diff options
Diffstat (limited to 'compiler/rustc_resolve/src/late')
| -rw-r--r-- | compiler/rustc_resolve/src/late/diagnostics.rs | 859 | ||||
| -rw-r--r-- | compiler/rustc_resolve/src/late/lifetimes.rs | 1855 |
2 files changed, 514 insertions, 2200 deletions
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs index 3b095eeeb..850f023b1 100644 --- a/compiler/rustc_resolve/src/late/diagnostics.rs +++ b/compiler/rustc_resolve/src/late/diagnostics.rs @@ -38,8 +38,8 @@ 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, + MethodWithSelf { called: bool }, + AssocFn { called: bool }, AssocType, AssocConst, } @@ -48,8 +48,14 @@ 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::MethodWithSelf { called: true } => { + "call the method with the fully-qualified path" + } + AssocSuggestion::MethodWithSelf { called: false } => { + "refer to the method with the fully-qualified path" + } + AssocSuggestion::AssocFn { called: true } => "call the associated function", + AssocSuggestion::AssocFn { called: false } => "refer to the associated function", AssocSuggestion::AssocConst => "use the associated `const`", AssocSuggestion::AssocType => "use the associated type", } @@ -130,6 +136,33 @@ pub(super) enum LifetimeElisionCandidate { Missing(MissingLifetime), } +/// Only used for diagnostics. +#[derive(Debug)] +struct BaseError { + msg: String, + fallback_label: String, + span: Span, + span_label: Option<(Span, &'static str)>, + could_be_expr: bool, + suggestion: Option<(Span, &'static str, String)>, +} + +#[derive(Debug)] +enum TypoCandidate { + Typo(TypoSuggestion), + Shadowed(Res), + None, +} + +impl TypoCandidate { + fn to_opt_suggestion(self) -> Option<TypoSuggestion> { + match self { + TypoCandidate::Typo(sugg) => Some(sugg), + TypoCandidate::Shadowed(_) | TypoCandidate::None => None, + } + } +} + impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { fn def_span(&self, def_id: DefId) -> Option<Span> { match def_id.krate { @@ -138,35 +171,18 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { } } - /// 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( + fn make_base_error( &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); - + ) -> BaseError { // Make the base error. - struct BaseError<'a> { - msg: String, - fallback_label: String, - span: Span, - span_label: Option<(Span, &'a str)>, - 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 { + if let Some(res) = res { BaseError { msg: format!("expected {}, found {} `{}`", expected, res.descr(), path_str), fallback_label: format!("not a {expected}"), @@ -277,8 +293,20 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { could_be_expr: false, suggestion, } - }; + } + } + /// 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>) { + debug!(?res, ?source); + let base_error = self.make_base_error(path, span, source, res); 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); @@ -289,41 +317,79 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { err.span_label(span, label); } - if let Some(sugg) = base_error.suggestion { - err.span_suggestion_verbose(sugg.0, sugg.1, sugg.2, Applicability::MaybeIncorrect); + if let Some(ref 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, - ); + self.suggest_bare_struct_literal(&mut err); + self.suggest_pattern_match_with_let(&mut err, source, span); + + self.suggest_self_or_self_ref(&mut err, path, span); + self.detect_assoct_type_constraint_meant_as_path(&mut err, &base_error); + if self.suggest_self_ty(&mut err, source, path, span) + || self.suggest_self_value(&mut err, source, path, span) + { + return (err, Vec::new()); } - 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 (found, candidates) = + self.try_lookup_name_relaxed(&mut err, source, path, span, res, &base_error); + if found { + return (err, candidates); + } + + if !self.type_ascription_suggestion(&mut err, base_error.span) { + let mut fallback = + self.suggest_trait_and_bounds(&mut err, source, res, span, &base_error); + fallback |= self.suggest_typo(&mut err, source, path, span, &base_error); + if fallback { + // Fallback label. + err.span_label(base_error.span, &base_error.fallback_label); + } + } + self.err_code_special_cases(&mut err, source, path, span); + + (err, candidates) + } + + fn detect_assoct_type_constraint_meant_as_path( + &self, + err: &mut Diagnostic, + base_error: &BaseError, + ) { + 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_error.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_self_or_self_ref(&mut self, err: &mut Diagnostic, path: &[Segment], span: Span) { let is_assoc_fn = self.self_type_is_available(); + let Some(path_last_segment) = path.last() else { return }; + let item_str = path_last_segment.ident; // 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( @@ -358,96 +424,25 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { } } } + } - 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()); - } - + fn try_lookup_name_relaxed( + &mut self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + source: PathSource<'_>, + path: &[Segment], + span: Span, + res: Option<Res>, + base_error: &BaseError, + ) -> (bool, Vec<ImportSuggestion>) { // Try to lookup name in more relaxed fashion for better error reporting. let ident = path.last().unwrap().ident; + let is_expected = &|res| source.is_expected(res); + let ns = source.namespace(); + let is_enum_variant = &|res| matches!(res, Res::Def(DefKind::Variant, _)); + let path_str = Segment::names_to_string(path); + let ident_span = path.last().map_or(span, |ident| ident.ident.span); + let mut candidates = self .r .lookup_import_candidates(ident, ns, &self.parent_scope, is_expected) @@ -494,7 +489,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { { // Already reported this issue on the lhs of the type ascription. err.delay_as_bug(); - return (err, candidates); + return (true, candidates); } } @@ -522,10 +517,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { ); } } + // Try Levenshtein algorithm. - let typo_sugg = self.lookup_typo_candidate(path, ns, is_expected); + let typo_sugg = + self.lookup_typo_candidate(path, source.namespace(), is_expected).to_opt_suggestion(); if path.len() == 1 && self.self_type_is_available() { - if let Some(candidate) = self.lookup_assoc_candidate(ident, ns, is_expected) { + if let Some(candidate) = + self.lookup_assoc_candidate(ident, ns, is_expected, source.is_call()) + { let self_is_available = self.self_value_is_available(path[0].ident.span); match candidate { AssocSuggestion::Field => { @@ -540,16 +539,21 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { err.span_label(span, "a field by this name exists in `Self`"); } } - AssocSuggestion::MethodWithSelf if self_is_available => { + AssocSuggestion::MethodWithSelf { called } if self_is_available => { + let msg = if called { + "you might have meant to call the method" + } else { + "you might have meant to refer to the method" + }; err.span_suggestion( span, - "you might have meant to call the method", + msg, format!("self.{path_str}"), Applicability::MachineApplicable, ); } - AssocSuggestion::MethodWithSelf - | AssocSuggestion::AssocFn + AssocSuggestion::MethodWithSelf { .. } + | AssocSuggestion::AssocFn { .. } | AssocSuggestion::AssocConst | AssocSuggestion::AssocType => { err.span_suggestion( @@ -560,8 +564,8 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { ); } } - self.r.add_typo_suggestion(&mut err, typo_sugg, ident_span); - return (err, candidates); + self.r.add_typo_suggestion(err, typo_sugg, ident_span); + return (true, candidates); } // If the first argument in call is `self` suggest calling a method. @@ -579,14 +583,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { format!("self.{path_str}({args_snippet})"), Applicability::MachineApplicable, ); - return (err, candidates); + return (true, 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, + err, span, source, res, @@ -594,106 +598,148 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { &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); + self.r.add_typo_suggestion(err, typo_sugg, ident_span); + return (true, candidates); } } + return (false, candidates); + } + fn suggest_trait_and_bounds( + &mut self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + source: PathSource<'_>, + res: Option<Res>, + span: Span, + base_error: &BaseError, + ) -> bool { 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 mut fallback = false; - let start_span = bounds[0].span(); - // `end_span` is the end of the poly trait ref (Foo + 'baz + Bar><) - let end_span = bounds.last().unwrap().span(); - // `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())); - } + 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(); - err.multipart_suggestion( - "if you meant to use a type and not a trait here, remove the bounds", - sugg, - Applicability::MaybeIncorrect, - ); + let start_span = bounds[0].span(); + // `end_span` is the end of the poly trait ref (Foo + 'baz + Bar><) + let end_span = bounds.last().unwrap().span(); + // `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); + fallback |= self.restrict_assoc_type_in_where_clause(span, err); + fallback + } - 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, - ); - } - _ => {} + fn suggest_typo( + &mut self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + source: PathSource<'_>, + path: &[Segment], + span: Span, + base_error: &BaseError, + ) -> bool { + let is_expected = &|res| source.is_expected(res); + let ident_span = path.last().map_or(span, |ident| ident.ident.span); + let typo_sugg = self.lookup_typo_candidate(path, source.namespace(), is_expected); + if let TypoCandidate::Shadowed(res) = typo_sugg + && let Some(id) = res.opt_def_id() + && let Some(sugg_span) = self.r.opt_span(id) + { + err.span_label( + sugg_span, + format!