src/librustc_resolve/macros.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use {AmbiguityError, CrateLint, Resolver, ResolutionError, is_known_tool, resolve_error};
  12 use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult, Segment, ToNameBinding};
  13 use ModuleOrUniformRoot;
  14 use Namespace::{self, *};
  15 use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
  16 use resolve_imports::ImportResolver;
  17 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX, DefIndex,
  18                          CrateNum, DefIndexAddressSpace};
  19 use rustc::hir::def::{Def, NonMacroAttrKind};
  20 use rustc::hir::map::{self, DefCollector};
  21 use rustc::{ty, lint};
  22 use syntax::ast::{self, Name, Ident};
  23 use syntax::attr;
  24 use syntax::errors::DiagnosticBuilder;
  25 use syntax::ext::base::{self, Determinacy};
  26 use syntax::ext::base::{MacroKind, SyntaxExtension, Resolver as SyntaxResolver};
  27 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
  28 use syntax::ext::hygiene::{self, Mark};
  29 use syntax::ext::tt::macro_rules;
  30 use syntax::feature_gate::{self, feature_err, emit_feature_err, is_builtin_attr_name, GateIssue};
  31 use syntax::feature_gate::EXPLAIN_DERIVE_UNDERSCORE;
  32 use syntax::fold::{self, Folder};
  33 use syntax::parse::parser::PathStyle;
  34 use syntax::parse::token::{self, Token};
  35 use syntax::ptr::P;
  36 use syntax::symbol::{Symbol, keywords};
  37 use syntax::tokenstream::{TokenStream, TokenTree, Delimited, DelimSpan};
  38 use syntax::util::lev_distance::find_best_match_for_name;
  39 use syntax_pos::{Span, DUMMY_SP};
  40 use errors::Applicability;
  41
  42 use std::cell::Cell;
  43 use std::mem;
  44 use rustc_data_structures::sync::Lrc;
  45
  46 #[derive(Clone, Debug)]
  47 pub struct InvocationData<'a> {
  48     def_index: DefIndex,
  49     /// Module in which the macro was invoked.
  50     crate module: Cell<Module<'a>>,
  51     /// Legacy scope in which the macro was invoked.
  52     /// The invocation path is resolved in this scope.
  53     crate parent_legacy_scope: Cell<LegacyScope<'a>>,
  54     /// Legacy scope *produced* by expanding this macro invocation,
  55     /// includes all the macro_rules items, other invocations, etc generated by it.
  56     /// Set to the parent scope if the macro is not expanded yet (as if the macro produced nothing).
  57     crate output_legacy_scope: Cell<LegacyScope<'a>>,
  58 }
  59
  60 impl<'a> InvocationData<'a> {
  61     pub fn root(graph_root: Module<'a>) -> Self {
  62         InvocationData {
  63             module: Cell::new(graph_root),
  64             def_index: CRATE_DEF_INDEX,
  65             parent_legacy_scope: Cell::new(LegacyScope::Empty),
  66             output_legacy_scope: Cell::new(LegacyScope::Empty),
  67         }
  68     }
  69 }
  70
  71 /// Binding produced by a `macro_rules` item.
  72 /// Not modularized, can shadow previous legacy bindings, etc.
  73 #[derive(Debug)]
  74 pub struct LegacyBinding<'a> {
  75     binding: &'a NameBinding<'a>,
  76     /// Legacy scope into which the `macro_rules` item was planted.
  77     parent_legacy_scope: LegacyScope<'a>,
  78     ident: Ident,
  79 }
  80
  81 /// Scope introduced by a `macro_rules!` macro.
  82 /// Starts at the macro's definition and ends at the end of the macro's parent module
  83 /// (named or unnamed), or even further if it escapes with `#[macro_use]`.
  84 /// Some macro invocations need to introduce legacy scopes too because they
  85 /// potentially can expand into macro definitions.
  86 #[derive(Copy, Clone, Debug)]
  87 pub enum LegacyScope<'a> {
  88     /// Created when invocation data is allocated in the arena,
  89     /// must be replaced with a proper scope later.
  90     Uninitialized,
  91     /// Empty "root" scope at the crate start containing no names.
  92     Empty,
  93     /// Scope introduced by a `macro_rules!` macro definition.
  94     Binding(&'a LegacyBinding<'a>),
  95     /// Scope introduced by a macro invocation that can potentially
  96     /// create a `macro_rules!` macro definition.
  97     Invocation(&'a InvocationData<'a>),
  98 }
  99
 100 /// Everything you need to resolve a macro or import path.
 101 #[derive(Clone, Debug)]
 102 pub struct ParentScope<'a> {
 103     crate module: Module<'a>,
 104     crate expansion: Mark,
 105     crate legacy: LegacyScope<'a>,
 106     crate derives: Vec<ast::Path>,
 107 }
 108
 109 // Macro namespace is separated into two sub-namespaces, one for bang macros and
 110 // one for attribute-like macros (attributes, derives).
 111 // We ignore resolutions from one sub-namespace when searching names in scope for another.
