use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion}; use crate::late::lifetimes::{ElisionFailureInfo, LifetimeContext}; use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind}; use crate::path_names_to_string; use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot}; use crate::{PathResult, PathSource, Segment}; use rustc_ast::visit::FnKind; use rustc_ast::{ self as ast, AssocItemKind, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind, NodeId, Path, Ty, TyKind, }; use rustc_ast_pretty::pprust::path_segment_to_string; use rustc_data_structures::fx::FxHashSet; use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder}; use rustc_hir as hir; use rustc_hir::def::Namespace::{self, *}; use rustc_hir::def::{self, CtorKind, CtorOf, DefKind}; use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE}; use rustc_hir::PrimTy; use rustc_session::parse::feature_err; use rustc_span::edition::Edition; use rustc_span::hygiene::MacroKind; use rustc_span::lev_distance::find_best_match_for_name; use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP}; use std::iter; use tracing::debug; type Res = def::Res; /// A field or associated item from self type suggested in case of resolution failure. enum AssocSuggestion { Field, MethodWithSelf, AssocFn, AssocType, AssocConst, } impl AssocSuggestion { fn action(&self) -> &'static str { match self { AssocSuggestion::Field => "use the available field", AssocSuggestion::MethodWithSelf => "call the method with the fully-qualified path", AssocSuggestion::AssocFn => "call the associated function", AssocSuggestion::AssocConst => "use the associated `const`", AssocSuggestion::AssocType => "use the associated type", } } } crate enum MissingLifetimeSpot<'tcx> { Generics(&'tcx hir::Generics<'tcx>), HigherRanked { span: Span, span_type: ForLifetimeSpanType }, Static, } crate enum ForLifetimeSpanType { BoundEmpty, BoundTail, TypeEmpty, TypeTail, } impl ForLifetimeSpanType { crate fn descr(&self) -> &'static str { match self { Self::BoundEmpty | Self::BoundTail => "bound", Self::TypeEmpty | Self::TypeTail => "type", } } crate fn suggestion(&self, sugg: &str) -> String { match self { Self::BoundEmpty | Self::TypeEmpty => format!("for<{}> ", sugg), Self::BoundTail | Self::TypeTail => format!(", {}", sugg), } } } impl<'tcx> Into> for &'tcx hir::Generics<'tcx> { fn into(self) -> MissingLifetimeSpot<'tcx> { MissingLifetimeSpot::Generics(self) } } fn is_self_type(path: &[Segment], namespace: Namespace) -> bool { namespace == TypeNS && path.len() == 1 && path[0].ident.name == kw::SelfUpper } fn is_self_value(path: &[Segment], namespace: Namespace) -> bool { namespace == ValueNS && path.len() == 1 && path[0].ident.name == kw::SelfLower } /// Gets the stringified path for an enum from an `ImportSuggestion` for an enum variant. fn import_candidate_to_enum_paths(suggestion: &ImportSuggestion) -> (String, String) { let variant_path = &suggestion.path; let variant_path_string = path_names_to_string(variant_path); let path_len = suggestion.path.segments.len(); let enum_path = ast::Path { span: suggestion.path.span, segments: suggestion.path.segments[0..path_len - 1].to_vec(), tokens: None, }; let enum_path_string = path_names_to_string(&enum_path); (variant_path_string, enum_path_string) } impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { fn def_span(&self, def_id: DefId) -> Option { match def_id.krate { LOCAL_CRATE => self.r.opt_span(def_id), _ => Some( self.r .session .source_map() .guess_head_span(self.r.cstore().get_span_untracked(def_id, self.r.session)), ), } } /// Handles error reporting for `smart_resolve_path_fragment` function. /// Creates base error and amends it with one short label and possibly some longer helps/notes. pub(crate) fn smart_resolve_report_errors( &mut self, path: &[Segment], span: Span, source: PathSource<'_>, res: Option, ) -> (DiagnosticBuilder<'a>, Vec) { let ident_span = path.last().map_or(span, |ident| ident.ident.span); let ns = source.namespace(); let is_expected = &|res| source.is_expected(res); let is_enum_variant = &|res| matches!(res, Res::Def(DefKind::Variant, _)); // Make the base error. let mut expected = source.descr_expected(); let path_str = Segment::names_to_string(path); let item_str = path.last().unwrap().ident; let (base_msg, fallback_label, base_span, could_be_expr) = if let Some(res) = res { ( format!("expected {}, found {} `{}`", expected, res.descr(), path_str), format!("not a {}", expected), span, match res { Res::Def(DefKind::Fn, _) => { // Verify whether this is a fn call or an Fn used as a type. self.r .session .source_map() .span_to_snippet(span) .map(|snippet| snippet.ends_with(')')) .unwrap_or(false) } Res::Def( DefKind::Ctor(..) | DefKind::AssocFn | DefKind::Const | DefKind::AssocConst, _, ) | Res::SelfCtor(_) | Res::PrimTy(_) | Res::Local(_) => true, _ => false, }, ) } else { let item_span = path.last().unwrap().ident.span; let (mod_prefix, mod_str) = if path.len() == 1 { (String::new(), "this scope".to_string()) } else if path.len() == 2 && path[0].ident.name == kw::PathRoot { if self.r.session.edition() > Edition::Edition2015 { // In edition 2018 onwards, the `::foo` syntax may only pull from the extern prelude // which overrides all other expectations of item type expected = "crate"; (String::new(), "the list of imported crates".to_string()) } else { (String::new(), "the crate root".to_string()) } } else if path.len() == 2 && path[0].ident.name == kw::Crate { (String::new(), "the crate root".to_string()) } else { let mod_path = &path[..path.len() - 1]; let mod_prefix = match self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No) { PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.res(), _ => None, } .map_or_else(String::new, |res| format!("{} ", res.descr())); (mod_prefix, format!("`{}`", Segment::names_to_string(mod_path))) }; ( format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str), if path_str == "async" && expected.starts_with("struct") { "`async` blocks are only allowed in Rust 2018 or later".to_string() } else { format!("not found in {}", mod_str) }, item_span, false, ) }; let code = source.error_code(res.is_some()); let mut err = self.r.session.struct_span_err_with_code(base_span, &base_msg, code); if let Some(span) = self.diagnostic_metadata.current_block_could_be_bare_struct_literal { err.multipart_suggestion( "you might have meant to write a `struct` literal", vec![ (span.shrink_to_lo(), "{ SomeStruct ".to_string()), (span.shrink_to_hi(), "}".to_string()), ], Applicability::HasPlaceholders, ); } match (source, self.diagnostic_metadata.in_if_condition) { (PathSource::Expr(_), Some(Expr { span, kind: ExprKind::Assign(..), .. })) => { err.span_suggestion_verbose( span.shrink_to_lo(), "you might have meant to use pattern matching", "let ".to_string(), Applicability::MaybeIncorrect, ); } _ => {} } let is_assoc_fn = self.self_type_is_available(span); // Emit help message for fake-self from other languages (e.g., `this` in Javascript). if ["this", "my"].contains(&item_str.as_str()) && is_assoc_fn { err.span_suggestion_short( span, "you might have meant to use `self` here instead", "self".to_string(), Applicability::MaybeIncorrect, ); if !self.self_value_is_available(path[0].ident.span, span) { if let Some((FnKind::Fn(_, _, sig, ..), fn_span)) = &self.diagnostic_metadata.current_function { let (span, sugg) = if let Some(param) = sig.decl.inputs.get(0) { (param.span.shrink_to_lo(), "&self, ") } else { ( self.r .session .source_map() .span_through_char(*fn_span, '(') .shrink_to_hi(), "&self", ) }; err.span_suggestion_verbose( span, "if you meant to use `self`, you are also missing a `self` receiver \ argument", sugg.to_string(), Applicability::MaybeIncorrect, ); } } } // Emit special messages for unresolved `Self` and `self`. if is_self_type(path, ns) { err.code(rustc_errors::error_code!