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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_resolve/src/late/diagnostics.rs | 2369 |
1 files changed, 2369 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs new file mode 100644 index 000000000..2b1f2b88e --- /dev/null +++ b/compiler/rustc_resolve/src/late/diagnostics.rs @@ -0,0 +1,2369 @@ +use crate::diagnostics::{ImportSuggestion, LabelSuggestion, TypoSuggestion}; +use crate::late::{AliasPossibility, LateResolutionVisitor, RibKind}; +use crate::late::{LifetimeBinderKind, LifetimeRes, LifetimeRibKind, LifetimeUseSet}; +use crate::path_names_to_string; +use crate::{Module, ModuleKind, ModuleOrUniformRoot}; +use crate::{PathResult, PathSource, Segment}; + +use rustc_ast::visit::{FnCtxt, FnKind, LifetimeCtxt}; +use rustc_ast::{ + self as ast, AssocItemKind, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind, + NodeId, Path, Ty, TyKind, DUMMY_NODE_ID, +}; +use rustc_ast_pretty::pprust::path_segment_to_string; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::{ + pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, + MultiSpan, +}; +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_ID, LOCAL_CRATE}; +use rustc_hir::PrimTy; +use rustc_session::lint; +use rustc_session::parse::feature_err; +use rustc_session::Session; +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, Span}; + +use std::iter; +use std::ops::Deref; + +use tracing::debug; + +type Res = def::Res<ast::NodeId>; + +/// 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", + } + } +} + +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) +} + +/// Description of an elided lifetime. +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)] +pub(super) struct MissingLifetime { + /// Used to overwrite the resolution with the suggestion, to avoid cascasing errors. + pub id: NodeId, + /// Where to suggest adding the lifetime. + pub span: Span, + /// How the lifetime was introduced, to have the correct space and comma. + pub kind: MissingLifetimeKind, + /// Number of elided lifetimes, used for elision in path. + pub count: usize, +} + +#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)] +pub(super) enum MissingLifetimeKind { + /// An explicit `'_`. + Underscore, + /// An elided lifetime `&' ty`. + Ampersand, + /// An elided lifetime in brackets with written brackets. + Comma, + /// An elided lifetime with elided brackets. + Brackets, +} + +/// Description of the lifetimes appearing in a function parameter. +/// This is used to provide a literal explanation to the elision failure. +#[derive(Clone, Debug)] +pub(super) struct ElisionFnParameter { + /// The index of the argument in the original definition. + pub index: usize, + /// The name of the argument if it's a simple ident. + pub ident: Option<Ident>, + /// The number of lifetimes in the parameter. + pub lifetime_count: usize, + /// The span of the parameter. + pub span: Span, +} + +/// Description of lifetimes that appear as candidates for elision. +/// This is used to suggest introducing an explicit lifetime. +#[derive(Debug)] +pub(super) enum LifetimeElisionCandidate { + /// This is not a real lifetime. + Ignore, + /// There is a named lifetime, we won't suggest anything. + Named, + Missing(MissingLifetime), +} + +impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { + fn def_span(&self, def_id: DefId) -> Option<Span> { + match def_id.krate { + LOCAL_CRATE => self.r.opt_span(def_id), + _ => Some(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<Res>, + ) -> (DiagnosticBuilder<'a, ErrorGuaranteed>, Vec<ImportSuggestion>) { + 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, _)); + + debug!(?res, ?source); + + // Make the base error. + struct BaseError<'a> { + msg: String, + fallback_label: String, + span: Span, + could_be_expr: bool, + suggestion: Option<(Span, &'a str, String)>, + } + let mut expected = source.descr_expected(); + let path_str = Segment::names_to_string(path); + let item_str = path.last().unwrap().ident; + let base_error = if let Some(res) = res { + BaseError { + msg: format!("expected {}, found {} `{}`", expected, res.descr(), path_str), + fallback_label: format!("not a {expected}"), + span, + could_be_expr: 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, + }, + suggestion: None, + } + } else { + let item_span = path.last().unwrap().ident.span; + let (mod_prefix, mod_str, suggestion) = if path.len() == 1 { + debug!