 112 fn sub_namespace_mismatch(requirement: Option<MacroKind>, candidate: Option<MacroKind>) -> bool {
 113     #[derive(PartialEq)]
 114     enum SubNS { Bang, AttrLike }
 115     let sub_ns = |kind| match kind {
 116         MacroKind::Bang => Some(SubNS::Bang),
 117         MacroKind::Attr | MacroKind::Derive => Some(SubNS::AttrLike),
 118         MacroKind::ProcMacroStub => None,
 119     };
 120     let requirement = requirement.and_then(|kind| sub_ns(kind));
 121     let candidate = candidate.and_then(|kind| sub_ns(kind));
 122     // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
 123     candidate.is_some() && requirement.is_some() && candidate != requirement
 124 }
 125
 126 impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
 127     fn next_node_id(&mut self) -> ast::NodeId {
 128         self.session.next_node_id()
 129     }
 130
 131     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
 132         let mark = Mark::fresh(Mark::root());
 133         let module = self.module_map[&self.definitions.local_def_id(id)];
 134         self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
 135             module: Cell::new(module),
 136             def_index: module.def_id().unwrap().index,
 137             parent_legacy_scope: Cell::new(LegacyScope::Empty),
 138             output_legacy_scope: Cell::new(LegacyScope::Empty),
 139         }));
 140         mark
 141     }
 142
 143     fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> {
 144         struct EliminateCrateVar<'b, 'a: 'b, 'crateloader: 'a>(
 145             &'b mut Resolver<'a, 'crateloader>, Span
 146         );
 147
 148         impl<'a, 'b, 'crateloader> Folder for EliminateCrateVar<'a, 'b, 'crateloader> {
 149             fn fold_path(&mut self, path: ast::Path) -> ast::Path {
 150                 match self.fold_qpath(None, path) {
 151                     (None, path) => path,
 152                     _ => unreachable!(),
 153                 }
 154             }
 155
 156             fn fold_qpath(&mut self, mut qself: Option<ast::QSelf>, mut path: ast::Path)
 157                           -> (Option<ast::QSelf>, ast::Path) {
 158                 qself = qself.map(|ast::QSelf { ty, path_span, position }| {
 159                     ast::QSelf {
 160                         ty: self.fold_ty(ty),
 161                         path_span: self.new_span(path_span),
 162                         position,
 163                     }
 164                 });
 165
 166                 if path.segments[0].ident.name == keywords::DollarCrate.name() {
 167                     let module = self.0.resolve_crate_root(path.segments[0].ident);
 168                     path.segments[0].ident.name = keywords::CrateRoot.name();
 169                     if !module.is_local() {
 170                         let span = path.segments[0].ident.span;
 171                         path.segments.insert(1, match module.kind {
 172                             ModuleKind::Def(_, name) => ast::PathSegment::from_ident(
 173                                 ast::Ident::with_empty_ctxt(name).with_span_pos(span)
 174                             ),
 175                             _ => unreachable!(),
 176                         });
 177                         if let Some(qself) = &mut qself {
 178                             qself.position += 1;
 179                         }
 180                     }
 181                 }
 182                 (qself, path)
 183             }
 184
 185             fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
 186                 fold::noop_fold_mac(mac, self)
 187             }
 188         }
 189
 190         let ret = EliminateCrateVar(self, item.span).fold_item(item);
 191         assert!(ret.len() == 1);
 192         ret.into_iter().next().unwrap()
 193     }
 194
 195     fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool {
 196         self.whitelisted_legacy_custom_derives.contains(&name)
 197     }
 198
 199     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
 200                                             derives: &[Mark]) {
 201         let invocation = self.invocations[&mark];
 202         self.collect_def_ids(mark, invocation, fragment);
 203
 204         self.current_module = invocation.module.get();
 205         self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
 206         self.current_module.unresolved_invocations.borrow_mut().extend(derives);
 207         self.invocations.extend(derives.iter().map(|&derive| (derive, invocation)));
 208         let mut visitor = BuildReducedGraphVisitor {
 209             resolver: self,
 210             current_legacy_scope: invocation.parent_legacy_scope.get(),
 211             expansion: mark,
 212         };
 213         fragment.visit_with(&mut visitor);
 214         invocation.output_legacy_scope.set(visitor.current_legacy_scope);
 215     }
 216
 217     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
 218         let def_id = DefId {
 219             krate: CrateNum::BuiltinMacros,
 220             index: DefIndex::from_array_index(self.macro_map.len(),
 221                                               DefIndexAddressSpace::Low),
 222         };
 223         let kind = ext.kind();
 224         self.macro_map.insert(def_id, ext);
 225         let binding = self.arenas.alloc_name_binding(NameBinding {
 226             kind: NameBindingKind::Def(Def::Macro(def_id, kind), false),
 227             span: DUMMY_SP,
 228             vis: ty::Visibility::Invisible,
 229             expansion: Mark::root(),
 230         });
 231         if self.builtin_macros.insert(ident.name, binding).is_some() {
 232             self.session.span_err(ident.span,
 233                                   &format!("built-in macro `{}` was already defined", ident));
 234         }
 235     }
 236
 237     fn resolve_imports(&mut self) {
 238         ImportResolver { resolver: self }.resolve_imports()
 239     }
 240
 241     // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
 242     fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>, allow_derive: bool)
 243                               -> Option<ast::Attribute> {
 244         if !allow_derive {
 245             return None;
 246         }
 247
 248         // Check for legacy derives
 249         for i in 0..attrs.len() {
 250             let name = attrs[i].name();
 251
 252             if name == "derive" {
 253                 let result = attrs[i].parse_list(&self.session.parse_sess, |parser| {
 254                     parser.parse_path_allowing_meta(PathStyle::Mod)
 255                 });
 256
 257                 let mut traits = match result {
 258                     Ok(traits) => traits,
 259                     Err(mut e) => {
 260                         e.cancel();