(E0411)); err.span_label( span, "`Self` is only available in impls, traits, and type definitions".to_string(), ); return (err, Vec::new()); } if is_self_value(path, ns) { debug!("smart_resolve_path_fragment: E0424, source={:?}", source); err.code(rustc_errors::error_code!(E0424)); err.span_label(span, match source { PathSource::Pat => "`self` value is a keyword and may not be bound to variables or shadowed" .to_string(), _ => "`self` value is a keyword only available in methods with a `self` parameter" .to_string(), }); if let Some((fn_kind, span)) = &self.diagnostic_metadata.current_function { // The current function has a `self' parameter, but we were unable to resolve // a reference to `self`. This can only happen if the `self` identifier we // are resolving came from a different hygiene context. if fn_kind.decl().inputs.get(0).map_or(false, |p| p.is_self()) { err.span_label(*span, "this function has a `self` parameter, but a macro invocation can only access identifiers it receives from parameters"); } else { let doesnt = if is_assoc_fn { let (span, sugg) = fn_kind .decl() .inputs .get(0) .map(|p| (p.span.shrink_to_lo(), "&self, ")) .unwrap_or_else(|| { // Try to look for the "(" after the function name, if possible. // This avoids placing the suggestion into the visibility specifier. let span = fn_kind .ident() .map_or(*span, |ident| span.with_lo(ident.span.hi())); ( self.r .session .source_map() .span_through_char(span, '(') .shrink_to_hi(), "&self", ) }); err.span_suggestion_verbose( span, "add a `self` receiver parameter to make the associated `fn` a method", sugg.to_string(), Applicability::MaybeIncorrect, ); "doesn't" } else { "can't" }; if let Some(ident) = fn_kind.ident() { err.span_label( ident.span, &format!("this function {} have a `self` parameter", doesnt), ); } } } return (err, Vec::new()); } // Try to lookup name in more relaxed fashion for better error reporting. let ident = path.last().unwrap().ident; let candidates = self .r .lookup_import_candidates(ident, ns, &self.parent_scope, is_expected) .into_iter() .filter(|ImportSuggestion { did, .. }| { match (did, res.and_then(|res| res.opt_def_id())) { (Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did, _ => true, } }) .collect::>(); let crate_def_id = DefId::local(CRATE_DEF_INDEX); if candidates.is_empty() && is_expected(Res::Def(DefKind::Enum, crate_def_id)) { let mut enum_candidates: Vec<_> = self .r .lookup_import_candidates(ident, ns, &self.parent_scope, is_enum_variant) .into_iter() .map(|suggestion| import_candidate_to_enum_paths(&suggestion)) .filter(|(_, enum_ty_path)| !enum_ty_path.starts_with("std::prelude::")) .collect(); if !enum_candidates.is_empty() { if let (PathSource::Type, Some(span)) = (source, self.diagnostic_metadata.current_type_ascription.last()) { if self .r .session .parse_sess .type_ascription_path_suggestions .borrow() .contains(span) { // Already reported this issue on the lhs of the type ascription. err.delay_as_bug(); return (err, candidates); } } enum_candidates.sort(); // Contextualize for E0412 "cannot find type", but don't belabor the point // (that it's a variant) for E0573 "expected type, found variant". let preamble = if res.is_none() { let others = match enum_candidates.len() { 1 => String::new(), 2 => " and 1 other".to_owned(), n => format!(" and {} others", n), }; format!("there is an enum variant `{}`{}; ", enum_candidates[0].0, others) } else { String::new() }; let msg = format!("{}try using the variant's enum", preamble); err.span_suggestions( span, &msg, enum_candidates.into_iter().map(|(_variant_path, enum_ty_path)| enum_ty_path), Applicability::MachineApplicable, ); } } if path.len() == 1 && self.self_type_is_available(span) { if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) { let self_is_available = self.self_value_is_available(path[0].ident.span, span); match candidate { AssocSuggestion::Field => { if self_is_available { err.span_suggestion( span, "you might have meant to use the available field", format!("self.{}", path_str), Applicability::MachineApplicable, ); } else { err.span_label(span, "a field by this name exists in `Self`"); } } AssocSuggestion::MethodWithSelf if self_is_available => { err.span_suggestion( span, "you might have meant to call the method", format!("self.{}", path_str), Applicability::MachineApplicable, ); } AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocFn | AssocSuggestion::AssocConst | AssocSuggestion::AssocType => { err.span_suggestion( span, &format!("you might have meant to {}", candidate.action()), format!("Self::{}", path_str), Applicability::MachineApplicable, ); } } return (err, candidates); } // If the first argument in call is `self` suggest calling a method. if let Some((call_span, args_span)) = self.call_has_self_arg(source) { let mut args_snippet = String::new(); if let Some(args_span) = args_span { if let Ok(snippet) = self.r.session.source_map().span_to_snippet(args_span) { args_snippet = snippet; } } err.span_suggestion( call_span, &format!("try calling `{}` as a method", ident), format!("self.{}({})", path_str, args_snippet), Applicability::MachineApplicable, ); return (err, candidates); } } // Try Levenshtein algorithm. let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected, span); // Try context-dependent help if relaxed lookup didn't work. if let Some(res) = res { if self.smart_resolve_context_dependent_help( &mut err, span, source, res, &path_str, &fallback_label, ) { // We do this to avoid losing a secondary span when we override the main error span. self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span); return (err, candidates); } } let is_macro = base_span.from_expansion() && base_span.desugaring_kind().is_none(); if !self.type_ascription_suggestion(&mut err, base_span) { let mut fallback = false; if let ( PathSource::Trait(AliasPossibility::Maybe), Some(Res::Def(DefKind::Struct | DefKind::Enum | DefKind::Union, _)), false, ) = (source, res, is_macro) { if let Some(bounds @ [_, .., _]) = self.diagnostic_metadata.current_trait_object { fallback = true; let spans: Vec = bounds .iter() .map(|bound| bound.span()) .filter(|&sp| sp != base_span) .collect(); let start_span = bounds.iter().map(|bound| bound.span()).next().unwrap(); // `end_span` is the end of the poly trait ref (Foo + 'baz + Bar><) let end_span = bounds.iter().map(|bound| bound.span()).last().unwrap(); // `last_bound_span` is the last bound of the poly trait ref (Foo + >'baz< + Bar) let last_bound_span = spans.last().cloned().unwrap(); let mut multi_span: MultiSpan = spans.clone().into(); for sp in spans { let msg = if sp == last_bound_span { format!( "...because of {} bound{}", if bounds.len() <= 2 { "this" } else { "these" }, if bounds.len() <= 2 { "" } else { "s" }, ) } else { String::new() }; multi_span.push_span_label(sp, msg); } multi_span.push_span_label( base_span, "expected this type to be a trait...".to_string(), ); err.span_help( multi_span, "`+` is used to constrain a \"trait object\" type with lifetimes or \ auto-traits; structs and enums can't be bound in that way", ); if bounds.iter().all(|bound| match bound { ast::GenericBound::Outlives(_) => true, ast::GenericBound::Trait(tr, _) => tr.span == base_span, }) { let mut sugg = vec![]; if base_span != start_span { sugg.push((start_span.until(base_span), String::new())); } if base_span != end_span { sugg.push((base_span.shrink_to_hi().to(end_span), String::new())); } err.multipart_suggestion( "if you meant to use a type and not a trait here, remove the bounds", sugg, Applicability::MaybeIncorrect, ); } } } fallback |= self.restrict_assoc_type_in_where_clause(span, &mut err); if !self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span) { fallback = true; match self.diagnostic_metadata.current_let_binding { Some((pat_sp, Some(ty_sp), None)) if ty_sp.contains(base_span) && could_be_expr => { err.span_suggestion_short( pat_sp.between(ty_sp), "use `=` if you meant to assign", " = ".to_string(), Applicability::MaybeIncorrect, ); } _ => {} } // If the trait has a single item (which wasn't matched by Levenshtein), suggest it let suggestion = self.get_single_associated_item(&path, span, &source, is_expected); self.r.add_typo_suggestion(&mut err, suggestion, ident_span); } if fallback { // Fallback label. err.span_label(base_span, fallback_label); } } if let Some(err_code) = &err.code { if err_code == &rustc_errors::error_code!