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