 261                         continue
 262                     }
 263                 };
 264
 265                 for j in 0..traits.len() {
 266                     if traits[j].segments.len() > 1 {
 267                         continue
 268                     }
 269                     let trait_name = traits[j].segments[0].ident.name;
 270                     let legacy_name = Symbol::intern(&format!("derive_{}", trait_name));
 271                     if !self.builtin_macros.contains_key(&legacy_name) {
 272                         continue
 273                     }
 274                     let span = traits.remove(j).span;
 275                     self.gate_legacy_custom_derive(legacy_name, span);
 276                     if traits.is_empty() {
 277                         attrs.remove(i);
 278                     } else {
 279                         let mut tokens = Vec::with_capacity(traits.len() - 1);
 280                         for (j, path) in traits.iter().enumerate() {
 281                             if j > 0 {
 282                                 tokens.push(TokenTree::Token(attrs[i].span, Token::Comma).into());
 283                             }
 284                             tokens.reserve((path.segments.len() * 2).saturating_sub(1));
 285                             for (k, segment) in path.segments.iter().enumerate() {
 286                                 if k > 0 {
 287                                     tokens.push(TokenTree::Token(path.span, Token::ModSep).into());
 288                                 }
 289                                 let tok = Token::from_ast_ident(segment.ident);
 290                                 tokens.push(TokenTree::Token(path.span, tok).into());
 291                             }
 292                         }
 293                         let delim_span = DelimSpan::from_single(attrs[i].span);
 294                         attrs[i].tokens = TokenTree::Delimited(delim_span, Delimited {
 295                             delim: token::Paren,
 296                             tts: TokenStream::concat(tokens).into(),
 297                         }).into();
 298                     }
 299                     return Some(ast::Attribute {
 300                         path: ast::Path::from_ident(Ident::new(legacy_name, span)),
 301                         tokens: TokenStream::empty(),
 302                         id: attr::mk_attr_id(),
 303                         style: ast::AttrStyle::Outer,
 304                         is_sugared_doc: false,
 305                         span,
 306                     });
 307                 }
 308             }
 309         }
 310
 311         None
 312     }
 313
 314     fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
 315                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
 316         let (path, kind, derives_in_scope, after_derive) = match invoc.kind {
 317             InvocationKind::Attr { attr: None, .. } =>
 318                 return Ok(None),
 319             InvocationKind::Attr { attr: Some(ref attr), ref traits, after_derive, .. } =>
 320                 (&attr.path, MacroKind::Attr, traits.clone(), after_derive),
 321             InvocationKind::Bang { ref mac, .. } =>
 322                 (&mac.node.path, MacroKind::Bang, Vec::new(), false),
 323             InvocationKind::Derive { ref path, .. } =>
 324                 (path, MacroKind::Derive, Vec::new(), false),
 325         };
 326
 327         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 328         let (def, ext) = self.resolve_macro_to_def(path, kind, &parent_scope, force)?;
 329
 330         if let Def::Macro(def_id, _) = def {
 331             if after_derive {
 332                 self.session.span_err(invoc.span(),
 333                                       "macro attributes must be placed before `#[derive]`");
 334             }
 335             self.macro_defs.insert(invoc.expansion_data.mark, def_id);
 336             let normal_module_def_id =
 337                 self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
 338             self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
 339                                                             normal_module_def_id);
 340             invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
 341             invoc.expansion_data.mark.set_is_builtin(def_id.krate == CrateNum::BuiltinMacros);
 342         }
 343
 344         Ok(Some(ext))
 345     }
 346
 347     fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
 348                           derives_in_scope: Vec<ast::Path>, force: bool)
 349                           -> Result<Lrc<SyntaxExtension>, Determinacy> {
 350         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 351         Ok(self.resolve_macro_to_def(path, kind, &parent_scope, force)?.1)
 352     }
 353
 354     fn check_unused_macros(&self) {
 355         for did in self.unused_macros.iter() {
 356             let id_span = match *self.macro_map[did] {
 357                 SyntaxExtension::NormalTT { def_info, .. } |
 358                 SyntaxExtension::DeclMacro { def_info, .. } => def_info,
 359                 _ => None,
 360             };
 361             if let Some((id, span)) = id_span {
 362                 let lint = lint::builtin::UNUSED_MACROS;
 363                 let msg = "unused macro definition";
 364                 self.session.buffer_lint(lint, id, span, msg);
 365             } else {
 366                 bug!("attempted to create unused macro error, but span not available");
 367             }
 368         }
 369     }
 370 }
 371
 372 impl<'a, 'cl> Resolver<'a, 'cl> {
 373     pub fn dummy_parent_scope(&mut self) -> ParentScope<'a> {
 374         self.invoc_parent_scope(Mark::root(), Vec::new())
 375     }
 376
 377     fn invoc_parent_scope(&mut self, invoc_id: Mark, derives: Vec<ast::Path>) -> ParentScope<'a> {
 378         let invoc = self.invocations[&invoc_id];
 379         ParentScope {
 380             module: invoc.module.get().nearest_item_scope(),
 381             expansion: invoc_id.parent(),
 382             legacy: invoc.parent_legacy_scope.get(),
 383             derives,
 384         }
 385     }
 386
 387     fn resolve_macro_to_def(
 388         &mut self,
 389         path: &ast::Path,
 390         kind: MacroKind,
 391         parent_scope: &ParentScope<'a>,
 392         force: bool,
 393     ) -> Result<(Def, Lrc<SyntaxExtension>), Determinacy> {
 394         let def = self.resolve_macro_to_def_inner(path, kind, parent_scope, force);
 395
 396         // Report errors and enforce feature gates for the resolved macro.
 397         if def != Err(Determinacy::Undetermined) {
 398             // Do not report duplicated errors on every undetermined resolution.