(?self.diagnostic_metadata.current_impl_items); + debug!(?self.diagnostic_metadata.current_function); + let suggestion = if let Some(items) = self.diagnostic_metadata.current_impl_items + && let Some((fn_kind, _)) = self.diagnostic_metadata.current_function + && self.current_trait_ref.is_none() + && let Some(FnCtxt::Assoc(_)) = fn_kind.ctxt() + && let Some(item) = items.iter().find(|i| { + if let AssocItemKind::Fn(fn_) = &i.kind + && !fn_.sig.decl.has_self() + && i.ident.name == item_str.name + { + debug!(?item_str.name); + debug!(?fn_.sig.decl.inputs); + return true + } + false + }) + { + Some(( + item_span, + "consider using the associated function", + format!("Self::{}", item.ident) + )) + } else { + None + }; + (String::new(), "this scope".to_string(), suggestion) + } 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(), None) + } else { + (String::new(), "the crate root".to_string(), None) + } + } else if path.len() == 2 && path[0].ident.name == kw::Crate { + (String::new(), "the crate root".to_string(), None) + } else { + let mod_path = &path[..path.len() - 1]; + let mod_prefix = match self.resolve_path(mod_path, Some(TypeNS), None) { + 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)), None) + }; + BaseError { + msg: format!("cannot find {expected} `{item_str}` in {mod_prefix}{mod_str}"), + fallback_label: 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}") + }, + span: item_span, + could_be_expr: false, + suggestion, + } + }; + + let code = source.error_code(res.is_some()); + let mut err = + self.r.session.struct_span_err_with_code(base_error.span, &base_error.msg, code); + + self.suggest_swapping_misplaced_self_ty_and_trait(&mut err, source, res, base_error.span); + + if let Some(sugg) = base_error.suggestion { + err.span_suggestion_verbose(sugg.0, sugg.1, sugg.2, Applicability::MaybeIncorrect); + } + + 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: expr_span, kind: ExprKind::Assign(lhs, _, _), .. }), + ) => { + // Icky heuristic so we don't suggest: + // `if (i + 2) = 2` => `if let (i + 2) = 2` (approximately pattern) + // `if 2 = i` => `if let 2 = i` (lhs needs to contain error span) + if lhs.is_approximately_pattern() && lhs.span.contains(span) { + err.span_suggestion_verbose( + expr_span.shrink_to_lo(), + "you might have meant to use pattern matching", + "let ", + Applicability::MaybeIncorrect, + ); + } + } + _ => {} + } + + let is_assoc_fn = self.self_type_is_available(); + // 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", + Applicability::MaybeIncorrect, + ); + if !self.self_value_is_available(path[0].ident.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, + Applicability::MaybeIncorrect, + ); + } + } + } + + self.detect_assoct_type_constraint_meant_as_path(base_error.span, &mut err); + + // 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(), + ); + if let Some(item_kind) = self.diagnostic_metadata.current_item { + err.span_label( + item_kind.ident.span, + format!( + "`Self` not allowed in {} {}", + item_kind.kind.article(), + item_kind.kind.descr() + ), + ); + } + 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", + _ => "`self` value is a keyword only available in methods with a `self` parameter", + }); + 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, + 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), + ); + } + } + } else if let Some(item_kind) = self.diagnostic_metadata.current_item { + err.span_label( + item_kind.ident.span, + format!( + "`self` not allowed in {} {}", + item_kind.kind.article(), + item_kind.kind.descr() + ), + ); + } + return (err, Vec::new()); + } + + // Try to lookup name in more relaxed fashion for better error reporting. + let ident = path.last().unwrap().ident; + let mut 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::<Vec<_>>(); + let crate_def_id = CRATE_DEF_ID.to_def_id(); + // Try to filter out intrinsics candidates, as long as we have + // some other candidates to suggest. + let intrinsic_candidates: Vec<_> = candidates + .drain_filter(|sugg| { + let path = path_names_to_string(&sugg.path); + path.starts_with("core::intrinsics::") || path.starts_with("std::intrinsics::") + }) + .collect(); + if candidates.is_empty() { + // Put them back if we have no more candidates to suggest... + candidates.extend(intrinsic_candidates); + } + 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, + ); + } + } + // Try Levenshtein algorithm. + let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected); + if path.len() == 1 && self.self_type_is_available() { + 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); + 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, + ); + } + } + self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span); + 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 `{ident}` as a method"), + format!