use crate::diagnostics::{ImportSuggestion, TypoSuggestion}; use crate::late::{LateResolutionVisitor, RibKind}; use crate::path_names_to_string; use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot}; use crate::{PathResult, PathSource, Segment}; use errors::{Applicability, DiagnosticBuilder}; use log::debug; use rustc::session::config::nightly_options; use rustc_data_structures::fx::FxHashSet; use rustc_hir::def::Namespace::{self, *}; use rustc_hir::def::{self, CtorKind, DefKind}; use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX}; use rustc_hir::PrimTy; use rustc_span::hygiene::MacroKind; use rustc_span::symbol::kw; use rustc_span::Span; use syntax::ast::{self, Expr, ExprKind, Ident, NodeId, Path, Ty, TyKind}; use syntax::util::lev_distance::find_best_match_for_name; use rustc_error_codes::*; type Res = def::Res; /// A field or associated item from self type suggested in case of resolution failure. enum AssocSuggestion { Field, MethodWithSelf, AssocItem, } 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(), }; let enum_path_string = path_names_to_string(&enum_path); (variant_path_string, enum_path_string) } impl<'a> LateResolutionVisitor<'a, '_> { /// 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| { if let Res::Def(DefKind::Variant, _) = res { true } else { false } }; // Make the base error. let 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(..), _) | Res::Def(DefKind::Method, _) | Res::Def(DefKind::Const, _) | Res::Def(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 { (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(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), 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); // Emit help message for fake-self from other languages (e.g., `this` in Javascript). if ["this", "my"].contains(&&*item_str.as_str()) && self.self_value_is_available(path[0].ident.span, span) { err.span_suggestion( span, "did you mean", "self".to_string(), Applicability::MaybeIncorrect, ); } // Emit special messages for unresolved `Self` and `self`. if is_self_type(path, ns) { err.code(errors::error_code!(E0411)); err.span_label( span, format!("`Self` is only available in impls, traits, and type definitions"), ); return (err, Vec::new()); } if is_self_value(path, ns) { debug!("smart_resolve_path_fragment: E0424, source={:?}", source); err.code(errors::error_code!(E0424)); err.span_label(span, match source { PathSource::Pat => format!( "`self` value is a keyword and may not be bound to variables or shadowed", ), _ => format!( "`self` value is a keyword only available in methods with a `self` parameter", ), }); if let Some(span) = &self.diagnostic_metadata.current_function { err.span_label(*span, "this function doesn't have a `self` parameter"); } 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, is_expected) .drain(..) .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 enum_candidates = self.r.lookup_import_candidates(ident, ns, is_enum_variant); let mut enum_candidates = enum_candidates .iter() .map(|suggestion| import_candidate_to_enum_paths(&suggestion)) .collect::>(); enum_candidates.sort(); if !enum_candidates.is_empty() { // 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) // Variants re-exported in prelude doesn't mean `prelude::v1` is the // type name! // FIXME: is there a more principled way to do this that // would work for other re-exports? .filter(|enum_ty_path| enum_ty_path != "std::prelude::v1") // Also write `Option` rather than `std::prelude::v1::Option`. .map(|enum_ty_path| { // FIXME #56861: DRY-er prelude filtering. enum_ty_path.trim_start_matches("std::prelude::v1::").to_owned() }), 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, "try", format!("self.