}{}", r, mutbl.prefix_str())); |
| s.push_normal(ty.to_string()); |
| } |
| |
| // process starts here |
| match (&t1.kind, &t2.kind) { |
| (&ty::Adt(def1, sub1), &ty::Adt(def2, sub2)) => { |
| let sub_no_defaults_1 = self.strip_generic_default_params(def1.did, sub1); |
| let sub_no_defaults_2 = self.strip_generic_default_params(def2.did, sub2); |
| let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new()); |
| let path1 = self.tcx.def_path_str(def1.did.clone()); |
| let path2 = self.tcx.def_path_str(def2.did.clone()); |
| if def1.did == def2.did { |
| // Easy case. Replace same types with `_` to shorten the output and highlight |
| // the differing ones. |
| // let x: Foo<Bar, Qux> = y::<Foo<Quz, Qux>>(); |
| // Foo<Bar, _> |
| // Foo<Quz, _> |
| // --- ^ type argument elided |
| // | |
| // highlighted in output |
| values.0.push_normal(path1); |
| values.1.push_normal(path2); |
| |
| // Avoid printing out default generic parameters that are common to both |
| // types. |
| let len1 = sub_no_defaults_1.len(); |
| let len2 = sub_no_defaults_2.len(); |
| let common_len = cmp::min(len1, len2); |
| let remainder1: Vec<_> = sub1.types().skip(common_len).collect(); |
| let remainder2: Vec<_> = sub2.types().skip(common_len).collect(); |
| let common_default_params = remainder1 |
| .iter() |
| .rev() |
| .zip(remainder2.iter().rev()) |
| .filter(|(a, b)| a == b) |
| .count(); |
| let len = sub1.len() - common_default_params; |
| let consts_offset = len - sub1.consts().count(); |
| |
| // Only draw `<...>` if there're lifetime/type arguments. |
| if len > 0 { |
| values.0.push_normal("<"); |
| values.1.push_normal("<"); |
| } |
| |
| fn lifetime_display(lifetime: Region<'_>) -> String { |
| let s = lifetime.to_string(); |
| if s.is_empty() { |
| "'_".to_string() |
| } else { |
| s |
| } |
| } |
| // At one point we'd like to elide all lifetimes here, they are irrelevant for |
| // all diagnostics that use this output |
| // |
| // Foo<'x, '_, Bar> |
| // Foo<'y, '_, Qux> |
| // ^^ ^^ --- type arguments are not elided |
| // | | |
| // | elided as they were the same |
| // not elided, they were different, but irrelevant |
| let lifetimes = sub1.regions().zip(sub2.regions()); |
| for (i, lifetimes) in lifetimes.enumerate() { |
| let l1 = lifetime_display(lifetimes.0); |
| let l2 = lifetime_display(lifetimes.1); |
| if lifetimes.0 == lifetimes.1 { |
| values.0.push_normal("'_"); |
| values.1.push_normal("'_"); |
| } else { |
| values.0.push_highlighted(l1); |
| values.1.push_highlighted(l2); |
| } |
| self.push_comma(&mut values.0, &mut values.1, len, i); |
| } |
| |
| // We're comparing two types with the same path, so we compare the type |
| // arguments for both. If they are the same, do not highlight and elide from the |
| // output. |
| // Foo<_, Bar> |
| // Foo<_, Qux> |
| // ^ elided type as this type argument was the same in both sides |
| let type_arguments = sub1.types().zip(sub2.types()); |
| let regions_len = sub1.regions().count(); |
| let num_display_types = consts_offset - regions_len; |
| for (i, (ta1, ta2)) in type_arguments.take(num_display_types).enumerate() { |
| let i = i + regions_len; |
| if ta1 == ta2 { |
| values.0.push_normal("_"); |
| values.1.push_normal("_"); |
| } else { |
| let (x1, x2) = self.cmp(ta1, ta2); |
| (values.0).0.extend(x1.0); |
| (values.1).0.extend(x2.0); |
| } |
| self.push_comma(&mut values.0, &mut values.1, len, i); |
| } |
| |
| // Do the same for const arguments, if they are equal, do not highlight and |
| // elide them from the output. |
| let const_arguments = sub1.consts().zip(sub2.consts()); |
| for (i, (ca1, ca2)) in const_arguments.enumerate() { |
| let i = i + consts_offset; |
| if ca1 == ca2 { |
| values.0.push_normal("_"); |
| values.1.push_normal("_"); |
