X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=src%2Flibrustc_resolve%2Flate.rs;h=e02cba6fbfd25793bd10f509083daebbe0a08869;hb=7bc94cc3c2ccef8b4d393910bb978a6487db1202;hp=4595b1ff3f1cbdcb5410cc335c1e692139e9dbac;hpb=af06bfb84c47add51a41153f6f71fc07d4c60a8d;p=rust.git diff --git a/src/librustc_resolve/late.rs b/src/librustc_resolve/late.rs index 4595b1ff3f1..e02cba6fbfd 100644 --- a/src/librustc_resolve/late.rs +++ b/src/librustc_resolve/late.rs @@ -9,7 +9,7 @@ use RibKind::*; use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding}; -use crate::{Module, ModuleOrUniformRoot, NameBinding, NameBindingKind, ParentScope, PathResult}; +use crate::{Module, ModuleOrUniformRoot, NameBindingKind, ParentScope, PathResult}; use crate::{ResolutionError, Resolver, Segment, UseError}; use log::debug; @@ -18,7 +18,7 @@ use rustc::hir::def::Namespace::{self, *}; use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX}; use rustc::hir::TraitCandidate; -use rustc::util::nodemap::FxHashMap; +use rustc::util::nodemap::{FxHashMap, FxHashSet}; use smallvec::{smallvec, SmallVec}; use syntax::{unwrap_or, walk_list}; use syntax::ast::*; @@ -35,8 +35,10 @@ type Res = def::Res; +type IdentMap = FxHashMap; + /// Map from the name in a pattern to its binding mode. -type BindingMap = FxHashMap; +type BindingMap = IdentMap; #[derive(Copy, Clone, Debug)] struct BindingInfo { @@ -73,6 +75,16 @@ fn descr(self) -> &'static str { } } +/// Denotes whether the context for the set of already bound bindings is a `Product` +/// or `Or` context. This is used in e.g., `fresh_binding` and `resolve_pattern_inner`. +/// See those functions for more information. +enum PatBoundCtx { + /// A product pattern context, e.g., `Variant(a, b)`. + Product, + /// An or-pattern context, e.g., `p_0 | ... | p_n`. + Or, +} + /// The rib kind restricts certain accesses, /// e.g. to a `Res::Local` of an outer item. #[derive(Copy, Clone, Debug)] @@ -143,7 +155,7 @@ impl RibKind<'_> { /// resolving, the name is looked up from inside out. #[derive(Debug)] crate struct Rib<'a, R = Res> { - pub bindings: FxHashMap, + pub bindings: IdentMap, pub kind: RibKind<'a>, } @@ -209,7 +221,7 @@ fn descr_expected(self) -> &'static str { ValueNS => "method or associated constant", MacroNS => bug!("associated macro"), }, - PathSource::Expr(parent) => match parent.map(|p| &p.node) { + PathSource::Expr(parent) => match parent.map(|p| &p.kind) { // "function" here means "anything callable" rather than `DefKind::Fn`, // this is not precise but usually more helpful than just "value". Some(&ExprKind::Call(..)) => "function", @@ -286,18 +298,18 @@ fn descr_expected(self) -> &'static str { } fn error_code(self, has_unexpected_resolution: bool) -> &'static str { - __diagnostic_used!(E0404); - __diagnostic_used!(E0405); - __diagnostic_used!(E0412); - __diagnostic_used!(E0422); - __diagnostic_used!(E0423); - __diagnostic_used!(E0425); - __diagnostic_used!(E0531); - __diagnostic_used!(E0532); - __diagnostic_used!(E0573); - __diagnostic_used!(E0574); - __diagnostic_used!(E0575); - __diagnostic_used!(E0576); + syntax::diagnostic_used!(E0404); + syntax::diagnostic_used!(E0405); + syntax::diagnostic_used!(E0412); + syntax::diagnostic_used!(E0422); + syntax::diagnostic_used!(E0423); + syntax::diagnostic_used!(E0425); + syntax::diagnostic_used!(E0531); + syntax::diagnostic_used!(E0532); + syntax::diagnostic_used!(E0573); + syntax::diagnostic_used!(E0574); + syntax::diagnostic_used!(E0575); + syntax::diagnostic_used!(E0576); match (self, has_unexpected_resolution) { (PathSource::Trait(_), true) => "E0404", (PathSource::Trait(_), false) => "E0405", @@ -372,7 +384,7 @@ fn visit_local(&mut self, local: &'tcx Local) { self.resolve_local(local); } fn visit_ty(&mut self, ty: &'tcx Ty) { - match ty.node { + match ty.kind { TyKind::Path(ref qself, ref path) => { self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type); } @@ -406,44 +418,32 @@ fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) { visit::walk_foreign_item(this, foreign_item); }); } - fn visit_fn(&mut self, - function_kind: FnKind<'tcx>, - declaration: &'tcx FnDecl, - _: Span, - _: NodeId) - { + fn visit_fn(&mut self, fn_kind: FnKind<'tcx>, declaration: &'tcx FnDecl, _: Span, _: NodeId) { debug!