use std::cmp::Reverse; use errors::{Applicability, DiagnosticBuilder, DiagnosticId}; use log::debug; use rustc::hir::def::*; use rustc::hir::def::Namespace::*; use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId}; use rustc::session::config::nightly_options; use syntax::ast::{ExprKind}; use syntax::symbol::keywords; use syntax_pos::Span; use crate::macros::ParentScope; use crate::resolve_imports::ImportResolver; use crate::{import_candidate_to_enum_paths, is_self_type, is_self_value, path_names_to_string}; use crate::{AssocSuggestion, CrateLint, ImportSuggestion, ModuleOrUniformRoot, PathResult, PathSource, Resolver, Segment}; impl<'a> Resolver<'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<'_>, def: Option, ) -> (DiagnosticBuilder<'a>, Vec) { let ident_span = path.last().map_or(span, |ident| ident.ident.span); let ns = source.namespace(); let is_expected = &|def| source.is_expected(def); let is_enum_variant = &|def| if let Def::Variant(..) = def { 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 code = source.error_code(def.is_some()); let (base_msg, fallback_label, base_span) = if let Some(def) = def { (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str), format!("not a {}", expected), span) } 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 == keywords::PathRoot.name() { (String::new(), "the crate root".to_string()) } else { let mod_path = &path[..path.len() - 1]; let mod_prefix = match self.resolve_path_without_parent_scope( mod_path, Some(TypeNS), false, span, CrateLint::No ) { PathResult::Module(ModuleOrUniformRoot::Module(module)) => module.def(), _ => None, }.map_or(String::new(), |def| format!("{} ", def.kind_name())); (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) }; let code = DiagnosticId::Error(code.into()); let mut err = self.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) { __diagnostic_used!(E0411); err.code(DiagnosticId::Error("E0411".into())); 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); __diagnostic_used!(E0424); err.code(DiagnosticId::Error("E0424".into())); 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 `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.lookup_import_candidates(ident, ns, is_expected) .drain(..) .filter(|ImportSuggestion { did, .. }| { match (did, def.and_then(|def| def.opt_def_id())) { (Some(suggestion_did), Some(actual_did)) => *suggestion_did != actual_did, _ => true, } }) .collect::>(); if candidates.is_empty() && is_expected(Def::Enum(DefId::local(CRATE_DEF_INDEX))) { let enum_candidates = self.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 def.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 => { err.span_suggestion( span, "try", format!("self.{}", path_str), Applicability::MachineApplicable, ); if !self_is_available { err.span_label(span, format!("`self` value is a keyword \ only available in \ methods with `self` parameter")); } } 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); } } let mut levenshtein_worked = false; // Try Levenshtein algorithm. let suggestion = self.lookup_typo_candidate(path, ns, is_expected, span); if let Some(suggestion) = suggestion { let msg = format!( "{} {} with a similar name exists", suggestion.article, suggestion.kind ); err.span_suggestion( ident_span, &msg, suggestion.candidate.to_string(), Applicability::MaybeIncorrect, ); levenshtein_worked = true; } // Try context-dependent help if relaxed lookup didn't work. if let Some(def) = def { if self.smart_resolve_context_dependent_help(&mut err, span, source, def, &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); } (err, candidates) } /// 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<'_>, def: Def, path_str: &str, fallback_label: &str, ) -> bool { let ns = source.namespace(); let is_expected = &|def| source.is_expected(def); match (def, source) { (Def::Macro(..), _) => { 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"); } } (Def::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?"); } } (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node { ExprKind::Field(_, ident) => { err.span_suggestion( parent.span, "use the path separator to refer to an item", format!("{}::{}", path_str, ident), Applicability::MaybeIncorrect, ); } ExprKind::MethodCall(ref segment, ..) => { let span = parent.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, ); } _ => return false, }, (Def::Enum(..), PathSource::TupleStruct) | (Def::Enum(..), PathSource::Expr(..)) => { if let Some(variants) = self.collect_enum_variants(def) { err.note(&format!("did you mean to use one \ of the following variants?\n{}", variants.iter() .map(|suggestion| path_names_to_string(suggestion)) .map(|suggestion| format!