("you might have meant to refer to this {}", res.descr()), + ); + return true; + } + let mut fallback = false; + let typo_sugg = typo_sugg.to_opt_suggestion(); + if !self.r.add_typo_suggestion(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 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); + if !self.r.add_typo_suggestion(err, suggestion, ident_span) { + fallback = !self.let_binding_suggestion(err, ident_span); } } + fallback + } + + fn err_code_special_cases( + &mut self, + err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, + source: PathSource<'_>, + path: &[Segment], + span: Span, + ) { 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 { + let ident = path.last().unwrap().ident; 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 { @@ -724,38 +770,116 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { } } } + } - (err, candidates) + /// Emit special messages for unresolved `Self` and `self`. + fn suggest_self_ty( + &mut self, + err: &mut Diagnostic, + source: PathSource<'_>, + path: &[Segment], + span: Span, + ) -> bool { + if !is_self_type(path, source.namespace()) { + return false; + } + 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() + ), + ); + } + true } - 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; + fn suggest_self_value( + &mut self, + err: &mut Diagnostic, + source: PathSource<'_>, + path: &[Segment], + span: Span, + ) -> bool { + if !is_self_value(path, source.namespace()) { + return false; + } + + 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", + }, + ); + let is_assoc_fn = self.self_type_is_available(); + 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" }; - 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, - ); - } + 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() + ), + ); } + true } fn suggest_swapping_misplaced_self_ty_and_trait( @@ -787,6 +911,45 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { } } + fn suggest_bare_struct_literal(&mut self, err: &mut Diagnostic) { + 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, + ); + } + } + + fn suggest_pattern_match_with_let( + &mut self, + err: &mut Diagnostic, + source: PathSource<'_>, + span: Span, + ) { + if let PathSource::Expr(_) = source && + let Some(Expr { + span: expr_span, + kind: ExprKind::Assign(lhs, _, _), + .. + }) = self.diagnostic_metadata.in_if_condition { + // 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, + ); + } + } + } + fn get_single_associated_item( &mut self, path: &[Segment], @@ -849,11 +1012,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { 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) - { + if !matches!( + partial_res.full_res(), + Some(hir::def::Res::Def(hir::def::DefKind::AssocTy, _)) + ) { return false; } (ty, position, path) @@ -867,11 +1029,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { 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) - { + if !matches!( + partial_res.full_res(), + Some(hir::def::Res::Def(hir::def::DefKind::TyParam, _)) + ) { return false; } if let ( @@ -959,41 +1120,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { // 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 sp = sm.span_look_ahead(span, None, Some(50)); 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; - } - } + let closing_span = sm.span_look_ahead(span, Some("}"), Some(50)); + let closing_brace: Option<Span> = sm + .span_to_snippet(closing_span) + .map_or(None, |s| if s == "}" { Some(span.to(closing_span)) } else { None }); (followed_by_brace, closing_brace) } @@ -1017,7 +1151,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { let (lhs_span, rhs_span) = match &expr.kind { ExprKind::Field(base, ident) => (base.span, ident.span), - ExprKind::MethodCall(_, args, span) => (args[0].span, *span), + ExprKind::MethodCall(_, receiver, _, span) => (receiver.span, *span), _ => return false, }; @@ -1330,7 +1464,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { Applicability::HasPlaceholders, ); } - (Res::SelfTy { .. }, _) if ns == ValueNS => { + (Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }, _) if ns == ValueNS => { err.span_label(span, fallback_label); err.note("can't use `Self` as a constructor, you must use the implemented struct"); } @@ -1363,7 +1497,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { .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, + (AssocItemKind::Type(..), Res::Def(DefKind::AssocTy, _)) => true, _ => false, }) .map(|(key, _)| key.ident.name) @@ -1377,6 +1511,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { ident: Ident, ns: Namespace, filter_fn: FilterFn, + called: bool, ) -> Option<AssocSuggestion> where FilterFn: Fn(Res) -> bool, @@ -1399,20 +1534,14 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { { // 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(Res::Def(DefKind::Struct | DefKind::Union, did)) = + resolution.full_res() + { + 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); } } - _ => {} } } } @@ -1424,10 +1553,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { 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 + AssocSuggestion::MethodWithSelf { called } } - ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn, - ast::AssocItemKind::TyAlias(..) => AssocSuggestion::AssocType, + ast::AssocItemKind::Fn(..) => AssocSuggestion::AssocFn { called }, + ast::AssocItemKind::Type(..) => AssocSuggestion::AssocType, ast::AssocItemKind::MacCall(_) => continue, }); } @@ -1445,10 +1574,12 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { let res = binding.res(); if filter_fn(res) { if self.r.has_self.contains(&res.def_id()) { - return Some(AssocSuggestion::MethodWithSelf); + return Some(AssocSuggestion::MethodWithSelf { called }); } else { match res { - Res::Def(DefKind::AssocFn, _) => return Some(AssocSuggestion::AssocFn), + Res::Def(DefKind::AssocFn, _) => { + return Some(AssocSuggestion::AssocFn { called }); + } Res::Def(DefKind::AssocConst, _) => { return Some(AssocSuggestion::AssocConst); } @@ -1470,22 +1601,38 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { path: &[Segment], ns: Namespace, filter_fn: &impl Fn(Res) -> bool, - ) -> Option<TypoSuggestion> { + ) -> TypoCandidate { let mut names = Vec::new(); if path.len() == 1 { + let mut ctxt = path.last().unwrap().ident.span.ctxt(); + // Search in lexical scope. // Walk backwards up the ribs in scope and collect candidates. for rib in self.ribs[ns].iter().rev() { + let rib_ctxt = if rib.kind.contains_params() { + ctxt.normalize_to_macros_2_0() + } else { + ctxt.normalize_to_macro_rules() + }; + // Locals and type parameters for (ident, &res) in &rib.bindings { - if filter_fn(res) { + if filter_fn(res) && ident.span.ctxt() == rib_ctxt { names.push(TypoSuggestion::typo_from_res(ident.name, res)); } } + + if let RibKind::MacroDefinition(def) = rib.kind && def == self.r.macro_def(ctxt) { + // If an invocation of this macro created `ident`, give up on `ident` + // and switch to `ident`'s source from the macro definition. + ctxt.remove_mark(); + continue; + } + // Items in scope if let RibKind::ModuleRibKind(module) = rib.kind { // Items from this module - self.r.add_module_candidates(module, &mut names, &filter_fn); + self.r.add_module_candidates(module, &mut names, &filter_fn, Some(ctxt)); if let ModuleKind::Block = module.kind { // We can see through blocks @@ -1511,7 +1658,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { })); if let Some(prelude) = self.r.prelude { - self.r.add_module_candidates(prelude, &mut names, &filter_fn); + self.r.add_module_candidates(prelude, &mut names, &filter_fn, None); } } break; @@ -1530,7 +1677,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { 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); + self.r.add_module_candidates(module, &mut names, &filter_fn, None); } } @@ -1543,10 +1690,17 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { name, None, ) { - Some(found) if found != name => { - names.into_iter().find(|suggestion| suggestion.candidate == found) + Some(found) => { + let Some(sugg) = names.into_iter().find(|suggestion| suggestion.candidate == found) else { + return TypoCandidate::None; + }; + if found == name { + TypoCandidate::Shadowed(sugg.res) + } else { + TypoCandidate::Typo(sugg) + } } - _ => None, + _ => TypoCandidate::None, } } @@ -1616,26 +1770,16 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { } } 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(_) => {} - } + // Try to find an assignment + let eq_span = sm.span_look_ahead(after_colon_sp, Some("="), Some(50)); + if let Ok(ref snippet) = sm.span_to_snippet(eq_span) && snippet == "=" { + err.span_suggestion( + base_span, + "maybe you meant to write an assignment here", + format!