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, Resolver, ResolutionError, resolve_error};
  12 use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult};
  13 use Namespace::{self, MacroNS};
  14 use build_reduced_graph::BuildReducedGraphVisitor;
  15 use resolve_imports::ImportResolver;
  16 use rustc_data_structures::indexed_vec::Idx;
  17 use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex};
  18 use rustc::hir::def::{Def, Export};
  19 use rustc::hir::map::{self, DefCollector};
  20 use rustc::{ty, lint};
  21 use syntax::ast::{self, Name, Ident};
  22 use syntax::attr::{self, HasAttrs};
  23 use syntax::codemap::respan;
  24 use syntax::errors::DiagnosticBuilder;
  25 use syntax::ext::base::{self, Annotatable, Determinacy, MultiModifier, MultiDecorator};
  26 use syntax::ext::base::{MacroKind, SyntaxExtension, Resolver as SyntaxResolver};
  27 use syntax::ext::expand::{Expansion, ExpansionKind, Invocation, InvocationKind, find_attr_invoc};
  28 use syntax::ext::hygiene::Mark;
  29 use syntax::ext::placeholders::placeholder;
  30 use syntax::ext::tt::macro_rules;
  31 use syntax::feature_gate::{self, emit_feature_err, GateIssue};
  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};
  38 use syntax::util::lev_distance::find_best_match_for_name;
  39 use syntax_pos::{Span, DUMMY_SP};
  40
  41 use std::cell::Cell;
  42 use std::mem;
  43 use std::rc::Rc;
  44
  45 #[derive(Clone)]
  46 pub struct InvocationData<'a> {
  47     pub module: Cell<Module<'a>>,
  48     pub def_index: DefIndex,
  49     // True if this expansion is in a `const_expr` position, for example `[u32; m!()]`.
  50     // c.f. `DefCollector::visit_const_expr`.
  51     pub const_expr: bool,
  52     // The scope in which the invocation path is resolved.
  53     pub legacy_scope: Cell<LegacyScope<'a>>,
  54     // The smallest scope that includes this invocation's expansion,
  55     // or `Empty` if this invocation has not been expanded yet.
  56     pub expansion: Cell<LegacyScope<'a>>,
  57 }
  58
  59 impl<'a> InvocationData<'a> {
  60     pub fn root(graph_root: Module<'a>) -> Self {
  61         InvocationData {
  62             module: Cell::new(graph_root),
  63             def_index: CRATE_DEF_INDEX,
  64             const_expr: false,
  65             legacy_scope: Cell::new(LegacyScope::Empty),
  66             expansion: Cell::new(LegacyScope::Empty),
  67         }
  68     }
  69 }
  70
  71 #[derive(Copy, Clone)]
  72 pub enum LegacyScope<'a> {
  73     Empty,
  74     Invocation(&'a InvocationData<'a>), // The scope of the invocation, not including its expansion
  75     Expansion(&'a InvocationData<'a>), // The scope of the invocation, including its expansion
  76     Binding(&'a LegacyBinding<'a>),
  77 }
  78
  79 pub struct LegacyBinding<'a> {
  80     pub parent: Cell<LegacyScope<'a>>,
  81     pub ident: Ident,
  82     def_id: DefId,
  83     pub span: Span,
  84 }
  85
  86 pub struct ProcMacError {
  87     crate_name: Symbol,
  88     name: Symbol,
  89     module: ast::NodeId,
  90     use_span: Span,
  91     warn_msg: &'static str,
  92 }
  93
  94 #[derive(Copy, Clone)]
  95 pub enum MacroBinding<'a> {
  96     Legacy(&'a LegacyBinding<'a>),
  97     Global(&'a NameBinding<'a>),
  98     Modern(&'a NameBinding<'a>),
  99 }
 100
 101 impl<'a> MacroBinding<'a> {
 102     pub fn span(self) -> Span {
 103         match self {
 104             MacroBinding::Legacy(binding) => binding.span,
 105             MacroBinding::Global(binding) | MacroBinding::Modern(binding) => binding.span,
 106         }
 107     }
 108
 109     pub fn binding(self) -> &'a NameBinding<'a> {
 110         match self {
 111             MacroBinding::Global(binding) | MacroBinding::Modern(binding) => binding,
 112             MacroBinding::Legacy(_) => panic!("unexpected MacroBinding::Legacy"),
 113         }
 114     }
 115 }
 116
 117 impl<'a> base::Resolver for Resolver<'a> {
 118     fn next_node_id(&mut self) -> ast::NodeId {
 119         self.session.next_node_id()
 120     }
 121
 122     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
 123         let mark = Mark::fresh(Mark::root());
 124         let module = self.module_map[&self.definitions.local_def_id(id)];
 125         self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