("(resolving function) entering function"); - let rib_kind = match function_kind { + let rib_kind = match fn_kind { FnKind::ItemFn(..) => FnItemRibKind, FnKind::Method(..) | FnKind::Closure(_) => NormalRibKind, }; // Create a value rib for the function. - self.ribs[ValueNS].push(Rib::new(rib_kind)); - - // Create a label rib for the function. - self.label_ribs.push(Rib::new(rib_kind)); - - // Add each argument to the rib. - self.resolve_params(&declaration.inputs); - - visit::walk_fn_ret_ty(self, &declaration.output); - - // Resolve the function body, potentially inside the body of an async closure - match function_kind { - FnKind::ItemFn(.., body) | - FnKind::Method(.., body) => { - self.visit_block(body); - } - FnKind::Closure(body) => { - self.visit_expr(body); - } - }; - - debug!("(resolving function) leaving function"); - - self.label_ribs.pop(); - self.ribs[ValueNS].pop(); + self.with_rib(ValueNS, rib_kind, |this| { + // Create a label rib for the function. + this.with_label_rib(rib_kind, |this| { + // Add each argument to the rib. + this.resolve_params(&declaration.inputs); + + visit::walk_fn_ret_ty(this, &declaration.output); + + // Resolve the function body, potentially inside the body of an async closure + match fn_kind { + FnKind::ItemFn(.., body) | + FnKind::Method(.., body) => this.visit_block(body), + FnKind::Closure(body) => this.visit_expr(body), + }; + + debug!("(resolving function) leaving function"); + }) + }); } fn visit_generics(&mut self, generics: &'tcx Generics) { @@ -522,13 +522,14 @@ fn new(resolver: &'b mut Resolver<'a>) -> LateResolutionVisitor<'a, 'b> { // although it may be useful to track other components as well for diagnostics. let graph_root = resolver.graph_root; let parent_scope = ParentScope::module(graph_root); + let start_rib_kind = ModuleRibKind(graph_root); LateResolutionVisitor { r: resolver, parent_scope, ribs: PerNS { - value_ns: vec![Rib::new(ModuleRibKind(graph_root))], - type_ns: vec![Rib::new(ModuleRibKind(graph_root))], - macro_ns: vec![Rib::new(ModuleRibKind(graph_root))], + value_ns: vec![Rib::new(start_rib_kind)], + type_ns: vec![Rib::new(start_rib_kind)], + macro_ns: vec![Rib::new(start_rib_kind)], }, label_ribs: Vec::new(), current_trait_ref: None, @@ -582,23 +583,32 @@ fn resolve_path( // generate a fake "implementation scope" containing all the // implementations thus found, for compatibility with old resolve pass. - fn with_scope(&mut self, id: NodeId, f: F) -> T - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) -> T - { + /// Do some `work` within a new innermost rib of the given `kind` in the given namespace (`ns`). + fn with_rib( + &mut self, + ns: Namespace, + kind: RibKind<'a>, + work: impl FnOnce(&mut Self) -> T, + ) -> T { + self.ribs[ns].push(Rib::new(kind)); + let ret = work(self); + self.ribs[ns].pop(); + ret + } + + fn with_scope(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { let id = self.r.definitions.local_def_id(id); let module = self.r.module_map.get(&id).cloned(); // clones a reference if let Some(module) = module { // Move down in the graph. let orig_module = replace(&mut self.parent_scope.module, module); - self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module))); - self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module))); - - let ret = f(self); - - self.parent_scope.module = orig_module; - self.ribs[ValueNS].pop(); - self.ribs[TypeNS].pop(); - ret + self.with_rib(ValueNS, ModuleRibKind(module), |this| { + this.with_rib(TypeNS, ModuleRibKind(module), |this| { + let ret = f(this); + this.parent_scope.module = orig_module; + ret + }) + }) } else { f(self) } @@ -690,9 +700,9 @@ fn future_proof_import(&mut self, use_tree: &UseTree) { fn resolve_item(&mut self, item: &Item) { let name = item.ident.name; - debug!("(resolving item) resolving {} ({:?})", name, item.node); + debug!("(resolving item) resolving {} ({:?