{}", path_str), Applicability::MachineApplicable, ); } AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => { err.span_suggestion( span, "try", 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); let levenshtein_worked = self.r.add_typo_suggestion(&mut err, typo_sugg, ident_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, ) { return (err, candidates); } } // Fallback label. if !levenshtein_worked { err.span_label(base_span, fallback_label); self.type_ascription_suggestion(&mut err, base_span); 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, ); } _ => {} } } (err, candidates) } /// 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(parent) = source { match &parent?.kind { ExprKind::Call(_, args) if args.len() > 0 => { 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.unwrap().span; let tail_args_span = if args.len() > 1 { Some(Span::new( args[1].span.lo(), args.last().unwrap().span.hi(), call_span.ctxt(), )) } else { None }; has_self_arg = Some((call_span, tail_args_span)); } break; } ExprKind::AddrOf(_, _, expr) => expr_kind = &expr.kind, _ => break, } } } _ => (), } }; return has_self_arg; } fn followed_by_brace(&self, span: Span) -> (bool, Option<(Span, String)>) { // 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 = match sm.span_to_snippet(sp) { Ok(ref snippet) if snippet == "{" => true, _ => false, }; // In case this could be a struct literal that needs to be surrounded // by parenthesis, 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 == "}" { let sp = span.to(sp); if let Ok(snippet) = sm.span_to_snippet(sp) { closing_brace = Some((sp, snippet)); } break; } } _ => break, } i += 1; // The bigger the span, the more likely we're incorrect -- // bound it to 100 chars long. if i > 100 { break; } } return (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 mut bad_struct_syntax_suggestion = |def_id: DefId| { let (followed_by_brace, closing_brace) = self.followed_by_brace(span); let mut suggested = false; match source { PathSource::Expr(Some(parent)) => { suggested = path_sep(err, &parent); } PathSource::Expr(None) if followed_by_brace == true => { if let Some((sp, snippet)) = closing_brace { err.span_suggestion( sp, "surround the struct literal with parenthesis", format!("({})", snippet), Applicability::MaybeIncorrect, ); } else { err.span_label( span, // Note the parenthesis surrounding the suggestion below format!("did you mean `({} {{ /* fields */ }})`?", path_str), ); } suggested = true; } _ => {} } if !suggested { if let Some(span) = self.r.definitions.opt_span(def_id) { err.span_label(span, &format!("`{}` defined here", path_str)); } err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?", path_str)); } }; match (res, source) { (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => { err.span_suggestion( span, "use `!` to invoke the macro", format!("{}!", path_str), Applicability::MaybeIncorrect, ); if path_str == "try" && span.rust_2015() { err.note("if you want the `try` keyword, you need to be in the 2018 edition"); } } (Res::Def(DefKind::TyAlias, _), PathSource::Trait(_)) => { err.span_label(span, "type aliases cannot be used as traits"); if nightly_options::is_nightly_build() { err.note("did you mean to use a trait alias?"); } } (Res::Def(DefKind::Mod, _), PathSource::Expr(Some(parent))) => { if !path_sep(err, &parent) { return false; } } (Res::Def(DefKind::Enum, def_id), PathSource::TupleStruct) | (Res::Def(DefKind::Enum, def_id), PathSource::Expr(..)) => { if let Some(variants) = self.collect_enum_variants(def_id) { if !variants.is_empty() { let msg = if variants.len() == 1 { "try using the enum's variant" } else { "try using one of the enum's variants" }; err.span_suggestions( span, msg, variants.iter().map(path_names_to_string), Applicability::MaybeIncorrect, ); } } else { err.note("did you mean to use one of the enum's variants?"); } } (Res::Def(DefKind::Struct, def_id), _) if ns == ValueNS => { if let Some((ctor_def, ctor_vis)) = self.r.struct_constructors.get(&def_id).cloned() { let accessible_ctor = self.r.is_accessible_from(ctor_vis, self.parent_scope.module); if is_expected(ctor_def) && !accessible_ctor { err.span_label( span, format!("constructor is not visible here due to private fields"), ); } } else { bad_struct_syntax_suggestion(def_id); } } (Res::Def(DefKind::Union, def_id), _) | (Res::Def(DefKind::Variant, def_id), _) | (Res::Def(DefKind::Ctor(_, CtorKind::Fictive), def_id), _) if ns == ValueNS => { bad_struct_syntax_suggestion(def_id); } (Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => { if let Some(span) = self.r.definitions.opt_span(def_id) { err.span_label(span, &format!