 126             module: Cell::new(module),
 127             def_index: module.def_id().unwrap().index,
 128             const_expr: false,
 129             legacy_scope: Cell::new(LegacyScope::Empty),
 130             expansion: Cell::new(LegacyScope::Empty),
 131         }));
 132         mark
 133     }
 134
 135     fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> {
 136         struct EliminateCrateVar<'b, 'a: 'b>(&'b mut Resolver<'a>, Span);
 137
 138         impl<'a, 'b> Folder for EliminateCrateVar<'a, 'b> {
 139             fn fold_path(&mut self, mut path: ast::Path) -> ast::Path {
 140                 let ident = path.segments[0].identifier;
 141                 if ident.name == keywords::DollarCrate.name() {
 142                     path.segments[0].identifier.name = keywords::CrateRoot.name();
 143                     let module = self.0.resolve_crate_root(ident.ctxt);
 144                     if !module.is_local() {
 145                         let span = path.segments[0].span;
 146                         path.segments.insert(1, match module.kind {
 147                             ModuleKind::Def(_, name) => ast::PathSegment::from_ident(
 148                                 ast::Ident::with_empty_ctxt(name), span
 149                             ),
 150                             _ => unreachable!(),
 151                         })
 152                     }
 153                 }
 154                 path
 155             }
 156
 157             fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
 158                 fold::noop_fold_mac(mac, self)
 159             }
 160         }
 161
 162         EliminateCrateVar(self, item.span).fold_item(item).expect_one("")
 163     }
 164
 165     fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool {
 166         self.whitelisted_legacy_custom_derives.contains(&name)
 167     }
 168
 169     fn visit_expansion(&mut self, mark: Mark, expansion: &Expansion, derives: &[Mark]) {
 170         let invocation = self.invocations[&mark];
 171         self.collect_def_ids(mark, invocation, expansion);
 172
 173         self.current_module = invocation.module.get();
 174         self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
 175         self.current_module.unresolved_invocations.borrow_mut().extend(derives);
 176         for &derive in derives {
 177             self.invocations.insert(derive, invocation);
 178         }
 179         let mut visitor = BuildReducedGraphVisitor {
 180             resolver: self,
 181             legacy_scope: LegacyScope::Invocation(invocation),
 182             expansion: mark,
 183         };
 184         expansion.visit_with(&mut visitor);
 185         invocation.expansion.set(visitor.legacy_scope);
 186     }
 187
 188     fn add_builtin(&mut self, ident: ast::Ident, ext: Rc<SyntaxExtension>) {
 189         let def_id = DefId {
 190             krate: BUILTIN_MACROS_CRATE,
 191             index: DefIndex::new(self.macro_map.len()),
 192         };
 193         let kind = ext.kind();
 194         self.macro_map.insert(def_id, ext);
 195         let binding = self.arenas.alloc_name_binding(NameBinding {
 196             kind: NameBindingKind::Def(Def::Macro(def_id, kind)),
 197             span: DUMMY_SP,
 198             vis: ty::Visibility::Invisible,
 199             expansion: Mark::root(),
 200         });
 201         self.global_macros.insert(ident.name, binding);
 202     }
 203
 204     fn resolve_imports(&mut self) {
 205         ImportResolver { resolver: self }.resolve_imports()
 206     }
 207
 208     // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
 209     fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>)
 210                               -> Option<ast::Attribute> {
 211         for i in 0..attrs.len() {
 212             let name = unwrap_or!(attrs[i].name(), continue);
 213
 214             if self.session.plugin_attributes.borrow().iter()
 215                     .any(|&(ref attr_nm, _)| name == &**attr_nm) {
 216                 attr::mark_known(&attrs[i]);
 217             }
 218
 219             match self.global_macros.get(&name).cloned() {
 220                 Some(binding) => match *binding.get_macro(self) {
