// Copyright 2016 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use {AmbiguityError, CrateLint, Resolver, ResolutionError, is_known_tool, resolve_error}; use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult, ToNameBinding}; use ModuleOrUniformRoot; use Namespace::{self, TypeNS, MacroNS}; use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport}; use resolve_imports::ImportResolver; use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex, DefIndexAddressSpace}; use rustc::hir::def::{Def, NonMacroAttrKind}; use rustc::hir::map::{self, DefCollector}; use rustc::{ty, lint}; use rustc::middle::cstore::CrateStore; use syntax::ast::{self, Name, Ident}; use syntax::attr; use syntax::errors::DiagnosticBuilder; use syntax::ext::base::{self, Determinacy, MultiModifier, MultiDecorator}; use syntax::ext::base::{MacroKind, SyntaxExtension, Resolver as SyntaxResolver}; use syntax::ext::expand::{AstFragment, Invocation, InvocationKind}; use syntax::ext::hygiene::{self, Mark}; use syntax::ext::tt::macro_rules; use syntax::feature_gate::{self, feature_err, emit_feature_err, is_builtin_attr_name, GateIssue}; use syntax::feature_gate::EXPLAIN_DERIVE_UNDERSCORE; use syntax::fold::{self, Folder}; use syntax::parse::parser::PathStyle; use syntax::parse::token::{self, Token}; use syntax::ptr::P; use syntax::symbol::{Symbol, keywords}; use syntax::tokenstream::{TokenStream, TokenTree, Delimited}; use syntax::util::lev_distance::find_best_match_for_name; use syntax_pos::{Span, DUMMY_SP}; use errors::Applicability; use std::cell::Cell; use std::mem; use rustc_data_structures::sync::Lrc; use rustc_data_structures::small_vec::ExpectOne; crate struct FromPrelude(bool); #[derive(Clone)] pub struct InvocationData<'a> { pub module: Cell>, pub def_index: DefIndex, // The scope in which the invocation path is resolved. pub legacy_scope: Cell>, // The smallest scope that includes this invocation's expansion, // or `Empty` if this invocation has not been expanded yet. pub expansion: Cell>, } impl<'a> InvocationData<'a> { pub fn root(graph_root: Module<'a>) -> Self { InvocationData { module: Cell::new(graph_root), def_index: CRATE_DEF_INDEX, legacy_scope: Cell::new(LegacyScope::Empty), expansion: Cell::new(LegacyScope::Empty), } } } #[derive(Copy, Clone)] pub enum LegacyScope<'a> { Empty, Invocation(&'a InvocationData<'a>), // The scope of the invocation, not including its expansion Expansion(&'a InvocationData<'a>), // The scope of the invocation, including its expansion Binding(&'a LegacyBinding<'a>), } // Binding produced by a `macro_rules` item. // Not modularized, can shadow previous legacy bindings, etc. pub struct LegacyBinding<'a> { binding: &'a NameBinding<'a>, parent: Cell>, ident: Ident, } pub struct ProcMacError { crate_name: Symbol, name: Symbol, module: ast::NodeId, use_span: Span, warn_msg: &'static str, } impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> { fn next_node_id(&mut self) -> ast::NodeId { self.session.next_node_id() } fn get_module_scope(&mut self, id: ast::NodeId) -> Mark { let mark = Mark::fresh(Mark::root()); let module = self.module_map[&self.definitions.local_def_id(id)]; self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData { module: Cell::new(module), def_index: module.def_id().unwrap().index, legacy_scope: Cell::new(LegacyScope::Empty), expansion: Cell::new(LegacyScope::Empty), })); mark } fn eliminate_crate_var(&mut self, item: P) -> P { struct EliminateCrateVar<'b, 'a: 'b, 'crateloader: 'a>( &'b mut Resolver<'a, 'crateloader>, Span ); impl<'a, 'b, 'crateloader> Folder for EliminateCrateVar<'a, 'b, 'crateloader> { fn fold_path(&mut self, path: ast::Path) -> ast::Path { match self.fold_qpath(None, path) { (None, path) => path, _ => unreachable!(), } } fn fold_qpath(&mut self, mut qself: Option, mut path: ast::Path) -> (Option, ast::Path) { qself = qself.map(|ast::QSelf { ty, path_span, position }| { ast::QSelf { ty: self.fold_ty(ty), path_span: self.new_span(path_span), position, } }); if path.segments[0].ident.name == keywords::DollarCrate.name() { let module = self.0.resolve_crate_root(path.segments[0].ident); path.segments[0].ident.name = keywords::CrateRoot.name(); if !module.is_local() { let span = path.segments[0].ident.span; path.segments.insert(1, match module.kind { ModuleKind::Def(_, name) => ast::PathSegment::from_ident( ast::Ident::with_empty_ctxt(name).with_span_pos(span) ), _ => unreachable!