| } else { |
| values.0.push_highlighted(ca1.to_string()); |
| values.1.push_highlighted(ca2.to_string()); |
| } |
| self.push_comma(&mut values.0, &mut values.1, len, i); |
| } |
| |
| // Close the type argument bracket. |
| // Only draw `<...>` if there're lifetime/type arguments. |
| if len > 0 { |
| values.0.push_normal(">"); |
| values.1.push_normal(">"); |
| } |
| values |
| } else { |
| // Check for case: |
| // let x: Foo<Bar<Qux> = foo::<Bar<Qux>>(); |
| // Foo<Bar<Qux> |
| // ------- this type argument is exactly the same as the other type |
| // Bar<Qux> |
| if self.cmp_type_arg( |
| &mut values.0, |
| &mut values.1, |
| path1.clone(), |
| sub_no_defaults_1, |
| path2.clone(), |
| &t2, |
| ).is_some() |
| { |
| return values; |
| } |
| // Check for case: |
| // let x: Bar<Qux> = y:<Foo<Bar<Qux>>>(); |
| // Bar<Qux> |
| // Foo<Bar<Qux>> |
| // ------- this type argument is exactly the same as the other type |
| if self.cmp_type_arg( |
| &mut values.1, |
| &mut values.0, |
| path2, |
| sub_no_defaults_2, |
| path1, |
| &t1, |
| ).is_some() |
| { |
| return values; |
| } |
| |
| // We can't find anything in common, highlight relevant part of type path. |
| // let x: foo::bar::Baz<Qux> = y:<foo::bar::Bar<Zar>>(); |
| // foo::bar::Baz<Qux> |
| // foo::bar::Bar<Zar> |
| // -------- this part of the path is different |
| |
| let t1_str = t1.to_string(); |
| let t2_str = t2.to_string(); |
| let min_len = t1_str.len().min(t2_str.len()); |
| |
| const SEPARATOR: &str = "::"; |
| let separator_len = SEPARATOR.len(); |
| let split_idx: usize = |
| t1_str.split(SEPARATOR) |
| .zip(t2_str.split(SEPARATOR)) |
| .take_while(|(mod1_str, mod2_str)| mod1_str == mod2_str) |
| .map(|(mod_str, _)| mod_str.len() + separator_len) |
| .sum(); |
| |
| debug!("cmp: separator_len={}, split_idx={}, min_len={}", |
| separator_len, split_idx, min_len |
| ); |
| |
| if split_idx >= min_len { |
| // paths are identical, highlight everything |
| ( |
| DiagnosticStyledString::highlighted(t1_str), |
| DiagnosticStyledString::highlighted(t2_str) |
| ) |
| } else { |
| let (common, uniq1) = t1_str.split_at(split_idx); |
| let (_, uniq2) = t2_str.split_at(split_idx); |
| debug!("cmp: common={}, uniq1={}, uniq2={}", common, uniq1, uniq2); |
| |
| values.0.push_normal(common); |
| values.0.push_highlighted(uniq1); |
| values.1.push_normal(common); |
| values.1.push_highlighted(uniq2); |
| |
| values |
| } |
| } |
| } |
| |
| // When finding T != &T, highlight only the borrow |
| (&ty::Ref(r1, ref_ty1, mutbl1), _) if equals(&ref_ty1, &t2) => { |
| let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new()); |
| push_ty_ref(&r1, ref_ty1, mutbl1, &mut values.0); |
| values.1.push_normal(t2.to_string()); |
| values |
| } |
| (_, &ty::Ref(r2, ref_ty2, mutbl2)) if equals(&t1, &ref_ty2) => { |
| let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new()); |
| values.0.push_normal(t1.to_string()); |
| push_ty_ref(&r2, ref_ty2, mutbl2, &mut values.1); |
| values |
| } |
| |
| // When encountering &T != &mut T, highlight only the borrow |
| (&ty::Ref(r1, ref_ty1, mutbl1), &ty::Ref(r2, ref_ty2, mutbl2)) |
| if equals(&ref_ty1, &ref_ty2) => |
| { |
| let mut values = (DiagnosticStyledString::new(), DiagnosticStyledString::new()); |
| push_ty_ref(&r1, ref_ty1, mutbl1, &mut values.0); |
| push_ty_ref(&r2, ref_ty2, mutbl2, &mut values.1); |
| values |
| } |
| |
| // When encountering tuples of the same size, highlight only the differing types |
| (&ty::Tuple(substs1), &ty::Tuple(substs2)) if substs1.len() == substs2.len() => { |
| let mut values = ( |
| DiagnosticStyledString::normal("("), |
| DiagnosticStyledString::normal("("), |
| ); |
| let len = substs1.len(); |
| for (i, (left, right)) in substs1.types().zip(substs2.types()).enumerate() { |