})", name, item.kind); - match item.node { + match item.kind { ItemKind::TyAlias(_, ref generics) | ItemKind::OpaqueTy(_, ref generics) | ItemKind::Fn(_, _, ref generics, _) => { @@ -730,7 +740,7 @@ fn resolve_item(&mut self, item: &Item) { AssocItemRibKind, ); this.with_generic_param_rib(generic_params, |this| { - match trait_item.node { + match trait_item.kind { TraitItemKind::Const(ref ty, ref default) => { this.visit_ty(ty); @@ -802,7 +812,7 @@ fn resolve_item(&mut self, item: &Item) { } fn with_generic_param_rib<'c, F>(&'c mut self, generic_params: GenericParameters<'a, 'c>, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) + where F: FnOnce(&mut Self) { debug!("with_generic_param_rib"); match generic_params { @@ -888,38 +898,24 @@ fn with_generic_param_rib<'c, F>(&'c mut self, generic_params: GenericParameters } } - fn with_label_rib(&mut self, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) - { - self.label_ribs.push(Rib::new(NormalRibKind)); + fn with_label_rib(&mut self, kind: RibKind<'a>, f: impl FnOnce(&mut Self)) { + self.label_ribs.push(Rib::new(kind)); f(self); self.label_ribs.pop(); } - fn with_item_rib(&mut self, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) - { - self.ribs[ValueNS].push(Rib::new(ItemRibKind)); - self.ribs[TypeNS].push(Rib::new(ItemRibKind)); - f(self); - self.ribs[TypeNS].pop(); - self.ribs[ValueNS].pop(); + fn with_item_rib(&mut self, f: impl FnOnce(&mut Self)) { + self.with_rib(ValueNS, ItemRibKind, |this| this.with_rib(TypeNS, ItemRibKind, f)) } - fn with_constant_rib(&mut self, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) - { + fn with_constant_rib(&mut self, f: impl FnOnce(&mut Self)) { debug!("with_constant_rib"); - self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind)); - self.label_ribs.push(Rib::new(ConstantItemRibKind)); - f(self); - self.label_ribs.pop(); - self.ribs[ValueNS].pop(); + self.with_rib(ValueNS, ConstantItemRibKind, |this| { + this.with_label_rib(ConstantItemRibKind, f); + }); } - fn with_current_self_type(&mut self, self_type: &Ty, f: F) -> T - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) -> T - { + fn with_current_self_type(&mut self, self_type: &Ty, f: impl FnOnce(&mut Self) -> T) -> T { // Handle nested impls (inside fn bodies) let previous_value = replace(&mut self.current_self_type, Some(self_type.clone())); let result = f(self); @@ -927,9 +923,7 @@ fn with_current_self_type(&mut self, self_type: &Ty, f: F) -> T result } - fn with_current_self_item(&mut self, self_item: &Item, f: F) -> T - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) -> T - { + fn with_current_self_item(&mut self, self_item: &Item, f: impl FnOnce(&mut Self) -> T) -> T { let previous_value = replace(&mut self.current_self_item, Some(self_item.id)); let result = f(self); self.current_self_item = previous_value; @@ -937,12 +931,14 @@ fn with_current_self_item(&mut self, self_item: &Item, f: F) -> T } /// When evaluating a `trait` use its associated types' idents for suggestionsa in E0412. - fn with_trait_items(&mut self, trait_items: &Vec, f: F) -> T - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) -> T - { + fn with_trait_items( + &mut self, + trait_items: &Vec, + f: impl FnOnce(&mut Self) -> T, + ) -> T { let trait_assoc_types = replace( &mut self.current_trait_assoc_types, - trait_items.iter().filter_map(|item| match &item.node { + trait_items.iter().filter_map(|item| match &item.kind { TraitItemKind::Type(bounds, _) if bounds.len() == 0 => Some(item.ident), _ => None, }).collect(), @@ -953,9 +949,11 @@ fn with_trait_items(&mut self, trait_items: &Vec, f: F) -> T } /// This is called to resolve a trait reference from an `impl` (i.e., `impl Trait for Foo`). - fn with_optional_trait_ref(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>, Option) -> T - { + fn with_optional_trait_ref( + &mut self, + opt_trait_ref: Option<&TraitRef>, + f: impl FnOnce(&mut Self, Option) -> T + ) -> T { let mut new_val = None; let mut new_id = None; if let Some(trait_ref) = opt_trait_ref { @@ -990,27 +988,18 @@ fn with_optional_trait_ref(&mut self, opt_trait_ref: Option<&TraitRef>, f: result } - fn with_self_rib(&mut self, self_res: Res, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) - { + fn with_self_rib_ns(&mut self, ns: Namespace, self_res: Res, f: impl FnOnce(&mut Self)) { let mut self_type_rib = Rib::new(NormalRibKind); // Plain insert (no renaming, since types are not currently