("let {}", base_snippet), + Applicability::MaybeIncorrect, + ); + show_label = false; } } } @@ -1652,6 +1796,31 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> { false } + fn let_binding_suggestion(&self, err: &mut Diagnostic, ident_span: Span) -> bool { + // try to give a suggestion for this pattern: `name = 1`, which is common in other languages + let mut added_suggestion = false; + if let Some(Expr { kind: ExprKind::Assign(lhs, _rhs, _), .. }) = self.diagnostic_metadata.in_assignment && + let ast::ExprKind::Path(None, _) = lhs.kind { + let sm = self.r.session.source_map(); + let line_span = sm.span_extend_to_line(ident_span); + let ident_name = sm.span_to_snippet(ident_span).unwrap(); + // HACK(chenyukang): make sure ident_name is at the starting of the line to protect against macros + if sm + .span_to_snippet(line_span) + .map_or(false, |s| s.trim().starts_with(&ident_name)) + { + err.span_suggestion_verbose( + ident_span.shrink_to_lo(), + "you might have meant to introduce a new binding", + "let ".to_string(), + Applicability::MaybeIncorrect, + ); + added_suggestion = true; + } + } + added_suggestion + } + fn find_module(&mut self, def_id: DefId) -> Option<(Module<'a>, ImportSuggestion)> { let mut result = None; let mut seen_modules = FxHashSet::default(); diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs deleted file mode 100644 index 4d9704617..000000000 --- a/compiler/rustc_resolve/src/late/lifetimes.rs +++ /dev/null @@ -1,1855 +0,0 @@ -//! Resolution of early vs late bound lifetimes. -//! -//! Name resolution for lifetimes is performed on the AST and embedded into HIR. From this -//! information, typechecking needs to transform the lifetime parameters into bound lifetimes. -//! Lifetimes can be early-bound or late-bound. Construction of typechecking terms needs to visit -//! the types in HIR to identify late-bound lifetimes and assign their Debruijn indices. This file -//! is also responsible for assigning their semantics to implicit lifetimes in trait objects. - -use rustc_ast::walk_list; -use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet}; -use rustc_errors::struct_span_err; -use rustc_hir as hir; -use rustc_hir::def::{DefKind, Res}; -use rustc_hir::def_id::LocalDefId; -use rustc_hir::intravisit::{self, Visitor}; -use rustc_hir::{GenericArg, GenericParam, GenericParamKind, HirIdMap, LifetimeName, Node}; -use rustc_middle::bug; -use rustc_middle::hir::map::Map; -use rustc_middle::hir::nested_filter; -use rustc_middle::middle::resolve_lifetime::*; -use rustc_middle::ty::{self, DefIdTree, TyCtxt}; -use rustc_span::def_id::DefId; -use rustc_span::symbol::{sym, Ident}; -use rustc_span::Span; -use std::fmt; - -trait RegionExt { - fn early(hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region); - - fn late(index: u32, hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region); - - fn id(&self) -> Option<DefId>; - - fn shifted(self, amount: u32) -> Region; - - fn shifted_out_to_binder(self, binder: ty::DebruijnIndex) -> Region; -} - -impl RegionExt for Region { - fn early(hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region) { - let def_id = hir_map.local_def_id(param.hir_id); - debug!("Region::early: def_id={:?}", def_id); - (def_id, Region::EarlyBound(def_id.to_def_id())) - } - - fn late(idx: u32, hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region) { - let depth = ty::INNERMOST; - let def_id = hir_map.local_def_id(param.hir_id); - debug!( - "Region::late: idx={:?}, param={:?} depth={:?} def_id={:?}", - idx, param, depth, def_id, - ); - (def_id, Region::LateBound(depth, idx, def_id.to_def_id())) - } - - fn id(&self) -> Option<DefId> { - match *self { - Region::Static => None, - - Region::EarlyBound(id) | Region::LateBound(_, _, id) | Region::Free(_, id) => Some(id), - } - } - - fn shifted(self, amount: u32) -> Region { - match self { - Region::LateBound(debruijn, idx, id) => { - Region::LateBound(debruijn.shifted_in(amount), idx, id) - } - _ => self, - } - } - - fn shifted_out_to_binder(self, binder: ty::DebruijnIndex) -> Region { - match self { - Region::LateBound(debruijn, index, id) => { - Region::LateBound(debruijn.shifted_out_to_binder(binder), index, id) - } - _ => self, - } - } -} - -/// Maps the id of each lifetime reference to the lifetime decl -/// that it corresponds to. -/// -/// FIXME. This struct gets converted to a `ResolveLifetimes` for -/// actual use. It has the same data, but indexed by `LocalDefId`. This -/// is silly. -#[derive(Debug, Default)] -struct NamedRegionMap { - // maps from every use of a named (not anonymous) lifetime to a - // `Region` describing how that region is bound - defs: HirIdMap<Region>, - - // Maps relevant hir items to the bound vars on them. These include: - // - function defs - // - function pointers - // - closures - // - trait refs - // - bound types (like `T` in `for<'a> T<'a>: Foo`) - late_bound_vars: HirIdMap<Vec<ty::BoundVariableKind>>, -} - -pub(crate) struct LifetimeContext<'a, 'tcx> { - pub(crate) tcx: TyCtxt<'tcx>, - map: &'a mut NamedRegionMap, - scope: ScopeRef<'a>, - - /// Indicates that we only care about the definition of a trait. This should - /// be false if the `Item` we are resolving lifetimes for is not a trait or - /// we eventually need lifetimes resolve for trait items. - trait_definition_only: bool, -} - -#[derive(Debug)] -enum Scope<'a> { - /// Declares lifetimes, and each can be early-bound or late-bound. - /// The `DebruijnIndex` of late-bound lifetimes starts at `1` and - /// it should be shifted by the number of `Binder`s in between the - /// declaration `Binder` and the location it's referenced from. - Binder { - /// We use an IndexMap here because we want these lifetimes in order - /// for diagnostics. - lifetimes: FxIndexMap<LocalDefId, Region>, - - scope_type: BinderScopeType, - - /// The late bound vars for a given item are stored by `HirId` to be - /// queried later. However, if we enter an elision scope, we have to - /// later append the elided bound vars to the list and need to know what - /// to append to. - hir_id: hir::HirId, - - s: ScopeRef<'a>, - - /// If this binder comes from a where clause, specify how it was created. - /// This is used to diagnose inaccessible lifetimes in APIT: - /// ```ignore (illustrative) - /// fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} - /// ``` - where_bound_origin: Option<hir::PredicateOrigin>, - }, - - /// Lifetimes introduced by a fn are scoped to the call-site for that fn, - /// if this is a fn body, otherwise the original definitions are used. - /// Unspecified lifetimes are inferred, unless an elision scope is nested, - /// e.g., `(&T, fn(&T) -> &T);` becomes `(&'_ T, for<'a> fn(&'a T) -> &'a T)`. - Body { - id: hir::BodyId, - s: ScopeRef<'a>, - }, - - /// A scope which either determines unspecified lifetimes or errors - /// on them (e.g., due to ambiguity). - Elision { - s: ScopeRef<'a>, - }, - - /// Use a specific lifetime (if `Some`) or leave it unset (to be - /// inferred in a function body or potentially error outside one), - /// for the default choice of lifetime in a trait object type. - ObjectLifetimeDefault { - lifetime: Option<Region>, - s: ScopeRef<'a>, - }, - - /// When we have nested trait refs, we concatenate late bound vars for inner - /// trait refs from outer ones. But we also need to include any HRTB - /// lifetimes encountered when identifying the trait that an associated type - /// is declared on. - Supertrait { - lifetimes: Vec<ty::BoundVariableKind>, - s: ScopeRef<'a>, - }, - - TraitRefBoundary { - s: ScopeRef<'a>, - }, - - Root, -} - -#[derive(Copy, Clone, Debug)] -enum BinderScopeType { - /// Any non-concatenating binder scopes. - Normal, - /// Within a syntactic trait ref, there may be multiple poly trait refs that - /// are nested (under the `associated_type_bounds` feature). The binders of - /// the inner poly trait refs are extended from the outer poly trait refs - /// and don't increase the late bound depth. If you had - /// `T: for<'a> Foo<Bar: for<'b> Baz<'a, 'b>>`, then the `for<'b>` scope - /// would be `Concatenating`. This also used in trait refs in where clauses - /// where we have two binders `for<> T: for<> Foo` (I've intentionally left - /// out any lifetimes because they aren't needed to show the two scopes). - /// The inner `for<>` has a scope of `Concatenating`. - Concatenating, -} - -// A helper struct for debugging scopes without printing parent scopes -struct TruncatedScopeDebug<'a>(&'a Scope<'a>); - -impl<'a> fmt::Debug for TruncatedScopeDebug<'a> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - match self.0 { - Scope::Binder { lifetimes, scope_type, hir_id, where_bound_origin, s: _ } => f - .debug_struct("Binder") - .field("lifetimes", lifetimes) - .field("scope_type", scope_type) - .field("hir_id", hir_id) - .field("where_bound_origin", where_bound_origin) - .field("s", &"..") - .finish(), - Scope::Body { id, s: _ } => { - f.debug_struct("Body").field("id", id).field("s", &"..").finish() - } - Scope::Elision { s: _ } => f.debug_struct("Elision").field("s", &"..").finish(), - Scope::ObjectLifetimeDefault { lifetime, s: _ } => f - .debug_struct("ObjectLifetimeDefault") - .field("lifetime", lifetime) - .field("s", &"..") - .finish(), - Scope::Supertrait { lifetimes, s: _ } => f - .debug_struct("Supertrait") - .field("lifetimes", lifetimes) - .field("s", &"..") - .finish(), - Scope::TraitRefBoundary { s: _ } => f.debug_struct("TraitRefBoundary").finish(), - Scope::Root => f.debug_struct("Root").finish(), - } - } -} - -type ScopeRef<'a> = &'a Scope<'a>; - -const ROOT_SCOPE: ScopeRef<'static> = &Scope::Root; - -pub fn provide(providers: &mut ty::query::Providers) { - *providers = ty::query::Providers { - resolve_lifetimes_trait_definition, - resolve_lifetimes, - - named_region_map: |tcx, id| resolve_lifetimes_for(tcx, id).defs.get(&id), - is_late_bound_map, - object_lifetime_default, - late_bound_vars_map: |tcx, id| resolve_lifetimes_for(tcx, id).late_bound_vars.get(&id), - - ..