(E0425) { for label_rib in &self.label_ribs { for (label_ident, node_id) in &label_rib.bindings { if format!("'{}", ident) == label_ident.to_string() { err.span_label(label_ident.span, "a label with a similar name exists"); if let PathSource::Expr(Some(Expr { kind: ExprKind::Break(None, Some(_)), .. })) = source { err.span_suggestion( span, "use the similarly named label", label_ident.name.to_string(), Applicability::MaybeIncorrect, ); // Do not lint against unused label when we suggest them. self.diagnostic_metadata.unused_labels.remove(node_id); } } } } } else if err_code == &rustc_errors::error_code!(E0412) { if let Some(correct) = Self::likely_rust_type(path) { err.span_suggestion( span, "perhaps you intended to use this type", correct.to_string(), Applicability::MaybeIncorrect, ); } } } (err, candidates) } fn get_single_associated_item( &mut self, path: &[Segment], span: Span, source: &PathSource<'_>, filter_fn: &impl Fn(Res) -> bool, ) -> Option { if let crate::PathSource::TraitItem(_) = source { let mod_path = &path[..path.len() - 1]; if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(mod_path, None, false, span, CrateLint::No) { let resolutions = self.r.resolutions(module).borrow(); let targets: Vec<_> = resolutions .iter() .filter_map(|(key, resolution)| { resolution.borrow().binding.map(|binding| binding.res()).and_then( |res| if filter_fn(res) { Some((key, res)) } else { None }, ) }) .collect(); if targets.len() == 1 { let target = targets[0]; return Some(TypoSuggestion::single_item_from_res( target.0.ident.name, target.1, )); } } } None } /// Given `where ::Baz: String`, suggest `where T: Bar`. fn restrict_assoc_type_in_where_clause( &mut self, span: Span, err: &mut DiagnosticBuilder<'_>, ) -> bool { // Detect that we are actually in a `where` predicate. let (bounded_ty, bounds, where_span) = if let Some(ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate { bounded_ty, bound_generic_params, bounds, span, })) = self.diagnostic_metadata.current_where_predicate { if !bound_generic_params.is_empty() { return false; } (bounded_ty, bounds, span) } else { return false; }; // Confirm that the target is an associated type. let (ty, position, path) = if let ast::TyKind::Path( Some(ast::QSelf { ty, position, .. }), path, ) = &bounded_ty.kind { // use this to verify that ident is a type param. let partial_res = if let Ok(Some(partial_res)) = self.resolve_qpath_anywhere( bounded_ty.id, None, &Segment::from_path(path), Namespace::TypeNS, span, true, CrateLint::No, ) { partial_res } else { return false; }; if !(matches!( partial_res.base_res(), hir::def::Res::Def(hir::def::DefKind::AssocTy, _) ) && partial_res.unresolved_segments() == 0) { return false; } (ty, position, path) } else { return false; }; if let ast::TyKind::Path(None, type_param_path) = &ty.peel_refs().kind { // Confirm that the `SelfTy` is a type parameter. let partial_res = if let Ok(Some(partial_res)) = self.resolve_qpath_anywhere( bounded_ty.id, None, &Segment::from_path(type_param_path), Namespace::TypeNS, span, true, CrateLint::No, ) { partial_res } else { return false; }; if !(matches!( partial_res.base_res(), hir::def::Res::Def(hir::def::DefKind::TyParam, _) ) && partial_res.unresolved_segments() == 0) { return false; } if let ( [ast::PathSegment { ident: constrain_ident, args: None, .. }], [ast::GenericBound::Trait(poly_trait_ref, ast::TraitBoundModifier::None)], ) = (&type_param_path.segments[..], &bounds[..]) { if let [ast::PathSegment { ident, args: None, .. }] = &poly_trait_ref.trait_ref.path.segments[..] { if ident.span == span { err.span_suggestion_verbose( *where_span, &format!("constrain the associated type to `{}`", ident), format!( "{}: {}<{} = {}>", self.r .session .source_map() .span_to_snippet(ty.span) // Account for `<&'a T as Foo>::Bar`. .unwrap_or_else(|_| constrain_ident.to_string()), path.segments[..*position] .iter() .map(|segment| path_segment_to_string(segment)) .collect::>() .join("::"), path.segments[*position..] .iter() .map(|segment| path_segment_to_string(segment)) .collect::>() .join("::"), ident, ), Applicability::MaybeIncorrect, ); } return true; } } } false } /// Check if the source is call expression and the first argument is `self`. If true, /// return the span of whole call and the span for all arguments expect the first one (`self`). fn call_has_self_arg(&self, source: PathSource<'_>) -> Option<(Span, Option)> { let mut has_self_arg = None; if let PathSource::Expr(Some(parent)) = source { match &parent.kind { ExprKind::Call(_, args) if !args.is_empty() => { let mut expr_kind = &args[0].kind; loop { match expr_kind { ExprKind::Path(_, arg_name) if arg_name.segments.len() == 1 => { if arg_name.segments[0].ident.name == kw::SelfLower { let call_span = parent.span; let tail_args_span = if args.len() > 1 { Some(Span::new( args[1].span.lo(), args.last().unwrap().span.hi(), call_span.ctxt(), None, )) } else { None }; has_self_arg = Some((call_span, tail_args_span)); } break; } ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind, _ => break, } } } _ => (), } }; has_self_arg } fn followed_by_brace(&self, span: Span) -> (bool, Option) { // HACK(estebank): find a better way to figure out that this was a // parser issue where a struct literal is being used on an expression // where a brace being opened means a block is being started. Look // ahead for the next text to see if `span` is followed by a `{`. let sm = self.r.session.source_map(); let mut sp = span; loop { sp = sm.next_point(sp); match sm.span_to_snippet(sp) { Ok(ref snippet) => { if snippet.chars().any(|c| !c.is_whitespace()) { break; } } _ => break, } } let followed_by_brace = matches!(sm.span_to_snippet(sp), Ok(ref snippet) if snippet == "{"); // In case this could be a struct literal that needs to be surrounded // by parentheses, find the appropriate span. let mut i = 0; let mut closing_brace = None; loop { sp = sm.next_point(sp); match sm.span_to_snippet(sp) { Ok(ref snippet) => { if snippet == "}" { closing_brace = Some(span.to(sp)); break; } } _ => break, } i += 1; // The bigger the span, the more likely we're incorrect -- // bound it to 100 chars long. if i > 100 { break; } } (followed_by_brace, closing_brace) } /// Provides context-dependent help for errors reported by the `smart_resolve_path_fragment` /// function. /// Returns `true` if able to provide context-dependent help. fn smart_resolve_context_dependent_help( &mut self, err: &mut DiagnosticBuilder<'a>, span: Span, source: PathSource<'_>, res: Res, path_str: &str, fallback_label: &str, ) -> bool { let ns = source.namespace(); let is_expected = &|res| source.is_expected(res); let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.kind { ExprKind::Field(_, ident) => { err.span_suggestion( expr.span, "use the path separator to refer to an item", format!("{}::{}", path_str, ident), Applicability::MaybeIncorrect, ); true } ExprKind::MethodCall(ref segment, ..) => { let span = expr.span.with_hi(segment.ident.span.hi()); err.span_suggestion( span, "use the path separator to refer to an item", format!