hygienic) self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res); - self.ribs[TypeNS].push(self_type_rib); + self.ribs[ns].push(self_type_rib); f(self); - self.ribs[TypeNS].pop(); + self.ribs[ns].pop(); } - fn with_self_struct_ctor_rib(&mut self, impl_id: DefId, f: F) - where F: FnOnce(&mut LateResolutionVisitor<'_, '_>) - { - let self_res = Res::SelfCtor(impl_id); - let mut self_type_rib = Rib::new(NormalRibKind); - self_type_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), self_res); - self.ribs[ValueNS].push(self_type_rib); - f(self); - self.ribs[ValueNS].pop(); + fn with_self_rib(&mut self, self_res: Res, f: impl FnOnce(&mut Self)) { + self.with_self_rib_ns(TypeNS, self_res, f) } fn resolve_implementation(&mut self, @@ -1038,15 +1027,15 @@ fn resolve_implementation(&mut self, this.visit_generics(generics); // Resolve the items within the impl. this.with_current_self_type(self_type, |this| { - this.with_self_struct_ctor_rib(item_def_id, |this| { - debug!("resolve_implementation with_self_struct_ctor_rib"); + this.with_self_rib_ns(ValueNS, Res::SelfCtor(item_def_id), |this| { + debug!("resolve_implementation with_self_rib_ns(ValueNS, ...)"); for impl_item in impl_items { // We also need a new scope for the impl item type parameters. let generic_params = HasGenericParams(&impl_item.generics, AssocItemRibKind); this.with_generic_param_rib(generic_params, |this| { use crate::ResolutionError::*; - match impl_item.node { + match impl_item.kind { ImplItemKind::Const(..) => { debug!( "resolve_implementation ImplItemKind::Const", @@ -1129,11 +1118,11 @@ fn check_trait_item(&mut self, ident: Ident, ns: Namespace, span: Span, err: } } - fn resolve_params(&mut self, params: &[Arg]) { - let mut bindings_list = FxHashMap::default(); - for param in params { - self.resolve_pattern(¶m.pat, PatternSource::FnParam, &mut bindings_list); - self.visit_ty(¶m.ty); + fn resolve_params(&mut self, params: &[Param]) { + let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())]; + for Param { pat, ty, .. } in params { + self.resolve_pattern(pat, PatternSource::FnParam, &mut bindings); + self.visit_ty(ty); debug!("(resolving function / closure) recorded parameter"); } } @@ -1146,72 +1135,93 @@ fn resolve_local(&mut self, local: &Local) { walk_list!(self, visit_expr, &local.init); // Resolve the pattern. - self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap::default()); + self.resolve_pattern_top(&local.pat, PatternSource::Let); } - // build a map from pattern identifiers to binding-info's. - // this is done hygienically. This could arise for a macro - // that expands into an or-pattern where one 'x' was from the - // user and one 'x' came from the macro. + /// build a map from pattern identifiers to binding-info's. + /// this is done hygienically. This could arise for a macro + /// that expands into an or-pattern where one 'x' was from the + /// user and one 'x' came from the macro. fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap { let mut binding_map = FxHashMap::default(); pat.walk(&mut |pat| { - if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node { - if sub_pat.is_some() || match self.r.partial_res_map.get(&pat.id) - .map(|res| res.base_res()) { - Some(Res::Local(..)) => true, - _ => false, - } { - let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode }; - binding_map.insert(ident, binding_info); + match pat.kind { + PatKind::Ident(binding_mode, ident, ref sub_pat) + if sub_pat.is_some() || self.is_base_res_local(pat.id) => + { + binding_map.insert(ident, BindingInfo { span: ident.span, binding_mode }); + } + PatKind::Or(ref ps) => { + // Check the consistency of this or-pattern and + // then add all bindings to the larger map. + for bm in self.check_consistent_bindings(ps) { + binding_map.extend(bm); + } + return false; } + _ => {} } + true }); binding_map } - // Checks that all of the arms in an or-pattern have exactly the - // same set of bindings, with the same binding modes for each. - fn check_consistent_bindings(&mut self, pats: &[P]) { + fn is_base_res_local(&self, nid: NodeId) -> bool { + match self.r.partial_res_map.get(&nid).map(|res| res.base_res()) { + Some(Res::Local(..)) => true, + _ => false, + } + } + + /// Checks that all of the arms in an or-pattern have exactly