src/librustc_resolve/macros.rs

   1 use crate::{AmbiguityError, AmbiguityKind, AmbiguityErrorMisc};
   2 use crate::{CrateLint, Resolver, ResolutionError, ScopeSet, Weak};
   3 use crate::{Module, ModuleKind, NameBinding, NameBindingKind, PathResult, Segment, ToNameBinding};
   4 use crate::{is_known_tool, resolve_error};
   5 use crate::ModuleOrUniformRoot;
   6 use crate::Namespace::*;
   7 use crate::build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
   8 use crate::resolve_imports::ImportResolver;
   9 use rustc::hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX};
  10 use rustc::hir::def::{self, DefKind, NonMacroAttrKind};
  11 use rustc::hir::map::{self, DefCollector};
  12 use rustc::{ty, lint};
  13 use rustc::{bug, span_bug};
  14 use syntax::ast::{self, Ident};
  15 use syntax::attr;
  16 use syntax::errors::DiagnosticBuilder;
  17 use syntax::ext::base::{self, Determinacy};
  18 use syntax::ext::base::{MacroKind, SyntaxExtension};
  19 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
  20 use syntax::ext::hygiene::Mark;
  21 use syntax::ext::tt::macro_rules;
  22 use syntax::feature_gate::{
  23     feature_err, is_builtin_attr_name, AttributeGate, GateIssue, Stability, BUILTIN_ATTRIBUTES,
  24 };
  25 use syntax::symbol::{Symbol, kw, sym};
  26 use syntax::visit::Visitor;
  27 use syntax::util::lev_distance::find_best_match_for_name;
  28 use syntax_pos::{Span, DUMMY_SP};
  29 use errors::Applicability;
  30
  31 use std::cell::Cell;
  32 use std::{mem, ptr};
  33 use rustc_data_structures::sync::Lrc;
  34
  35 type Res = def::Res<ast::NodeId>;
  36
  37 #[derive(Clone, Debug)]
  38 pub struct InvocationData<'a> {
  39     def_index: DefIndex,
  40     /// The module in which the macro was invoked.
  41     crate module: Cell<Module<'a>>,
  42     /// The legacy scope in which the macro was invoked.
  43     /// The invocation path is resolved in this scope.
  44     crate parent_legacy_scope: Cell<LegacyScope<'a>>,
  45     /// The legacy scope *produced* by expanding this macro invocation,
  46     /// includes all the macro_rules items, other invocations, etc generated by it.
  47     /// `None` if the macro is not expanded yet.
  48     crate output_legacy_scope: Cell<Option<LegacyScope<'a>>>,
  49 }
  50
  51 impl<'a> InvocationData<'a> {
  52     pub fn root(graph_root: Module<'a>) -> Self {
  53         InvocationData {
  54             module: Cell::new(graph_root),
  55             def_index: CRATE_DEF_INDEX,
  56             parent_legacy_scope: Cell::new(LegacyScope::Empty),
  57             output_legacy_scope: Cell::new(Some(LegacyScope::Empty)),
  58         }
  59     }
  60 }
  61
  62 /// Binding produced by a `macro_rules` item.
  63 /// Not modularized, can shadow previous legacy bindings, etc.
  64 #[derive(Debug)]
  65 pub struct LegacyBinding<'a> {
  66     binding: &'a NameBinding<'a>,
  67     /// Legacy scope into which the `macro_rules` item was planted.
  68     parent_legacy_scope: LegacyScope<'a>,
  69     ident: Ident,
  70 }
  71
  72 /// The scope introduced by a `macro_rules!` macro.
  73 /// This starts at the macro's definition and ends at the end of the macro's parent
  74 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
  75 /// Some macro invocations need to introduce legacy scopes too because they
  76 /// can potentially expand into macro definitions.
  77 #[derive(Copy, Clone, Debug)]
  78 pub enum LegacyScope<'a> {
  79     /// Created when invocation data is allocated in the arena;
  80     /// must be replaced with a proper scope later.
  81     Uninitialized,
  82     /// Empty "root" scope at the crate start containing no names.