("- `{}`", suggestion)) .collect::>() .join("\n"))); } else { err.note("did you mean to use one of the enum's variants?"); } }, (Def::Struct(def_id), _) if ns == ValueNS => { if let Some((ctor_def, ctor_vis)) = self.struct_constructors.get(&def_id).cloned() { let accessible_ctor = self.is_accessible(ctor_vis); if is_expected(ctor_def) && !accessible_ctor { err.span_label(span, format!("constructor is not visible \ here due to private fields")); } } else { // 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.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; } } match source { PathSource::Expr(Some(parent)) => { match parent.node { ExprKind::MethodCall(ref path_assignment, _) => { err.span_suggestion( sm.start_point(parent.span) .to(path_assignment.ident.span), "use `::` to access an associated function", format!("{}::{}", path_str, path_assignment.ident), Applicability::MaybeIncorrect ); }, _ => { err.span_label( span, format!("did you mean `{} {{ /* fields */ }}`?", path_str), ); }, } }, 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, format!("did you mean `({} {{ /* fields */ }})`?", path_str), ); } }, _ => { err.span_label( span, format!("did you mean `{} {{ /* fields */ }}`?", path_str), ); }, } } } (Def::Union(..), _) | (Def::Variant(..), _) | (Def::VariantCtor(_, CtorKind::Fictive), _) if ns == ValueNS => { err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?", path_str)); } (Def::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"); } (Def::TyAlias(_), _) | (Def::AssociatedTy(..), _) if ns == ValueNS => { err.note("can't use a type alias as a constructor"); } _ => return false, } true } } impl<'a, 'b:'a> ImportResolver<'a, 'b> { /// Adds suggestions for a path that cannot be resolved. pub(crate) fn make_path_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { debug!("make_path_suggestion: span={:?} path={:?}", span, path); match (path.get(0), path.get(1)) { // `{{root}}::ident::...` on both editions. // On 2015 `{{root}}` is usually added implicitly. (Some(fst), Some(snd)) if fst.ident.name == keywords::PathRoot.name() && !snd.ident.is_path_segment_keyword() => {} // `ident::...` on 2018. (Some(fst), _) if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() => { // Insert a placeholder that's later replaced by `self`/`super`/etc. path.insert(0, Segment::from_ident(keywords::Invalid.ident())); } _ => return None, } self.make_missing_self_suggestion(span, path.clone(), parent_scope) .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope)) .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope)) .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope)) } /// Suggest a missing `self::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `self::foo`? /// ``` fn make_missing_self_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `self` and check if that is valid. path[0].ident.name = keywords::SelfLower.name(); let result = self.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, None)) } else { None } } /// Suggests a missing `crate::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `crate::foo`? /// ``` fn make_missing_crate_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = keywords::Crate.name(); let result = self.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some(( path, Some( "`use` statements changed in Rust 2018; read more at \ ".to_string() ), )) } else { None } } /// Suggests a missing `super::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `super::foo`? /// ``` fn make_missing_super_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = keywords::Super.name(); let result = self.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, None)) } else { None } } /// Suggests a missing external crate name if that resolves to an correct module. /// /// ``` /// | /// LL | use foobar::Baz; /// | ^^^^^^ did you mean `baz::foobar`? /// ``` /// /// Used when importing a submodule of an external crate but missing that crate's /// name as the first part of path. fn make_external_crate_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { if path[1].ident.span.rust_2015() { return None; } // Sort extern crate names in reverse order to get // 1) some consistent ordering for emitted dignostics, and // 2) `std` suggestions before `core` suggestions. let mut extern_crate_names = self.resolver.extern_prelude.iter().map(|(ident, _)| ident.name).collect::>(); extern_crate_names.sort_by_key(|name| Reverse(name.as_str())); for name in extern_crate_names.into_iter() { // Replace first ident with a crate name and check if that is valid. path[0].ident.name = name; let result = self.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_external_crate_suggestion: name={:?} path={:?} result={:?}", name, path, result); if let PathResult::Module(..) = result { return Some((path, None)); } } None } }