the + /// same set of bindings, with the same binding modes for each. + fn check_consistent_bindings(&mut self, pats: &[P]) -> Vec { let mut missing_vars = FxHashMap::default(); let mut inconsistent_vars = FxHashMap::default(); - for pat_outer in pats.iter() { - let map_outer = self.binding_mode_map(&pat_outer); - - for pat_inner in pats.iter().filter(|pat| pat.id != pat_outer.id) { - let map_inner = self.binding_mode_map(&pat_inner); - - for (&key_inner, &binding_inner) in map_inner.iter() { - match map_outer.get(&key_inner) { - None => { // missing binding - let binding_error = missing_vars - .entry(key_inner.name) - .or_insert(BindingError { - name: key_inner.name, - origin: BTreeSet::new(), - target: BTreeSet::new(), - could_be_path: - key_inner.name.as_str().starts_with(char::is_uppercase) - }); - binding_error.origin.insert(binding_inner.span); - binding_error.target.insert(pat_outer.span); - } - Some(binding_outer) => { // check consistent binding - if binding_outer.binding_mode != binding_inner.binding_mode { - inconsistent_vars - .entry(key_inner.name) - .or_insert((binding_inner.span, binding_outer.span)); - } + // 1) Compute the binding maps of all arms. + let maps = pats.iter() + .map(|pat| self.binding_mode_map(pat)) + .collect::>(); + + // 2) Record any missing bindings or binding mode inconsistencies. + for (map_outer, pat_outer) in pats.iter().enumerate().map(|(idx, pat)| (&maps[idx], pat)) { + // Check against all arms except for the same pattern which is always self-consistent. + let inners = pats.iter().enumerate() + .filter(|(_, pat)| pat.id != pat_outer.id) + .flat_map(|(idx, _)| maps[idx].iter()) + .map(|(key, binding)| (key.name, map_outer.get(&key), binding)); + + for (name, info, &binding_inner) in inners { + match info { + None => { // The inner binding is missing in the outer. + let binding_error = missing_vars + .entry(name) + .or_insert_with(|| BindingError { + name, + origin: BTreeSet::new(), + target: BTreeSet::new(), + could_be_path: name.as_str().starts_with(char::is_uppercase), + }); + binding_error.origin.insert(binding_inner.span); + binding_error.target.insert(pat_outer.span); + } + Some(binding_outer) => { + if binding_outer.binding_mode != binding_inner.binding_mode { + // The binding modes in the outer and inner bindings differ. + inconsistent_vars + .entry(name) + .or_insert((binding_inner.span, binding_outer.span)); } } } } } + // 3) Report all missing variables we found. let mut missing_vars = missing_vars.iter_mut().collect::>(); missing_vars.sort(); for (name, mut v) in missing_vars { @@ -1223,212 +1233,245 @@ fn check_consistent_bindings(&mut self, pats: &[P]) { ResolutionError::VariableNotBoundInPattern(v)); } + // 4) Report all inconsistencies in binding modes we found. let mut inconsistent_vars = inconsistent_vars.iter().collect::>(); inconsistent_vars.sort(); for (name, v) in inconsistent_vars { self.r.report_error(v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1)); } - } - fn resolve_arm(&mut self, arm: &Arm) { - self.ribs[ValueNS].push(Rib::new(NormalRibKind)); - - self.resolve_pats(&arm.pats, PatternSource::Match); - - if let Some(ref expr) = arm.guard { - self.visit_expr(expr) - } - self.visit_expr(&arm.body); - - self.ribs[ValueNS].pop(); + // 5) Finally bubble up all the binding maps. + maps } - /// Arising from `source`, resolve a sequence of patterns (top level or-patterns). - fn resolve_pats(&mut self, pats: &[P], source: PatternSource) { - let mut bindings_list = FxHashMap::default(); - for pat in pats { - self.resolve_pattern(pat, source, &mut bindings_list); - } - // This has to happen *after* we determine which pat_idents are variants - if pats.len() > 1 { - self.check_consistent_bindings(pats); - } + /// Check the consistency of the outermost or-patterns. + fn check_consistent_bindings_top(&mut self, pat: &Pat) { + pat.walk(&mut |pat| match pat.kind { + PatKind::Or(ref ps) => { + self.check_consistent_bindings(ps); + false + }, + _ => true, + }) } - fn resolve_block(&mut self, block: &Block) { - debug!("(resolving block) entering block"); - // Move down in the graph, if there's an anonymous module rooted here. - let orig_module = self.parent_scope.module; - let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference - - let mut num_macro_definition_ribs = 0; - if let Some(anonymous_module) = anonymous_module { - debug!