 399             for segment in &path.segments {
 400                 if let Some(args) = &segment.args {
 401                     self.session.span_err(args.span(), "generic arguments in macro path");
 402                 }
 403             }
 404         }
 405
 406         let def = def?;
 407
 408         match def {
 409             Def::Macro(def_id, macro_kind) => {
 410                 self.unused_macros.remove(&def_id);
 411                 if macro_kind == MacroKind::ProcMacroStub {
 412                     let msg = "can't use a procedural macro from the same crate that defines it";
 413                     self.session.span_err(path.span, msg);
 414                     return Err(Determinacy::Determined);
 415                 }
 416             }
 417             Def::NonMacroAttr(attr_kind) => {
 418                 if kind == MacroKind::Attr {
 419                     let features = self.session.features_untracked();
 420                     if attr_kind == NonMacroAttrKind::Custom {
 421                         assert!(path.segments.len() == 1);
 422                         let name = path.segments[0].ident.name.as_str();
 423                         if name.starts_with("rustc_") {
 424                             if !features.rustc_attrs {
 425                                 let msg = "unless otherwise specified, attributes with the prefix \
 426                                            `rustc_` are reserved for internal compiler diagnostics";
 427                                 feature_err(&self.session.parse_sess, "rustc_attrs", path.span,
 428                                             GateIssue::Language, &msg).emit();
 429                             }
 430                         } else if name.starts_with("derive_") {
 431                             if !features.custom_derive {
 432                                 feature_err(&self.session.parse_sess, "custom_derive", path.span,
 433                                             GateIssue::Language, EXPLAIN_DERIVE_UNDERSCORE).emit();
 434                             }
 435                         } else if !features.custom_attribute {
 436                             let msg = format!("The attribute `{}` is currently unknown to the \
 437                                                compiler and may have meaning added to it in the \
 438                                                future", path);
 439                             feature_err(&self.session.parse_sess, "custom_attribute", path.span,
 440                                         GateIssue::Language, &msg).emit();
 441                         }
 442                     }
 443                 } else {
 444                     // Not only attributes, but anything in macro namespace can result in
 445                     // `Def::NonMacroAttr` definition (e.g. `inline!()`), so we must report
 446                     // an error for those cases.
 447                     let msg = format!("expected a macro, found {}", def.kind_name());
 448                     self.session.span_err(path.span, &msg);
 449                     return Err(Determinacy::Determined);
 450                 }
 451             }
 452             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 453         }
 454
 455         Ok((def, self.get_macro(def)))
 456     }
 457
 458     pub fn resolve_macro_to_def_inner(
 459         &mut self,
 460         path: &ast::Path,
 461         kind: MacroKind,
 462         parent_scope: &ParentScope<'a>,
 463         force: bool,
 464     ) -> Result<Def, Determinacy> {
 465         let path_span = path.span;
 466         let mut path = Segment::from_path(path);
 467
 468         // Possibly apply the macro helper hack
 469         if kind == MacroKind::Bang && path.len() == 1 &&
 470            path[0].ident.span.ctxt().outer().expn_info()
 471                .map_or(false, |info| info.local_inner_macros) {
 472             let root = Ident::new(keywords::DollarCrate.name(), path[0].ident.span);
 473             path.insert(0, Segment::from_ident(root));
 474         }
 475
 476         if path.len() > 1 {
 477             let def = match self.resolve_path(None, &path, Some(MacroNS), parent_scope,
 478                                               false, path_span, CrateLint::No) {
 479                 PathResult::NonModule(path_res) => match path_res.base_def() {
 480                     Def::Err => Err(Determinacy::Determined),
 481                     def @ _ => {
 482                         if path_res.unresolved_segments() > 0 {
 483                             self.found_unresolved_macro = true;
 484                             self.session.span_err(path_span,
 485                                                   "fail to resolve non-ident macro path");
 486                             Err(Determinacy::Determined)
 487                         } else {
 488                             Ok(def)
 489                         }
 490                     }
 491                 },
 492                 PathResult::Module(..) => unreachable!(),
 493                 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
 494                 _ => {
 495                     self.found_unresolved_macro = true;
 496                     Err(Determinacy::Determined)
 497                 },
 498             };
 499
 500             parent_scope.module.macro_resolutions.borrow_mut()
 501                 .push((path, parent_scope.clone(), path_span));
 502
 503             def
 504         } else {
 505             let binding = self.early_resolve_ident_in_lexical_scope(
 506                 path[0].ident, MacroNS, Some(kind), parent_scope, false, force, path_span
 507             );
 508             match binding {
 509                 Ok(..) => {}
 510                 Err(Determinacy::Determined) => self.found_unresolved_macro = true,
 511                 Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
 512             }
 513
 514             parent_scope.module.legacy_macro_resolutions.borrow_mut()
 515                 .push((path[0].ident, kind, parent_scope.clone(), binding.ok()));
 516
 517             binding.map(|binding| binding.def_ignoring_ambiguity())
 518         }
 519     }
 520
 521     // Resolve an identifier in lexical scope.
 522     // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
 523     // expansion and import resolution (perhaps they can be merged in the future).
 524     // The function is used for resolving initial segments of macro paths (e.g. `foo` in
 525     // `foo::bar!(); or `foo!();`) and can be used for "uniform path" imports in the future.
 526     crate fn early_resolve_ident_in_lexical_scope(
 527         &mut self,
 528         mut ident: Ident,
 529         ns: Namespace,
 530         kind: Option<MacroKind>,
 531         parent_scope: &ParentScope<'a>,
 532         record_used: bool,
 533         force: bool,
 534         path_span: Span,
 535     ) -> Result<&'a NameBinding<'a>, Determinacy> {
 536         // General principles:
 537         // 1. Not controlled (user-defined) names should have higher priority than controlled names
 538         //    built into the language or standard library. This way we can add new names into the
 539         //    language or standard library without breaking user code.
 540         // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
 541         // Places to search (in order of decreasing priority):
 542         // (Type NS)
 543         // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
 544         //    (open set, not controlled).