| let (x1, x2) = self.cmp(left, right); |
| (values.0).0.extend(x1.0); |
| (values.1).0.extend(x2.0); |
| self.push_comma(&mut values.0, &mut values.1, len, i); |
| } |
| if len == 1 { // Keep the output for single element tuples as `(ty,)`. |
| values.0.push_normal(","); |
| values.1.push_normal(","); |
| } |
| values.0.push_normal(")"); |
| values.1.push_normal(")"); |
| values |
| } |
| |
| (ty::FnDef(did1, substs1), ty::FnDef(did2, substs2)) => { |
| let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1); |
| let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2); |
| let mut values = self.cmp_fn_sig(&sig1, &sig2); |
| let path1 = format!(" {{{}}}", self.tcx.def_path_str_with_substs(*did1, substs1)); |
| let path2 = format!(" {{{}}}", self.tcx.def_path_str_with_substs(*did2, substs2)); |
| let same_path = path1 == path2; |
| values.0.push(path1, !same_path); |
| values.1.push(path2, !same_path); |
| values |
| } |
| |
| (ty::FnDef(did1, substs1), ty::FnPtr(sig2)) => { |
| let sig1 = self.tcx.fn_sig(*did1).subst(self.tcx, substs1); |
| let mut values = self.cmp_fn_sig(&sig1, sig2); |
| values.0.push_normal(format!( |
| " {{{}}}", |
| self.tcx.def_path_str_with_substs(*did1, substs1)), |
| ); |
| values |
| } |
| |
| (ty::FnPtr(sig1), ty::FnDef(did2, substs2)) => { |
| let sig2 = self.tcx.fn_sig(*did2).subst(self.tcx, substs2); |
| let mut values = self.cmp_fn_sig(sig1, &sig2); |
| values.1.push_normal(format!( |
| " {{{}}}", |
| self.tcx.def_path_str_with_substs(*did2, substs2)), |
| ); |
| values |
| } |
| |
| (ty::FnPtr(sig1), ty::FnPtr(sig2)) => { |
| self.cmp_fn_sig(sig1, sig2) |
| } |
| |
| _ => { |
| if t1 == t2 { |
| // The two types are the same, elide and don't highlight. |
| ( |
| DiagnosticStyledString::normal("_"), |
| DiagnosticStyledString::normal("_"), |
| ) |
| } else { |
| // We couldn't find anything in common, highlight everything. |
| ( |
| DiagnosticStyledString::highlighted(t1.to_string()), |
| DiagnosticStyledString::highlighted(t2.to_string()), |
| ) |
| } |
| } |
| } |
| } |
| |
| pub fn note_type_err( |
| &self, |
| diag: &mut DiagnosticBuilder<'tcx>, |
| cause: &ObligationCause<'tcx>, |
| secondary_span: Option<(Span, String)>, |
| mut values: Option<ValuePairs<'tcx>>, |
| terr: &TypeError<'tcx>, |
| ) { |
| // For some types of errors, expected-found does not make |
| // sense, so just ignore the values we were given. |
| match terr { |
| TypeError::CyclicTy(_) => { |
| values = None; |
| } |
| _ => {} |
| } |
| |
| debug!("note_type_err(diag={:?})", diag); |
| let (expected_found, exp_found, is_simple_error) = match values { |
| None => (None, None, false), |
| Some(values) => { |
| let (is_simple_error, exp_found) = match values { |
| ValuePairs::Types(exp_found) => { |
| let is_simple_err = exp_found.expected.is_simple_text() |
| && exp_found.found.is_simple_text(); |
| |
| (is_simple_err, Some(exp_found)) |
| } |
| _ => (false, None), |
| }; |
| let vals = match self.values_str(&values) { |
| Some((expected, found)) => Some((expected, found)), |
| None => { |
| // Derived error. Cancel the emitter. |
| diag.cancel(); |
| return; |
| } |
| }; |
| (vals, exp_found, is_simple_error) |
| } |
| }; |
| |
| let span = cause.span(self.tcx); |
| |
| // Ignore msg for object safe coercion |
| // since E0038 message will be printed |
| match terr { |
| TypeError::ObjectUnsafeCoercion(_) => {} |
| _ => { |
| diag.span_label(span, terr.to_string()); |
| if let Some((sp, msg)) = secondary_span { |
| diag.span_label(sp, msg); |
| } |
| } |
| }; |
| |
| if let Some((expected, found)) = expected_found { |
| let expected_label = exp_found.map_or("type".into(), |ef| ef.expected.prefix_string()); |
| let found_label = exp_found.map_or("type".into(), |ef| ef.found.prefix_string()); |