*providers - }; -} - -/// Like `resolve_lifetimes`, but does not resolve lifetimes for trait items. -/// Also does not generate any diagnostics. -/// -/// This is ultimately a subset of the `resolve_lifetimes` work. It effectively -/// resolves lifetimes only within the trait "header" -- that is, the trait -/// and supertrait list. In contrast, `resolve_lifetimes` resolves all the -/// lifetimes within the trait and its items. There is room to refactor this, -/// for example to resolve lifetimes for each trait item in separate queries, -/// but it's convenient to do the entire trait at once because the lifetimes -/// from the trait definition are in scope within the trait items as well. -/// -/// The reason for this separate call is to resolve what would otherwise -/// be a cycle. Consider this example: -/// -/// ```ignore UNSOLVED (maybe @jackh726 knows what lifetime parameter to give Sub) -/// trait Base<'a> { -/// type BaseItem; -/// } -/// trait Sub<'b>: for<'a> Base<'a> { -/// type SubItem: Sub<BaseItem = &'b u32>; -/// } -/// ``` -/// -/// When we resolve `Sub` and all its items, we also have to resolve `Sub<BaseItem = &'b u32>`. -/// To figure out the index of `'b`, we have to know about the supertraits -/// of `Sub` so that we can determine that the `for<'a>` will be in scope. -/// (This is because we -- currently at least -- flatten all the late-bound -/// lifetimes into a single binder.) This requires us to resolve the -/// *trait definition* of `Sub`; basically just enough lifetime information -/// to look at the supertraits. -#[instrument(level = "debug", skip(tcx))] -fn resolve_lifetimes_trait_definition( - tcx: TyCtxt<'_>, - local_def_id: LocalDefId, -) -> ResolveLifetimes { - convert_named_region_map(do_resolve(tcx, local_def_id, true)) -} - -/// Computes the `ResolveLifetimes` map that contains data for an entire `Item`. -/// You should not read the result of this query directly, but rather use -/// `named_region_map`, `is_late_bound_map`, etc. -#[instrument(level = "debug", skip(tcx))] -fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> ResolveLifetimes { - convert_named_region_map(do_resolve(tcx, local_def_id, false)) -} - -fn do_resolve( - tcx: TyCtxt<'_>, - local_def_id: LocalDefId, - trait_definition_only: bool, -) -> NamedRegionMap { - let item = tcx.hir().expect_item(local_def_id); - let mut named_region_map = - NamedRegionMap { defs: Default::default(), late_bound_vars: Default::default() }; - let mut visitor = LifetimeContext { - tcx, - map: &mut named_region_map, - scope: ROOT_SCOPE, - trait_definition_only, - }; - visitor.visit_item(item); - - named_region_map -} - -fn convert_named_region_map(named_region_map: NamedRegionMap) -> ResolveLifetimes { - let mut rl = ResolveLifetimes::default(); - - for (hir_id, v) in named_region_map.defs { - let map = rl.defs.entry(hir_id.owner).or_default(); - map.insert(hir_id.local_id, v); - } - for (hir_id, v) in named_region_map.late_bound_vars { - let map = rl.late_bound_vars.entry(hir_id.owner).or_default(); - map.insert(hir_id.local_id, v); - } - - debug!(?rl.defs); - rl -} - -/// Given `any` owner (structs, traits, trait methods, etc.), does lifetime resolution. -/// There are two important things this does. -/// First, we have to resolve lifetimes for -/// the entire *`Item`* that contains this owner, because that's the largest "scope" -/// where we can have relevant lifetimes. -/// Second, if we are asking for lifetimes in a trait *definition*, we use `resolve_lifetimes_trait_definition` -/// instead of `resolve_lifetimes`, which does not descend into the trait items and does not emit diagnostics. -/// This allows us to avoid cycles. Importantly, if we ask for lifetimes for lifetimes that have an owner -/// other than the trait itself (like the trait methods or associated types), then we just use the regular -/// `resolve_lifetimes`. -fn resolve_lifetimes_for<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> &'tcx ResolveLifetimes { - let item_id = item_for(tcx, def_id); - if item_id == def_id { - let item = tcx.hir().item(hir::ItemId { def_id: item_id }); - match item.kind { - hir::ItemKind::Trait(..) => tcx.resolve_lifetimes_trait_definition(item_id), - _ => tcx.resolve_lifetimes(item_id), - } - } else { - tcx.resolve_lifetimes(item_id) - } -} - -/// Finds the `Item` that contains the given `LocalDefId` -fn item_for(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> LocalDefId { - match tcx.hir().find_by_def_id(local_def_id) { - Some(Node::Item(item)) => { - return item.def_id; - } - _ => {} - } - let item = { - let hir_id = tcx.hir().local_def_id_to_hir_id(local_def_id); - let mut parent_iter = tcx.hir().parent_iter(hir_id); - loop { - let node = parent_iter.next().map(|n| n.1); - match node { - Some(hir::Node::Item(item)) => break item.def_id, - Some(hir::Node::Crate(_)) | None => bug!("Called `item_for` on an Item."), - _ => {} - } - } - }; - item -} - -fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::BoundVariableKind { - match region { - Region::LateBound(_, _, def_id) => { - let name = tcx.hir().name(tcx.hir().local_def_id_to_hir_id(def_id.expect_local())); - ty::BoundVariableKind::Region(ty::BrNamed(*def_id, name)) - } - _ => bug!("{:?} is not a late region", region), - } -} - -impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { - /// Returns the binders in scope and the type of `Binder` that should be created for a poly trait ref. - fn poly_trait_ref_binder_info(&mut self) -> (Vec<ty::BoundVariableKind>, BinderScopeType) { - let mut scope = self.scope; - let mut supertrait_lifetimes = vec![]; - loop { - match scope { - Scope::Body { .. } | Scope::Root => { - break (vec![], BinderScopeType::Normal); - } - - Scope::Elision { s, .. } | Scope::ObjectLifetimeDefault { s, .. } => { - scope = s; - } - - Scope::Supertrait { s, lifetimes } => { - supertrait_lifetimes = lifetimes.clone(); - scope = s; - } - - Scope::TraitRefBoundary { .. } => { - // We should only see super trait lifetimes if there is a `Binder` above - assert!(supertrait_lifetimes.is_empty()); - break (vec![], BinderScopeType::Normal); - } - - Scope::Binder { hir_id, .. } => { - // Nested poly trait refs have the binders concatenated - let mut full_binders = - self.map.late_bound_vars.entry(*hir_id).or_default().clone(); - full_binders.extend(supertrait_lifetimes.into_iter()); - break (full_binders, BinderScopeType::Concatenating); - } - } - } - } -} -impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { - type NestedFilter = nested_filter::All; - - fn nested_visit_map(&mut self) -> Self::Map { - self.tcx.hir() - } - - // We want to nest trait/impl items in their parent, but nothing else. - fn visit_nested_item(&mut self, _: hir::ItemId) {} - - fn visit_trait_item_ref(&mut self, ii: &'tcx hir::TraitItemRef) { - if !self.trait_definition_only { - intravisit::walk_trait_item_ref(self, ii) - } - } - - fn visit_nested_body(&mut self, body: hir::BodyId) { - let body = self.tcx.hir().body(body); - self.with(Scope::Body { id: body.id(), s: self.scope }, |this| { - this.visit_body(body); - }); - } - - fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) { - if let hir::ExprKind::Closure(hir::Closure { - binder, bound_generic_params, fn_decl, .. - }) = e.kind - { - if let &hir::ClosureBinder::For { span: for_sp, .. } = binder { - fn span_of_infer(ty: &hir::Ty<'_>) -> Option<Span> { - struct V(Option<Span>); - - impl<'v> Visitor<'v> for V { - fn visit_ty(&mut self, t: &'v hir::Ty<'v>) { - match t.kind { - _ if self.0.is_some() => (), - hir::TyKind::Infer => { - self.0 = Some(t.span); - } - _ => intravisit::walk_ty(self, t), - } - } - } - - let mut v = V(None); - v.visit_ty(ty); - v.0 - } - - let infer_in_rt_sp = match fn_decl.output { - hir::FnRetTy::DefaultReturn(sp) => Some(sp), - hir::FnRetTy::Return(ty) => span_of_infer(ty), - }; - - let infer_spans = fn_decl - .inputs - .into_iter() - .filter_map(span_of_infer) - .chain(infer_in_rt_sp) - .collect::<Vec<_>>(); - - if !infer_spans.is_empty() { - self.tcx.sess - .struct_span_err( - infer_spans, - "implicit types in closure signatures are forbidden when `for<...>` is present", - ) - .span_label(for_sp, "`for<...>` is here") - .emit(); - } - } - - let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) = - bound_generic_params - .iter() - .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. })) - .enumerate() - .map(|(late_bound_idx, param)| { - let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param); - let r = late_region_as_bound_region(self.tcx, &pair.1); - (pair, r) - }) - .unzip(); - - self.map.late_bound_vars.insert(e.hir_id, binders); - let scope = Scope::Binder { - hir_id: e.hir_id, - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - - self.with(scope, |this| { - // a closure has no bounds, so everything - // contained within is scoped within its binder. - intravisit::walk_expr(this, e) - }); - } else { - intravisit::walk_expr(self, e) - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) { - match &item.kind { - hir::ItemKind::Impl(hir::Impl { of_trait, .. }) => { - if let Some(of_trait) = of_trait { - self.map.late_bound_vars.insert(of_trait.hir_ref_id, Vec::default()); - } - } - _ => {} - } - match item.kind { - hir::ItemKind::Fn(_, ref generics, _) => { - self.visit_early_late(item.hir_id(), generics, |this| { - intravisit::walk_item(this, item); - }); - } - - hir::ItemKind::ExternCrate(_) - | hir::ItemKind::Use(..) - | hir::ItemKind::Macro(..) - | hir::ItemKind::Mod(..) - | hir::ItemKind::ForeignMod { .. } - | hir::ItemKind::GlobalAsm(..) => { - // These sorts of items have no lifetime parameters at all. - intravisit::walk_item(self, item); - } - hir::ItemKind::Static(..) | hir::ItemKind::Const(..) => { - // No lifetime parameters, but implied 'static. - self.with(Scope::Elision { s: self.scope }, |this| { - intravisit::walk_item(this, item) - }); - } - hir::ItemKind::OpaqueTy(hir::OpaqueTy { .. }) => { - // Opaque types are visited when we visit the - // `TyKind::OpaqueDef`, so that they have the lifetimes from - // their parent opaque_ty in scope. - // - // The core idea here is that since OpaqueTys are generated with the impl Trait as - // their owner, we can keep going until we find the Item that owns that. We then - // conservatively add all resolved lifetimes. Otherwise we run into problems in - // cases like `type Foo<'a> = impl Bar<As = impl Baz + 'a>`. - for (_hir_id, node) in - self.tcx.hir().parent_iter(self.tcx.hir().local_def_id_to_hir_id(item.def_id)) - { - match node { - hir::Node::Item(parent_item) => { - let resolved_lifetimes: &ResolveLifetimes = - self.tcx.resolve_lifetimes(item_for(self.tcx, parent_item.def_id)); - // We need to add *all* deps, since opaque tys may want them from *us* - for (&owner, defs) in resolved_lifetimes.defs.iter() { - defs.iter().for_each(|(&local_id, region)| { - self.map.defs.insert(hir::HirId { owner, local_id }, *region); - }); - } - for (&owner, late_bound_vars) in - resolved_lifetimes.late_bound_vars.iter() - { - late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| { - self.map.late_bound_vars.insert( - hir::HirId { owner, local_id }, - late_bound_vars.clone(), - ); - }); - } - break; - } - hir::Node::Crate(_) => bug!