 221                     MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
 222                         return Some(attrs.remove(i))
 223                     }
 224                     _ => {}
 225                 },
 226                 None => {}
 227             }
 228         }
 229
 230         // Check for legacy derives
 231         for i in 0..attrs.len() {
 232             let name = unwrap_or!(attrs[i].name(), continue);
 233
 234             if name == "derive" {
 235                 let result = attrs[i].parse_list(&self.session.parse_sess, |parser| {
 236                     parser.parse_path_allowing_meta(PathStyle::Mod)
 237                 });
 238
 239                 let mut traits = match result {
 240                     Ok(traits) => traits,
 241                     Err(mut e) => {
 242                         e.cancel();
 243                         continue
 244                     }
 245                 };
 246
 247                 for j in 0..traits.len() {
 248                     if traits[j].segments.len() > 1 {
 249                         continue
 250                     }
 251                     let trait_name = traits[j].segments[0].identifier.name;
 252                     let legacy_name = Symbol::intern(&format!("derive_{}", trait_name));
 253                     if !self.global_macros.contains_key(&legacy_name) {
 254                         continue
 255                     }
 256                     let span = traits.remove(j).span;
 257                     self.gate_legacy_custom_derive(legacy_name, span);
 258                     if traits.is_empty() {
 259                         attrs.remove(i);
 260                     } else {
 261                         let mut tokens = Vec::new();
 262                         for (j, path) in traits.iter().enumerate() {
 263                             if j > 0 {
 264                                 tokens.push(TokenTree::Token(attrs[i].span, Token::Comma).into());
 265                             }
 266                             for (k, segment) in path.segments.iter().enumerate() {
 267                                 if k > 0 {
 268                                     tokens.push(TokenTree::Token(path.span, Token::ModSep).into());
 269                                 }
 270                                 let tok = Token::Ident(segment.identifier);
 271                                 tokens.push(TokenTree::Token(path.span, tok).into());
 272                             }
 273                         }
 274                         attrs[i].tokens = TokenTree::Delimited(attrs[i].span, Delimited {
 275                             delim: token::Paren,
 276                             tts: TokenStream::concat(tokens).into(),
 277                         }).into();
 278                     }
 279                     return Some(ast::Attribute {
 280                         path: ast::Path::from_ident(span, Ident::with_empty_ctxt(legacy_name)),
 281                         tokens: TokenStream::empty(),
 282                         id: attr::mk_attr_id(),
 283                         style: ast::AttrStyle::Outer,
 284                         is_sugared_doc: false,
 285                         span,
 286                     });
 287                 }
 288             }
 289         }
 290
 291         None
 292     }
 293
 294     fn resolve_invoc(&mut self, invoc: &mut Invocation, scope: Mark, force: bool)
 295                      -> Result<Option<Rc<SyntaxExtension>>, Determinacy> {
 296         let def = match invoc.kind {
 297             InvocationKind::Attr { attr: None, .. } => return Ok(None),
 298             _ => self.resolve_invoc_to_def(invoc, scope, force)?,
 299         };
 300
 301         self.macro_defs.insert(invoc.expansion_data.mark, def.def_id());
 302         let normal_module_def_id =
 303             self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
 304         self.definitions.add_macro_def_scope(invoc.expansion_data.mark, normal_module_def_id);
 305
 306         self.unused_macros.remove(&def.def_id());
 307         let ext = self.get_macro(def);
 308         if ext.is_modern() {
 309             invoc.expansion_data.mark.set_modern();
 310         }
 311         Ok(Some(ext))
 312     }
 313
 314     fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