("self.{path_str}({args_snippet})"), + Applicability::MachineApplicable, + ); + return (err, candidates); + } + } + + // 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, + &base_error.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_error.span.from_expansion() && base_error.span.desugaring_kind().is_none(); + if !self.type_ascription_suggestion(&mut err, base_error.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<Span> = bounds + .iter() + .map(|bound| bound.span()) + .filter(|&sp| sp != base_error.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 {these} bound{s}", + these = pluralize!("this", bounds.len() - 1), + s = pluralize!(bounds.len() - 1), + ) + } else { + String::new() + }; + multi_span.push_span_label(sp, msg); + } + multi_span + .push_span_label(base_error.span, "expected this type to be a trait..."); + 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_error.span, + }) { + let mut sugg = vec![]; + if base_error.span != start_span { + sugg.push((start_span.until(base_error.span), String::new())); + } + if base_error.span != end_span { + sugg.push((base_error.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_error.span) && base_error.could_be_expr => + { + err.span_suggestion_short( + pat_sp.between(ty_sp), + "use `=` if you meant to assign", + " = ", + 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, &source, is_expected); + self.r.add_typo_suggestion(&mut err, suggestion, ident_span); + } + if fallback { + // Fallback label. + err.span_label(base_error.span, base_error.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, + 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, + Applicability::MaybeIncorrect, + ); + } + } + } + + (err, candidates) + } + + fn detect_assoct_type_constraint_meant_as_path(&self, base_span: Span, err: &mut Diagnostic) { + let Some(ty) = self.diagnostic_metadata.current_type_path else { return; }; + let TyKind::Path(_, path) = &ty.kind else { return; }; + for segment in &path.segments { + let Some(params) = &segment.args else { continue; }; + let ast::GenericArgs::AngleBracketed(ref params) = params.deref() else { continue; }; + for param in ¶ms.args { + let ast::AngleBracketedArg::Constraint(constraint) = param else { continue; }; + let ast::AssocConstraintKind::Bound { bounds } = &constraint.kind else { + continue; + }; + for bound in bounds { + let ast::GenericBound::Trait(trait_ref, ast::TraitBoundModifier::None) + = bound else + { + continue; + }; + if base_span == trait_ref.span { + err.span_suggestion_verbose( + constraint.ident.span.between(trait_ref.span), + "you might have meant to write a path instead of an associated type bound", + "::", + Applicability::MachineApplicable, + ); + } + } + } + } + } + + fn suggest_swapping_misplaced_self_ty_and_trait( + &mut self, + err: &mut Diagnostic, + source: PathSource<'_>, + res: Option<Res>, + span: Span, + ) { + if let Some((trait_ref, self_ty)) = + self.diagnostic_metadata.currently_processing_impl_trait.clone() + && let TyKind::Path(_, self_ty_path) = &self_ty.kind + && let PathResult::Module(ModuleOrUniformRoot::Module(module)) = + self.resolve_path(&Segment::from_path(self_ty_path), Some(TypeNS), None) + && let ModuleKind::Def(DefKind::Trait, ..) = module.kind + && trait_ref.path.span == span + && let PathSource::Trait(_) = source + && let Some(Res::Def(DefKind::Struct | DefKind::Enum | DefKind::Union, _)) = res + && let Ok(self_ty_str) = + self.r.session.source_map().span_to_snippet(self_ty.span) + && let Ok(trait_ref_str) = + self.r.session.source_map().span_to_snippet(trait_ref.path.span) + { + err.multipart_suggestion( + "`impl` items mention the trait being implemented first and the type it is being implemented for second", + vec![(trait_ref.path.span, self_ty_str), (self_ty.span, trait_ref_str)], + Applicability::MaybeIncorrect, + ); + } + } + + fn get_single_associated_item( + &mut