| match (&terr, expected == found) { |
| (TypeError::Sorts(values), extra) => { |
| let sort_string = |ty: Ty<'tcx>| match (extra, &ty.kind) { |
| (true, ty::Opaque(def_id, _)) => format!( |
| " (opaque type at {})", |
| self.tcx.sess.source_map() |
| .mk_substr_filename(self.tcx.def_span(*def_id)), |
| ), |
| (true, _) => format!(" ({})", ty.sort_string(self.tcx)), |
| (false, _) => "".to_string(), |
| }; |
| if !(values.expected.is_simple_text() && values.found.is_simple_text()) || ( |
| exp_found.map_or(false, |ef| { |
| // This happens when the type error is a subset of the expectation, |
| // like when you have two references but one is `usize` and the other |
| // is `f32`. In those cases we still want to show the `note`. If the |
| // value from `ef` is `Infer(_)`, then we ignore it. |
| if !ef.expected.is_ty_infer() { |
| ef.expected != values.expected |
| } else if !ef.found.is_ty_infer() { |
| ef.found != values.found |
| } else { |
| false |
| } |
| }) |
| ) { |
| diag.note_expected_found_extra( |
| &expected_label, |
| expected, |
| &found_label, |
| found, |
| &sort_string(values.expected), |
| &sort_string(values.found), |
| ); |
| } |
| } |
| (TypeError::ObjectUnsafeCoercion(_), _) => { |
| diag.note_unsuccessfull_coercion(found, expected); |
| } |
| (_, _) => { |
| debug!( |
| "note_type_err: exp_found={:?}, expected={:?} found={:?}", |
| exp_found, expected, found |
| ); |
| if !is_simple_error || terr.must_include_note() { |
| diag.note_expected_found(&expected_label, expected, &found_label, found); |
| } |
| } |
| } |
| } |
| if let Some(exp_found) = exp_found { |
| self.suggest_as_ref_where_appropriate(span, &exp_found, diag); |
| } |
| |
| // In some (most?) cases cause.body_id points to actual body, but in some cases |
| // it's a actual definition. According to the comments (e.g. in |
| // librustc_typeck/check/compare_method.rs:compare_predicate_entailment) the latter |
| // is relied upon by some other code. This might (or might not) need cleanup. |
| let body_owner_def_id = self.tcx.hir().opt_local_def_id(cause.body_id) |
| .unwrap_or_else(|| { |
| self.tcx.hir().body_owner_def_id(hir::BodyId { hir_id: cause.body_id }) |
| }); |
| self.check_and_note_conflicting_crates(diag, terr); |
| self.tcx.note_and_explain_type_err(diag, terr, span, body_owner_def_id); |
| |
| // It reads better to have the error origin as the final |
| // thing. |
| self.note_error_origin(diag, &cause, exp_found); |
| } |
| |
| /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate, |
| /// suggests it. |
| fn suggest_as_ref_where_appropriate( |
| &self, |
| span: Span, |
| exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, |
| diag: &mut DiagnosticBuilder<'tcx>, |
| ) { |
| match (&exp_found.expected.kind, &exp_found.found.kind) { |
| (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) => { |
| if let ty::Adt(found_def, found_substs) = found_ty.kind { |
| let path_str = format!("{:?}", exp_def); |
| if exp_def == &found_def { |
| let opt_msg = "you can convert from `&Option<T>` to `Option<&T>` using \ |
| `.as_ref()`"; |
| let result_msg = "you can convert from `&Result<T, E>` to \ |
| `Result<&T, &E>` using `.as_ref()`"; |
| let have_as_ref = &[ |
| ("std::option::Option", opt_msg), |
| ("core::option::Option", opt_msg), |
| ("std::result::Result", result_msg), |
| ("core::result::Result", result_msg), |
| ]; |
| if let Some(msg) = have_as_ref.iter() |
| .filter_map(|(path, msg)| if &path_str == path { |
| Some(msg) |
| } else { |
| None |
| }).next() |
| { |
| let mut show_suggestion = true; |
| for (exp_ty, found_ty) in exp_substs.types().zip(found_substs.types()) { |
| match exp_ty.kind { |
| ty::Ref(_, exp_ty, _) => { |
| match (&exp_ty.kind, &found_ty.kind) { |
| (_, ty::Param(_)) | |