  83     Empty,
  84     /// The scope introduced by a `macro_rules!` macro definition.
  85     Binding(&'a LegacyBinding<'a>),
  86     /// The scope introduced by a macro invocation that can potentially
  87     /// create a `macro_rules!` macro definition.
  88     Invocation(&'a InvocationData<'a>),
  89 }
  90
  91 /// Everything you need to resolve a macro or import path.
  92 #[derive(Clone, Debug)]
  93 pub struct ParentScope<'a> {
  94     crate module: Module<'a>,
  95     crate expansion: Mark,
  96     crate legacy: LegacyScope<'a>,
  97     crate derives: Vec<ast::Path>,
  98 }
  99
 100 // Macro namespace is separated into two sub-namespaces, one for bang macros and
 101 // one for attribute-like macros (attributes, derives).
 102 // We ignore resolutions from one sub-namespace when searching names in scope for another.
 103 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
 104     #[derive(PartialEq)]
 105     enum SubNS { Bang, AttrLike }
 106     let sub_ns = |kind| match kind {
 107         MacroKind::Bang => Some(SubNS::Bang),
 108         MacroKind::Attr | MacroKind::Derive => Some(SubNS::AttrLike),
 109         MacroKind::ProcMacroStub => None,
 110     };
 111     let requirement = requirement.and_then(|kind| sub_ns(kind));
 112     let candidate = candidate.and_then(|kind| sub_ns(kind));
 113     // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
 114     candidate.is_none() || requirement.is_none() || candidate == requirement
 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             parent_legacy_scope: Cell::new(LegacyScope::Empty),
 129             output_legacy_scope: Cell::new(Some(LegacyScope::Empty)),
 130         }));
 131         mark
 132     }
 133
 134     fn resolve_dollar_crates(&mut self, fragment: &AstFragment) {
 135         struct ResolveDollarCrates<'a, 'b: 'a> {
 136             resolver: &'a mut Resolver<'b>
 137         }
 138         impl<'a> Visitor<'a> for ResolveDollarCrates<'a, '_> {
 139             fn visit_ident(&mut self, ident: Ident) {
 140                 if ident.name == kw::DollarCrate {
 141                     let name = match self.resolver.resolve_crate_root(ident).kind {
 142                         ModuleKind::Def(.., name) if name != kw::Invalid => name,
 143                         _ => kw::Crate,
 144                     };
 145                     ident.span.ctxt().set_dollar_crate_name(name);
 146                 }
 147             }
 148             fn visit_mac(&mut self, _: &ast::Mac) {}
 149         }
 150
 151         fragment.visit_with(&mut ResolveDollarCrates { resolver: self });
 152     }
 153
 154     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
 155                                             derives: &[Mark]) {
 156         let invocation = self.invocations[&mark];
 157         self.collect_def_ids(mark, invocation, fragment);
 158
 159         self.current_module = invocation.module.get();
 160         self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
 161         self.current_module.unresolved_invocations.borrow_mut().extend(derives);
 162         self.invocations.extend(derives.iter().map(|&derive| (derive, invocation)));
 163         let mut visitor = BuildReducedGraphVisitor {
 164             resolver: self,
 165             current_legacy_scope: invocation.parent_legacy_scope.get(),
 166             expansion: mark,
 167         };
 168         fragment.visit_with(&mut visitor);
 169         invocation.output_legacy_scope.set(Some(visitor.current_legacy_scope));
 170     }
 171
 172     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
 173         let def_id = DefId {
 174             krate: CrateNum::BuiltinMacros,
 175             index: DefIndex::from(self.macro_map.len()),
 176         };
 177         let kind = ext.kind();
 178         self.macro_map.insert(def_id, ext);
 179         let binding = self.arenas.alloc_name_binding(NameBinding {
 180             kind: NameBindingKind::Res(Res::Def(DefKind::Macro(kind), def_id), false),
 181             ambiguity: None,
 182             span: DUMMY_SP,
 183             vis: ty::Visibility::Public,
 184             expansion: Mark::root(),
 185         });
 186         if self.builtin_macros.insert(ident.name, binding).is_some() {
 187             self.session.span_err(ident.span,