("{}::{}", path_str, segment.ident), Applicability::MaybeIncorrect, ); true } _ => false, }; let find_span = |source: &PathSource<'_>, err: &mut DiagnosticBuilder<'_>| { match source { PathSource::Expr(Some(Expr { span, kind: ExprKind::Call(_, _), .. })) | PathSource::TupleStruct(span, _) => { // We want the main underline to cover the suggested code as well for // cleaner output. err.set_span(*span); *span } _ => span, } }; let mut bad_struct_syntax_suggestion = |def_id: DefId| { let (followed_by_brace, closing_brace) = self.followed_by_brace(span); match source { PathSource::Expr(Some( parent @ Expr { kind: ExprKind::Field(..) | ExprKind::MethodCall(..), .. }, )) if path_sep(err, &parent) => {} PathSource::Expr( None | Some(Expr { kind: ExprKind::Path(..) | ExprKind::Binary(..) | ExprKind::Unary(..) | ExprKind::If(..) | ExprKind::While(..) | ExprKind::ForLoop(..) | ExprKind::Match(..), .. }), ) if followed_by_brace => { if let Some(sp) = closing_brace { err.span_label(span, fallback_label); err.multipart_suggestion( "surround the struct literal with parentheses", vec![ (sp.shrink_to_lo(), "(".to_string()), (sp.shrink_to_hi(), ")".to_string()), ], Applicability::MaybeIncorrect, ); } else { err.span_label( span, // Note the parentheses surrounding the suggestion below format!( "you might want to surround a struct literal with parentheses: \ `({} {{ /* fields */ }})`?", path_str ), ); } } PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => { let span = find_span(&source, err); if let Some(span) = self.def_span(def_id) { err.span_label(span, &format!("`{}` defined here", path_str)); } let (tail, descr, applicability) = match source { PathSource::Pat | PathSource::TupleStruct(..) => { ("", "pattern", Applicability::MachineApplicable) } _ => (": val", "literal", Applicability::HasPlaceholders), }; let (fields, applicability) = match self.r.field_names.get(&def_id) { Some(fields) => ( fields .iter() .map(|f| format!("{}{}", f.node, tail)) .collect::>() .join(", "), applicability, ), None => ("/* fields */".to_string(), Applicability::HasPlaceholders), }; let pad = match self.r.field_names.get(&def_id) { Some(fields) if fields.is_empty() => "", _ => " ", }; err.span_suggestion( span, &format!("use struct {} syntax instead", descr), format!("{path_str} {{{pad}{fields}{pad}}}"), applicability, ); } _ => { err.span_label(span, fallback_label); } } }; match (res, source) { ( Res::Def(DefKind::Macro(MacroKind::Bang), _), PathSource::Expr(Some(Expr { kind: ExprKind::Index(..) | ExprKind::Call(..), .. })) | PathSource::Struct, ) => { err.span_label(span, fallback_label); err.span_suggestion_verbose( span.shrink_to_hi(), "use `!` to invoke the macro", "!".to_string(), Applicability::MaybeIncorrect, ); if path_str == "try" && span.rust_2015() { err.note("if you want the `try` keyword, you need Rust 2018 or later"); } } (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => { err.span_label(span, fallback_label); } (Res::Def(DefKind::TyAlias, def_id), PathSource::Trait(_)) => { err.span_label(span, "type aliases cannot be used as traits"); if self.r.session.is_nightly_build() { let msg = "you might have meant to use `#![feature(trait_alias)]` instead of a \ `type` alias"; if let Some(span) = self.def_span(def_id) { if let Ok(snip) = self.r.session.source_map().span_to_snippet(span) { // The span contains a type alias so we should be able to // replace `type` with `trait`. let snip = snip.replacen("type", "trait", 1); err.span_suggestion(span, msg, snip, Applicability::MaybeIncorrect); } else { err.span_help(span, msg); } } else { err.help(msg); } } } (Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => { if !path_sep(err, &parent) { return false; } } ( Res::Def(DefKind::Enum, def_id), PathSource::TupleStruct(..) | PathSource::Expr(..), ) => { if self .diagnostic_metadata .current_type_ascription .last() .map(|sp| { self.r .session .parse_sess .type_ascription_path_suggestions .borrow() .contains(&sp) }) .unwrap_or(false) { err.delay_as_bug(); // We already suggested changing `:` into `::` during parsing. return false; } self.suggest_using_enum_variant(err, source, def_id, span); } (Res::Def(DefKind::Struct, def_id), source) if ns == ValueNS => { let (ctor_def, ctor_vis, fields) = if let Some(struct_ctor) = self.r.struct_constructors.get(&def_id).cloned() { if let PathSource::Expr(Some(parent)) = source { if let ExprKind::Field(..) | ExprKind::MethodCall(..) = parent.kind { bad_struct_syntax_suggestion(def_id); return true; } } struct_ctor } else { bad_struct_syntax_suggestion(def_id); return true; }; let is_accessible = self.r.is_accessible_from(ctor_vis, self.parent_scope.module); if !is_expected(ctor_def) || is_accessible { return true; } let field_spans = match source { // e.g. `if let Enum::TupleVariant(field1, field2) = _` PathSource::TupleStruct(_, pattern_spans) => { err.set_primary_message( "cannot match against a tuple struct which contains private fields", ); // Use spans of the tuple struct pattern. Some(Vec::from(pattern_spans)) } // e.g. `let _ = Enum::TupleVariant(field1, field2);` _ if source.is_call() => { err.set_primary_message( "cannot initialize a tuple struct which contains private fields", ); // Use spans of the tuple struct definition. self.r .field_names .get(&def_id) .map(|fields| fields.iter().map(|f| f.span).collect::>()) } _ => None, }; if let Some(spans) = field_spans.filter(|spans| spans.len() > 0 && fields.len() == spans.len()) { let non_visible_spans: Vec = iter::zip(&fields, &spans) .filter(|(vis, _)| { !self.r.is_accessible_from(**vis, self.parent_scope.module) }) .map(|(_, span)| *span) .collect(); if non_visible_spans.len() > 0 { let mut m: rustc_span::MultiSpan = non_visible_spans.clone().into(); non_visible_spans .into_iter() .for_each(|s| m.push_span_label(s, "private field".to_string())); err.span_note(m, "constructor is not visible here due to private fields"); } return true; } err.span_label( span, "constructor is not visible here due to private fields".to_string(), ); } ( Res::Def( DefKind::Union | DefKind::Variant | DefKind::Ctor(_, CtorKind::Fictive), def_id, ), _, ) if ns == ValueNS => { bad_struct_syntax_suggestion(def_id); } (Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id), _) if ns == ValueNS => { match source { PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => { let span = find_span(&source, err); if let Some(span) = self.def_span(def_id) { err.span_label(span, &format!("`{}` defined here", path_str)); } err.span_suggestion( span, &"use this syntax instead", format!("{path_str}"), Applicability::MaybeIncorrect, ); } _ => return false, } } (Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => { if let Some(span) = self.def_span(def_id) { err.span_label(span, &format!("`{}` defined here", path_str)); } let fields = self.r.field_names.get(&def_id).map_or_else( || "/* fields */".to_string(), |fields| vec!["_"; fields.len()].join(", "), ); err.span_suggestion( span, "use the tuple variant pattern syntax instead", format!("{}({})", path_str, fields), Applicability::HasPlaceholders, ); } (Res::SelfTy(..), _) if ns == ValueNS => { err.span_label(span, fallback_label); err.note("can't use `Self` as a constructor, you must use the implemented struct"); } (Res::Def(DefKind::TyAlias | DefKind::AssocTy, _), _) if ns == ValueNS => { err.note("can't use a type alias as a constructor"); } _ => return false, } true } /// Given the target `ident` and `kind`, search for the similarly named associated item /// in `self.current_trait_ref`. crate fn find_similarly_named_assoc_item( &mut self, ident: Symbol, kind: &AssocItemKind, ) -> Option { let Some((module, _)) = &self.current_trait_ref else { return None; }; if ident == kw::Underscore { // We do nothing for `_`. return None; } let resolutions = self.r.resolutions(module); let targets = resolutions .borrow() .iter() .filter_map(|(key, res)| res.borrow().binding.map(|binding| (key, binding.res()))) .filter(|(_, res)| match (kind, res) { (AssocItemKind::Const(..), Res::Def(DefKind::AssocConst, _)) => true, (AssocItemKind::Fn(_), Res::Def(DefKind::AssocFn, _)) => true, (AssocItemKind::TyAlias(..), Res::Def(DefKind::AssocTy, _)) => true, _ => false, }) .map(|(key, _)| key.ident.name) .collect::>(); find_best_match_for_name(&targets, ident, None) } fn lookup_assoc_candidate( &mut self, ident: Ident, ns: Namespace, filter_fn: FilterFn, ) -> Option where FilterFn: Fn(Res) -> bool, { fn extract_node_id(t: &Ty) -> Option { match t.kind { TyKind::Path(None, _) => Some(t.id), TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty), // This doesn't handle the remaining `Ty` variants as they are not // that commonly the self_type, it might be interesting to provide // support for those in future. _ => None, } } // Fields are generally expected in the same contexts as locals. if filter_fn(Res::Local(ast::DUMMY_NODE_ID)) { if let Some(node_id) = self.diagnostic_metadata.current_self_type.as_ref().and_then(extract_node_id) { // Look for a field with the same name in the current self_type. if let Some(resolution) = self.r.partial_res_map.get(&node_id) { match resolution.base_res() { Res::Def(DefKind::Struct | DefKind::Union, did) if resolution.unresolved_segments() == 0 => { if let Some(field_names) = self.r.field_names.get(&did) { if field_names .iter() .any(|&field_name| ident.name == field_name.node) { return Some(AssocSuggestion::Field); } } } _ => {} } } } } if let Some(items) = self.diagnostic_metadata.current_trait_assoc_items { for assoc_item in items { if assoc_item.ident == ident { return Some(match &assoc_item.kind { ast::AssocItemKind::Const(..) => AssocSuggestion::AssocConst, ast::AssocItemKind::Fn(box ast::Fn { sig, .. }) if sig.decl.has_self() => { AssocSuggestion::MethodWithSelf } ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn, ast::AssocItemKind::TyAlias(..) => AssocSuggestion::AssocType, ast::AssocItemKind::MacCall(_) => continue, }); } } } // Look for associated items in the current trait. if let Some((module, _)) = self.current_trait_ref { if let Ok(binding) = self.r.resolve_ident_in_module( ModuleOrUniformRoot::Module(module), ident, ns, &self.parent_scope, false, module.span, ) { let res = binding.res(); if filter_fn(res) { if self.r.has_self.contains(&res.def_id()) { return Some(AssocSuggestion::MethodWithSelf); } else { match res { Res::Def(DefKind::AssocFn, _) => return Some(AssocSuggestion::AssocFn), Res::Def(DefKind::AssocConst, _) => { return Some(AssocSuggestion::AssocConst); } Res::Def(DefKind::AssocTy, _) => { return Some(AssocSuggestion::AssocType); } _ => {} } } } } } None } fn lookup_typo_candidate( &mut self, path: &[Segment], ns: Namespace, filter_fn: &impl Fn(Res) -> bool, span: Span, ) -> Option { let mut names = Vec::new(); if path.len() == 1 { // Search in lexical scope. // Walk backwards up the ribs in scope and collect candidates. for rib in self.ribs[ns].iter().rev() { // Locals and type parameters for (ident, &res) in &rib.bindings { if filter_fn(res) { names.push(TypoSuggestion::typo_from_res(ident.name, res)); } } // Items in scope if let RibKind::ModuleRibKind(module) = rib.kind { // Items from this module self.r.add_module_candidates(module, &mut names, &filter_fn); if let ModuleKind::Block(..) = module.kind { // We can see through blocks } else { // Items from the prelude if !module.no_implicit_prelude { let extern_prelude = self.r.extern_prelude.clone(); names.extend(extern_prelude.iter().flat_map(|(ident, _)| { self.r.crate_loader.maybe_process_path_extern(ident.name).and_then( |crate_id| { let crate_mod = Res::Def( DefKind::Mod, DefId { krate: crate_id, index: CRATE_DEF_INDEX }, ); if filter_fn(crate_mod) { Some(TypoSuggestion::typo_from_res( ident.name, crate_mod, )) } else { None } }, ) })); if let Some(prelude) = self.r.prelude { self.r.add_module_candidates(prelude, &mut names, &filter_fn); } } break; } } } // Add primitive types to the mix if filter_fn(Res::PrimTy(PrimTy::Bool)) { names.extend(PrimTy::ALL.iter().map(|prim_ty| { TypoSuggestion::typo_from_res(prim_ty.name(), Res::PrimTy(*prim_ty)) })) } } else { // Search in module. let mod_path = &path[..path.len() - 1]; if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No) { self.r.add_module_candidates(module, &mut names, &filter_fn); } } let name = path[path.len() - 1].ident.name; // Make sure error reporting is deterministic. names.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap()); match find_best_match_for_name( &names.iter().map(|suggestion| suggestion.candidate).collect::>(), name, None, ) { Some(found) if found != name => { names.into_iter().find(|suggestion| suggestion.candidate == found) } _ => None, } } // Returns the name of the Rust type approximately corresponding to // a type name in another programming language. fn likely_rust_type(path: &[Segment]) -> Option { let name = path[path.len() - 1].ident.as_str(); // Common Java types Some(match name { "byte" => sym::u8, // In Java, bytes are signed, but in practice one almost always wants unsigned bytes. "short" => sym::i16, "boolean" => sym::bool, "int" => sym::i32, "long" => sym::i64, "float" => sym::f32, "double" => sym::f64, _ => return None, }) } /// Only used in a specific case of type ascription suggestions fn get_colon_suggestion_span(&self, start: Span) -> Span { let sm = self.r.session.source_map(); start.to(sm.next_point(start)) } fn type_ascription_suggestion(&self, err: &mut DiagnosticBuilder<'_>, base_span: Span) -> bool { let sm = self.r.session.source_map(); let base_snippet = sm.span_to_snippet(base_span); if let Some(&sp) = self.diagnostic_metadata.current_type_ascription.last() { if let Ok(snippet) = sm.span_to_snippet(sp) { let len = snippet.trim_end().len() as u32; if snippet.trim() == ":" { let colon_sp = sp.with_lo(sp.lo() + BytePos(len - 1)).with_hi(sp.lo() + BytePos(len)); let mut show_label = true; if sm.is_multiline(sp) { err.span_suggestion_short( colon_sp, "maybe you meant to write `;` here", ";".to_string(), Applicability::MaybeIncorrect, ); } else { let after_colon_sp = self.get_colon_suggestion_span(colon_sp.shrink_to_hi()); if snippet.len() == 1 { // `foo:bar` err.span_suggestion( colon_sp, "maybe you meant to write a path separator here", "::".to_string(), Applicability::MaybeIncorrect, ); show_label = false; if !self .r .session .parse_sess .type_ascription_path_suggestions .borrow_mut() .insert(colon_sp) { err.delay_as_bug(); } } if let Ok(base_snippet) = base_snippet { let mut sp = after_colon_sp; for _ in 0..100 { // Try to find an assignment sp = sm.next_point(sp); let snippet = sm.span_to_snippet(sp.to(sm.next_point(sp))); match snippet { Ok(ref x) if x.as_str() == "=" => { err.span_suggestion( base_span, "maybe you meant to write an assignment here", format!("let {}", base_snippet), Applicability::MaybeIncorrect, ); show_label = false; break; } Ok(ref x) if x.as_str() == "\n" => break, Err(_) => break, Ok(_) => {} } } } } if show_label { err.span_label( base_span, "expecting a type here because of type ascription", ); } return show_label; } } } false } fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> { let mut result = None; let mut seen_modules = FxHashSet::default(); let mut worklist = vec![(self.r.graph_root, Vec::new())]; while let Some((in_module, path_segments)) = worklist.pop() { // abort if the module is already found if result.is_some() { break; } in_module.for_each_child(self.r, |_, ident, _, name_binding| { // abort if the module is already found or if name_binding is private external if result.is_some() || !name_binding.vis.is_visible_locally() { return; } if let Some(module) = name_binding.module() { // form the path let mut path_segments = path_segments.clone(); path_segments.push(ast::PathSegment::from_ident(ident)); let module_def_id = module.def_id(); if module_def_id == def_id { let path = Path { span: name_binding.span, segments: path_segments, tokens: None }; result = Some(( module, ImportSuggestion { did: Some(def_id), descr: "module", path, accessible: true, note: None, }, )); } else { // add the module to the lookup if seen_modules.insert(module_def_id) { worklist.push((module, path_segments)); } } } }); } result } fn collect_enum_ctors(&mut self, def_id: DefId) -> Option> { self.find_module(def_id).map(|(enum_module, enum_import_suggestion)| { let mut variants = Vec::new(); enum_module.for_each_child(self.r, |_, ident, _, name_binding| { if let Res::Def(DefKind::Ctor(CtorOf::Variant, kind), def_id) = name_binding.res() { let mut segms = enum_import_suggestion.path.segments.clone(); segms.push(ast::PathSegment::from_ident(ident)); let path = Path { span: name_binding.span, segments: segms, tokens: None }; variants.push((path, def_id, kind)); } }); variants }) } /// Adds a suggestion for using an enum's variant when an enum is used instead. fn suggest_using_enum_variant( &mut self, err: &mut DiagnosticBuilder<'a>, source: PathSource<'_>, def_id: DefId, span: Span, ) { let variants = match self.collect_enum_ctors(def_id) { Some(variants) => variants, None => { err.note("you might have meant to use one of the enum's variants"); return; } }; let suggest_only_tuple_variants = matches!