(), }); if let Some(qself) = &mut qself { qself.position += 1; } } } (qself, path) } fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac { fold::noop_fold_mac(mac, self) } } EliminateCrateVar(self, item.span).fold_item(item).expect_one("") } fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool { self.whitelisted_legacy_custom_derives.contains(&name) } fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment, derives: &[Mark]) { let invocation = self.invocations[&mark]; self.collect_def_ids(mark, invocation, fragment); self.current_module = invocation.module.get(); self.current_module.unresolved_invocations.borrow_mut().remove(&mark); self.current_module.unresolved_invocations.borrow_mut().extend(derives); for &derive in derives { self.invocations.insert(derive, invocation); } let mut visitor = BuildReducedGraphVisitor { resolver: self, legacy_scope: LegacyScope::Invocation(invocation), expansion: mark, }; fragment.visit_with(&mut visitor); invocation.expansion.set(visitor.legacy_scope); } fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc) { let def_id = DefId { krate: BUILTIN_MACROS_CRATE, index: DefIndex::from_array_index(self.macro_map.len(), DefIndexAddressSpace::Low), }; let kind = ext.kind(); self.macro_map.insert(def_id, ext); let binding = self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Def(Def::Macro(def_id, kind), false), span: DUMMY_SP, vis: ty::Visibility::Invisible, expansion: Mark::root(), }); self.macro_prelude.insert(ident.name, binding); } fn add_unshadowable_attr(&mut self, ident: ast::Ident, ext: Lrc) { let def_id = DefId { krate: BUILTIN_MACROS_CRATE, index: DefIndex::from_array_index(self.macro_map.len(), DefIndexAddressSpace::Low), }; let kind = ext.kind(); self.macro_map.insert(def_id, ext); let binding = self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Def(Def::Macro(def_id, kind), false), span: DUMMY_SP, vis: ty::Visibility::Invisible, expansion: Mark::root(), }); self.unshadowable_attrs.insert(ident.name, binding); } fn resolve_imports(&mut self) { ImportResolver { resolver: self }.resolve_imports() } // Resolves attribute and derive legacy macros from `#![plugin(..)]`. fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec, allow_derive: bool) -> Option { for i in 0..attrs.len() { let name = attrs[i].name(); if self.session.plugin_attributes.borrow().iter() .any(|&(ref attr_nm, _)| name == &**attr_nm) { attr::mark_known(&attrs[i]); } match self.macro_prelude.get(&name).cloned() { Some(binding) => match *binding.get_macro(self) { MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => { return Some(attrs.remove(i)) } _ => {} }, None => {} } } if !allow_derive { return None } // Check for legacy derives for i in 0..attrs.len() { let name = attrs[i].name(); if name == "derive" { let result = attrs[i].parse_list(&self.session.parse_sess, |parser| { parser.parse_path_allowing_meta(PathStyle::Mod) }); let mut traits = match result { Ok(traits) => traits, Err(mut e) => { e.cancel(); continue } }; for j in 0..traits.len() { if traits[j].segments.len() > 1 { continue } let trait_name = traits[j].segments[0].ident.name; let legacy_name = Symbol::intern(&format!("derive_{}", trait_name)); if !self.macro_prelude.contains_key(&legacy_name) { continue } let span = traits.remove(j).span; self.gate_legacy_custom_derive(legacy_name, span); if traits.is_empty() { attrs.remove(i); } else { let mut tokens = Vec::new(); for (j, path) in traits.iter().enumerate() { if j > 0 { tokens.push(TokenTree::Token(attrs[i].span, Token::Comma).into()); } for (k, segment) in path.segments.iter().enumerate() { if k > 0 { tokens.push(TokenTree::Token(path.span, Token::ModSep).into()); } let tok = Token::from_ast_ident(segment.ident); tokens.push(TokenTree::Token(path.span, tok).into()); } } attrs[i].tokens = TokenTree::Delimited(attrs[i].span, Delimited { delim: token::Paren, tts: TokenStream::concat(tokens).into(), }).into(); } return Some(ast::Attribute { path: ast::Path::from_ident(Ident::new(legacy_name, span)), tokens: TokenStream::empty(), id: attr::mk_attr_id(), style: ast::AttrStyle::Outer, is_sugared_doc: false, span, }); } } } None } fn resolve_macro_invocation(&mut self, invoc: &Invocation, scope: Mark, force: bool) -> Result>, Determinacy> { let (path, kind, derives_in_scope) = match invoc.kind { InvocationKind::Attr { attr: None, .. } => return Ok(None), InvocationKind::Attr { attr: Some(ref attr), ref traits, .. } => (&attr.path, MacroKind::Attr, &traits[..]), InvocationKind::Bang { ref mac, .. } => (&mac.node.path, MacroKind::Bang, &[][..]), InvocationKind::Derive { ref path, .. } => (path, MacroKind::Derive, &[][..]), }; let (def, ext) = self.resolve_macro_to_def(path, kind, scope, derives_in_scope, force)?; if let Def::Macro(def_id, _) = def { self.macro_defs.insert(invoc.expansion_data.mark, def_id); let normal_module_def_id = self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id; self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark, normal_module_def_id); invoc.expansion_data.mark.set_default_transparency(ext.default_transparency()); invoc.expansion_data.mark.set_is_builtin(def_id.krate == BUILTIN_MACROS_CRATE); } Ok(Some(ext)) } fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark, derives_in_scope: &[ast::Path], force: bool) -> Result, Determinacy> { Ok(self.resolve_macro_to_def(path, kind, scope, derives_in_scope, force)?.1) } fn check_unused_macros(&self) { for did in self.unused_macros.iter() { let id_span = match *self.macro_map[did] { SyntaxExtension::NormalTT { def_info, .. } | SyntaxExtension::DeclMacro { def_info, .. } => def_info, _ => None, }; if let Some((id, span)) = id_span { let lint = lint::builtin::UNUSED_MACROS; let msg = "unused macro definition"; self.session.buffer_lint(lint, id, span, msg); } else { bug!("attempted to create unused macro error, but span not available"); } } } } impl<'a, 'cl> Resolver<'a, 'cl> { fn resolve_macro_to_def(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark, derives_in_scope: &[ast::Path], force: bool) -> Result<(Def, Lrc), Determinacy> { let def = self.resolve_macro_to_def_inner(path, kind, scope, derives_in_scope, force); // Report errors and enforce feature gates for the resolved macro. if def != Err(Determinacy::Undetermined) { // Do not report duplicated errors on every undetermined resolution. for segment in &path.segments { if let Some(args) = &segment.args { self.session.span_err(args.span(), "generic arguments in macro path"); } } } let def = def?; match def { Def::Macro(def_id, macro_kind) => { self.unused_macros.remove(&def_id); if macro_kind == MacroKind::ProcMacroStub { let msg = "can't use a procedural macro from the same crate that defines it"; self.session.span_err(path.span, msg); return Err(Determinacy::Determined); } } Def::NonMacroAttr(attr_kind) => { if kind == MacroKind::Attr { let features = self.session.features_untracked(); if attr_kind == NonMacroAttrKind::Custom { assert!(path.segments.len() == 1); let name = path.segments[0].ident.name.as_str(); if name.starts_with("rustc_") { if !features.rustc_attrs { let msg = "unless otherwise specified, attributes with the prefix \ `rustc_` are reserved for internal compiler diagnostics"; feature_err(&self.session.parse_sess, "rustc_attrs", path.span, GateIssue::Language, &msg).emit(); } } else if name.starts_with("derive_") { if !features.custom_derive { feature_err(&self.session.parse_sess, "custom_derive", path.span, GateIssue::Language, EXPLAIN_DERIVE_UNDERSCORE).emit(); } } else if !features.custom_attribute { let msg = format!("The attribute `{}` is currently unknown to the \ compiler and may have meaning added to it in the \ future", path); feature_err(&self.session.parse_sess, "custom_attribute", path.span, GateIssue::Language, &msg).emit(); } } } else { // Not only attributes, but anything in macro namespace can result in // `Def::NonMacroAttr` definition (e.g. `inline!()`), so we must report // an error for those cases. let msg = format!("expected a macro, found {}", def.kind_name()); self.session.span_err(path.span, &msg); return Err(Determinacy::Determined); } } _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"), } Ok((def, self.get_macro(def))) } pub fn resolve_macro_to_def_inner(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark, derives_in_scope: &[ast::Path], force: bool) -> Result { let ast::Path { ref segments, span } = *path; let mut path: Vec<_> = segments.iter().map(|seg| seg.ident).collect(); let invocation = self.invocations[&scope]; let module = invocation.module.get(); self.current_module = if module.is_trait() { module.parent.unwrap() } else { module }; // Possibly apply the macro helper hack if kind == MacroKind::Bang && path.len() == 1 && path[0].span.ctxt().outer().expn_info().map_or(false, |info| info.local_inner_macros) { let root = Ident::new(keywords::DollarCrate.name(), path[0].span); path.insert(0, root); } if path.len() > 1 { let res = self.resolve_path(None, &path, Some(MacroNS), false, span, CrateLint::No); let def = match res { PathResult::NonModule(path_res) => match path_res.base_def() { Def::Err => Err(Determinacy::Determined), def @ _ => { if path_res.unresolved_segments() > 0 { self.found_unresolved_macro = true; self.session.span_err(span, "fail to resolve non-ident macro path"); Err(Determinacy::Determined) } else { Ok(def) } } }, PathResult::Module(..) => unreachable!(), PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined), _ => { self.found_unresolved_macro = true; Err(Determinacy::Determined) }, }; self.current_module.nearest_item_scope().macro_resolutions.borrow_mut() .push((path.into_boxed_slice(), span)); return def; } if kind == MacroKind::Attr { if let Some(ext) = self.unshadowable_attrs.get(&path[0].name) { return Ok(ext.def()); } } let legacy_resolution = self.resolve_legacy_scope(&invocation.legacy_scope, path[0], false); let result = if let Some(legacy_binding) = legacy_resolution { Ok(legacy_binding.def()) } else { match self.resolve_lexical_macro_path_segment(path[0], MacroNS, false, force, kind == MacroKind::Attr, span) { Ok((binding, _)) => Ok(binding.def_ignoring_ambiguity()), Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined), Err(Determinacy::Determined) => { self.found_unresolved_macro = true; Err(Determinacy::Determined) } } }; self.current_module.nearest_item_scope().legacy_macro_resolutions.borrow_mut() .push((scope, path[0], kind, result.ok())); if let Ok(Def::NonMacroAttr(NonMacroAttrKind::Custom)) = result {} else { return result; } // At this point we've found that the `attr` is determinately unresolved and thus can be // interpreted as a custom attribute. Normally custom attributes are feature gated, but // it may be a custom attribute whitelisted by a derive macro and they do not require // a feature gate. // // So here we look through all of the derive annotations in scope and try to resolve them. // If they themselves successfully resolve *and* one of the resolved derive macros // whitelists this attribute's name, then this is a registered attribute and we can convert // it from a "generic custom attrite" into a "known derive helper attribute". assert!(kind == MacroKind::Attr); enum ConvertToDeriveHelper { Yes, No, DontKnow } let mut convert_to_derive_helper = ConvertToDeriveHelper::No; for derive in derives_in_scope { match self.resolve_macro_path(derive, MacroKind::Derive, scope, &[], force) { Ok(ext) => if let SyntaxExtension::ProcMacroDerive(_, ref inert_attrs, _) = *ext { if inert_attrs.contains(&path[0].name) { convert_to_derive_helper = ConvertToDeriveHelper::Yes; break } }, Err(Determinacy::Undetermined) => convert_to_derive_helper = ConvertToDeriveHelper::DontKnow, Err(Determinacy::Determined) => {} } } match convert_to_derive_helper { ConvertToDeriveHelper::Yes => Ok(Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper)), ConvertToDeriveHelper::No => result, ConvertToDeriveHelper::DontKnow => Err(Determinacy::determined(force)), } } // Resolve the initial segment of a non-global macro path // (e.g. `foo` in `foo::bar!(); or `foo!();`). // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during // expansion and import resolution (perhaps they can be merged in the future). crate fn resolve_lexical_macro_path_segment( &mut self, mut ident: Ident, ns: Namespace, record_used: bool, force: bool, is_attr: bool, path_span: Span ) -> Result<(&'a NameBinding<'a>, FromPrelude), Determinacy> { // General principles: // 1. Not controlled (user-defined) names should have higher priority than controlled names // built into the language or standard library. This way we can add new names into the // language or standard library without breaking user code. // 2. "Closed set" below means new names can appear after the current resolution attempt. // Places to search (in order of decreasing priority): // (Type NS) // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet // (open set, not controlled). // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 3. Extern prelude (closed, not controlled). // 4. Tool modules (closed, controlled right now, but not in the future). // 5. Standard library prelude (de-facto closed, controlled). // 6. Language prelude (closed, controlled). // (Macro NS) // 1. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 2. Macro prelude (language, standard library, user-defined legacy plugins lumped into // one set) (open, the open part is from macro expansions, not controlled). // 2a. User-defined prelude from macro-use // (open, the open part is from macro expansions, not controlled). // 2b. Standard library prelude, currently just a macro-use (closed, controlled) // 2c. Language prelude, perhaps including builtin attributes // (closed, controlled, except for legacy plugins). // 3. Builtin attributes (closed, controlled). assert!(ns == TypeNS || ns == MacroNS); assert!(force || !record_used); // `record_used` implies `force` ident = ident.modern(); // Names from inner scope that can't shadow names from outer scopes, e.g. // mod m { ... } // { // use prefix::*; // if this imports another `m`, then it can't shadow the outer `m` // // and we have and ambiguity error // m::mac!(); // } // This includes names from globs and from macro expansions. let mut potentially_ambiguous_result: Option<(&NameBinding, FromPrelude)> = None; enum WhereToResolve<'a> { Module(Module<'a>), MacroPrelude, BuiltinAttrs, ExternPrelude, ToolPrelude, StdLibPrelude, PrimitiveTypes, } // Go through all the scopes and try to resolve the name. let mut where_to_resolve = WhereToResolve::Module(self.current_module); let mut use_prelude = !self.current_module.no_implicit_prelude; loop { let result = match where_to_resolve { WhereToResolve::Module(module) => { let orig_current_module = mem::replace(&mut self.current_module, module); let binding = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(module), ident, ns, true, record_used, path_span, ); self.current_module = orig_current_module; binding.map(|binding| (binding, FromPrelude(false))) } WhereToResolve::MacroPrelude => { match self.macro_prelude.get(&ident.name).cloned() { Some(binding) => Ok((binding, FromPrelude(true))), None => Err(Determinacy::Determined), } } WhereToResolve::BuiltinAttrs => { // FIXME: Only built-in attributes are not considered as candidates for // non-attributes to fight off regressions on stable channel (#53205). // We need to come up with some more principled approach instead. if is_attr && is_builtin_attr_name(ident.name) { let binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin), ty::Visibility::Public, ident.span, Mark::root()) .to_name_binding(self.arenas); Ok((binding, FromPrelude(true))) } else { Err(Determinacy::Determined) } } WhereToResolve::ExternPrelude => { if use_prelude && self.extern_prelude.contains(&ident.name) { if !self.session.features_untracked().extern_prelude && !self.ignore_extern_prelude_feature { feature_err(&self.session.parse_sess, "extern_prelude", ident.span, GateIssue::Language, "access to extern crates through prelude is experimental") .emit(); } let crate_id = self.crate_loader.process_path_extern(ident.name, ident.span); let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX }); self.populate_module_if_necessary(crate_root); let binding = (crate_root, ty::Visibility::Public, ident.span, Mark::root()).to_name_binding(self.arenas); Ok((binding, FromPrelude(true))) } else { Err(Determinacy::Determined) } } WhereToResolve::ToolPrelude => { if use_prelude && is_known_tool(ident.name) { let binding = (Def::ToolMod, ty::Visibility::Public, ident.span, Mark::root()).to_name_binding(self.arenas); Ok((binding, FromPrelude(true))) } else { Err(Determinacy::Determined) } } WhereToResolve::StdLibPrelude => { let mut result = Err(Determinacy::Determined); if use_prelude { if let Some(prelude) = self.prelude { if let Ok(binding) = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(prelude), ident, ns, false, false, path_span, ) { result = Ok((binding, FromPrelude(true))); } } } result } WhereToResolve::PrimitiveTypes => { if let Some(prim_ty) = self.primitive_type_table.primitive_types.get(&ident.name).cloned() { let binding = (Def::PrimTy(prim_ty), ty::Visibility::Public, ident.span, Mark::root()).to_name_binding(self.arenas); Ok((binding, FromPrelude(true))) } else { Err(Determinacy::Determined) } } }; macro_rules! continue_search { () => { where_to_resolve = match where_to_resolve { WhereToResolve::Module(module) => { match self.hygienic_lexical_parent(module, &mut ident.span) { Some(parent_module) => WhereToResolve::Module(parent_module), None => { use_prelude = !module.no_implicit_prelude; if ns == MacroNS { WhereToResolve::MacroPrelude } else { WhereToResolve::ExternPrelude } } } } WhereToResolve::MacroPrelude => WhereToResolve::BuiltinAttrs, WhereToResolve::BuiltinAttrs => break, // nowhere else to search WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude, WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude, WhereToResolve::StdLibPrelude => WhereToResolve::PrimitiveTypes, WhereToResolve::PrimitiveTypes => break, // nowhere else to search }; continue; }} match result { Ok(result) => { if !record_used { return Ok(result); } // Found a solution that is ambiguous with a previously found solution. // Push an ambiguity error for later reporting and // return something for better recovery. if let Some(previous_result) = potentially_ambiguous_result { if result.0.def() != previous_result.0.def() { self.ambiguity_errors.push(AmbiguityError { span: path_span, name: ident.name, b1: previous_result.0, b2: result.0, }); return Ok(previous_result); } } // Found a solution that's not an ambiguity yet, but is "suspicious" and // can participate in ambiguities later on. // Remember it and go search for other solutions in outer scopes. if result.0.is_glob_import() || result.0.expansion != Mark::root() { potentially_ambiguous_result = Some(result); continue_search!(); } // Found a solution that can't be ambiguous, great success. return Ok(result); }, Err(Determinacy::Determined) => { continue_search!(); } Err(Determinacy::Undetermined) => return Err(Determinacy::determined(force)), } } // Previously found potentially ambiguous result turned out to not be ambiguous after all. if let Some(previous_result) = potentially_ambiguous_result { return Ok(previous_result); } let determinacy = Determinacy::determined(force); if determinacy == Determinacy::Determined && is_attr { // For single-segment attributes interpret determinate "no resolution" as a custom // attribute. (Lexical resolution implies the first segment and is_attr should imply // the last segment, so we are certainly working with a single-segment attribute here.) assert!(ns == MacroNS); let binding = (Def::NonMacroAttr(NonMacroAttrKind::Custom), ty::Visibility::Public, ident.span, Mark::root()) .to_name_binding(self.arenas); Ok((binding, FromPrelude(true))) } else { Err(determinacy) } } fn resolve_legacy_scope(&mut self, scope: &'a Cell>, ident: Ident, record_used: bool) -> Option<&'a NameBinding<'a>> { let ident = ident.modern(); // Names from inner scope that can't shadow names from outer scopes, e.g. // macro_rules! mac { ... } // { // define_mac!(); // if this generates another `macro_rules! mac`, then it can't shadow // // the outer `mac` and we have and ambiguity error // mac!(); // } let mut potentially_ambiguous_result: Option<&NameBinding> = None; // Go through all the scopes and try to resolve the name. let mut where_to_resolve = scope; loop { let result = match where_to_resolve.get() { LegacyScope::Binding(legacy_binding) => if ident == legacy_binding.ident { Some(legacy_binding.binding) } else { None } _ => None, }; macro_rules! continue_search { () => { where_to_resolve = match where_to_resolve.get() { LegacyScope::Binding(binding) => &binding.parent, LegacyScope::Invocation(invocation) => &invocation.legacy_scope, LegacyScope::Expansion(invocation) => match invocation.expansion.get() { LegacyScope::Empty => &invocation.legacy_scope, LegacyScope::Binding(..) | LegacyScope::Expansion(..) => &invocation.expansion, LegacyScope::Invocation(..) => { where_to_resolve.set(invocation.legacy_scope.get()); where_to_resolve } } LegacyScope::Empty => break, // nowhere else to search }; continue; }} match result { Some(result) => { if !record_used { return Some(result); } // Found a solution that is ambiguous with a previously found solution. // Push an ambiguity error for later reporting and // return something for better recovery. if let Some(previous_result) = potentially_ambiguous_result { if result.def() != previous_result.def() { self.ambiguity_errors.push(AmbiguityError { span: ident.span, name: ident.name, b1: previous_result, b2: result, }); return Some(previous_result); } } // Found a solution that's not an ambiguity yet, but is "suspicious" and // can participate in ambiguities later on. // Remember it and go search for other solutions in outer scopes. if result.expansion != Mark::root() { potentially_ambiguous_result = Some(result); continue_search!(); } // Found a solution that can't be ambiguous. return Some(result); } None => { continue_search!