("No Item about an OpaqueTy"), - _ => {} - } - } - } - hir::ItemKind::TyAlias(_, ref generics) - | hir::ItemKind::Enum(_, ref generics) - | hir::ItemKind::Struct(_, ref generics) - | hir::ItemKind::Union(_, ref generics) - | hir::ItemKind::Trait(_, _, ref generics, ..) - | hir::ItemKind::TraitAlias(ref generics, ..) - | hir::ItemKind::Impl(hir::Impl { ref generics, .. }) => { - // These kinds of items have only early-bound lifetime parameters. - let lifetimes = generics - .params - .iter() - .filter_map(|param| match param.kind { - GenericParamKind::Lifetime { .. } => { - Some(Region::early(self.tcx.hir(), param)) - } - GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None, - }) - .collect(); - self.map.late_bound_vars.insert(item.hir_id(), vec![]); - let scope = Scope::Binder { - hir_id: item.hir_id(), - lifetimes, - scope_type: BinderScopeType::Normal, - s: ROOT_SCOPE, - where_bound_origin: None, - }; - self.with(scope, |this| { - let scope = Scope::TraitRefBoundary { s: this.scope }; - this.with(scope, |this| { - intravisit::walk_item(this, item); - }); - }); - } - } - } - - fn visit_foreign_item(&mut self, item: &'tcx hir::ForeignItem<'tcx>) { - match item.kind { - hir::ForeignItemKind::Fn(_, _, ref generics) => { - self.visit_early_late(item.hir_id(), generics, |this| { - intravisit::walk_foreign_item(this, item); - }) - } - hir::ForeignItemKind::Static(..) => { - intravisit::walk_foreign_item(self, item); - } - hir::ForeignItemKind::Type => { - intravisit::walk_foreign_item(self, item); - } - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) { - match ty.kind { - hir::TyKind::BareFn(ref c) => { - let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) = c - .generic_params - .iter() - .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. })) - .enumerate() - .map(|(late_bound_idx, param)| { - let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param); - let r = late_region_as_bound_region(self.tcx, &pair.1); - (pair, r) - }) - .unzip(); - self.map.late_bound_vars.insert(ty.hir_id, binders); - let scope = Scope::Binder { - hir_id: ty.hir_id, - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - self.with(scope, |this| { - // a bare fn has no bounds, so everything - // contained within is scoped within its binder. - intravisit::walk_ty(this, ty); - }); - } - hir::TyKind::TraitObject(bounds, ref lifetime, _) => { - debug!(?bounds, ?lifetime, "TraitObject"); - let scope = Scope::TraitRefBoundary { s: self.scope }; - self.with(scope, |this| { - for bound in bounds { - this.visit_poly_trait_ref(bound); - } - }); - match lifetime.name { - LifetimeName::ImplicitObjectLifetimeDefault => { - // If the user does not write *anything*, we - // use the object lifetime defaulting - // rules. So e.g., `Box<dyn Debug>` becomes - // `Box<dyn Debug + 'static>`. - self.resolve_object_lifetime_default(lifetime) - } - LifetimeName::Infer => { - // If the user writes `'_`, we use the *ordinary* elision - // rules. So the `'_` in e.g., `Box<dyn Debug + '_>` will be - // resolved the same as the `'_` in `&'_ Foo`. - // - // cc #48468 - } - LifetimeName::Param(..) | LifetimeName::Static => { - // If the user wrote an explicit name, use that. - self.visit_lifetime(lifetime); - } - LifetimeName::Error => {} - } - } - hir::TyKind::Rptr(ref lifetime_ref, ref mt) => { - self.visit_lifetime(lifetime_ref); - let scope = Scope::ObjectLifetimeDefault { - lifetime: self.map.defs.get(&lifetime_ref.hir_id).cloned(), - s: self.scope, - }; - self.with(scope, |this| this.visit_ty(&mt.ty)); - } - hir::TyKind::OpaqueDef(item_id, lifetimes, _in_trait) => { - // Resolve the lifetimes in the bounds to the lifetime defs in the generics. - // `fn foo<'a>() -> impl MyTrait<'a> { ... }` desugars to - // `type MyAnonTy<'b> = impl MyTrait<'b>;` - // ^ ^ this gets resolved in the scope of - // the opaque_ty generics - let opaque_ty = self.tcx.hir().item(item_id); - let (generics, bounds) = match opaque_ty.kind { - hir::ItemKind::OpaqueTy(hir::OpaqueTy { - origin: hir::OpaqueTyOrigin::TyAlias, - .. - }) => { - intravisit::walk_ty(self, ty); - - // Elided lifetimes are not allowed in non-return - // position impl Trait - let scope = Scope::TraitRefBoundary { s: self.scope }; - self.with(scope, |this| { - let scope = Scope::Elision { s: this.scope }; - this.with(scope, |this| { - intravisit::walk_item(this, opaque_ty); - }) - }); - - return; - } - hir::ItemKind::OpaqueTy(hir::OpaqueTy { - origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..), - ref generics, - bounds, - .. - }) => (generics, bounds), - ref i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i), - }; - - // Resolve the lifetimes that are applied to the opaque type. - // These are resolved in the current scope. - // `fn foo<'a>() -> impl MyTrait<'a> { ... }` desugars to - // `fn foo<'a>() -> MyAnonTy<'a> { ... }` - // ^ ^this gets resolved in the current scope - for lifetime in lifetimes { - let hir::GenericArg::Lifetime(lifetime) = lifetime else { - continue - }; - self.visit_lifetime(lifetime); - - // Check for predicates like `impl for<'a> Trait<impl OtherTrait<'a>>` - // and ban them. Type variables instantiated inside binders aren't - // well-supported at the moment, so this doesn't work. - // In the future, this should be fixed and this error should be removed. - let def = self.map.defs.get(&lifetime.hir_id).cloned(); - let Some(Region::LateBound(_, _, def_id)) = def else { - continue - }; - let Some(def_id) = def_id.as_local() else { - continue - }; - let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id); - // Ensure that the parent of the def is an item, not HRTB - let parent_id = self.tcx.hir().get_parent_node(hir_id); - if !parent_id.is_owner() { - if !self.trait_definition_only { - struct_span_err!( - self.tcx.sess, - lifetime.span, - E0657, - "`impl Trait` can only capture lifetimes \ - bound at the fn or impl level" - ) - .emit(); - } - self.uninsert_lifetime_on_error(lifetime, def.unwrap()); - } - if let hir::Node::Item(hir::Item { - kind: hir::ItemKind::OpaqueTy { .. }, .. - }) = self.tcx.hir().get(parent_id) - { - if !self.trait_definition_only { - let mut err = self.tcx.sess.struct_span_err( - lifetime.span, - "higher kinded lifetime bounds on nested opaque types are not supported yet", - ); - err.span_note(self.tcx.def_span(def_id), "lifetime declared here"); - err.emit(); - } - self.uninsert_lifetime_on_error(lifetime, def.unwrap()); - } - } - - // We want to start our early-bound indices at the end of the parent scope, - // not including any parent `impl Trait`s. - let mut lifetimes = FxIndexMap::default(); - debug!(?generics.params); - for param in generics.params { - match param.kind { - GenericParamKind::Lifetime { .. } => { - let (def_id, reg) = Region::early(self.tcx.hir(), ¶m); - lifetimes.insert(def_id, reg); - } - GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {} - } - } - self.map.late_bound_vars.insert(ty.hir_id, vec![]); - - let scope = Scope::Binder { - hir_id: ty.hir_id, - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - self.with(scope, |this| { - let scope = Scope::TraitRefBoundary { s: this.scope }; - this.with(scope, |this| { - this.visit_generics(generics); - for bound in bounds { - this.visit_param_bound(bound); - } - }) - }); - } - _ => intravisit::walk_ty(self, ty), - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { - use self::hir::TraitItemKind::*; - match trait_item.kind { - Fn(_, _) => { - self.visit_early_late(trait_item.hir_id(), &trait_item.generics, |this| { - intravisit::walk_trait_item(this, trait_item) - }); - } - Type(bounds, ref ty) => { - let generics = &trait_item.generics; - let lifetimes = generics - .params - .iter() - .filter_map(|param| match param.kind { - GenericParamKind::Lifetime { .. } => { - Some(Region::early(self.tcx.hir(), param)) - } - GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None, - }) - .collect(); - self.map.late_bound_vars.insert(trait_item.hir_id(), vec![]); - let scope = Scope::Binder { - hir_id: trait_item.hir_id(), - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - self.with(scope, |this| { - let scope = Scope::TraitRefBoundary { s: this.scope }; - this.with(scope, |this| { - this.visit_generics(generics); - for bound in bounds { - this.visit_param_bound(bound); - } - if let Some(ty) = ty { - this.visit_ty(ty); - } - }) - }); - } - Const(_, _) => { - // Only methods and types support generics. - assert!