 545         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 546         //    (open, not controlled).
 547         // 3. Extern prelude (closed, not controlled).
 548         // 4. Tool modules (closed, controlled right now, but not in the future).
 549         // 5. Standard library prelude (de-facto closed, controlled).
 550         // 6. Language prelude (closed, controlled).
 551         // (Value NS)
 552         // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
 553         //    (open set, not controlled).
 554         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 555         //    (open, not controlled).
 556         // 3. Standard library prelude (de-facto closed, controlled).
 557         // (Macro NS)
 558         // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
 559         //    are currently reported as errors. They should be higher in priority than preludes
 560         //    and probably even names in modules according to the "general principles" above. They
 561         //    also should be subject to restricted shadowing because are effectively produced by
 562         //    derives (you need to resolve the derive first to add helpers into scope), but they
 563         //    should be available before the derive is expanded for compatibility.
 564         //    It's mess in general, so we are being conservative for now.
 565         // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
 566         //    priority than prelude macros, but create ambiguities with macros in modules.
 567         // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 568         //    (open, not controlled). Have higher priority than prelude macros, but create
 569         //    ambiguities with `macro_rules`.
 570         // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
 571         // 4a. User-defined prelude from macro-use
 572         //    (open, the open part is from macro expansions, not controlled).
 573         // 4b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
 574         // 5. Language prelude: builtin macros (closed, controlled, except for legacy plugins).
 575         // 6. Language prelude: builtin attributes (closed, controlled).
 576         // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
 577         //    but introduced by legacy plugins using `register_attribute`. Priority is somewhere
 578         //    in prelude, not sure where exactly (creates ambiguities with any other prelude names).
 579
 580         enum WhereToResolve<'a> {
 581             DeriveHelpers,
 582             MacroRules(LegacyScope<'a>),
 583             Module(Module<'a>),
 584             MacroUsePrelude,
 585             BuiltinMacros,
 586             BuiltinAttrs,
 587             LegacyPluginHelpers,
 588             ExternPrelude,
 589             ToolPrelude,
 590             StdLibPrelude,
 591             BuiltinTypes,
 592         }
 593
 594         bitflags! {
 595             struct Flags: u8 {
 596                 const DERIVE_HELPERS = 1 << 0;
 597                 const MACRO_RULES    = 1 << 1;
 598                 const MODULE         = 1 << 2;
 599                 const PRELUDE        = 1 << 3;
 600             }
 601         }
 602
 603         assert!(force || !record_used); // `record_used` implies `force`
 604         ident = ident.modern();
 605
 606         // This is *the* result, resolution from the scope closest to the resolved identifier.
 607         // However, sometimes this result is "weak" because it comes from a glob import or
 608         // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
 609         // mod m { ... } // solution in outer scope
 610         // {
 611         //     use prefix::*; // imports another `m` - innermost solution
 612         //                    // weak, cannot shadow the outer `m`, need to report ambiguity error
 613         //     m::mac!();
 614         // }
 615         // So we have to save the innermost solution and continue searching in outer scopes
 616         // to detect potential ambiguities.
 617         let mut innermost_result: Option<(&NameBinding, Flags, /* conflicts with */ Flags)> = None;
 618
 619         // Go through all the scopes and try to resolve the name.
 620         let mut where_to_resolve = WhereToResolve::DeriveHelpers;
 621         let mut use_prelude = !parent_scope.module.no_implicit_prelude;
 622         loop {
 623             let result = match where_to_resolve {
 624                 WhereToResolve::DeriveHelpers => {
 625                     let mut result = Err(Determinacy::Determined);
 626                     for derive in &parent_scope.derives {
 627                         let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
 628                         if let Ok((_, ext)) = self.resolve_macro_to_def(derive, MacroKind::Derive,
 629                                                                         &parent_scope, force) {
 630                             if let SyntaxExtension::ProcMacroDerive(_, helper_attrs, _) = &*ext {
 631                                 if helper_attrs.contains(&ident.name) {
 632                                     let binding =
 633                                         (Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
 634                                         ty::Visibility::Public, derive.span, Mark::root())
 635                                         .to_name_binding(self.arenas);
 636                                     result = Ok((binding, Flags::DERIVE_HELPERS, Flags::all()));
 637                                     break;
 638                                 }
 639                             }
 640                         }
 641                     }
 642                     result
 643                 }
 644                 WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 645                     LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
 646                         Ok((legacy_binding.binding, Flags::MACRO_RULES, Flags::empty())),
 647                     _ => Err(Determinacy::Determined),
 648                 }
 649                 WhereToResolve::Module(module) => {
 650                     let orig_current_module = mem::replace(&mut self.current_module, module);
 651                     let binding = self.resolve_ident_in_module_unadjusted(
 652                         ModuleOrUniformRoot::Module(module),
 653                         ident,
 654                         ns,
 655                         true,
 656                         record_used,
 657                         path_span,
 658                     );
 659                     self.current_module = orig_current_module;
 660                     binding.map(|binding| (binding, Flags::MODULE, Flags::empty()))
 661                 }
 662                 WhereToResolve::MacroUsePrelude => {
 663                     match self.macro_use_prelude.get(&ident.name).cloned() {
 664                         Some(binding) => Ok((binding, Flags::PRELUDE, Flags::empty())),
 665                         None => Err(Determinacy::Determined),
 666                     }
 667                 }
 668                 WhereToResolve::BuiltinMacros => {
 669                     match self.builtin_macros.get(&ident.name).cloned() {
 670                         Some(binding) => Ok((binding, Flags::PRELUDE, Flags::empty())),