 315                      -> Result<Rc<SyntaxExtension>, Determinacy> {
 316         self.resolve_macro_to_def(scope, path, kind, force).map(|def| {
 317             self.unused_macros.remove(&def.def_id());
 318             self.get_macro(def)
 319         })
 320     }
 321
 322     fn check_unused_macros(&self) {
 323         for did in self.unused_macros.iter() {
 324             let id_span = match *self.macro_map[did] {
 325                 SyntaxExtension::NormalTT { def_info, .. } => def_info,
 326                 SyntaxExtension::DeclMacro(.., osp) => osp,
 327                 _ => None,
 328             };
 329             if let Some((id, span)) = id_span {
 330                 let lint = lint::builtin::UNUSED_MACROS;
 331                 let msg = "unused macro definition";
 332                 self.session.buffer_lint(lint, id, span, msg);
 333             } else {
 334                 bug!("attempted to create unused macro error, but span not available");
 335             }
 336         }
 337     }
 338 }
 339
 340 impl<'a> Resolver<'a> {
 341     fn resolve_invoc_to_def(&mut self, invoc: &mut Invocation, scope: Mark, force: bool)
 342                             -> Result<Def, Determinacy> {
 343         let (attr, traits, item) = match invoc.kind {
 344             InvocationKind::Attr { ref mut attr, ref traits, ref mut item } => (attr, traits, item),
 345             InvocationKind::Bang { ref mac, .. } => {
 346                 return self.resolve_macro_to_def(scope, &mac.node.path, MacroKind::Bang, force);
 347             }
 348             InvocationKind::Derive { ref path, .. } => {
 349                 return self.resolve_macro_to_def(scope, path, MacroKind::Derive, force);
 350             }
 351         };
 352
 353
 354         let path = attr.as_ref().unwrap().path.clone();
 355         let mut determinacy = Determinacy::Determined;
 356         match self.resolve_macro_to_def(scope, &path, MacroKind::Attr, force) {
 357             Ok(def) => return Ok(def),
 358             Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
 359             Err(Determinacy::Determined) if force => return Err(Determinacy::Determined),
 360             Err(Determinacy::Determined) => {}
 361         }
 362
 363         let attr_name = match path.segments.len() {
 364             1 => path.segments[0].identifier.name,
 365             _ => return Err(determinacy),
 366         };
 367         for path in traits {
 368             match self.resolve_macro(scope, path, MacroKind::Derive, force) {
 369                 Ok(ext) => if let SyntaxExtension::ProcMacroDerive(_, ref inert_attrs) = *ext {
 370                     if inert_attrs.contains(&attr_name) {
 371                         // FIXME(jseyfried) Avoid `mem::replace` here.
 372                         let dummy_item = placeholder(ExpansionKind::Items, ast::DUMMY_NODE_ID)
 373                             .make_items().pop().unwrap();
 374                         let dummy_item = Annotatable::Item(dummy_item);
 375                         *item = mem::replace(item, dummy_item).map_attrs(|mut attrs| {
 376                             let inert_attr = attr.take().unwrap();
 377                             attr::mark_known(&inert_attr);
 378                             if self.proc_macro_enabled {
 379                                 *attr = find_attr_invoc(&mut attrs);
 380                             }
 381                             attrs.push(inert_attr);
 382                             attrs
 383                         });
 384                     }
 385                     return Err(Determinacy::Undetermined);
 386                 },
 387                 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
 388                 Err(Determinacy::Determined) => {}
 389             }
 390         }
 391
 392         Err(determinacy)
 393     }
 394
 395     fn resolve_macro_to_def(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
 396                             -> Result<Def, Determinacy> {
 397         let def = self.resolve_macro_to_def_inner(scope, path, kind, force);
 398         if def != Err(Determinacy::Undetermined) {
 399             // Do not report duplicated errors on every undetermined resolution.