| (_, ty::Infer(_)) | |
| (ty::Param(_), _) | |
| (ty::Infer(_), _) => {} |
| _ if ty::TyS::same_type(exp_ty, found_ty) => {} |
| _ => show_suggestion = false, |
| }; |
| } |
| ty::Param(_) | ty::Infer(_) => {} |
| _ => show_suggestion = false, |
| } |
| } |
| if let (Ok(snippet), true) = ( |
| self.tcx.sess.source_map().span_to_snippet(span), |
| show_suggestion, |
| ) { |
| diag.span_suggestion( |
| span, |
| msg, |
| format!("{}.as_ref()", snippet), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| } |
| } |
| _ => {} |
| } |
| } |
| |
| pub fn report_and_explain_type_error( |
| &self, |
| trace: TypeTrace<'tcx>, |
| terr: &TypeError<'tcx>, |
| ) -> DiagnosticBuilder<'tcx> { |
| debug!( |
| "report_and_explain_type_error(trace={:?}, terr={:?})", |
| trace, terr |
| ); |
| |
| let span = trace.cause.span(self.tcx); |
| let failure_code = trace.cause.as_failure_code(terr); |
| let mut diag = match failure_code { |
| FailureCode::Error0038(did) => { |
| let violations = self.tcx.object_safety_violations(did); |
| self.tcx.report_object_safety_error(span, did, violations) |
| } |
| FailureCode::Error0317(failure_str) => { |
| struct_span_err!(self.tcx.sess, span, E0317, "{}", failure_str) |
| } |
| FailureCode::Error0580(failure_str) => { |
| struct_span_err!(self.tcx.sess, span, E0580, "{}", failure_str) |
| } |
| FailureCode::Error0308(failure_str) => { |
| struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str) |
| } |
| FailureCode::Error0644(failure_str) => { |
| struct_span_err!(self.tcx.sess, span, E0644, "{}", failure_str) |
| } |
| }; |
| self.note_type_err(&mut diag, &trace.cause, None, Some(trace.values), terr); |
| diag |
| } |
| |
| fn values_str( |
| &self, |
| values: &ValuePairs<'tcx>, |
| ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> { |
| match *values { |
| infer::Types(ref exp_found) => self.expected_found_str_ty(exp_found), |
| infer::Regions(ref exp_found) => self.expected_found_str(exp_found), |
| infer::Consts(ref exp_found) => self.expected_found_str(exp_found), |
| infer::TraitRefs(ref exp_found) => { |
| let pretty_exp_found = ty::error::ExpectedFound { |
| expected: exp_found.expected.print_only_trait_path(), |
| found: exp_found.found.print_only_trait_path() |
| }; |
| self.expected_found_str(&pretty_exp_found) |
| }, |
| infer::PolyTraitRefs(ref exp_found) => { |
| let pretty_exp_found = ty::error::ExpectedFound { |
| expected: exp_found.expected.print_only_trait_path(), |
| found: exp_found.found.print_only_trait_path() |
| }; |
| self.expected_found_str(&pretty_exp_found) |
| }, |
| } |
| } |
| |
| fn expected_found_str_ty( |
| &self, |
| exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, |
| ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> { |
| let exp_found = self.resolve_vars_if_possible(exp_found); |
| if exp_found.references_error() { |
| return None; |
| } |
| |
| Some(self.cmp(exp_found.expected, exp_found.found)) |
| } |
| |
| /// Returns a string of the form "expected `{}`, found `{}`". |
| fn expected_found_str<T: fmt::Display + TypeFoldable<'tcx>>( |
| &self, |
| exp_found: &ty::error::ExpectedFound<T>, |
| ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> { |
| let exp_found = self.resolve_vars_if_possible(exp_found); |
| if exp_found.references_error() { |
| return None; |
| } |
| |
| Some(( |
| DiagnosticStyledString::highlighted(exp_found.expected.to_string()), |
| DiagnosticStyledString::highlighted(exp_found.found.to_string()), |
| )) |
| } |
| |
| pub fn report_generic_bound_failure( |
| &self, |
| region_scope_tree: ®ion::ScopeTree, |
| span: Span, |
| origin: Option<SubregionOrigin<'tcx>>, |
| bound_kind: GenericKind<'tcx>, |
| sub: Region<'tcx>, |
| ) { |
| self.construct_generic_bound_failure(region_scope_tree, span, origin, bound_kind, sub) |