(trait_item.generics.params.is_empty()); - intravisit::walk_trait_item(self, trait_item); - } - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { - use self::hir::ImplItemKind::*; - match impl_item.kind { - Fn(..) => self.visit_early_late(impl_item.hir_id(), &impl_item.generics, |this| { - intravisit::walk_impl_item(this, impl_item) - }), - TyAlias(ref ty) => { - let generics = &impl_item.generics; - let lifetimes: FxIndexMap<LocalDefId, Region> = generics - .params - .iter() - .filter_map(|param| match param.kind { - GenericParamKind::Lifetime { .. } => { - Some(Region::early(self.tcx.hir(), param)) - } - GenericParamKind::Const { .. } | GenericParamKind::Type { .. } => None, - }) - .collect(); - self.map.late_bound_vars.insert(ty.hir_id, vec![]); - let scope = Scope::Binder { - hir_id: ty.hir_id, - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - self.with(scope, |this| { - let scope = Scope::TraitRefBoundary { s: this.scope }; - this.with(scope, |this| { - this.visit_generics(generics); - this.visit_ty(ty); - }) - }); - } - Const(_, _) => { - // Only methods and types support generics. - assert!(impl_item.generics.params.is_empty()); - intravisit::walk_impl_item(self, impl_item); - } - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime) { - match lifetime_ref.name { - hir::LifetimeName::Static => self.insert_lifetime(lifetime_ref, Region::Static), - hir::LifetimeName::Param(param_def_id, _) => { - self.resolve_lifetime_ref(param_def_id, lifetime_ref) - } - // If we've already reported an error, just ignore `lifetime_ref`. - hir::LifetimeName::Error => {} - // Those will be resolved by typechecking. - hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Infer => {} - } - } - - fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, _: hir::HirId) { - for (i, segment) in path.segments.iter().enumerate() { - let depth = path.segments.len() - i - 1; - if let Some(ref args) = segment.args { - self.visit_segment_args(path.res, depth, args); - } - } - } - - fn visit_fn( - &mut self, - fk: intravisit::FnKind<'tcx>, - fd: &'tcx hir::FnDecl<'tcx>, - body_id: hir::BodyId, - _: Span, - _: hir::HirId, - ) { - let output = match fd.output { - hir::FnRetTy::DefaultReturn(_) => None, - hir::FnRetTy::Return(ref ty) => Some(&**ty), - }; - self.visit_fn_like_elision(&fd.inputs, output, matches!(fk, intravisit::FnKind::Closure)); - intravisit::walk_fn_kind(self, fk); - self.visit_nested_body(body_id) - } - - fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) { - let scope = Scope::TraitRefBoundary { s: self.scope }; - self.with(scope, |this| { - for param in generics.params { - match param.kind { - GenericParamKind::Lifetime { .. } => {} - GenericParamKind::Type { ref default, .. } => { - if let Some(ref ty) = default { - this.visit_ty(&ty); - } - } - GenericParamKind::Const { ref ty, default } => { - this.visit_ty(&ty); - if let Some(default) = default { - this.visit_body(this.tcx.hir().body(default.body)); - } - } - } - } - for predicate in generics.predicates { - match predicate { - &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate { - ref bounded_ty, - bounds, - ref bound_generic_params, - origin, - .. - }) => { - let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) = - bound_generic_params - .iter() - .filter(|param| { - matches!(param.kind, GenericParamKind::Lifetime { .. }) - }) - .enumerate() - .map(|(late_bound_idx, param)| { - let pair = - Region::late(late_bound_idx as u32, this.tcx.hir(), param); - let r = late_region_as_bound_region(this.tcx, &pair.1); - (pair, r) - }) - .unzip(); - this.map.late_bound_vars.insert(bounded_ty.hir_id, binders.clone()); - // Even if there are no lifetimes defined here, we still wrap it in a binder - // scope. If there happens to be a nested poly trait ref (an error), that - // will be `Concatenating` anyways, so we don't have to worry about the depth - // being wrong. - let scope = Scope::Binder { - hir_id: bounded_ty.hir_id, - lifetimes, - s: this.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: Some(origin), - }; - this.with(scope, |this| { - this.visit_ty(&bounded_ty); - walk_list!(this, visit_param_bound, bounds); - }) - } - &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate { - ref lifetime, - bounds, - .. - }) => { - this.visit_lifetime(lifetime); - walk_list!(this, visit_param_bound, bounds); - - if lifetime.name != hir::LifetimeName::Static { - for bound in bounds { - let hir::GenericBound::Outlives(ref lt) = bound else { - continue; - }; - if lt.name != hir::LifetimeName::Static { - continue; - } - this.insert_lifetime(lt, Region::Static); - this.tcx - .sess - .struct_span_warn( - lifetime.span, - &format!( - "unnecessary lifetime parameter `{}`", - lifetime.name.ident(), - ), - ) - .help(&format!( - "you can use the `'static` lifetime directly, in place of `{}`", - lifetime.name.ident(), - )) - .emit(); - } - } - } - &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate { - ref lhs_ty, - ref rhs_ty, - .. - }) => { - this.visit_ty(lhs_ty); - this.visit_ty(rhs_ty); - } - } - } - }) - } - - fn visit_param_bound(&mut self, bound: &'tcx hir::GenericBound<'tcx>) { - match bound { - hir::GenericBound::LangItemTrait(_, _, hir_id, _) => { - // FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go - // through the regular poly trait ref code, so we don't get another - // chance to introduce a binder. For now, I'm keeping the existing logic - // of "if there isn't a Binder scope above us, add one", but I - // imagine there's a better way to go about this. - let (binders, scope_type) = self.poly_trait_ref_binder_info(); - - self.map.late_bound_vars.insert(*hir_id, binders); - let scope = Scope::Binder { - hir_id: *hir_id, - lifetimes: FxIndexMap::default(), - s: self.scope, - scope_type, - where_bound_origin: None, - }; - self.with(scope, |this| { - intravisit::walk_param_bound(this, bound); - }); - } - _ => intravisit::walk_param_bound(self, bound), - } - } - - fn visit_poly_trait_ref(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) { - debug!("visit_poly_trait_ref(trait_ref={:?})", trait_ref); - - let (mut binders, scope_type) = self.poly_trait_ref_binder_info(); - - let initial_bound_vars = binders.len() as u32; - let mut lifetimes: FxIndexMap<LocalDefId, Region> = FxIndexMap::default(); - let binders_iter = trait_ref - .bound_generic_params - .iter() - .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. })) - .enumerate() - .map(|(late_bound_idx, param)| { - let pair = - Region::late(initial_bound_vars + late_bound_idx as u32, self.tcx.hir(), param); - let r = late_region_as_bound_region(self.tcx, &pair.1); - lifetimes.insert(pair.0, pair.1); - r - }); - binders.extend(binders_iter); - - debug!(?binders); - self.map.late_bound_vars.insert(trait_ref.trait_ref.hir_ref_id, binders); - - // Always introduce a scope here, even if this is in a where clause and - // we introduced the binders around the bounded Ty. In that case, we - // just reuse the concatenation functionality also present in nested trait - // refs. - let scope = Scope::Binder { - hir_id: trait_ref.trait_ref.hir_ref_id, - lifetimes, - s: self.scope, - scope_type, - where_bound_origin: None, - }; - self.with(scope, |this| { - walk_list!(this, visit_generic_param, trait_ref.bound_generic_params); - this.visit_trait_ref(&trait_ref.trait_ref); - }); - } -} - -fn object_lifetime_default<'tcx>(tcx: TyCtxt<'tcx>, param_def_id: DefId) -> ObjectLifetimeDefault { - debug_assert_eq!(tcx.def_kind(param_def_id), DefKind::TyParam); - let param_def_id = param_def_id.expect_local(); - let parent_def_id = tcx.local_parent(param_def_id); - let generics = tcx.hir().get_generics(parent_def_id).unwrap(); - let param_hir_id = tcx.local_def_id_to_hir_id(param_def_id); - let param = generics.params.iter().find(|p| p.hir_id == param_hir_id).unwrap(); - - // Scan the bounds and where-clauses on parameters to extract bounds - // of the form `T:'a` so as to determine the `ObjectLifetimeDefault` - // for each type parameter. - match param.kind { - GenericParamKind::Type { .. } => { - let mut set = Set1::Empty; - - // Look for `type: ...` where clauses. - for bound in generics.bounds_for_param(param_def_id) { - // Ignore `for<'a> type: ...` as they can change what - // lifetimes mean (although we could "just" handle it). - if !bound.bound_generic_params.is_empty() { - continue; - } - - for bound in bound.bounds { - if let hir::GenericBound::Outlives(ref lifetime) = *bound { - set.insert(lifetime.name.normalize_to_macros_2_0()); - } - } - } - - match set { - Set1::Empty => ObjectLifetimeDefault::Empty, - Set1::One(hir::LifetimeName::Static) => ObjectLifetimeDefault::Static, - Set1::One(hir::LifetimeName::Param(param_def_id, _)) => { - ObjectLifetimeDefault::Param(param_def_id.to_def_id()) - } - _ => ObjectLifetimeDefault::Ambiguous, - } - } - _ => { - bug!("object_lifetime_default_raw must only be called on a type parameter") - } - } -} - -impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { - fn with<F>(&mut self, wrap_scope: Scope<'_>, f: F) - where - F: for<'b> FnOnce(&mut LifetimeContext<'b, 'tcx>), - { - let LifetimeContext { tcx, map, .. } = self; - let mut this = LifetimeContext { - tcx: *tcx, - map, - scope: &wrap_scope, - trait_definition_only: self.trait_definition_only, - }; - let span = debug_span!