self, + path: &[Segment], + source: &PathSource<'_>, + filter_fn: &impl Fn(Res) -> bool, + ) -> Option<TypoSuggestion> { + 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, None) + { + 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 <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`. + fn restrict_assoc_type_in_where_clause(&mut self, span: Span, err: &mut Diagnostic) -> 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 Some(partial_res) = self.r.partial_res_map.get(&bounded_ty.id) 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; + }; + + let peeled_ty = ty.peel_refs(); + if let ast::TyKind::Path(None, type_param_path) = &peeled_ty.kind { + // Confirm that the `SelfTy` is a type parameter. + let Some(partial_res) = self.r.partial_res_map.get(&peeled_ty.id) 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::<Vec<_>>() + .join("::"), + path.segments[*position..] + .iter() + .map(|segment| path_segment_to_string(segment)) + .collect::<Vec<_>>() + .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<Span>)> { + 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<Span>) { + // 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 Diagnostic, + 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 Diagnostic, 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 Diagnostic| { + 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::<Vec<String>>() + .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", + "!", + 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.downgrade_to_delayed_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::<Vec<_>>()) + } + _ => None, + }; + + if let Some(spans) = + field_spans.filter(|spans| spans.len() > 0 && fields.len() == spans.len()) + { + let non_visible_spans: Vec<Span> = 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: MultiSpan = non_visible_spans.clone().into(); + non_visible_spans + .into_iter() + .for_each(|s| m.push_span_label(s, "private field")); + 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"); + } + ( + 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", + 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`. + pub(crate) fn find_similarly_named_assoc_item( + &mut self, + ident: Symbol, + kind: &AssocItemKind, + ) -> Option<Symbol> { + let (module, _) = self.current_trait_ref.as_ref()?; + 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::<Vec<_>>(); + + find_best_match_for_name(&targets, ident, None) + } + + fn lookup_assoc_candidate<FilterFn>( + &mut self, + ident: Ident, + ns: Namespace, + filter_fn: FilterFn, + ) -> Option<AssocSuggestion> + where + FilterFn: Fn(Res) -> bool, + { + fn extract_node_id(t: &Ty) -> Option<NodeId> { + 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.maybe_resolve_ident_in_module( + ModuleOrUniformRoot::Module(module), + ident, + ns, + &self.parent_scope, + ) { + 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, + ) -> Option<TypoSuggestion> { + 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, crate_id.as_def_id()); + + 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), None) + { + 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::<Vec<Symbol>>(), + 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<Symbol> { + 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, + "Bool" => sym::bool, + "Boolean" => sym::bool, + "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 Diagnostic, 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", + ";", + 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", + "::", + Applicability::MaybeIncorrect, + ); + show_label = false; + if !self + .r + .session + .parse_sess + .type_ascription_path_suggestions + .borrow_mut() + .insert(colon_sp) + { + err.downgrade_to_delayed_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<Vec<(Path, DefId, CtorKind)>> { + 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 Diagnostic, + source: PathSource<'_>, + def_id: DefId, + span: Span, + ) { + let Some(variants) = self.collect_enum_ctors(def_id) else { + 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::<Vec<_>>(); + + 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::<Vec<_>>(); + + 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::<Vec<_>>(); + + 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"); + } + } + } + + pub(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.name != kw::SelfUpper => { + (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<T>()` + } + ( + Some(Item { + kind: + kind @ ItemKind::Fn(..) + | kind @ ItemKind::Enum(..) + | kind @ ItemKind::Struct(..) + | kind @ ItemKind::Union(..), + .. + }), + true, _ + ) + // Without the 2nd `true`, we'd suggest `impl <T>` 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<T: A>(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. + pub(crate) fn suggestion_for_label_in_rib( + &self, + rib_index: usize, + label: Ident, + ) -> Option<LabelSuggestion> { + // 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.eq_ctxt(label.span)) + .map(|(id, _)| id.name) + .collect::<Vec<Symbol>>(); + + 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) + }) + } + + pub(crate) fn maybe_report_lifetime_uses( + &mut self, + generics_span: Span, + params: &[ast::GenericParam], + ) { + for (param_index, param) in params.iter().enumerate() { + let GenericParamKind::Lifetime = param.kind else { continue }; + + let def_id = self.r.local_def_id(param.id); + + let use_set = self.lifetime_uses.remove(&def_id); + debug!( + "Use set for {:?}({:?} at {:?}) is {:?}", + def_id, param.ident, param.ident.span, use_set + ); + + let deletion_span = || { + if params.len() == 1 { + // if sole lifetime, remove the entire `<>` brackets + generics_span + } else if param_index == 0 { + // if removing within `<>` brackets, we also want to + // delete a leading or trailing comma as appropriate + param.span().to(params[param_index + 1].span().shrink_to_lo()) + } else { + // if removing within `<>` brackets, we also want to + // delete a leading or trailing comma as appropriate + params[param_index - 1].span().shrink_to_hi().to(param.span()) + } + }; + match use_set { + Some(LifetimeUseSet::Many) => {} + Some(LifetimeUseSet::One { use_span, use_ctxt }) => { + debug!(?param.ident, ?param.ident.span, ?use_span); + + let elidable = matches!(use_ctxt, LifetimeCtxt::Rptr); + + let deletion_span = deletion_span(); + self.r.lint_buffer.buffer_lint_with_diagnostic( + lint::builtin::SINGLE_USE_LIFETIMES, + param.id, + param.ident.span, + &format!("lifetime parameter `{}` only used once", param.ident), + lint::BuiltinLintDiagnostics::SingleUseLifetime { + param_span: param.ident.span, + use_span: Some((use_span, elidable)), + deletion_span, + }, + ); + } + None => { + debug!(?param.ident, ?param.ident.span); + + let deletion_span = deletion_span(); + self.r.lint_buffer.buffer_lint_with_diagnostic( + lint::builtin::UNUSED_LIFETIMES, + param.id, + param.ident.span, + &format!("lifetime parameter `{}` never used", param.ident), + lint::BuiltinLintDiagnostics::SingleUseLifetime { + param_span: param.ident.span, + use_span: None, + deletion_span, + }, + ); + } + } + } + } + + pub(crate) fn emit_undeclared_lifetime_error( + &self, + lifetime_ref: &ast::Lifetime, + outer_lifetime_ref: Option<Ident>, + ) { + debug_assert_ne!(lifetime_ref.ident.name, kw::UnderscoreLifetime); + let mut err = if let Some(outer) = outer_lifetime_ref { + let mut err = struct_span_err!( + self.r.session, + lifetime_ref.ident.span, + E0401, + "can't use generic parameters from outer item", + ); + err.span_label(lifetime_ref.ident.span, "use of generic parameter from outer item"); + err.span_label(outer.span, "lifetime parameter from outer item"); + err + } else { + let mut err = struct_span_err!( + self.r.session, + lifetime_ref.ident.span, + E0261, + "use of undeclared lifetime name `{}`", + lifetime_ref.ident + ); + err.span_label(lifetime_ref.ident.span, "undeclared lifetime"); + err + }; + self.suggest_introducing_lifetime( + &mut err, + Some(lifetime_ref.ident.name.as_str()), + |err, _, span, message, suggestion| { + err.span_suggestion(span, message, suggestion, Applicability::MaybeIncorrect); + true + }, + ); + err.emit(); + } + + fn suggest_introducing_lifetime( + &self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + name: Option<&str>, + suggest: impl Fn(&mut DiagnosticBuilder<'_, ErrorGuaranteed>, bool, Span, &str, String) -> bool, + ) { + let mut suggest_note = true; + for rib in self.lifetime_ribs.iter().rev() { + let mut should_continue = true; + match rib.kind { + LifetimeRibKind::Generics { binder: _, span, kind } => { + if !span.can_be_used_for_suggestions() && suggest_note && let Some(name) = name { + suggest_note = false; // Avoid displaying the same help multiple times. + err.span_label( + span, + &format!