 400             path.segments.iter().find(|segment| segment.parameters.is_some()).map(|segment| {
 401                 self.session.span_err(segment.parameters.as_ref().unwrap().span(),
 402                                       "generic arguments in macro path");
 403             });
 404         }
 405         def
 406     }
 407
 408     fn resolve_macro_to_def_inner(&mut self, scope: Mark, path: &ast::Path,
 409                                   kind: MacroKind, force: bool)
 410                                   -> Result<Def, Determinacy> {
 411         let ast::Path { ref segments, span } = *path;
 412         let path: Vec<_> = segments.iter().map(|seg| respan(seg.span, seg.identifier)).collect();
 413         let invocation = self.invocations[&scope];
 414         let module = invocation.module.get();
 415         self.current_module = if module.is_trait() { module.parent.unwrap() } else { module };
 416
 417         if path.len() > 1 {
 418             if !self.use_extern_macros && self.gated_errors.insert(span) {
 419                 let msg = "non-ident macro paths are experimental";
 420                 let feature = "use_extern_macros";
 421                 emit_feature_err(&self.session.parse_sess, feature, span, GateIssue::Language, msg);
 422                 self.found_unresolved_macro = true;
 423                 return Err(Determinacy::Determined);
 424             }
 425
 426             let def = match self.resolve_path(&path, Some(MacroNS), false, span) {
 427                 PathResult::NonModule(path_res) => match path_res.base_def() {
 428                     Def::Err => Err(Determinacy::Determined),
 429                     def @ _ => Ok(def),
 430                 },
 431                 PathResult::Module(..) => unreachable!(),
 432                 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
 433                 _ => {
 434                     self.found_unresolved_macro = true;
 435                     Err(Determinacy::Determined)
 436                 },
 437             };
 438             let path = path.iter().map(|p| p.node).collect::<Vec<_>>();
 439             self.current_module.nearest_item_scope().macro_resolutions.borrow_mut()
 440                 .push((path.into_boxed_slice(), span));
 441             return def;
 442         }
 443
 444         let legacy_resolution = self.resolve_legacy_scope(&invocation.legacy_scope,
 445                                                           path[0].node,
 446                                                           false);
 447         let result = if let Some(MacroBinding::Legacy(binding)) = legacy_resolution {
 448             Ok(Def::Macro(binding.def_id, MacroKind::Bang))
 449         } else {
 450             match self.resolve_lexical_macro_path_segment(path[0].node, MacroNS, false, span) {
 451                 Ok(binding) => Ok(binding.binding().def_ignoring_ambiguity()),
 452                 Err(Determinacy::Undetermined) if !force => return Err(Determinacy::Undetermined),
 453                 Err(_) => {
 454                     self.found_unresolved_macro = true;
 455                     Err(Determinacy::Determined)
 456                 }
 457             }
 458         };
 459
 460         self.current_module.nearest_item_scope().legacy_macro_resolutions.borrow_mut()
 461             .push((scope, path[0].node, span, kind));
 462
 463         result
 464     }
 465
 466     // Resolve the initial segment of a non-global macro path (e.g. `foo` in `foo::bar!();`)
 467     pub fn resolve_lexical_macro_path_segment(&mut self,
 468                                               mut ident: Ident,
 469                                               ns: Namespace,
 470                                               record_used: bool,
 471                                               path_span: Span)
 472                                               -> Result<MacroBinding<'a>, Determinacy> {
 473         ident = ident.modern();
 474         let mut module = Some(self.current_module);
 475         let mut potential_illegal_shadower = Err(Determinacy::Determined);
 476         let determinacy =
 477             if record_used { Determinacy::Determined } else { Determinacy::Undetermined };
 478         loop {
 479             let orig_current_module = self.current_module;
 480             let result = if let Some(module) = module {
 481                 self.current_module = module; // Lexical resolutions can never be a privacy error.
 482                 // Since expanded macros may not shadow the lexical scope and
 483                 // globs may not shadow global macros (both enforced below),
 484                 // we resolve with restricted shadowing (indicated by the penultimate argument).