("(resolving block) found anonymous module, moving down"); - self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module))); - self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module))); - self.parent_scope.module = anonymous_module; - } else { - self.ribs[ValueNS].push(Rib::new(NormalRibKind)); - } - - // Descend into the block. - for stmt in &block.stmts { - if let StmtKind::Item(ref item) = stmt.node { - if let ItemKind::MacroDef(..) = item.node { - num_macro_definition_ribs += 1; - let res = self.r.definitions.local_def_id(item.id); - self.ribs[ValueNS].push(Rib::new(MacroDefinition(res))); - self.label_ribs.push(Rib::new(MacroDefinition(res))); - } - } - - self.visit_stmt(stmt); - } - - // Move back up. - self.parent_scope.module = orig_module; - for _ in 0 .. num_macro_definition_ribs { - self.ribs[ValueNS].pop(); - self.label_ribs.pop(); - } - self.ribs[ValueNS].pop(); - if anonymous_module.is_some() { - self.ribs[TypeNS].pop(); - } - debug!("(resolving block) leaving block"); + fn resolve_arm(&mut self, arm: &Arm) { + self.with_rib(ValueNS, NormalRibKind, |this| { + this.resolve_pattern_top(&arm.pat, PatternSource::Match); + walk_list!(this, visit_expr, &arm.guard); + this.visit_expr(&arm.body); + }); } - fn fresh_binding(&mut self, - ident: Ident, - pat_id: NodeId, - outer_pat_id: NodeId, - pat_src: PatternSource, - bindings: &mut FxHashMap) - -> Res { - // Add the binding to the local ribs, if it - // doesn't already exist in the bindings map. (We - // must not add it if it's in the bindings map - // because that breaks the assumptions later - // passes make about or-patterns.) - let ident = ident.modern_and_legacy(); - let mut res = Res::Local(pat_id); - match bindings.get(&ident).cloned() { - Some(id) if id == outer_pat_id => { - // `Variant(a, a)`, error - self.r.report_error( - ident.span, - ResolutionError::IdentifierBoundMoreThanOnceInSamePattern( - &ident.as_str()) - ); - } - Some(..) if pat_src == PatternSource::FnParam => { - // `fn f(a: u8, a: u8)`, error - self.r.report_error( - ident.span, - ResolutionError::IdentifierBoundMoreThanOnceInParameterList( - &ident.as_str()) - ); - } - Some(..) if pat_src == PatternSource::Match || - pat_src == PatternSource::Let => { - // `Variant1(a) | Variant2(a)`, ok - // Reuse definition from the first `a`. - res = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident]; - } - Some(..) => { - span_bug!(ident.span, "two bindings with the same name from \ - unexpected pattern source {:?}", pat_src); - } - None => { - // A completely fresh binding, add to the lists if it's valid. - if ident.name != kw::Invalid { - bindings.insert(ident, outer_pat_id); - self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident, res); - } - } - } + /// Arising from `source`, resolve a top level pattern. + fn resolve_pattern_top(&mut self, pat: &Pat, pat_src: PatternSource) { + let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())]; + self.resolve_pattern(pat, pat_src, &mut bindings); + } - res + fn resolve_pattern( + &mut self, + pat: &Pat, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet); 1]>, + ) { + self.resolve_pattern_inner(pat, pat_src, bindings); + // This has to happen *after* we determine which pat_idents are variants: + self.check_consistent_bindings_top(pat); + visit::walk_pat(self, pat); } - fn resolve_pattern(&mut self, - pat: &Pat, - pat_src: PatternSource, - // Maps idents to the node ID for the - // outermost pattern that binds them. - bindings: &mut FxHashMap) { + /// Resolve bindings in a pattern. This is a helper to `resolve_pattern`. + /// + /// ### `bindings` + /// + /// A stack of sets of bindings accumulated. + /// + /// In each set, `PatBoundCtx::Product` denotes that a found binding in it should + /// be interpreted as re-binding an already bound binding. This results in an error. + /// Meanwhile, `PatBound::Or` denotes that a found binding in the set should result + /// in reusing this binding rather than creating a fresh one. + /// + /// When called at the top level, the stack must have a single