| .emit() |
| } |
| |
| pub fn construct_generic_bound_failure( |
| &self, |
| region_scope_tree: ®ion::ScopeTree, |
| span: Span, |
| origin: Option<SubregionOrigin<'tcx>>, |
| bound_kind: GenericKind<'tcx>, |
| sub: Region<'tcx>, |
| ) -> DiagnosticBuilder<'a> { |
| // Attempt to obtain the span of the parameter so we can |
| // suggest adding an explicit lifetime bound to it. |
| let type_param_span = match (self.in_progress_tables, bound_kind) { |
| (Some(ref table), GenericKind::Param(ref param)) => { |
| let table = table.borrow(); |
| table.local_id_root.and_then(|did| { |
| let generics = self.tcx.generics_of(did); |
| // Account for the case where `did` corresponds to `Self`, which doesn't have |
| // the expected type argument. |
| if !(generics.has_self && param.index == 0) { |
| let type_param = generics.type_param(param, self.tcx); |
| let hir = &self.tcx.hir(); |
| hir.as_local_hir_id(type_param.def_id).map(|id| { |
| // Get the `hir::Param` to verify whether it already has any bounds. |
| // We do this to avoid suggesting code that ends up as `T: 'a'b`, |
| // instead we suggest `T: 'a + 'b` in that case. |
| let mut has_bounds = false; |
| if let Node::GenericParam(param) = hir.get(id) { |
| has_bounds = !param.bounds.is_empty(); |
| } |
| let sp = hir.span(id); |
| // `sp` only covers `T`, change it so that it covers |
| // `T:` when appropriate |
| let is_impl_trait = bound_kind.to_string().starts_with("impl "); |
| let sp = if has_bounds && !is_impl_trait { |
| sp.to(self.tcx |
| .sess |
| .source_map() |
| .next_point(self.tcx.sess.source_map().next_point(sp))) |
| } else { |
| sp |
| }; |
| (sp, has_bounds, is_impl_trait) |
| }) |
| } else { |
| None |
| } |
| }) |
| } |
| _ => None, |
| }; |
| |
| let labeled_user_string = match bound_kind { |
| GenericKind::Param(ref p) => format!("the parameter type `{}`", p), |
| GenericKind::Projection(ref p) => format!("the associated type `{}`", p), |
| }; |
| |
| if let Some(SubregionOrigin::CompareImplMethodObligation { |
| span, |
| item_name, |
| impl_item_def_id, |
| trait_item_def_id, |
| }) = origin |
| { |
| return self.report_extra_impl_obligation( |
| span, |
| item_name, |
| impl_item_def_id, |
| trait_item_def_id, |
| &format!("`{}: {}`", bound_kind, sub), |
| ); |
| } |
| |
| fn binding_suggestion<'tcx, S: fmt::Display>( |
| err: &mut DiagnosticBuilder<'tcx>, |
| type_param_span: Option<(Span, bool, bool)>, |
| bound_kind: GenericKind<'tcx>, |
| sub: S, |
| ) { |
| let consider = format!( |
| "consider adding an explicit lifetime bound {}", |
| if type_param_span.map(|(_, _, is_impl_trait)| is_impl_trait).unwrap_or(false) { |
| format!(" `{}` to `{}`...", sub, bound_kind) |
| } else { |
| format!("`{}: {}`...", bound_kind, sub) |
| }, |
| ); |
| if let Some((sp, has_lifetimes, is_impl_trait)) = type_param_span { |
| let suggestion = if is_impl_trait { |
| format!("{} + {}", bound_kind, sub) |
| } else { |
| let tail = if has_lifetimes { " + " } else { "" }; |
| format!("{}: {}{}", bound_kind, sub, tail) |
| }; |
| err.span_suggestion_short( |
| sp, |
| &consider, |
| suggestion, |
| Applicability::MaybeIncorrect, // Issue #41966 |
| ); |
| } else { |
| err.help(&consider); |
| } |
| } |
| |
| let mut err = match *sub { |
| ty::ReEarlyBound(_) |
| | ty::ReFree(ty::FreeRegion { |
| bound_region: ty::BrNamed(..), |
| .. |
| }) => { |
| // Does the required lifetime have a nice name we can print? |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0309, |
| "{} may not live long enough", |
| labeled_user_string |
| ); |
| binding_suggestion(&mut err, type_param_span, bound_kind, sub); |
| err |
| } |
| |
| ty::ReStatic => { |
| // Does the required lifetime have a nice name we can print? |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0310, |