 485                 self.resolve_ident_in_module_unadjusted(
 486                     module, ident, ns, true, record_used, path_span,
 487                 ).map(MacroBinding::Modern)
 488             } else {
 489                 self.global_macros.get(&ident.name).cloned().ok_or(determinacy)
 490                     .map(MacroBinding::Global)
 491             };
 492             self.current_module = orig_current_module;
 493
 494             match result.map(MacroBinding::binding) {
 495                 Ok(binding) => {
 496                     if !record_used {
 497                         return result;
 498                     }
 499                     if let Ok(MacroBinding::Modern(shadower)) = potential_illegal_shadower {
 500                         if shadower.def() != binding.def() {
 501                             let name = ident.name;
 502                             self.ambiguity_errors.push(AmbiguityError {
 503                                 span: path_span,
 504                                 name,
 505                                 b1: shadower,
 506                                 b2: binding,
 507                                 lexical: true,
 508                                 legacy: false,
 509                             });
 510                             return potential_illegal_shadower;
 511                         }
 512                     }
 513                     if binding.expansion != Mark::root() ||
 514                        (binding.is_glob_import() && module.unwrap().def().is_some()) {
 515                         potential_illegal_shadower = result;
 516                     } else {
 517                         return result;
 518                     }
 519                 },
 520                 Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
 521                 Err(Determinacy::Determined) => {}
 522             }
 523
 524             module = match module {
 525                 Some(module) => self.hygienic_lexical_parent(module, &mut ident.ctxt),
 526                 None => return potential_illegal_shadower,
 527             }
 528         }
 529     }
 530
 531     pub fn resolve_legacy_scope(&mut self,
 532                                 mut scope: &'a Cell<LegacyScope<'a>>,
 533                                 ident: Ident,
 534                                 record_used: bool)
 535                                 -> Option<MacroBinding<'a>> {
 536         let ident = ident.modern();
 537         let mut possible_time_travel = None;
 538         let mut relative_depth: u32 = 0;
 539         let mut binding = None;
 540         loop {
 541             match scope.get() {
 542                 LegacyScope::Empty => break,
 543                 LegacyScope::Expansion(invocation) => {
 544                     match invocation.expansion.get() {
 545                         LegacyScope::Invocation(_) => scope.set(invocation.legacy_scope.get()),
 546                         LegacyScope::Empty => {
 547                             if possible_time_travel.is_none() {
 548                                 possible_time_travel = Some(scope);
 549                             }
 550                             scope = &invocation.legacy_scope;
 551                         }
 552                         _ => {
 553                             relative_depth += 1;
 554                             scope = &invocation.expansion;
 555                         }
 556                     }
 557                 }
 558                 LegacyScope::Invocation(invocation) => {
 559                     relative_depth = relative_depth.saturating_sub(1);
 560                     scope = &invocation.legacy_scope;
 561                 }
 562                 LegacyScope::Binding(potential_binding) => {
 563                     if potential_binding.ident == ident {
 564                         if (!self.use_extern_macros || record_used) && relative_depth > 0 {
 565                             self.disallowed_shadowing.push(potential_binding);
 566                         }
 567                         binding = Some(potential_binding);
 568                         break
 569                     }
 570                     scope = &potential_binding.parent;
 571                 }
 572             };
 573         }
 574
 575         let binding = if let Some(binding) = binding {
 576             MacroBinding::Legacy(binding)
 577         } else if let Some(binding) = self.global_macros.get(&ident.name).cloned() {
 578             if !self.use_extern_macros {
 579                 self.record_use(ident, MacroNS, binding, DUMMY_SP);
 580             }
 581             MacroBinding::Global(binding)
 582         } else {
 583             return None;
 584         };
 585
 586         if !self.use_extern_macros {
 587             if let Some(scope) = possible_time_travel {
 588                 // Check for disallowed shadowing later
 589                 self.lexical_macro_resolutions.push((ident, scope));
 590             }
 591         }
 592
 593         Some(binding)
 594     }
 595
 596     pub fn finalize_current_module_macro_resolutions(&mut self) {
 597         let module = self.current_module;
 598         for &(ref path, span) in module.macro_resolutions.borrow().iter() {
 599             let path = path.iter().map(|p| respan(span, *p)).collect::<Vec<_>>();
 600             match self.resolve_path(&path, Some(MacroNS), true, span) {
 601                 PathResult::NonModule(_) => {},
 602                 PathResult::Failed(span, msg, _) => {
 603                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
 604                 }
 605                 _ => unreachable!(),
 606             }
 607         }
 608
 609         for &(mark, ident, span, kind) in module.legacy_macro_resolutions.borrow().iter() {
 610             let legacy_scope = &self.invocations[&mark].legacy_scope;
 611             let legacy_resolution = self.resolve_legacy_scope(legacy_scope, ident, true);
 612             let resolution = self.resolve_lexical_macro_path_segment(ident, MacroNS, true, span);
 613             match (legacy_resolution, resolution) {
 614                 (Some(MacroBinding::Legacy(legacy_binding)), Ok(MacroBinding::Modern(binding))) => {
 615                     let msg1 = format!("`{}` could refer to the macro defined here", ident);
 616                     let msg2 = format!("`{}` could also refer to the macro imported here", ident);
 617                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", ident))
 618                         .span_note(legacy_binding.span, &msg1)
 619                         .span_note(binding.span, &msg2)
 620                         .emit();
 621                 },
 622                 (Some(MacroBinding::Global(binding)), Ok(MacroBinding::Global(_))) => {
 623                     self.record_use(ident, MacroNS, binding, span);
 624                     self.err_if_macro_use_proc_macro(ident.name, span, binding);
 625                 },
 626                 (None, Err(_)) => {
 627                     let msg = match kind {
 628                         MacroKind::Bang =>
 629                             format!("cannot find macro `{}!` in this scope", ident),
 630                         MacroKind::Attr =>
 631                             format!("cannot find attribute macro `{}` in this scope", ident),
 632                         MacroKind::Derive =>
 633                             format!("cannot find derive macro `{}` in this scope", ident),
 634                     };
 635                     let mut err = self.session.struct_span_err(span, &msg);
 636                     self.suggest_macro_name(&ident.name.as_str(), kind, &mut err, span);
 637                     err.emit();
 638                 },
 639                 _ => {},
 640             };
 641         }
 642     }
 643
 644     fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
 645                           err: &mut DiagnosticBuilder<'a>, span: Span) {
 646         // First check if this is a locally-defined bang macro.