element + /// with `PatBound::Product`. Otherwise, pushing to the stack happens as + /// or-patterns (`p_0 | ... | p_n`) are encountered and the context needs + /// to be switched to `PatBoundCtx::Or` and then `PatBoundCtx::Product` for each `p_i`. + /// When each `p_i` has been dealt with, the top set is merged with its parent. + /// When a whole or-pattern has been dealt with, the thing happens. + /// + /// See the implementation and `fresh_binding` for more details. + fn resolve_pattern_inner( + &mut self, + pat: &Pat, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet); 1]>, + ) { // Visit all direct subpatterns of this pattern. - let outer_pat_id = pat.id; pat.walk(&mut |pat| { - debug!("resolve_pattern pat={:?} node={:?}", pat, pat.node); - match pat.node { - PatKind::Ident(bmode, ident, ref opt_pat) => { - // First try to resolve the identifier as some existing - // entity, then fall back to a fresh binding. - let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, - None, pat.span) - .and_then(LexicalScopeBinding::item); - let res = binding.map(NameBinding::res).and_then(|res| { - let is_syntactic_ambiguity = opt_pat.is_none() && - bmode == BindingMode::ByValue(Mutability::Immutable); - match res { - Res::Def(DefKind::Ctor(_, CtorKind::Const), _) | - Res::Def(DefKind::Const, _) if is_syntactic_ambiguity => { - // Disambiguate in favor of a unit struct/variant - // or constant pattern. - self.r.record_use(ident, ValueNS, binding.unwrap(), false); - Some(res) - } - Res::Def(DefKind::Ctor(..), _) - | Res::Def(DefKind::Const, _) - | Res::Def(DefKind::Static, _) => { - // This is unambiguously a fresh binding, either syntactically - // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves - // to something unusable as a pattern (e.g., constructor function), - // but we still conservatively report an error, see - // issues/33118#issuecomment-233962221 for one reason why. - self.r.report_error( - ident.span, - ResolutionError::BindingShadowsSomethingUnacceptable( - pat_src.descr(), ident.name, binding.unwrap()) - ); - None - } - Res::Def(DefKind::Fn, _) | Res::Err => { - // These entities are explicitly allowed - // to be shadowed by fresh bindings. - None - } - res => { - span_bug!(ident.span, "unexpected resolution for an \ - identifier in pattern: {:?}", res); - } - } - }).unwrap_or_else(|| { - self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings) - }); - + debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind); + match pat.kind { + PatKind::Ident(bmode, ident, ref sub) => { + // First try to resolve the identifier as some existing entity, + // then fall back to a fresh binding. + let has_sub = sub.is_some(); + let res = self.try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub) + .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings)); self.r.record_partial_res(pat.id, PartialRes::new(res)); } - PatKind::TupleStruct(ref path, ..) => { self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct); } - PatKind::Path(ref qself, ref path) => { self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat); } - PatKind::Struct(ref path, ..) => { self.smart_resolve_path(pat.id, None, path, PathSource::Struct); } - + PatKind::Or(ref ps) => { + // Add a new set of bindings to the stack. `Or` here records that when a + // binding already exists in this set, it should not result in an error because + // `V1(a) | V2(a)` must be allowed and are checked for consistency later. + bindings.push((PatBoundCtx::Or, Default::default())); + for p in ps { + // Now we need to switch back to a product context so that each + // part of the or-pattern internally rejects already bound names. + // For example, `V1(a) | V2(a, a)` and `V1(a, a) | V2(a)` are bad. + bindings.push((PatBoundCtx::Product, Default::default())); + self.resolve_pattern_inner(p, pat_src, bindings); + // Move up the non-overlapping bindings to the or-pattern. + // Existing bindings just get "merged". + let collected = bindings.pop().unwrap().1; + bindings.last_mut().unwrap().1.extend(collected); + } + // This or-pattern itself can itself be part of a product, + // e.g. `(V1(a) | V2(a), a)` or `(a, V1(a) | V2(a))`. + // Both cases bind `a` again in a product