| "{} may not live long enough", |
| labeled_user_string |
| ); |
| binding_suggestion(&mut err, type_param_span, bound_kind, "'static"); |
| err |
| } |
| |
| _ => { |
| // If not, be less specific. |
| let mut err = struct_span_err!( |
| self.tcx.sess, |
| span, |
| E0311, |
| "{} may not live long enough", |
| labeled_user_string |
| ); |
| err.help(&format!( |
| "consider adding an explicit lifetime bound for `{}`", |
| bound_kind |
| )); |
| self.tcx.note_and_explain_region( |
| region_scope_tree, |
| &mut err, |
| &format!("{} must be valid for ", labeled_user_string), |
| sub, |
| "...", |
| ); |
| err |
| } |
| }; |
| |
| if let Some(origin) = origin { |
| self.note_region_origin(&mut err, &origin); |
| } |
| err |
| } |
| |
| fn report_sub_sup_conflict( |
| &self, |
| region_scope_tree: ®ion::ScopeTree, |
| var_origin: RegionVariableOrigin, |
| sub_origin: SubregionOrigin<'tcx>, |
| sub_region: Region<'tcx>, |
| sup_origin: SubregionOrigin<'tcx>, |
| sup_region: Region<'tcx>, |
| ) { |
| let mut err = self.report_inference_failure(var_origin); |
| |
| self.tcx.note_and_explain_region( |
| region_scope_tree, |
| &mut err, |
| "first, the lifetime cannot outlive ", |
| sup_region, |
| "...", |
| ); |
| |
| match (&sup_origin, &sub_origin) { |
| (&infer::Subtype(ref sup_trace), &infer::Subtype(ref sub_trace)) => { |
| debug!("report_sub_sup_conflict: var_origin={:?}", var_origin); |
| debug!("report_sub_sup_conflict: sub_region={:?}", sub_region); |
| debug!("report_sub_sup_conflict: sub_origin={:?}", sub_origin); |
| debug!("report_sub_sup_conflict: sup_region={:?}", sup_region); |
| debug!("report_sub_sup_conflict: sup_origin={:?}", sup_origin); |
| debug!("report_sub_sup_conflict: sup_trace={:?}", sup_trace); |
| debug!("report_sub_sup_conflict: sub_trace={:?}", sub_trace); |
| debug!("report_sub_sup_conflict: sup_trace.values={:?}", sup_trace.values); |
| debug!("report_sub_sup_conflict: sub_trace.values={:?}", sub_trace.values); |
| |
| if let (Some((sup_expected, sup_found)), Some((sub_expected, sub_found))) = ( |
| self.values_str(&sup_trace.values), |
| self.values_str(&sub_trace.values), |
| ) { |
| if sub_expected == sup_expected && sub_found == sup_found { |
| self.tcx.note_and_explain_region( |
| region_scope_tree, |
| &mut err, |
| "...but the lifetime must also be valid for ", |
| sub_region, |
| "...", |
| ); |
| err.span_note(sup_trace.cause.span, &format!( |
| "...so that the {}", |
| sup_trace.cause.as_requirement_str() |
| )); |
| |
| err.note_expected_found( |
| &"", |
| sup_expected, |
| &"", |
| sup_found |
| ); |
| err.emit(); |
| return; |
| } |
| } |
| } |
| _ => {} |
| } |
| |
| self.note_region_origin(&mut err, &sup_origin); |
| |
| self.tcx.note_and_explain_region( |
| region_scope_tree, |
| &mut err, |
| "but, the lifetime must be valid for ", |
| sub_region, |
| "...", |
| ); |
| |
| self.note_region_origin(&mut err, &sub_origin); |
| err.emit(); |
| } |
| } |
| |
| impl<'a, 'tcx> InferCtxt<'a, 'tcx> { |
| fn report_inference_failure( |
| &self, |
| var_origin: RegionVariableOrigin, |
| ) -> DiagnosticBuilder<'tcx> { |
| let br_string = |br: ty::BoundRegion| { |
| let mut s = match br { |
| ty::BrNamed(_, name) => name.to_string(), |
| _ => String::new(), |
| }; |
| if !s.is_empty() { |
| s.push_str(" "); |
| } |
| s |
| }; |
| let var_description = match var_origin { |
| infer::MiscVariable(_) => String::new(), |
| infer::PatternRegion(_) => " for pattern".to_string(), |
| infer::AddrOfRegion(_) => " for borrow expression".to_string(), |
| infer::Autoref(_) => " for autoref".to_string(), |
| infer::Coercion(_) => " for automatic coercion".to_string(), |
| infer::LateBoundRegion(_, br, infer::FnCall) => { |