 671                         None => Err(Determinacy::Determined),
 672                     }
 673                 }
 674                 WhereToResolve::BuiltinAttrs => {
 675                     if is_builtin_attr_name(ident.name) {
 676                         let binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
 677                                        ty::Visibility::Public, ident.span, Mark::root())
 678                                        .to_name_binding(self.arenas);
 679                         Ok((binding, Flags::PRELUDE, Flags::empty()))
 680                     } else {
 681                         Err(Determinacy::Determined)
 682                     }
 683                 }
 684                 WhereToResolve::LegacyPluginHelpers => {
 685                     if self.session.plugin_attributes.borrow().iter()
 686                                                      .any(|(name, _)| ident.name == &**name) {
 687                         let binding = (Def::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
 688                                        ty::Visibility::Public, ident.span, Mark::root())
 689                                        .to_name_binding(self.arenas);
 690                         Ok((binding, Flags::PRELUDE, Flags::PRELUDE))
 691                     } else {
 692                         Err(Determinacy::Determined)
 693                     }
 694                 }
 695                 WhereToResolve::ExternPrelude => {
 696                     let mut result = Err(Determinacy::Determined);
 697                     if use_prelude {
 698                         if let Some(binding) = self.extern_prelude_get(ident, !record_used,
 699                                                                        innermost_result.is_some()) {
 700                             result = Ok((binding, Flags::PRELUDE, Flags::empty()));
 701                         }
 702                     }
 703                     result
 704                 }
 705                 WhereToResolve::ToolPrelude => {
 706                     if use_prelude && is_known_tool(ident.name) {
 707                         let binding = (Def::ToolMod, ty::Visibility::Public,
 708                                        ident.span, Mark::root()).to_name_binding(self.arenas);
 709                         Ok((binding, Flags::PRELUDE, Flags::empty()))
 710                     } else {
 711                         Err(Determinacy::Determined)
 712                     }
 713                 }
 714                 WhereToResolve::StdLibPrelude => {
 715                     let mut result = Err(Determinacy::Determined);
 716                     if use_prelude {
 717                         if let Some(prelude) = self.prelude {
 718                             if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
 719                                 ModuleOrUniformRoot::Module(prelude),
 720                                 ident,
 721                                 ns,
 722                                 false,
 723                                 false,
 724                                 path_span,
 725                             ) {
 726                                 result = Ok((binding, Flags::PRELUDE, Flags::empty()));
 727                             }
 728                         }
 729                     }
 730                     result
 731                 }
 732                 WhereToResolve::BuiltinTypes => {
 733                     match self.primitive_type_table.primitive_types.get(&ident.name).cloned() {
 734                         Some(prim_ty) => {
 735                             let binding = (Def::PrimTy(prim_ty), ty::Visibility::Public,
 736                                            ident.span, Mark::root()).to_name_binding(self.arenas);
 737                             Ok((binding, Flags::PRELUDE, Flags::empty()))
 738                         }
 739                         None => Err(Determinacy::Determined)
 740                     }
 741                 }
 742             };
 743
 744             macro_rules! continue_search { () => {
 745                 where_to_resolve = match where_to_resolve {
 746                     WhereToResolve::DeriveHelpers =>
 747                         WhereToResolve::MacroRules(parent_scope.legacy),
 748                     WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 749                         LegacyScope::Binding(binding) =>
 750                             WhereToResolve::MacroRules(binding.parent_legacy_scope),
 751                         LegacyScope::Invocation(invocation) =>
 752                             WhereToResolve::MacroRules(invocation.output_legacy_scope.get()),
 753                         LegacyScope::Empty => WhereToResolve::Module(parent_scope.module),
 754                         LegacyScope::Uninitialized => unreachable!(),
 755                     }
 756                     WhereToResolve::Module(module) => {
 757                         match self.hygienic_lexical_parent(module, &mut ident.span) {
 758                             Some(parent_module) => WhereToResolve::Module(parent_module),
 759                             None => {
 760                                 use_prelude = !module.no_implicit_prelude;
 761                                 match ns {
 762                                     TypeNS => WhereToResolve::ExternPrelude,
 763                                     ValueNS => WhereToResolve::StdLibPrelude,
 764                                     MacroNS => WhereToResolve::MacroUsePrelude,
 765                                 }
 766                             }
 767                         }
 768                     }
 769                     WhereToResolve::MacroUsePrelude => WhereToResolve::BuiltinMacros,
 770                     WhereToResolve::BuiltinMacros => WhereToResolve::BuiltinAttrs,
 771                     WhereToResolve::BuiltinAttrs => WhereToResolve::LegacyPluginHelpers,
 772                     WhereToResolve::LegacyPluginHelpers => break, // nowhere else to search
 773                     WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
 774                     WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
 775                     WhereToResolve::StdLibPrelude => match ns {
 776                         TypeNS => WhereToResolve::BuiltinTypes,
 777                         ValueNS => break, // nowhere else to search
 778                         MacroNS => unreachable!(),
 779                     }
 780                     WhereToResolve::BuiltinTypes => break, // nowhere else to search
 781                 };
 782
 783                 continue;
 784             }}
 785
 786             match result {
 787                 Ok((binding, flags, ambig_flags)) => {
 788                     if sub_namespace_mismatch(kind, binding.macro_kind()) {
 789                         continue_search!();
 790                     }
 791
 792                     if !record_used {
 793                         return Ok(binding);
 794                     }
 795
 796                     if let Some((innermost_binding, innermost_flags, innermost_ambig_flags))
 797                             = innermost_result {
 798                         // Found another solution, if the first one was "weak", report an error.