(source, PathSource::TupleStruct(..)) || source.is_call(); if suggest_only_tuple_variants { // Suggest only tuple variants regardless of whether they have fields and do not // suggest path with added parentheses. let suggestable_variants = variants .iter() .filter(|(.., kind)| *kind == CtorKind::Fn) .map(|(variant, ..)| path_names_to_string(variant)) .collect::>(); let non_suggestable_variant_count = variants.len() - suggestable_variants.len(); let source_msg = if source.is_call() { "to construct" } else if matches!(source, PathSource::TupleStruct(..)) { "to match against" } else { unreachable!() }; if !suggestable_variants.is_empty() { let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 { format!("try {} the enum's variant", source_msg) } else { format!("try {} one of the enum's variants", source_msg) }; err.span_suggestions( span, &msg, suggestable_variants.into_iter(), Applicability::MaybeIncorrect, ); } // If the enum has no tuple variants.. if non_suggestable_variant_count == variants.len() { err.help(&format!("the enum has no tuple variants {}", source_msg)); } // If there are also non-tuple variants.. if non_suggestable_variant_count == 1 { err.help(&format!( "you might have meant {} the enum's non-tuple variant", source_msg )); } else if non_suggestable_variant_count >= 1 { err.help(&format!( "you might have meant {} one of the enum's non-tuple variants", source_msg )); } } else { let needs_placeholder = |def_id: DefId, kind: CtorKind| { let has_no_fields = self.r.field_names.get(&def_id).map_or(false, |f| f.is_empty()); match kind { CtorKind::Const => false, CtorKind::Fn | CtorKind::Fictive if has_no_fields => false, _ => true, } }; let mut suggestable_variants = variants .iter() .filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind)) .map(|(variant, _, kind)| (path_names_to_string(variant), kind)) .map(|(variant, kind)| match kind { CtorKind::Const => variant, CtorKind::Fn => format!("({}())", variant), CtorKind::Fictive => format!("({} {{}})", variant), }) .collect::>(); if !suggestable_variants.is_empty() { let msg = if suggestable_variants.len() == 1 { "you might have meant to use the following enum variant" } else { "you might have meant to use one of the following enum variants" }; err.span_suggestions( span, msg, suggestable_variants.drain(..), Applicability::MaybeIncorrect, ); } let suggestable_variants_with_placeholders = variants .iter() .filter(|(_, def_id, kind)| needs_placeholder(*def_id, *kind)) .map(|(variant, _, kind)| (path_names_to_string(variant), kind)) .filter_map(|(variant, kind)| match kind { CtorKind::Fn => Some(format!("({}(/* fields */))", variant)), CtorKind::Fictive => Some(format!("({} {{ /* fields */ }})", variant)), _ => None, }) .collect::>(); if !suggestable_variants_with_placeholders.is_empty() { let msg = match ( suggestable_variants.is_empty(), suggestable_variants_with_placeholders.len(), ) { (true, 1) => "the following enum variant is available", (true, _) => "the following enum variants are available", (false, 1) => "alternatively, the following enum variant is available", (false, _) => "alternatively, the following enum variants are also available", }; err.span_suggestions( span, msg, suggestable_variants_with_placeholders.into_iter(), Applicability::HasPlaceholders, ); } }; if def_id.is_local() { if let Some(span) = self.def_span(def_id) { err.span_note(span, "the enum is defined here"); } } } crate fn report_missing_type_error( &self, path: &[Segment], ) -> Option<(Span, &'static str, String, Applicability)> { let (ident, span) = match path { [segment] if !segment.has_generic_args => { (segment.ident.to_string(), segment.ident.span) } _ => return None, }; let mut iter = ident.chars().map(|c| c.is_uppercase()); let single_uppercase_char = matches!(iter.next(), Some(true)) && matches!(iter.next(), None); if !self.diagnostic_metadata.currently_processing_generics && !single_uppercase_char { return None; } match (self.diagnostic_metadata.current_item, single_uppercase_char, self.diagnostic_metadata.currently_processing_generics) { (Some(Item { kind: ItemKind::Fn(..), ident, .. }), _, _) if ident.name == sym::main => { // Ignore `fn main()` as we don't want to suggest `fn main()` } ( Some(Item { kind: kind @ ItemKind::Fn(..) | kind @ ItemKind::Enum(..) | kind @ ItemKind::Struct(..) | kind @ ItemKind::Union(..), .. }), true, _ ) // Without the 2nd `true`, we'd suggest `impl ` for `impl T` when a type `T` isn't found | (Some(Item { kind: kind @ ItemKind::Impl(..), .. }), true, true) | (Some(Item { kind, .. }), false, _) => { // Likely missing type parameter. if let Some(generics) = kind.generics() { if span.overlaps(generics.span) { // Avoid the following: // error[E0405]: cannot find trait `A` in this scope // --> $DIR/typo-suggestion-named-underscore.rs:CC:LL // | // L | fn foo(x: T) {} // Shouldn't suggest underscore // | ^- help: you might be missing a type parameter: `, A` // | | // | not found in this scope return None; } let msg = "you might be missing a type parameter"; let (span, sugg) = if let [.., param] = &generics.params[..] { let span = if let [.., bound] = ¶m.bounds[..] { bound.span() } else if let GenericParam { kind: GenericParamKind::Const { ty, kw_span: _, default }, .. } = param { default.as_ref().map(|def| def.value.span).unwrap_or(ty.span) } else { param.ident.span }; (span, format!(", {}", ident)) } else { (generics.span, format!("<{}>", ident)) }; // Do not suggest if this is coming from macro expansion. if span.can_be_used_for_suggestions() { return Some(( span.shrink_to_hi(), msg, sugg, Applicability::MaybeIncorrect, )); } } } _ => {} } None } /// Given the target `label`, search the `rib_index`th label rib for similarly named labels, /// optionally returning the closest match and whether it is reachable. crate fn suggestion_for_label_in_rib( &self, rib_index: usize, label: Ident, ) -> Option { // Are ribs from this `rib_index` within scope? let within_scope = self.is_label_valid_from_rib(rib_index); let rib = &self.label_ribs[rib_index]; let names = rib .bindings .iter() .filter(|(id, _)| id.span.ctxt() == label.span.ctxt()) .map(|(id, _)| id.name) .collect::>(); find_best_match_for_name(&names, label.name, None).map(|symbol| { // Upon finding a similar name, get the ident that it was from - the span // contained within helps make a useful diagnostic. In addition, determine // whether this candidate is within scope. let (ident, _) = rib.bindings.iter().find(|(ident, _)| ident.name == symbol).unwrap(); (*ident, within_scope) }) } } impl<'tcx> LifetimeContext<'_, 'tcx> { crate fn report_missing_lifetime_specifiers( &self, spans: Vec, count: usize, ) -> DiagnosticBuilder<'tcx> { struct_span_err!( self.tcx.sess, spans, E0106, "missing lifetime specifier{}", pluralize!(count) ) } crate fn emit_undeclared_lifetime_error(&self, lifetime_ref: &hir::Lifetime) { let mut err = struct_span_err!