| format!(" for lifetime parameter {}in function call", br_string(br)) |
| } |
| infer::LateBoundRegion(_, br, infer::HigherRankedType) => { |
| format!(" for lifetime parameter {}in generic type", br_string(br)) |
| } |
| infer::LateBoundRegion(_, br, infer::AssocTypeProjection(def_id)) => format!( |
| " for lifetime parameter {}in trait containing associated type `{}`", |
| br_string(br), |
| self.tcx.associated_item(def_id).ident |
| ), |
| infer::EarlyBoundRegion(_, name) => format!(" for lifetime parameter `{}`", name), |
| infer::BoundRegionInCoherence(name) => { |
| format!(" for lifetime parameter `{}` in coherence check", name) |
| } |
| infer::UpvarRegion(ref upvar_id, _) => { |
| let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id); |
| format!(" for capture of `{}` by closure", var_name) |
| } |
| infer::NLL(..) => bug!("NLL variable found in lexical phase"), |
| }; |
| |
| struct_span_err!( |
| self.tcx.sess, |
| var_origin.span(), |
| E0495, |
| "cannot infer an appropriate lifetime{} \ |
| due to conflicting requirements", |
| var_description |
| ) |
| } |
| } |
| |
| enum FailureCode { |
| Error0038(DefId), |
| Error0317(&'static str), |
| Error0580(&'static str), |
| Error0308(&'static str), |
| Error0644(&'static str), |
| } |
| |
| impl<'tcx> ObligationCause<'tcx> { |
| fn as_failure_code(&self, terr: &TypeError<'tcx>) -> FailureCode { |
| use self::FailureCode::*; |
| use crate::traits::ObligationCauseCode::*; |
| match self.code { |
| CompareImplMethodObligation { .. } => Error0308("method not compatible with trait"), |
| MatchExpressionArm(box MatchExpressionArmCause { source, .. }) => |
| Error0308(match source { |
| hir::MatchSource::IfLetDesugar { .. } => |
| "`if let` arms have incompatible types", |
| hir::MatchSource::TryDesugar => { |
| "try expression alternatives have incompatible types" |
| } |
| _ => "match arms have incompatible types", |
| }), |
| IfExpression { .. } => Error0308("if and else have incompatible types"), |
| IfExpressionWithNoElse => Error0317("if may be missing an else clause"), |
| MainFunctionType => Error0580("main function has wrong type"), |
| StartFunctionType => Error0308("start function has wrong type"), |
| IntrinsicType => Error0308("intrinsic has wrong type"), |
| MethodReceiver => Error0308("mismatched `self` parameter type"), |
| |
| // In the case where we have no more specific thing to |
| // say, also take a look at the error code, maybe we can |
| // tailor to that. |
| _ => match terr { |
| TypeError::CyclicTy(ty) if ty.is_closure() || ty.is_generator() => { |
| Error0644("closure/generator type that references itself") |
| } |
| TypeError::IntrinsicCast => { |
| Error0308("cannot coerce intrinsics to function pointers") |
| } |
| TypeError::ObjectUnsafeCoercion(did) => Error0038(did.clone()), |
| _ => Error0308("mismatched types"), |
| }, |
| } |
| } |
| |
| fn as_requirement_str(&self) -> &'static str { |
| use crate::traits::ObligationCauseCode::*; |
| match self.code { |
| CompareImplMethodObligation { .. } => "method type is compatible with trait", |
| ExprAssignable => "expression is assignable", |
| MatchExpressionArm(box MatchExpressionArmCause { source, .. }) => match source { |
| hir::MatchSource::IfLetDesugar { .. } => "`if let` arms have compatible types", |
| _ => "match arms have compatible types", |
| }, |
| IfExpression { .. } => "if and else have incompatible types", |
| IfExpressionWithNoElse => "if missing an else returns ()", |
| MainFunctionType => "`main` function has the correct type", |
| StartFunctionType => "`start` function has the correct type", |
| IntrinsicType => "intrinsic has the correct type", |
| MethodReceiver => "method receiver has the correct type", |
| _ => "types are compatible", |
| } |
| } |
| } |