 647         let suggestion = if let MacroKind::Bang = kind {
 648             find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None)
 649         } else {
 650             None
 651         // Then check global macros.
 652         }.or_else(|| {
 653             // FIXME: get_macro needs an &mut Resolver, can we do it without cloning?
 654             let global_macros = self.global_macros.clone();
 655             let names = global_macros.iter().filter_map(|(name, binding)| {
 656                 if binding.get_macro(self).kind() == kind {
 657                     Some(name)
 658                 } else {
 659                     None
 660                 }
 661             });
 662             find_best_match_for_name(names, name, None)
 663         // Then check modules.
 664         }).or_else(|| {
 665             if !self.use_extern_macros {
 666                 return None;
 667             }
 668             let is_macro = |def| {
 669                 if let Def::Macro(_, def_kind) = def {
 670                     def_kind == kind
 671                 } else {
 672                     false
 673                 }
 674             };
 675             let ident = Ident::from_str(name);
 676             self.lookup_typo_candidate(&vec![respan(span, ident)], MacroNS, is_macro, span)
 677         });
 678
 679         if let Some(suggestion) = suggestion {
 680             if suggestion != name {
 681                 if let MacroKind::Bang = kind {
 682                     err.span_suggestion(span, "you could try the macro",
 683                                         format!("{}!", suggestion));
 684                 } else {
 685                     err.span_suggestion(span, "try", suggestion.to_string());
 686                 }
 687             } else {
 688                 err.help("have you added the `#[macro_use]` on the module/import?");
 689             }
 690         }
 691     }
 692
 693     fn collect_def_ids(&mut self,
 694                        mark: Mark,
 695                        invocation: &'a InvocationData<'a>,
 696                        expansion: &Expansion) {
 697         let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
 698         let InvocationData { def_index, const_expr, .. } = *invocation;
 699
 700         let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
 701             invocations.entry(invoc.mark).or_insert_with(|| {
 702                 arenas.alloc_invocation_data(InvocationData {
 703                     def_index: invoc.def_index,
 704                     const_expr: invoc.const_expr,
 705                     module: Cell::new(graph_root),
 706                     expansion: Cell::new(LegacyScope::Empty),
 707                     legacy_scope: Cell::new(LegacyScope::Empty),
 708                 })
 709             });
 710         };
 711
 712         let mut def_collector = DefCollector::new(&mut self.definitions, mark);
 713         def_collector.visit_macro_invoc = Some(visit_macro_invoc);
 714         def_collector.with_parent(def_index, |def_collector| {
 715             if const_expr {
 716                 if let Expansion::Expr(ref expr) = *expansion {
 717                     def_collector.visit_const_expr(expr);
 718                 }
 719             }
 720             expansion.visit_with(def_collector)
 721         });
 722     }
 723
 724     pub fn define_macro(&mut self,
 725                         item: &ast::Item,
 726                         expansion: Mark,
 727                         legacy_scope: &mut LegacyScope<'a>) {
 728         self.local_macro_def_scopes.insert(item.id, self.current_module);
 729         let ident = item.ident;
 730         if ident.name == "macro_rules" {
 731             self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
 732         }
 733
 734         let def_id = self.definitions.local_def_id(item.id);
 735         let ext = Rc::new(macro_rules::compile(&self.session.parse_sess,
 736                                                &self.session.features,
 737                                                item));
 738         self.macro_map.insert(def_id, ext);
 739
 740         let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
 741         if def.legacy {
 742             let ident = ident.modern();