 799                         if binding.def() != innermost_binding.def() &&
 800                            (innermost_binding.is_glob_import() ||
 801                             innermost_binding.may_appear_after(parent_scope.expansion, binding) ||
 802                             innermost_flags.intersects(ambig_flags) ||
 803                             flags.intersects(innermost_ambig_flags) ||
 804                             (innermost_flags.contains(Flags::MACRO_RULES) &&
 805                              flags.contains(Flags::MODULE) &&
 806                              !self.disambiguate_legacy_vs_modern(innermost_binding, binding))) {
 807                             self.ambiguity_errors.push(AmbiguityError {
 808                                 ident,
 809                                 b1: innermost_binding,
 810                                 b2: binding,
 811                             });
 812                             return Ok(innermost_binding);
 813                         }
 814                     } else {
 815                         // Found the first solution.
 816                         innermost_result = Some((binding, flags, ambig_flags));
 817                     }
 818
 819                     continue_search!();
 820                 },
 821                 Err(Determinacy::Determined) => {
 822                     continue_search!();
 823                 }
 824                 Err(Determinacy::Undetermined) => return Err(Determinacy::determined(force)),
 825             }
 826         }
 827
 828         // The first found solution was the only one, return it.
 829         if let Some((binding, ..)) = innermost_result {
 830             return Ok(binding);
 831         }
 832
 833         let determinacy = Determinacy::determined(force);
 834         if determinacy == Determinacy::Determined && kind == Some(MacroKind::Attr) {
 835             // For single-segment attributes interpret determinate "no resolution" as a custom
 836             // attribute. (Lexical resolution implies the first segment and attr kind should imply
 837             // the last segment, so we are certainly working with a single-segment attribute here.)
 838             assert!(ns == MacroNS);
 839             let binding = (Def::NonMacroAttr(NonMacroAttrKind::Custom),
 840                            ty::Visibility::Public, ident.span, Mark::root())
 841                            .to_name_binding(self.arenas);
 842             Ok(binding)
 843         } else {
 844             Err(determinacy)
 845         }
 846     }
 847
 848     pub fn finalize_current_module_macro_resolutions(&mut self) {
 849         let module = self.current_module;
 850
 851         let macro_resolutions =
 852             mem::replace(&mut *module.macro_resolutions.borrow_mut(), Vec::new());
 853         for (mut path, parent_scope, path_span) in macro_resolutions {
 854             // FIXME: Path resolution will ICE if segment IDs present.
 855             for seg in &mut path { seg.id = None; }
 856             match self.resolve_path(None, &path, Some(MacroNS), &parent_scope,
 857                                     true, path_span, CrateLint::No) {
 858                 PathResult::NonModule(_) => {},
 859                 PathResult::Failed(span, msg, _) => {
 860                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
 861                 }
 862                 _ => unreachable!(),
 863             }
 864         }
 865
 866         let legacy_macro_resolutions =
 867             mem::replace(&mut *module.legacy_macro_resolutions.borrow_mut(), Vec::new());
 868         for (ident, kind, parent_scope, initial_binding) in legacy_macro_resolutions {
 869             let binding = self.early_resolve_ident_in_lexical_scope(
 870                 ident, MacroNS, Some(kind), &parent_scope, true, true, ident.span
 871             );
 872             match binding {
 873                 Ok(binding) => {
 874                     let def = binding.def_ignoring_ambiguity();
 875                     if let Some(initial_binding) = initial_binding {
 876                         self.record_use(ident, MacroNS, initial_binding);
 877                         let initial_def = initial_binding.def_ignoring_ambiguity();
 878                         if self.ambiguity_errors.is_empty() &&
 879                            def != initial_def && def != Def::Err {
 880                             // Make sure compilation does not succeed if preferred macro resolution
 881                             // has changed after the macro had been expanded. In theory all such
 882                             // situations should be reported as ambiguity errors, so this is a bug.
 883                             span_bug!(ident.span, "inconsistent resolution for a macro");
 884                         }
 885                     } else {
 886                         // It's possible that the macro was unresolved (indeterminate) and silently
 887                         // expanded into a dummy fragment for recovery during expansion.
 888                         // Now, post-expansion, the resolution may succeed, but we can't change the
 889                         // past and need to report an error.
 890                         let msg = format!("cannot determine resolution for the {} `{}`",
 891                                           kind.descr(), ident);
 892                         let msg_note = "import resolution is stuck, try simplifying macro imports";
 893                         self.session.struct_span_err(ident.span, &msg).note(msg_note).emit();
 894                     }
 895                 }
 896                 Err(..) => {
 897                     assert!(initial_binding.is_none());
 898                     let bang = if kind == MacroKind::Bang { "!" } else { "" };
 899                     let msg =
 900                         format!("cannot find {} `{}{}` in this scope", kind.descr(), ident, bang);
 901                     let mut err = self.session.struct_span_err(ident.span, &msg);
 902                     self.suggest_macro_name(&ident.as_str(), kind, &mut err, ident.span);
 903                     err.emit();
 904                 }
 905             }
 906         }
 907
 908         let builtin_attrs = mem::replace(&mut *module.builtin_attrs.borrow_mut(), Vec::new());
 909         for (ident, parent_scope) in builtin_attrs {
 910             let binding = self.early_resolve_ident_in_lexical_scope(
 911                 ident, MacroNS, Some(MacroKind::Attr), &parent_scope, true, true, ident.span
 912             );
 913             if let Ok(binding) = binding {
 914                 if binding.def_ignoring_ambiguity() !=
 915                         Def::NonMacroAttr(NonMacroAttrKind::Builtin) {
 916                     let builtin_binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
 917                                            ty::Visibility::Public, ident.span, Mark::root())
 918                                            .to_name_binding(self.arenas);
 919                     self.report_ambiguity_error(ident, binding, builtin_binding);
 920                 }
 921             }
 922         }
 923     }
 924
 925     fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
 926                           err: &mut DiagnosticBuilder<'a>, span: Span) {
 927         // First check if this is a locally-defined bang macro.