( + "lifetime `{}` is missing in item created through this procedural macro", + name, + ), + ); + continue; + } + + let higher_ranked = matches!( + kind, + LifetimeBinderKind::BareFnType + | LifetimeBinderKind::PolyTrait + | LifetimeBinderKind::WhereBound + ); + let (span, sugg) = if span.is_empty() { + let sugg = format!( + "{}<{}>{}", + if higher_ranked { "for" } else { "" }, + name.unwrap_or("'a"), + if higher_ranked { " " } else { "" }, + ); + (span, sugg) + } else { + let span = + self.r.session.source_map().span_through_char(span, '<').shrink_to_hi(); + let sugg = format!("{}, ", name.unwrap_or("'a")); + (span, sugg) + }; + if higher_ranked { + let message = format!( + "consider making the {} lifetime-generic with a new `{}` lifetime", + kind.descr(), + name.unwrap_or("'a"), + ); + should_continue = suggest(err, true, span, &message, sugg); + err.note_once( + "for more information on higher-ranked polymorphism, visit \ + https://doc.rust-lang.org/nomicon/hrtb.html", + ); + } else if let Some(name) = name { + let message = format!("consider introducing lifetime `{}` here", name); + should_continue = suggest(err, false, span, &message, sugg); + } else { + let message = format!("consider introducing a named lifetime parameter"); + should_continue = suggest(err, false, span, &message, sugg); + } + } + LifetimeRibKind::Item => break, + _ => {} + } + if !should_continue { + break; + } + } + } + + pub(crate) fn emit_non_static_lt_in_const_generic_error(&self, lifetime_ref: &ast::Lifetime) { + struct_span_err!( + self.r.session, + lifetime_ref.ident.span, + E0771, + "use of non-static lifetime `{}` in const generic", + lifetime_ref.ident + ) + .note( + "for more information, see issue #74052 \ + <https://github.com/rust-lang/rust/issues/74052>", + ) + .emit(); + } + + /// 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. + pub(crate) fn maybe_emit_forbidden_non_static_lifetime_error( + &self, + lifetime_ref: &ast::Lifetime, + ) { + let feature_active = self.r.session.features_untracked().generic_const_exprs; + if !feature_active { + feature_err( + &self.r.session.parse_sess, + sym::generic_const_exprs, + lifetime_ref.ident.span, + "a non-static lifetime is not allowed in a `const`", + ) + .emit(); + } + } + + pub(crate) fn report_missing_lifetime_specifiers( + &mut self, + lifetime_refs: Vec<MissingLifetime>, + function_param_lifetimes: Option<(Vec<MissingLifetime>, Vec<ElisionFnParameter>)>, + ) -> ErrorGuaranteed { + let num_lifetimes: usize = lifetime_refs.iter().map(|lt| lt.count).sum(); + let spans: Vec<_> = lifetime_refs.iter().map(|lt| lt.span).collect(); + + let mut err = struct_span_err!( + self.r.session, + spans, + E0106, + "missing lifetime specifier{}", + pluralize!(num_lifetimes) + ); + self.add_missing_lifetime_specifiers_label( + &mut err, + lifetime_refs, + function_param_lifetimes, + ); + err.emit() + } + + pub(crate) fn add_missing_lifetime_specifiers_label( + &mut self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + lifetime_refs: Vec<MissingLifetime>, + function_param_lifetimes: Option<(Vec<MissingLifetime>, Vec<ElisionFnParameter>)>, + ) { + for < in &lifetime_refs { + err.span_label( + lt.span, + format!( + "expected {} lifetime parameter{}", + if lt.count == 1 { "named".to_string() } else { lt.count.to_string() }, + pluralize!(lt.count), + ), + ); + } + + let mut in_scope_lifetimes: Vec<_> = self + .lifetime_ribs + .iter() + .rev() + .take_while(|rib| !matches!(rib.kind, LifetimeRibKind::Item)) + .flat_map(|rib| rib.bindings.iter()) + .map(|(&ident, &res)| (ident, res)) + .filter(|(ident, _)| ident.name != kw::UnderscoreLifetime) + .collect(); + debug!(?in_scope_lifetimes); + + debug!(?function_param_lifetimes); + if let Some((param_lifetimes, params)) = &function_param_lifetimes { + let elided_len = param_lifetimes.len(); + let num_params = params.len(); + + let mut m = String::new(); + + for (i, info) in params.iter().enumerate() { + let ElisionFnParameter { ident, index, lifetime_count, span } = *info; + debug_assert_ne!(lifetime_count, 0); + + err.span_label(span, ""); + + if i != 0 { + if i + 1 < num_params { + m.push_str(", "); + } else if num_params == 2 { + m.push_str(" or "); + } else { + m.push_str(", or "); + } + } + + let help_name = if let Some(ident) = ident { + format!("`{}`", ident) + } else { + format!