 743             self.macro_names.insert(ident);
 744             *legacy_scope = LegacyScope::Binding(self.arenas.alloc_legacy_binding(LegacyBinding {
 745                 parent: Cell::new(*legacy_scope), ident: ident, def_id: def_id, span: item.span,
 746             }));
 747             if attr::contains_name(&item.attrs, "macro_export") {
 748                 let def = Def::Macro(def_id, MacroKind::Bang);
 749                 self.macro_exports
 750                     .push(Export { ident: ident.modern(), def: def, span: item.span });
 751             } else {
 752                 self.unused_macros.insert(def_id);
 753             }
 754         } else {
 755             let module = self.current_module;
 756             let def = Def::Macro(def_id, MacroKind::Bang);
 757             let vis = self.resolve_visibility(&item.vis);
 758             if vis != ty::Visibility::Public {
 759                 self.unused_macros.insert(def_id);
 760             }
 761             self.define(module, ident, MacroNS, (def, vis, item.span, expansion));
 762         }
 763     }
 764
 765     /// Error if `ext` is a Macros 1.1 procedural macro being imported by `#[macro_use]`
 766     fn err_if_macro_use_proc_macro(&mut self, name: Name, use_span: Span,
 767                                    binding: &NameBinding<'a>) {
 768         use self::SyntaxExtension::*;
 769
 770         let krate = binding.def().def_id().krate;
 771
 772         // Plugin-based syntax extensions are exempt from this check
 773         if krate == BUILTIN_MACROS_CRATE { return; }
 774
 775         let ext = binding.get_macro(self);
 776
 777         match *ext {
 778             // If `ext` is a procedural macro, check if we've already warned about it
 779             AttrProcMacro(_) | ProcMacro(_) => if !self.warned_proc_macros.insert(name) { return; },
 780             _ => return,
 781         }
 782
 783         let warn_msg = match *ext {
 784             AttrProcMacro(_) => "attribute procedural macros cannot be \
 785                                  imported with `#[macro_use]`",
 786             ProcMacro(_) => "procedural macros cannot be imported with `#[macro_use]`",
 787             _ => return,
 788         };
 789
 790         let def_id = self.current_module.normal_ancestor_id;
 791         let node_id = self.definitions.as_local_node_id(def_id).unwrap();
 792
 793         self.proc_mac_errors.push(ProcMacError {
 794             crate_name: self.cstore.crate_name_untracked(krate),
 795             name,
 796             module: node_id,
 797             use_span,
 798             warn_msg,
 799         });
 800     }
 801
 802     pub fn report_proc_macro_import(&mut self, krate: &ast::Crate) {
 803         for err in self.proc_mac_errors.drain(..) {
 804             let (span, found_use) = ::UsePlacementFinder::check(krate, err.module);
 805
 806             if let Some(span) = span {
 807                 let found_use = if found_use { "" } else { "\n" };
 808                 self.session.struct_span_err(err.use_span, err.warn_msg)
 809                     .span_suggestion(
 810                         span,
 811                         "instead, import the procedural macro like any other item",
 812                         format!("use {}::{};{}", err.crate_name, err.name, found_use),
 813                     ).emit();
 814             } else {
 815                 self.session.struct_span_err(err.use_span, err.warn_msg)
 816                     .help(&format!("instead, import the procedural macro like any other item: \
 817                                     `use {}::{};`", err.crate_name, err.name))
 818                     .emit();
 819             }
 820         }
 821     }
 822
 823     fn gate_legacy_custom_derive(&mut self, name: Symbol, span: Span) {
 824         if !self.session.features.borrow().custom_derive {
 825             let sess = &self.session.parse_sess;
 826             let explain = feature_gate::EXPLAIN_CUSTOM_DERIVE;
 827             emit_feature_err(sess, "custom_derive", span, GateIssue::Language, explain);
 828         } else if !self.is_whitelisted_legacy_custom_derive(name) {
 829             self.session.span_warn(span, feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE);
 830         }
 831     }
 832 }