 928         let suggestion = if let MacroKind::Bang = kind {
 929             find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None)
 930         } else {
 931             None
 932         // Then check global macros.
 933         }.or_else(|| {
 934             let names = self.builtin_macros.iter().chain(self.macro_use_prelude.iter())
 935                                                   .filter_map(|(name, binding)| {
 936                 if binding.macro_kind() == Some(kind) { Some(name) } else { None }
 937             });
 938             find_best_match_for_name(names, name, None)
 939         // Then check modules.
 940         }).or_else(|| {
 941             let is_macro = |def| {
 942                 if let Def::Macro(_, def_kind) = def {
 943                     def_kind == kind
 944                 } else {
 945                     false
 946                 }
 947             };
 948             let ident = Ident::new(Symbol::intern(name), span);
 949             self.lookup_typo_candidate(&[Segment::from_ident(ident)], MacroNS, is_macro, span)
 950         });
 951
 952         if let Some(suggestion) = suggestion {
 953             if suggestion != name {
 954                 if let MacroKind::Bang = kind {
 955                     err.span_suggestion_with_applicability(
 956                         span,
 957                         "you could try the macro",
 958                         suggestion.to_string(),
 959                         Applicability::MaybeIncorrect
 960                     );
 961                 } else {
 962                     err.span_suggestion_with_applicability(
 963                         span,
 964                         "try",
 965                         suggestion.to_string(),
 966                         Applicability::MaybeIncorrect
 967                     );
 968                 }
 969             } else {
 970                 err.help("have you added the `#[macro_use]` on the module/import?");
 971             }
 972         }
 973     }
 974
 975     fn collect_def_ids(&mut self,
 976                        mark: Mark,
 977                        invocation: &'a InvocationData<'a>,
 978                        fragment: &AstFragment) {
 979         let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
 980         let InvocationData { def_index, .. } = *invocation;
 981
 982         let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
 983             invocations.entry(invoc.mark).or_insert_with(|| {
 984                 arenas.alloc_invocation_data(InvocationData {
 985                     def_index: invoc.def_index,
 986                     module: Cell::new(graph_root),
 987                     parent_legacy_scope: Cell::new(LegacyScope::Uninitialized),
 988                     output_legacy_scope: Cell::new(LegacyScope::Uninitialized),
 989                 })
 990             });
 991         };
 992
 993         let mut def_collector = DefCollector::new(&mut self.definitions, mark);
 994         def_collector.visit_macro_invoc = Some(visit_macro_invoc);
 995         def_collector.with_parent(def_index, |def_collector| {
 996             fragment.visit_with(def_collector)
 997         });
 998     }
 999
1000     pub fn define_macro(&mut self,
1001                         item: &ast::Item,
1002                         expansion: Mark,
1003                         current_legacy_scope: &mut LegacyScope<'a>) {
1004         self.local_macro_def_scopes.insert(item.id, self.current_module);
1005         let ident = item.ident;
1006         if ident.name == "macro_rules" {
1007             self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
1008         }
1009
1010         let def_id = self.definitions.local_def_id(item.id);
1011         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
1012                                                &self.session.features_untracked(),
1013                                                item, hygiene::default_edition()));
1014         self.macro_map.insert(def_id, ext);
1015
1016         let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
1017         if def.legacy {
1018             let ident = ident.modern();
1019             self.macro_names.insert(ident);
1020             let def = Def::Macro(def_id, MacroKind::Bang);
1021             let vis = ty::Visibility::Invisible; // Doesn't matter for legacy bindings
1022             let binding = (def, vis, item.span, expansion).to_name_binding(self.arenas);
1023             self.set_binding_parent_module(binding, self.current_module);
1024             let legacy_binding = self.arenas.alloc_legacy_binding(LegacyBinding {
1025                 parent_legacy_scope: *current_legacy_scope, binding, ident
1026             });
1027             *current_legacy_scope = LegacyScope::Binding(legacy_binding);
1028             self.all_macros.insert(ident.name, def);
1029             if attr::contains_name(&item.attrs, "macro_export") {
1030                 let module = self.graph_root;
1031                 let vis = ty::Visibility::Public;
1032                 self.define(module, ident, MacroNS,
1033                             (def, vis, item.span, expansion, IsMacroExport));
1034             } else {
1035                 if !attr::contains_name(&item.attrs, "rustc_doc_only_macro") {
1036                     self.check_reserved_macro_name(ident, MacroNS);
1037                 }
1038                 self.unused_macros.insert(def_id);
1039             }
1040         } else {
1041             let module = self.current_module;
1042             let def = Def::Macro(def_id, MacroKind::Bang);
1043             let vis = self.resolve_visibility(&item.vis);
1044             if vis != ty::Visibility::Public {
1045                 self.unused_macros.insert(def_id);
1046             }
1047             self.define(module, ident, MacroNS, (def, vis, item.span, expansion));
1048         }
1049     }
1050
1051     fn gate_legacy_custom_derive(&mut self, name: Symbol, span: Span) {
1052         if !self.session.features_untracked().custom_derive {
1053             let sess = &self.session.parse_sess;
1054             let explain = feature_gate::EXPLAIN_CUSTOM_DERIVE;
1055             emit_feature_err(sess, "custom_derive", span, GateIssue::Language, explain);
1056         } else if !self.is_whitelisted_legacy_custom_derive(name) {
1057             self.session.span_warn(span, feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE);
1058         }
1059     }
1060 }