("argument {}", index + 1) + }; + + if lifetime_count == 1 { + m.push_str(&help_name[..]) + } else { + m.push_str(&format!("one of {}'s {} lifetimes", help_name, lifetime_count)[..]) + } + } + + if num_params == 0 { + err.help( + "this function's return type contains a borrowed value, \ + but there is no value for it to be borrowed from", + ); + if in_scope_lifetimes.is_empty() { + in_scope_lifetimes = vec![( + Ident::with_dummy_span(kw::StaticLifetime), + (DUMMY_NODE_ID, LifetimeRes::Static), + )]; + } + } else if elided_len == 0 { + err.help( + "this function's return type contains a borrowed value with \ + an elided lifetime, but the lifetime cannot be derived from \ + the arguments", + ); + if in_scope_lifetimes.is_empty() { + in_scope_lifetimes = vec![( + Ident::with_dummy_span(kw::StaticLifetime), + (DUMMY_NODE_ID, LifetimeRes::Static), + )]; + } + } else if num_params == 1 { + err.help(&format!( + "this function's return type contains a borrowed value, \ + but the signature does not say which {} it is borrowed from", + m + )); + } else { + err.help(&format!( + "this function's return type contains a borrowed value, \ + but the signature does not say whether it is borrowed from {}", + m + )); + } + } + + let existing_name = match &in_scope_lifetimes[..] { + [] => Symbol::intern("'a"), + [(existing, _)] => existing.name, + _ => Symbol::intern("'lifetime"), + }; + + let mut spans_suggs: Vec<_> = Vec::new(); + let build_sugg = |lt: MissingLifetime| match lt.kind { + MissingLifetimeKind::Underscore => { + debug_assert_eq!(lt.count, 1); + (lt.span, existing_name.to_string()) + } + MissingLifetimeKind::Ampersand => { + debug_assert_eq!(lt.count, 1); + (lt.span.shrink_to_hi(), format!("{} ", existing_name)) + } + MissingLifetimeKind::Comma => { + let sugg: String = std::iter::repeat([existing_name.as_str(), ", "]) + .take(lt.count) + .flatten() + .collect(); + (lt.span.shrink_to_hi(), sugg) + } + MissingLifetimeKind::Brackets => { + let sugg: String = std::iter::once("<") + .chain( + std::iter::repeat(existing_name.as_str()).take(lt.count).intersperse(", "), + ) + .chain([">"]) + .collect(); + (lt.span.shrink_to_hi(), sugg) + } + }; + for < in &lifetime_refs { + spans_suggs.push(build_sugg(lt)); + } + debug!(?spans_suggs); + match in_scope_lifetimes.len() { + 0 => { + if let Some((param_lifetimes, _)) = function_param_lifetimes { + for lt in param_lifetimes { + spans_suggs.push(build_sugg(lt)) + } + } + self.suggest_introducing_lifetime( + err, + None, + |err, higher_ranked, span, message, intro_sugg| { + err.multipart_suggestion_verbose( + message, + std::iter::once((span, intro_sugg)) + .chain(spans_suggs.clone()) + .collect(), + Applicability::MaybeIncorrect, + ); + higher_ranked + }, + ); + } + 1 => { + err.multipart_suggestion_verbose( + &format!("consider using the `{}` lifetime", existing_name), + spans_suggs, + Applicability::MaybeIncorrect, + ); + + // Record as using the suggested resolution. + let (_, (_, res)) = in_scope_lifetimes[0]; + for < in &lifetime_refs { + self.r.lifetimes_res_map.insert(lt.id, res); + } + } + _ => { + let lifetime_spans: Vec<_> = + in_scope_lifetimes.iter().map(|(ident, _)| ident.span).collect(); + err.span_note(lifetime_spans, "these named lifetimes are available to use"); + + if spans_suggs.len() > 0 { + // This happens when we have `Foo<T>` 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, + ); + } + } + } + } +} + +/// Report lifetime/lifetime shadowing as an error. +pub fn signal_lifetime_shadowing(sess: &Session, orig: Ident, shadower: Ident) { + let mut err = struct_span_err!( + sess, + shadower.span, + E0496, + "lifetime name `{}` shadows a lifetime name that is already in scope", + orig.name, + ); + err.span_label(orig.span, "first declared here"); + err.span_label(shadower.span, format!("lifetime `{}` already in scope", orig.name)); + err.emit(); +} + +/// Shadowing involving a label is only a warning for historical reasons. +//FIXME: make this a proper lint. +pub fn signal_label_shadowing(sess: &Session, orig: Span, shadower: Ident) { + let name = shadower.name; + let shadower = shadower.span; + let mut err = sess.struct_span_warn( + shadower, + &format!("label name `{}` shadows a label name that is already in scope", name), + ); + err.span_label(orig, "first declared here"); + err.span_label(shadower, format!("label `{}` already in scope", name)); + err.emit(); +} |