("scope", scope = ?TruncatedScopeDebug(&this.scope)); - { - let _enter = span.enter(); - f(&mut this); - } - } - - /// Visits self by adding a scope and handling recursive walk over the contents with `walk`. - /// - /// Handles visiting fns and methods. These are a bit complicated because we must distinguish - /// early- vs late-bound lifetime parameters. We do this by checking which lifetimes appear - /// within type bounds; those are early bound lifetimes, and the rest are late bound. - /// - /// For example: - /// - /// fn foo<'a,'b,'c,T:Trait<'b>>(...) - /// - /// Here `'a` and `'c` are late bound but `'b` is early bound. Note that early- and late-bound - /// lifetimes may be interspersed together. - /// - /// If early bound lifetimes are present, we separate them into their own list (and likewise - /// for late bound). They will be numbered sequentially, starting from the lowest index that is - /// already in scope (for a fn item, that will be 0, but for a method it might not be). Late - /// bound lifetimes are resolved by name and associated with a binder ID (`binder_id`), so the - /// ordering is not important there. - fn visit_early_late<F>( - &mut self, - hir_id: hir::HirId, - generics: &'tcx hir::Generics<'tcx>, - walk: F, - ) where - F: for<'b, 'c> FnOnce(&'b mut LifetimeContext<'c, 'tcx>), - { - let mut named_late_bound_vars = 0; - let lifetimes: FxIndexMap<LocalDefId, Region> = generics - .params - .iter() - .filter_map(|param| match param.kind { - GenericParamKind::Lifetime { .. } => { - if self.tcx.is_late_bound(param.hir_id) { - let late_bound_idx = named_late_bound_vars; - named_late_bound_vars += 1; - Some(Region::late(late_bound_idx, self.tcx.hir(), param)) - } else { - Some(Region::early(self.tcx.hir(), param)) - } - } - GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None, - }) - .collect(); - - let binders: Vec<_> = generics - .params - .iter() - .filter(|param| { - matches!(param.kind, GenericParamKind::Lifetime { .. }) - && self.tcx.is_late_bound(param.hir_id) - }) - .enumerate() - .map(|(late_bound_idx, param)| { - let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param); - late_region_as_bound_region(self.tcx, &pair.1) - }) - .collect(); - self.map.late_bound_vars.insert(hir_id, binders); - let scope = Scope::Binder { - hir_id, - lifetimes, - s: self.scope, - scope_type: BinderScopeType::Normal, - where_bound_origin: None, - }; - self.with(scope, walk); - } - - #[instrument(level = "debug", skip(self))] - fn resolve_lifetime_ref( - &mut self, - region_def_id: LocalDefId, - lifetime_ref: &'tcx hir::Lifetime, - ) { - // Walk up the scope chain, tracking the number of fn scopes - // that we pass through, until we find a lifetime with the - // given name or we run out of scopes. - // search. - let mut late_depth = 0; - let mut scope = self.scope; - let mut outermost_body = None; - let result = loop { - match *scope { - Scope::Body { id, s } => { - outermost_body = Some(id); - scope = s; - } - - Scope::Root => { - break None; - } - - Scope::Binder { ref lifetimes, scope_type, s, where_bound_origin, .. } => { - if let Some(&def) = lifetimes.get(®ion_def_id) { - break Some(def.shifted(late_depth)); - } - match scope_type { - BinderScopeType::Normal => late_depth += 1, - BinderScopeType::Concatenating => {} - } - // Fresh lifetimes in APIT used to be allowed in async fns and forbidden in - // regular fns. - if let Some(hir::PredicateOrigin::ImplTrait) = where_bound_origin - && let hir::LifetimeName::Param(_, hir::ParamName::Fresh) = lifetime_ref.name - && let hir::IsAsync::NotAsync = self.tcx.asyncness(lifetime_ref.hir_id.owner) - && !self.tcx.features().anonymous_lifetime_in_impl_trait - { - rustc_session::parse::feature_err( - &self.tcx.sess.parse_sess, - sym::anonymous_lifetime_in_impl_trait, - lifetime_ref.span, - "anonymous lifetimes in `impl Trait` are unstable", - ).emit(); - return; - } - scope = s; - } - - Scope::Elision { s, .. } - | Scope::ObjectLifetimeDefault { s, .. } - | Scope::Supertrait { s, .. } - | Scope::TraitRefBoundary { s, .. } => { - scope = s; - } - } - }; - - if let Some(mut def) = result { - if let Region::EarlyBound(..) = def { - // Do not free early-bound regions, only late-bound ones. - } else if let Some(body_id) = outermost_body { - let fn_id = self.tcx.hir().body_owner(body_id); - match self.tcx.hir().get(fn_id) { - Node::Item(&hir::Item { kind: hir::ItemKind::Fn(..), .. }) - | Node::TraitItem(&hir::TraitItem { - kind: hir::TraitItemKind::Fn(..), .. - }) - | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) => { - let scope = self.tcx.hir().local_def_id(fn_id); - def = Region::Free(scope.to_def_id(), def.id().unwrap()); - } - _ => {} - } - } - - self.insert_lifetime(lifetime_ref, def); - return; - } - - // We may fail to resolve higher-ranked lifetimes that are mentioned by APIT. - // AST-based resolution does not care for impl-trait desugaring, which are the - // responibility of lowering. This may create a mismatch between the resolution - // AST found (`region_def_id`) which points to HRTB, and what HIR allows. - // ``` - // fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} - // ``` - // - // In such case, walk back the binders to diagnose it properly. - let mut scope = self.scope; - loop { - match *scope { - Scope::Binder { - where_bound_origin: Some(hir::PredicateOrigin::ImplTrait), .. - } => { - let mut err = self.tcx.sess.struct_span_err( - lifetime_ref.span, - "`impl Trait` can only mention lifetimes bound at the fn or impl level", - ); - err.span_note(self.tcx.def_span(region_def_id), "lifetime declared here"); - err.emit(); - return; - } - Scope::Root => break, - Scope::Binder { s, .. } - | Scope::Body { s, .. } - | Scope::Elision { s, .. } - | Scope::ObjectLifetimeDefault { s, .. } - | Scope::Supertrait { s, .. } - | Scope::TraitRefBoundary { s, .. } => { - scope = s; - } - } - } - - self.tcx.sess.delay_span_bug( - lifetime_ref.span, - &format!("Could not resolve {:?} in scope {:#?}", lifetime_ref, self.scope,), - ); - } - - #[instrument(level = "debug", skip(self))] - fn visit_segment_args( - &mut self, - res: Res, - depth: usize, - generic_args: &'tcx hir::GenericArgs<'tcx>, - ) { - if generic_args.parenthesized { - self.visit_fn_like_elision( - generic_args.inputs(), - Some(generic_args.bindings[0].ty()), - false, - ); - return; - } - - for arg in generic_args.args { - if let hir::GenericArg::Lifetime(lt) = arg { - self.visit_lifetime(lt); - } - } - - // Figure out if this is a type/trait segment, - // which requires object lifetime defaults. - let type_def_id = match res { - Res::Def(DefKind::AssocTy, def_id) if depth == 1 => Some(self.tcx.parent(def_id)), - Res::Def(DefKind::Variant, def_id) if depth == 0 => Some(self.tcx.parent(def_id)), - Res::Def( - DefKind::Struct - | DefKind::Union - | DefKind::Enum - | DefKind::TyAlias - | DefKind::Trait, - def_id, - ) if depth == 0 => Some(def_id), - _ => None, - }; - - debug!(?type_def_id); - - // Compute a vector of defaults, one for each type parameter, - // per the rules given in RFCs 599 and 1156. Example: - // - // ```rust - // struct Foo<'a, T: 'a, U> { } - // ``` - // - // If you have `Foo<'x, dyn Bar, dyn Baz>`, we want to default - // `dyn Bar` to `dyn Bar + 'x` (because of the `T: 'a` bound) - // and `dyn Baz` to `dyn Baz + 'static` (because there is no - // such bound). - // - // Therefore, we would compute `object_lifetime_defaults` to a - // vector like `['x, 'static]`. Note that the vector only - // includes type parameters. - let object_lifetime_defaults = type_def_id.map_or_else(Vec::new, |def_id| { - let in_body = { - let mut scope = self.scope; - loop { - match *scope { - Scope::Root => break false, - - Scope::Body { .. } => break true, - - Scope::Binder { s, .. } - | Scope::Elision { s, .. } - | Scope::ObjectLifetimeDefault { s, .. } - | Scope::Supertrait { s, .. } - | Scope::TraitRefBoundary { s, .. } => { - scope = s; - } - } - } - }; - - let map = &self.map; - let generics = self.tcx.generics_of(def_id); - - // `type_def_id` points to an item, so there is nothing to inherit generics from. - debug_assert_eq!(generics.parent_count, 0); - - let set_to_region = |set: ObjectLifetimeDefault| match set { - ObjectLifetimeDefault::Empty => { - if in_body { - None - } else { - Some(Region::Static) - } - } - ObjectLifetimeDefault::Static => Some(Region::Static), - ObjectLifetimeDefault::Param(param_def_id) => { - // This index can be used with `generic_args` since `parent_count == 0`. - let index = generics.param_def_id_to_index[¶m_def_id] as usize; - generic_args.args.get(index).and_then(|arg| match arg { - GenericArg::Lifetime(lt) => map.defs.get(<.hir_id).copied(), - _ => None, - }) - } - ObjectLifetimeDefault::Ambiguous => None, - }; - generics - .params - .iter() - .filter_map(|param| { - match self.tcx.def_kind(param.def_id) { - // Generic consts don't impose any constraints. - // - // We still store a dummy value here to allow generic parameters - // in an arbitrary order. - DefKind::ConstParam => Some(ObjectLifetimeDefault::Empty), - DefKind::TyParam => Some(self.tcx.object_lifetime_default(param.def_id)), - // We may also get a `Trait` or `TraitAlias` because of how generics `Self` parameter - // works. Ignore it because it can't have a meaningful lifetime default. - DefKind::LifetimeParam | DefKind::Trait | DefKind::TraitAlias => None, - dk => bug!("unexpected def_kind {:?}", dk), - } - }) - .map(set_to_region) - .collect() - }); - - debug!