(); } } } // Previously found potentially ambiguous result turned out to not be ambiguous after all. if let Some(previous_result) = potentially_ambiguous_result { return Some(previous_result); } None } pub fn finalize_current_module_macro_resolutions(&mut self) { let module = self.current_module; for &(ref path, span) in module.macro_resolutions.borrow().iter() { match self.resolve_path(None, &path, Some(MacroNS), true, span, CrateLint::No) { PathResult::NonModule(_) => {}, PathResult::Failed(span, msg, _) => { resolve_error(self, span, ResolutionError::FailedToResolve(&msg)); } _ => unreachable!(), } } for &(mark, ident, kind, def) in module.legacy_macro_resolutions.borrow().iter() { let span = ident.span; let legacy_scope = &self.invocations[&mark].legacy_scope; let legacy_resolution = self.resolve_legacy_scope(legacy_scope, ident, true); let resolution = self.resolve_lexical_macro_path_segment(ident, MacroNS, true, true, kind == MacroKind::Attr, span); let check_consistency = |this: &Self, new_def: Def| { if let Some(def) = def { if this.ambiguity_errors.is_empty() && new_def != def && new_def != Def::Err { // Make sure compilation does not succeed if preferred macro resolution // has changed after the macro had been expanded. In theory all such // situations should be reported as ambiguity errors, so this is span-bug. span_bug!(span, "inconsistent resolution for a macro"); } } else { // It's possible that the macro was unresolved (indeterminate) and silently // expanded into a dummy fragment for recovery during expansion. // Now, post-expansion, the resolution may succeed, but we can't change the // past and need to report an error. let msg = format!("cannot determine resolution for the {} `{}`", kind.descr(), ident); let msg_note = "import resolution is stuck, try simplifying macro imports"; this.session.struct_span_err(span, &msg).note(msg_note).emit(); } }; match (legacy_resolution, resolution) { (None, Err(_)) => { assert!(def.is_none()); let bang = if kind == MacroKind::Bang { "!" } else { "" }; let msg = format!("cannot find {} `{}{}` in this scope", kind.descr(), ident, bang); let mut err = self.session.struct_span_err(span, &msg); self.suggest_macro_name(&ident.as_str(), kind, &mut err, span); err.emit(); }, (Some(legacy_binding), Ok((binding, FromPrelude(from_prelude)))) if !from_prelude || legacy_binding.expansion != Mark::root() => { if legacy_binding.def_ignoring_ambiguity() != binding.def_ignoring_ambiguity() { self.report_ambiguity_error(ident.name, span, legacy_binding, binding); } }, // OK, non-macro-expanded legacy wins over prelude even if defs are different (Some(legacy_binding), Ok(_)) | // OK, unambiguous resolution (Some(legacy_binding), Err(_)) => { check_consistency(self, legacy_binding.def()); } // OK, unambiguous resolution (None, Ok((binding, FromPrelude(from_prelude)))) => { check_consistency(self, binding.def_ignoring_ambiguity()); if from_prelude { self.record_use(ident, MacroNS, binding, span); self.err_if_macro_use_proc_macro(ident.name, span, binding); } } }; } } fn suggest_macro_name(&mut self, name: &str, kind: MacroKind, err: &mut DiagnosticBuilder<'a>, span: Span) { // First check if this is a locally-defined bang macro. let suggestion = if let MacroKind::Bang = kind { find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None) } else { None // Then check global macros. }.or_else(|| { // FIXME: get_macro needs an &mut Resolver, can we do it without cloning? let macro_prelude = self.macro_prelude.clone(); let names = macro_prelude.iter().filter_map(|(name, binding)| { if binding.get_macro(self).kind() == kind { Some(name) } else { None } }); find_best_match_for_name(names, name, None) // Then check modules. }).or_else(|| { let is_macro = |def| { if let Def::Macro(_, def_kind) = def { def_kind == kind } else { false } }; let ident = Ident::new(Symbol::intern(name), span); self.lookup_typo_candidate(&[ident], MacroNS, is_macro, span) }); if let Some(suggestion) = suggestion { if suggestion != name { if let MacroKind::Bang = kind { err.span_suggestion_with_applicability( span, "you could try the macro", suggestion.to_string(), Applicability::MaybeIncorrect ); } else { err.span_suggestion_with_applicability( span, "try", suggestion.to_string(), Applicability::MaybeIncorrect ); } } else { err.help("have you added the `#[macro_use]` on the module/import?"); } } } fn collect_def_ids(&mut self, mark: Mark, invocation: &'a InvocationData<'a>, fragment: &AstFragment) { let Resolver { ref mut invocations, arenas, graph_root, .. } = *self; let InvocationData { def_index, .. } = *invocation; let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| { invocations.entry(invoc.mark).or_insert_with(|| { arenas.alloc_invocation_data(InvocationData { def_index: invoc.def_index, module: Cell::new(graph_root), expansion: Cell::new(LegacyScope::Empty), legacy_scope: Cell::new(LegacyScope::Empty), }) }); }; let mut def_collector = DefCollector::new(&mut self.definitions, mark); def_collector.visit_macro_invoc = Some(visit_macro_invoc); def_collector.with_parent(def_index, |def_collector| { fragment.visit_with(def_collector) }); } pub fn define_macro(&mut self, item: &ast::Item, expansion: Mark, legacy_scope: &mut LegacyScope<'a>) { self.local_macro_def_scopes.insert(item.id, self.current_module); let ident = item.ident; if ident.name == "macro_rules" { self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`"); } let def_id = self.definitions.local_def_id(item.id); let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess, &self.session.features_untracked(), item, hygiene::default_edition())); self.macro_map.insert(def_id, ext); let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() }; if def.legacy { let ident = ident.modern(); self.macro_names.insert(ident); let def = Def::Macro(def_id, MacroKind::Bang); let vis = ty::Visibility::Invisible; // Doesn't matter for legacy bindings let binding = (def, vis, item.span, expansion).to_name_binding(self.arenas); *legacy_scope = LegacyScope::Binding(self.arenas.alloc_legacy_binding( LegacyBinding { parent: Cell::new(*legacy_scope), binding, ident } )); self.all_macros.insert(ident.name, def); if attr::contains_name(&item.attrs, "macro_export") { let module = self.graph_root; let vis = ty::Visibility::Public; self.define(module, ident, MacroNS, (def, vis, item.span, expansion, IsMacroExport)); } else { self.unused_macros.insert(def_id); } } else { let module = self.current_module; let def = Def::Macro(def_id, MacroKind::Bang); let vis = self.resolve_visibility(&item.vis); if vis != ty::Visibility::Public { self.unused_macros.insert(def_id); } self.define(module, ident, MacroNS, (def, vis, item.span, expansion)); } } /// Error if `ext` is a Macros 1.1 procedural macro being imported by `#[macro_use]` fn err_if_macro_use_proc_macro(&mut self, name: Name, use_span: Span, binding: &NameBinding<'a>) { let krate = match binding.def() { Def::NonMacroAttr(..) | Def::Err => return, Def::Macro(def_id, _) => def_id.krate, _ => unreachable!(), }; // Plugin-based syntax extensions are exempt from this check if krate == BUILTIN_MACROS_CRATE { return; } let ext = binding.get_macro(self); match *ext { // If `ext` is a procedural macro, check if we've already warned about it SyntaxExtension::AttrProcMacro(..) | SyntaxExtension::ProcMacro { .. } => if !self.warned_proc_macros.insert(name) { return; }, _ => return, } let warn_msg = match *ext { SyntaxExtension::AttrProcMacro(..) => "attribute procedural macros cannot be imported with `#[macro_use]`", SyntaxExtension::ProcMacro { .. } => "procedural macros cannot be imported with `#[macro_use]`", _ => return, }; let def_id = self.current_module.normal_ancestor_id; let node_id = self.definitions.as_local_node_id(def_id).unwrap(); self.proc_mac_errors.push(ProcMacError { crate_name: self.cstore.crate_name_untracked(krate), name, module: node_id, use_span, warn_msg, }); } pub fn report_proc_macro_import(&mut self, krate: &ast::Crate) { for err in self.proc_mac_errors.drain(..) { let (span, found_use) = ::UsePlacementFinder::check(krate, err.module); if let Some(span) = span { let found_use = if found_use { "" } else { "\n" }; self.session.struct_span_err(err.use_span, err.warn_msg) .span_suggestion_with_applicability( span, "instead, import the procedural macro like any other item", format!("use {}::{};{}", err.crate_name, err.name, found_use), Applicability::MachineApplicable ).emit(); } else { self.session.struct_span_err(err.use_span, err.warn_msg) .help(&format!("instead, import the procedural macro like any other item: \ `use {}::{};`", err.crate_name, err.name)) .emit(); } } } fn gate_legacy_custom_derive(&mut self, name: Symbol, span: Span) { if !self.session.features_untracked().custom_derive { let sess = &self.session.parse_sess; let explain = feature_gate::EXPLAIN_CUSTOM_DERIVE; emit_feature_err(sess, "custom_derive", span, GateIssue::Language, explain); } else if !self.is_whitelisted_legacy_custom_derive(name) { self.session.span_warn(span, feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE); } } }