pattern and must be rejected. + let collected = bindings.pop().unwrap().1; + bindings.last_mut().unwrap().1.extend(collected); + + // Prevent visiting `ps` as we've already done so above. + return false; + } _ => {} } true }); + } - visit::walk_pat(self, pat); + fn fresh_binding( + &mut self, + ident: Ident, + pat_id: NodeId, + pat_src: PatternSource, + bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet); 1]>, + ) -> Res { + // Add the binding to the local ribs, if it doesn't already exist in the bindings map. + // (We must not add it if it's in the bindings map because that breaks the assumptions + // later passes make about or-patterns.) + let ident = ident.modern_and_legacy(); + + // Walk outwards the stack of products / or-patterns and + // find out if the identifier has been bound in any of these. + let mut already_bound_and = false; + let mut already_bound_or = false; + for (is_sum, set) in bindings.iter_mut().rev() { + match (is_sum, set.get(&ident).cloned()) { + // Already bound in a product pattern, e.g. `(a, a)` which is not allowed. + (PatBoundCtx::Product, Some(..)) => already_bound_and = true, + // Already bound in an or-pattern, e.g. `V1(a) | V2(a)`. + // This is *required* for consistency which is checked later. + (PatBoundCtx::Or, Some(..)) => already_bound_or = true, + // Not already bound here. + _ => {} + } + } + + if already_bound_and { + // Overlap in a product pattern somewhere; report an error. + use ResolutionError::*; + let error = match pat_src { + // `fn f(a: u8, a: u8)`: + PatternSource::FnParam => IdentifierBoundMoreThanOnceInParameterList, + // `Variant(a, a)`: + _ => IdentifierBoundMoreThanOnceInSamePattern, + }; + self.r.report_error(ident.span, error(&ident.as_str())); + } + + // Record as bound if it's valid: + let ident_valid = ident.name != kw::Invalid; + if ident_valid { + bindings.last_mut().unwrap().1.insert(ident); + } + + if already_bound_or { + // `Variant1(a) | Variant2(a)`, ok + // Reuse definition from the first `a`. + self.innermost_rib_bindings(ValueNS)[&ident] + } else { + let res = Res::Local(pat_id); + if ident_valid { + // A completely fresh binding add to the set if it's valid. + self.innermost_rib_bindings(ValueNS).insert(ident, res); + } + res + } + } + + fn innermost_rib_bindings(&mut self, ns: Namespace) -> &mut IdentMap { + &mut self.ribs[ns].last_mut().unwrap().bindings + } + + fn try_resolve_as_non_binding( + &mut self, + pat_src: PatternSource, + pat: &Pat, + bm: BindingMode, + ident: Ident, + has_sub: bool, + ) -> Option { + let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None, pat.span)?.item()?; + let res = binding.res(); + + // An immutable (no `mut`) by-value (no `ref`) binding pattern without + // a sub pattern (no `@ $pat`) is syntactically ambiguous as it could + // also be interpreted as a path to e.g. a constant, variant, etc. + let is_syntactic_ambiguity = !has_sub && bm == BindingMode::ByValue(Mutability::Immutable); + + match res { + Res::Def(DefKind::Ctor(_, CtorKind::Const), _) | + Res::Def(DefKind::Const, _) if is_syntactic_ambiguity => { + // Disambiguate in favor of a unit struct/variant or constant pattern. + self.r.record_use(ident, ValueNS, binding, false); + Some(res) + } + Res::Def(DefKind::Ctor(..), _) + | Res::Def(DefKind::Const, _) + | Res::Def(DefKind::Static, _) => { + // This is unambiguously a fresh binding, either syntactically + // (e.g., `IDENT @ PAT` or `ref IDENT`) or because `IDENT` resolves + // to something unusable as a pattern (e.g., constructor function), + // but we still conservatively report an error, see + // issues/33118#issuecomment-233962221 for one reason why. + self.r.report_error( + ident.span, + ResolutionError::BindingShadowsSomethingUnacceptable( + pat_src.descr(), + ident.name, + binding, + ), + ); + None + } + Res::Def(DefKind::Fn, _) | Res::Err => { + // These entities are explicitly allowed to be shadowed by fresh bindings. + None + } + res => { + span_bug!(ident.span, "unexpected resolution for an \ + identifier in pattern: {:?}", res); + } + } } // High-level and context dependent path resolution routine. @@ -1726,12 +1769,10 @@ fn resolve_qpath( Some(result) } - fn with_resolved_label(&mut self, label: Option