(?object_lifetime_defaults); - - let mut i = 0; - for arg in generic_args.args { - match arg { - GenericArg::Lifetime(_) => {} - GenericArg::Type(ty) => { - if let Some(<) = object_lifetime_defaults.get(i) { - let scope = Scope::ObjectLifetimeDefault { lifetime: lt, s: self.scope }; - self.with(scope, |this| this.visit_ty(ty)); - } else { - self.visit_ty(ty); - } - i += 1; - } - GenericArg::Const(ct) => { - self.visit_anon_const(&ct.value); - i += 1; - } - GenericArg::Infer(inf) => { - self.visit_id(inf.hir_id); - i += 1; - } - } - } - - // Hack: when resolving the type `XX` in binding like `dyn - // Foo<'b, Item = XX>`, the current object-lifetime default - // would be to examine the trait `Foo` to check whether it has - // a lifetime bound declared on `Item`. e.g., if `Foo` is - // declared like so, then the default object lifetime bound in - // `XX` should be `'b`: - // - // ```rust - // trait Foo<'a> { - // type Item: 'a; - // } - // ``` - // - // but if we just have `type Item;`, then it would be - // `'static`. However, we don't get all of this logic correct. - // - // Instead, we do something hacky: if there are no lifetime parameters - // to the trait, then we simply use a default object lifetime - // bound of `'static`, because there is no other possibility. On the other hand, - // if there ARE lifetime parameters, then we require the user to give an - // explicit bound for now. - // - // This is intended to leave room for us to implement the - // correct behavior in the future. - let has_lifetime_parameter = - generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_))); - - // Resolve lifetimes found in the bindings, so either in the type `XX` in `Item = XX` or - // in the trait ref `YY<...>` in `Item: YY<...>`. - for binding in generic_args.bindings { - let scope = Scope::ObjectLifetimeDefault { - lifetime: if has_lifetime_parameter { None } else { Some(Region::Static) }, - s: self.scope, - }; - if let Some(type_def_id) = type_def_id { - let lifetimes = LifetimeContext::supertrait_hrtb_lifetimes( - self.tcx, - type_def_id, - binding.ident, - ); - self.with(scope, |this| { - let scope = Scope::Supertrait { - lifetimes: lifetimes.unwrap_or_default(), - s: this.scope, - }; - this.with(scope, |this| this.visit_assoc_type_binding(binding)); - }); - } else { - self.with(scope, |this| this.visit_assoc_type_binding(binding)); - } - } - } - - /// Returns all the late-bound vars that come into scope from supertrait HRTBs, based on the - /// associated type name and starting trait. - /// For example, imagine we have - /// ```ignore (illustrative) - /// trait Foo<'a, 'b> { - /// type As; - /// } - /// trait Bar<'b>: for<'a> Foo<'a, 'b> {} - /// trait Bar: for<'b> Bar<'b> {} - /// ``` - /// In this case, if we wanted to the supertrait HRTB lifetimes for `As` on - /// the starting trait `Bar`, we would return `Some(['b, 'a])`. - fn supertrait_hrtb_lifetimes( - tcx: TyCtxt<'tcx>, - def_id: DefId, - assoc_name: Ident, - ) -> Option<Vec<ty::BoundVariableKind>> { - let trait_defines_associated_type_named = |trait_def_id: DefId| { - tcx.associated_items(trait_def_id) - .find_by_name_and_kind(tcx, assoc_name, ty::AssocKind::Type, trait_def_id) - .is_some() - }; - - use smallvec::{smallvec, SmallVec}; - let mut stack: SmallVec<[(DefId, SmallVec<[ty::BoundVariableKind; 8]>); 8]> = - smallvec![(def_id, smallvec![])]; - let mut visited: FxHashSet<DefId> = FxHashSet::default(); - loop { - let Some((def_id, bound_vars)) = stack.pop() else { - break None; - }; - // See issue #83753. If someone writes an associated type on a non-trait, just treat it as - // there being no supertrait HRTBs. - match tcx.def_kind(def_id) { - DefKind::Trait | DefKind::TraitAlias | DefKind::Impl => {} - _ => break None, - } - - if trait_defines_associated_type_named(def_id) { - break Some(bound_vars.into_iter().collect()); - } - let predicates = - tcx.super_predicates_that_define_assoc_type((def_id, Some(assoc_name))); - let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| { - let bound_predicate = pred.kind(); - match bound_predicate.skip_binder() { - ty::PredicateKind::Trait(data) => { - // The order here needs to match what we would get from `subst_supertrait` - let pred_bound_vars = bound_predicate.bound_vars(); - let mut all_bound_vars = bound_vars.clone(); - all_bound_vars.extend(pred_bound_vars.iter()); - let super_def_id = data.trait_ref.def_id; - Some((super_def_id, all_bound_vars)) - } - _ => None, - } - }); - - let obligations = obligations.filter(|o| visited.insert(o.0)); - stack.extend(obligations); - } - } - - #[instrument(level = "debug", skip(self))] - fn visit_fn_like_elision( - &mut self, - inputs: &'tcx [hir::Ty<'tcx>], - output: Option<&'tcx hir::Ty<'tcx>>, - in_closure: bool, - ) { - self.with(Scope::Elision { s: self.scope }, |this| { - for input in inputs { - this.visit_ty(input); - } - if !in_closure && let Some(output) = output { - this.visit_ty(output); - } - }); - if in_closure && let Some(output) = output { - self.visit_ty(output); - } - } - - fn resolve_object_lifetime_default(&mut self, lifetime_ref: &'tcx hir::Lifetime) { - debug!("resolve_object_lifetime_default(lifetime_ref={:?})", lifetime_ref); - let mut late_depth = 0; - let mut scope = self.scope; - let lifetime = loop { - match *scope { - Scope::Binder { s, scope_type, .. } => { - match scope_type { - BinderScopeType::Normal => late_depth += 1, - BinderScopeType::Concatenating => {} - } - scope = s; - } - - Scope::Root | Scope::Elision { .. } => break Region::Static, - - Scope::Body { .. } | Scope::ObjectLifetimeDefault { lifetime: None, .. } => return, - - Scope::ObjectLifetimeDefault { lifetime: Some(l), .. } => break l, - - Scope::Supertrait { s, .. } | Scope::TraitRefBoundary { s, .. } => { - scope = s; - } - } - }; - self.insert_lifetime(lifetime_ref, lifetime.shifted(late_depth)); - } - - #[instrument(level = "debug", skip(self))] - fn insert_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime, def: Region) { - debug!( - node = ?self.tcx.hir().node_to_string(lifetime_ref.hir_id), - span = ?self.tcx.sess.source_map().span_to_diagnostic_string(lifetime_ref.span) - ); - self.map.defs.insert(lifetime_ref.hir_id, def); - } - - /// Sometimes we resolve a lifetime, but later find that it is an - /// error (esp. around impl trait). In that case, we remove the - /// entry into `map.defs` so as not to confuse later code. - fn uninsert_lifetime_on_error(&mut self, lifetime_ref: &'tcx hir::Lifetime, bad_def: Region) { - let old_value = self.map.defs.remove(&lifetime_ref.hir_id); - assert_eq!(old_value, Some(bad_def)); - } -} - -/// Detects late-bound lifetimes and inserts them into -/// `late_bound`. -/// -/// A region declared on a fn is **late-bound** if: -/// - it is constrained by an argument type; -/// - it does not appear in a where-clause. -/// -/// "Constrained" basically means that it appears in any type but -/// not amongst the inputs to a projection. In other words, `<&'a -/// T as Trait<''b>>::Foo` does not constrain `'a` or `'b`. -fn is_late_bound_map(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<&FxIndexSet<LocalDefId>> { - let hir_id = tcx.hir().local_def_id_to_hir_id(def_id); - let decl = tcx.hir().fn_decl_by_hir_id(hir_id)?; - let generics = tcx.hir().get_generics(def_id)?; - - let mut late_bound = FxIndexSet::default(); - - let mut constrained_by_input = ConstrainedCollector::default(); - for arg_ty in decl.inputs { - constrained_by_input.visit_ty(arg_ty); - } - - let mut appears_in_output = AllCollector::default(); - intravisit::walk_fn_ret_ty(&mut appears_in_output, &decl.output); - - debug!(?constrained_by_input.regions); - - // Walk the lifetimes that appear in where clauses. - // - // Subtle point: because we disallow nested bindings, we can just - // ignore binders here and scrape up all names we see. - let mut appears_in_where_clause = AllCollector::default(); - appears_in_where_clause.visit_generics(generics); - debug!(?appears_in_where_clause.regions); - - // Late bound regions are those that: - // - appear in the inputs - // - do not appear in the where-clauses - // - are not implicitly captured by `impl Trait` - for param in generics.params { - match param.kind { - hir::GenericParamKind::Lifetime { .. } => { /* fall through */ } - - // Neither types nor consts are late-bound. - hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => continue, - } - - let param_def_id = tcx.hir().local_def_id(param.hir_id); - - // appears in the where clauses? early-bound. - if appears_in_where_clause.regions.contains(¶m_def_id) { - continue; - } - - // does not appear in the inputs, but appears in the return type? early-bound. - if !constrained_by_input.regions.contains(¶m_def_id) - && appears_in_output.regions.contains(¶m_def_id) - { - continue; - } - - debug!("lifetime {:?} with id {:?} is late-bound", param.name.ident(), param.hir_id); - - let inserted = late_bound.insert(param_def_id); - assert!(inserted, "visited lifetime {:?} twice", param.hir_id); - } - - debug!(?late_bound); - return Some(tcx.arena.alloc(late_bound)); - - #[derive(Default)] - struct ConstrainedCollector { - regions: FxHashSet<LocalDefId>, - } - - impl<'v> Visitor<'v> for ConstrainedCollector { - fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { - match ty.kind { - hir::TyKind::Path( - hir::QPath::Resolved(Some(_), _) | hir::QPath::TypeRelative(..), - ) => { - // ignore lifetimes appearing in associated type - // projections, as they are not *constrained* - // (defined above) - } - - hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => { - // consider only the lifetimes on the final - // segment; I am not sure it's even currently - // valid to have them elsewhere, but even if it - // is, those would be potentially inputs to - // projections - if let Some(last_segment) = path.segments.last() { - self.visit_path_segment(last_segment); - } - } - - _ => { - intravisit::walk_ty(self, ty); - } - } - } - - fn visit_lifetime(&mut self, lifetime_ref: &'v hir::Lifetime) { - if let hir::LifetimeName::Param(def_id, _) = lifetime_ref.name { - self.regions.insert(def_id); - } - } - } - - #[derive(Default)] - struct AllCollector { - regions: FxHashSet<LocalDefId>, - } - - impl<'v> Visitor<'v> for AllCollector { - fn visit_lifetime(&mut self, lifetime_ref: &'v hir::Lifetime) { - if let hir::LifetimeName::Param(def_id, _) = lifetime_ref.name { - self.regions.insert(def_id); - } - } - } -} |