( self.tcx.sess, lifetime_ref.span, E0261, "use of undeclared lifetime name `{}`", lifetime_ref ); err.span_label(lifetime_ref.span, "undeclared lifetime"); let mut suggests_in_band = false; let mut suggested_spans = vec![]; for missing in &self.missing_named_lifetime_spots { match missing { MissingLifetimeSpot::Generics(generics) => { let (span, sugg) = if let Some(param) = generics.params.iter().find(|p| { !matches!( p.kind, hir::GenericParamKind::Type { synthetic: true, .. } | hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided, } ) }) { (param.span.shrink_to_lo(), format!("{}, ", lifetime_ref)) } else { suggests_in_band = true; (generics.span, format!("<{}>", lifetime_ref)) }; if suggested_spans.contains(&span) { continue; } suggested_spans.push(span); if span.can_be_used_for_suggestions() { err.span_suggestion( span, &format!("consider introducing lifetime `{}` here", lifetime_ref), sugg, Applicability::MaybeIncorrect, ); } } MissingLifetimeSpot::HigherRanked { span, span_type } => { err.span_suggestion( *span, &format!( "consider making the {} lifetime-generic with a new `{}` lifetime", span_type.descr(), lifetime_ref ), span_type.suggestion(&lifetime_ref.to_string()), Applicability::MaybeIncorrect, ); err.note( "for more information on higher-ranked polymorphism, visit \ https://doc.rust-lang.org/nomicon/hrtb.html", ); } _ => {} } } if self.tcx.sess.is_nightly_build() && !self.tcx.features().in_band_lifetimes && suggests_in_band { err.help( "if you want to experiment with in-band lifetime bindings, \ add `#![feature(in_band_lifetimes)]` to the crate attributes", ); } err.emit(); } /// Returns whether to add `'static` lifetime to the suggested lifetime list. crate fn report_elision_failure( &mut self, db: &mut DiagnosticBuilder<'_>, params: &[ElisionFailureInfo], ) -> bool { let mut m = String::new(); let len = params.len(); let elided_params: Vec<_> = params.iter().cloned().filter(|info| info.lifetime_count > 0).collect(); let elided_len = elided_params.len(); for (i, info) in elided_params.into_iter().enumerate() { let ElisionFailureInfo { parent, index, lifetime_count: n, have_bound_regions, span } = info; db.span_label(span, ""); let help_name = if let Some(ident) = parent.and_then(|body| self.tcx.hir().body(body).params[index].pat.simple_ident()) { format!("`{}`", ident) } else { format!("argument {}", index + 1) }; m.push_str( &(if n == 1 { help_name } else { format!( "one of {}'s {} {}lifetimes", help_name, n, if have_bound_regions { "free " } else { "" } ) })[..], ); if elided_len == 2 && i == 0 { m.push_str(" or "); } else if i + 2 == elided_len { m.push_str(", or "); } else if i != elided_len - 1 { m.push_str(", "); } } if len == 0 { db.help( "this function's return type contains a borrowed value, \ but there is no value for it to be borrowed from", ); true } else if elided_len == 0 { db.help( "this function's return type contains a borrowed value with \ an elided lifetime, but the lifetime cannot be derived from \ the arguments", ); true } else if elided_len == 1 { db.help(&format!( "this function's return type contains a borrowed value, \ but the signature does not say which {} it is borrowed from", m )); false } else { db.help(&format!( "this function's return type contains a borrowed value, \ but the signature does not say whether it is borrowed from {}", m )); false } } crate fn report_elided_lifetime_in_ty(&self, lifetime_refs: &[&hir::Lifetime]) { let Some(missing_lifetime) = lifetime_refs.iter().find(|lt| { lt.name == hir::LifetimeName::Implicit(true) }) else { return }; let mut spans: Vec<_> = lifetime_refs.iter().map(|lt| lt.span).collect(); spans.sort(); let mut spans_dedup = spans.clone(); spans_dedup.dedup(); let spans_with_counts: Vec<_> = spans_dedup .into_iter() .map(|sp| (sp, spans.iter().filter(|nsp| *nsp == &sp).count())) .collect(); self.tcx.struct_span_lint_hir( rustc_session::lint::builtin::ELIDED_LIFETIMES_IN_PATHS, missing_lifetime.hir_id, spans, |lint| { let mut db = lint.build("hidden lifetime parameters in types are deprecated"); self.add_missing_lifetime_specifiers_label( &mut db, spans_with_counts, &FxHashSet::from_iter([kw::UnderscoreLifetime]), Vec::new(), &[], ); db.emit() }, ); } // FIXME(const_generics): This patches over an ICE caused by non-'static lifetimes in const // generics. We are disallowing this until we can decide on how we want to handle non-'static // lifetimes in const generics. See issue #74052 for discussion. crate fn emit_non_static_lt_in_const_generic_error(&self, lifetime_ref: &hir::Lifetime) { let mut err = struct_span_err!( self.tcx.sess, lifetime_ref.span, E0771, "use of non-static lifetime `{}` in const generic", lifetime_ref ); err.note( "for more information, see issue #74052 \ ", ); err.emit(); } crate fn is_trait_ref_fn_scope(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) -> bool { if let def::Res::Def(_, did) = trait_ref.trait_ref.path.res { if [ self.tcx.lang_items().fn_once_trait(), self.tcx.lang_items().fn_trait(), self.tcx.lang_items().fn_mut_trait(), ] .contains(&Some(did)) { let (span, span_type) = match &trait_ref.bound_generic_params { [] => (trait_ref.span.shrink_to_lo(), ForLifetimeSpanType::BoundEmpty), [.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail), }; self.missing_named_lifetime_spots .push(MissingLifetimeSpot::HigherRanked { span, span_type }); return true; } }; false } crate fn add_missing_lifetime_specifiers_label( &self, err: &mut DiagnosticBuilder<'_>, mut spans_with_counts: Vec<(Span, usize)>, lifetime_names: &FxHashSet, lifetime_spans: Vec, params: &[ElisionFailureInfo], ) { let snippets: Vec> = spans_with_counts .iter() .map(|(span, _)| self.tcx.sess.source_map().span_to_snippet(*span).ok()) .collect(); // Empty generics are marked with a span of "<", but since from now on // that information is in the snippets it can be removed from the spans. for ((span, _), snippet) in spans_with_counts.iter_mut().zip(&snippets) { if snippet.as_deref() == Some("<") { *span = span.shrink_to_hi(); } } for &(span, count) in &spans_with_counts { err.span_label( span, format!( "expected {} lifetime parameter{}", if count == 1 { "named".to_string() } else { count.to_string() }, pluralize!(count), ), ); } let suggest_existing = |err: &mut DiagnosticBuilder<'_>, name: &str, formatters: Vec String>>>| { if let Some(MissingLifetimeSpot::HigherRanked { span: for_span, span_type }) = self.missing_named_lifetime_spots.iter().rev().next() { // When we have `struct S<'a>(&'a dyn Fn(&X) -> &X);` we want to not only suggest // using `'a`, but also introduce the concept of HRLTs by suggesting // `struct S<'a>(&'a dyn for<'b> Fn(&X) -> &'b X);`. (#72404) let mut introduce_suggestion = vec![]; let a_to_z_repeat_n = |n| { (b'a'..=b'z').map(move |c| { let mut s = '\''.to_string(); s.extend(std::iter::repeat(char::from(c)).take(n)); s }) }; // If all single char lifetime names are present, we wrap around and double the chars. let lt_name = (1..) .flat_map(a_to_z_repeat_n) .find(|lt| !lifetime_names.contains(&Symbol::intern(<))) .unwrap(); let msg = format!( "consider making the {} lifetime-generic with a new `{}` lifetime", span_type.descr(), lt_name, ); err.note( "for more information on higher-ranked polymorphism, visit \ https://doc.rust-lang.org/nomicon/hrtb.html", ); let for_sugg = span_type.suggestion(<_name); for param in params { if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) { if snippet.starts_with('&') && !snippet.starts_with("&'") { introduce_suggestion .push((param.span, format!("&{} {}", lt_name, &snippet[1..]))); } else if let Some(stripped) = snippet.strip_prefix("&'_ ") { introduce_suggestion .push((param.span, format!