("`{}` defined here", path_str)); } err.span_label(span, format!("did you mean `{}( /* fields */ )`?", path_str)); } (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, _), _) | (Res::Def(DefKind::AssocTy, _), _) if ns == ValueNS => { err.note("can't use a type alias as a constructor"); } _ => return false, } true } 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, did) | Res::Def(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); } } } _ => {} } } } } for assoc_type_ident in &self.diagnostic_metadata.current_trait_assoc_types { if *assoc_type_ident == ident { return Some(AssocSuggestion::AssocItem); } } // 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) { return Some(if self.r.has_self.contains(&res.def_id()) { AssocSuggestion::MethodWithSelf } else { AssocSuggestion::AssocItem }); } } } 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::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, ident.span) .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::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( self.r.primitive_type_table.primitive_types.iter().map(|(name, prim_ty)| { TypoSuggestion::from_res(*name, Res::PrimTy(*prim_ty)) }), ) } } else { // Search in module. let mod_path = &path[..path.len() - 1]; if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS), false, span, CrateLint::No) { if let ModuleOrUniformRoot::Module(module) = module { 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_cached_key(|suggestion| suggestion.candidate.as_str()); match find_best_match_for_name( names.iter().map(|suggestion| &suggestion.candidate), &name.as_str(), None, ) { Some(found) if found != name => { names.into_iter().find(|suggestion| suggestion.candidate == found) } _ => None, } } /// Only used in a specific case of type ascription suggestions fn get_colon_suggestion_span(&self, start: Span) -> Span { let cm = self.r.session.source_map(); start.to(cm.next_point(start)) } fn type_ascription_suggestion(&self, err: &mut DiagnosticBuilder<'_>, base_span: Span) { let cm = self.r.session.source_map(); let base_snippet = cm.span_to_snippet(base_span); if let Some(sp) = self.diagnostic_metadata.current_type_ascription.last() { let mut sp = *sp; loop { // Try to find the `:`; bail on first non-':' / non-whitespace. sp = cm.next_point(sp); if let Ok(snippet) = cm.span_to_snippet(sp.to(cm.next_point(sp))) { let line_sp = cm.lookup_char_pos(sp.hi()).line; let line_base_sp = cm.lookup_char_pos(base_span.lo()).line; if snippet == ":" { let mut show_label = true; if line_sp != line_base_sp { err.span_suggestion_short( sp, "did you mean to use `;` here instead?", ";".to_string(), Applicability::MaybeIncorrect, ); } else { let colon_sp = self.get_colon_suggestion_span(sp); let after_colon_sp = self.get_colon_suggestion_span(colon_sp.shrink_to_hi()); if !cm .span_to_snippet(after_colon_sp) .map(|s| s == " ") .unwrap_or(false) { err.span_suggestion( colon_sp, "maybe you meant to write a path separator here", "::".to_string(), Applicability::MaybeIncorrect, ); show_label = false; } if let Ok(base_snippet) = base_snippet { let mut sp = after_colon_sp; for _ in 0..100 { // Try to find an assignment sp = cm.next_point(sp); let snippet = cm.span_to_snippet(sp.to(cm.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", ); } break; } else if !snippet.trim().is_empty() { debug!("tried to find type ascription `:` token, couldn't find it"); break; } } else { break; } } } } 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().unwrap(); if module_def_id == def_id { let path = Path { span: name_binding.span, segments: path_segments }; result = Some((module, ImportSuggestion { did: Some(def_id), path })); } else { // add the module to the lookup if seen_modules.insert(module_def_id) { worklist.push((module, path_segments)); } } } }); } result } fn collect_enum_variants(&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::Variant, _) = name_binding.res() { let mut segms = enum_import_suggestion.path.segments.clone(); segms.push(ast::PathSegment::from_ident(ident)); variants.push(Path { span: name_binding.span, segments: segms }); } }); variants }) } }