("&{} {}", lt_name, stripped))); } } } introduce_suggestion.push((*for_span, for_sugg)); for ((span, _), formatter) in spans_with_counts.iter().zip(formatters.iter()) { if let Some(formatter) = formatter { introduce_suggestion.push((*span, formatter(<_name))); } } err.multipart_suggestion_verbose( &msg, introduce_suggestion, Applicability::MaybeIncorrect, ); } let spans_suggs: Vec<_> = formatters .into_iter() .zip(spans_with_counts.iter()) .filter_map(|(formatter, (span, _))| { if let Some(formatter) = formatter { Some((*span, formatter(name))) } else { None } }) .collect(); if spans_suggs.is_empty() { // If all the spans come from macros, we cannot extract snippets and then // `formatters` only contains None and `spans_suggs` is empty. return; } err.multipart_suggestion_verbose( &format!( "consider using the `{}` lifetime", lifetime_names.iter().next().unwrap() ), spans_suggs, Applicability::MaybeIncorrect, ); }; let suggest_new = |err: &mut DiagnosticBuilder<'_>, suggs: Vec>| { for missing in self.missing_named_lifetime_spots.iter().rev() { let mut introduce_suggestion = vec![]; let msg; let should_break; introduce_suggestion.push(match missing { MissingLifetimeSpot::Generics(generics) => { if generics.span == DUMMY_SP { // Account for malformed generics in the HIR. This shouldn't happen, // but if we make a mistake elsewhere, mainly by keeping something in // `missing_named_lifetime_spots` that we shouldn't, like associated // `const`s or making a mistake in the AST lowering we would provide // non-sensical suggestions. Guard against that by skipping these. // (#74264) continue; } msg = "consider introducing a named lifetime parameter".to_string(); should_break = true; if let Some(param) = generics.params.iter().find(|p| { !matches!( p.kind, hir::GenericParamKind::Type { synthetic: true, .. } | hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided } ) }) { (param.span.shrink_to_lo(), "'a, ".to_string()) } else { (generics.span, "<'a>".to_string()) } } MissingLifetimeSpot::HigherRanked { span, span_type } => { msg = format!( "consider making the {} lifetime-generic with a new `'a` lifetime", span_type.descr(), ); should_break = false; err.note( "for more information on higher-ranked polymorphism, visit \ https://doc.rust-lang.org/nomicon/hrtb.html", ); (*span, span_type.suggestion("'a")) } MissingLifetimeSpot::Static => { let mut spans_suggs = Vec::new(); for ((span, count), snippet) in spans_with_counts.iter().copied().zip(snippets.iter()) { let (span, sugg) = match snippet.as_deref() { Some("&") => (span.shrink_to_hi(), "'static ".to_owned()), Some("'_") => (span, "'static".to_owned()), Some(snippet) if !snippet.ends_with('>') => { if snippet == "" { ( span, std::iter::repeat("'static") .take(count) .collect::>() .join(", "), ) } else if snippet == "<" || snippet == "(" { ( span.shrink_to_hi(), std::iter::repeat("'static") .take(count) .collect::>() .join(", "), ) } else { ( span.shrink_to_hi(), format!( "<{}>", std::iter::repeat("'static") .take(count) .collect::>() .join(", "), ), ) } } _ => continue, }; spans_suggs.push((span, sugg.to_string())); } err.multipart_suggestion_verbose( "consider using the `'static` lifetime", spans_suggs, Applicability::MaybeIncorrect, ); continue; } }); struct Lifetime(Span, String); impl Lifetime { fn is_unnamed(&self) -> bool { self.1.starts_with('&') && !self.1.starts_with("&'") } fn is_underscore(&self) -> bool { self.1.starts_with("&'_ ") } fn is_named(&self) -> bool { self.1.starts_with("&'") } fn suggestion(&self, sugg: String) -> Option<(Span, String)> { Some( match ( self.is_unnamed(), self.is_underscore(), self.is_named(), sugg.starts_with('&'), ) { (true, _, _, false) => (self.span_unnamed_borrow(), sugg), (true, _, _, true) => { (self.span_unnamed_borrow(), sugg[1..].to_string()) } (_, true, _, false) => { (self.span_underscore_borrow(), sugg.trim().to_string()) } (_, true, _, true) => { (self.span_underscore_borrow(), sugg[1..].trim().to_string()) } (_, _, true, false) => { (self.span_named_borrow(), sugg.trim().to_string()) } (_, _, true, true) => { (self.span_named_borrow(), sugg[1..].trim().to_string()) } _ => return None, }, ) } fn span_unnamed_borrow(&self) -> Span { let lo = self.0.lo() + BytePos(1); self.0.with_lo(lo).with_hi(lo) } fn span_named_borrow(&self) -> Span { let lo = self.0.lo() + BytePos(1); self.0.with_lo(lo) } fn span_underscore_borrow(&self) -> Span { let lo = self.0.lo() + BytePos(1); let hi = lo + BytePos(2); self.0.with_lo(lo).with_hi(hi) } } for param in params { if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) { if let Some((span, sugg)) = Lifetime(param.span, snippet).suggestion("'a ".to_string()) { introduce_suggestion.push((span, sugg)); } } } for (span, sugg) in spans_with_counts.iter().copied().zip(suggs.iter()).filter_map( |((span, _), sugg)| match &sugg { Some(sugg) => Some((span, sugg.to_string())), _ => None, }, ) { let (span, sugg) = self .tcx .sess .source_map() .span_to_snippet(span) .ok() .and_then(|snippet| Lifetime(span, snippet).suggestion(sugg.clone())) .unwrap_or((span, sugg)); introduce_suggestion.push((span, sugg.to_string())); } err.multipart_suggestion_verbose( &msg, introduce_suggestion, Applicability::MaybeIncorrect, ); if should_break { break; } } }; let lifetime_names: Vec<_> = lifetime_names.iter().collect(); match &lifetime_names[..] { [name] => { let mut suggs: Vec String>>> = Vec::new(); for (snippet, (_, count)) in snippets.iter().zip(spans_with_counts.iter().copied()) { suggs.push(match snippet.as_deref() { Some("&") => Some(Box::new(|name| format!("&{} ", name))), Some("'_") => Some(Box::new(|n| n.to_string())), Some("") => Some(Box::new(move |n| format!("{}, ", n).repeat(count))), Some("<") => Some(Box::new(move |n| { std::iter::repeat(n).take(count).collect::>().join(", ") })), Some(snippet) if !snippet.ends_with('>') => Some(Box::new(move |name| { format!( "{}<{}>", snippet, std::iter::repeat(name.to_string()) .take(count) .collect::>() .join(", ") ) })), _ => None, }); } suggest_existing(err, name.as_str(), suggs); } [] => { let mut suggs = Vec::new(); for (snippet, (_, count)) in snippets.iter().cloned().zip(spans_with_counts.iter().copied()) { suggs.push(match snippet.as_deref() { Some("&") => Some("&'a ".to_string()), Some("'_") => Some("'a".to_string()), Some("") => { Some(std::iter::repeat("'a, ").take(count).collect::>().join("")) } Some("<") => { Some(std::iter::repeat("'a").take(count).collect::>().join(", ")) } Some(snippet) => Some(format!( "{}<{}>", snippet, std::iter::repeat("'a").take(count).collect::>().join(", "), )), None => None, }); } suggest_new(err, suggs); } lts if lts.len() > 1 => { err.span_note(lifetime_spans, "these named lifetimes are available to use"); let mut spans_suggs: Vec<_> = Vec::new(); for ((span, _), snippet) in spans_with_counts.iter().copied().zip(snippets.iter()) { match snippet.as_deref() { Some("") => spans_suggs.push((span, "'lifetime, ".to_string())), Some("&") => spans_suggs .push((span.with_lo(span.lo() + BytePos(1)), "'lifetime ".to_string())), _ => {} } } if spans_suggs.len() > 0 { // This happens when we have `Foo` where we point at the space before `T`, // but this can be confusing so we give a suggestion with placeholders. err.multipart_suggestion_verbose( "consider using one of the available lifetimes here", spans_suggs, Applicability::HasPlaceholders, ); } } _ => unreachable!(), } } /// Non-static lifetimes are prohibited in anonymous constants under `min_const_generics`. /// This function will emit an error if `generic_const_exprs` is not enabled, the body identified by /// `body_id` is an anonymous constant and `lifetime_ref` is non-static. crate fn maybe_emit_forbidden_non_static_lifetime_error( &self, body_id: hir::BodyId, lifetime_ref: &'tcx hir::Lifetime, ) { let is_anon_const = matches!( self.tcx.def_kind(self.tcx.hir().body_owner_def_id(body_id)), hir::def::DefKind::AnonConst ); let is_allowed_lifetime = matches!( lifetime_ref.name, hir::LifetimeName::Implicit(_) | hir::LifetimeName::Static | hir::LifetimeName::Underscore ); if !self.tcx.lazy_normalization() && is_anon_const && !is_allowed_lifetime { feature_err( &self.tcx.sess.parse_sess, sym::generic_const_exprs, lifetime_ref.span, "a non-static lifetime is not allowed in a `const`", ) .emit(); } } }