 188                                   &format!("built-in macro `{}` was already defined", ident));
 189         }
 190     }
 191
 192     fn resolve_imports(&mut self) {
 193         ImportResolver { resolver: self }.resolve_imports()
 194     }
 195
 196     fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
 197                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
 198         let (path, kind, derives_in_scope, after_derive) = match invoc.kind {
 199             InvocationKind::Attr { attr: None, .. } =>
 200                 return Ok(None),
 201             InvocationKind::Attr { attr: Some(ref attr), ref traits, after_derive, .. } =>
 202                 (&attr.path, MacroKind::Attr, traits.clone(), after_derive),
 203             InvocationKind::Bang { ref mac, .. } =>
 204                 (&mac.node.path, MacroKind::Bang, Vec::new(), false),
 205             InvocationKind::Derive { ref path, .. } =>
 206                 (path, MacroKind::Derive, Vec::new(), false),
 207         };
 208
 209         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 210         let (res, ext) = match self.resolve_macro_to_res(path, kind, &parent_scope, true, force) {
 211             Ok((res, ext)) => (res, ext),
 212             Err(Determinacy::Determined) if kind == MacroKind::Attr => {
 213                 // Replace unresolved attributes with used inert attributes for better recovery.
 214                 return Ok(Some(Lrc::new(SyntaxExtension::NonMacroAttr { mark_used: true })));
 215             }
 216             Err(determinacy) => return Err(determinacy),
 217         };
 218
 219         if let Res::Def(DefKind::Macro(_), def_id) = res {
 220             if after_derive {
 221                 self.session.span_err(invoc.span(),
 222                                       "macro attributes must be placed before `#[derive]`");
 223             }
 224             self.macro_defs.insert(invoc.expansion_data.mark, def_id);
 225             let normal_module_def_id =
 226                 self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
 227             self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
 228                                                             normal_module_def_id);
 229             invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
 230         }
 231
 232         Ok(Some(ext))
 233     }
 234
 235     fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
 236                           derives_in_scope: Vec<ast::Path>, force: bool)
 237                           -> Result<Lrc<SyntaxExtension>, Determinacy> {
 238         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 239         Ok(self.resolve_macro_to_res(path, kind, &parent_scope, false, force)?.1)
 240     }
 241
 242     fn check_unused_macros(&self) {
 243         for did in self.unused_macros.iter() {
 244             let id_span = match *self.macro_map[did] {
 245                 SyntaxExtension::NormalTT { def_info, .. } |
 246                 SyntaxExtension::DeclMacro { def_info, .. } => def_info,
 247                 _ => None,
 248             };
 249             if let Some((id, span)) = id_span {
 250                 let lint = lint::builtin::UNUSED_MACROS;
 251                 let msg = "unused macro definition";
 252                 self.session.buffer_lint(lint, id, span, msg);
 253             } else {
 254                 bug!("attempted to create unused macro error, but span not available");
 255             }
 256         }
 257     }
 258 }
 259
 260 impl<'a> Resolver<'a> {
 261     pub fn dummy_parent_scope(&self) -> ParentScope<'a> {
 262         self.invoc_parent_scope(Mark::root(), Vec::new())
 263     }
 264
 265     fn invoc_parent_scope(&self, invoc_id: Mark, derives: Vec<ast::Path>) -> ParentScope<'a> {
 266         let invoc = self.invocations[&invoc_id];
 267         ParentScope {
 268             module: invoc.module.get().nearest_item_scope(),
 269             expansion: invoc_id.parent(),
 270             legacy: invoc.parent_legacy_scope.get(),
 271             derives,
 272         }
 273     }
 274
 275     fn resolve_macro_to_res(
 276         &mut self,
 277         path: &ast::Path,
 278         kind: MacroKind,
 279         parent_scope: &ParentScope<'a>,
 280         trace: bool,
 281         force: bool,
 282     ) -> Result<(Res, Lrc<SyntaxExtension>), Determinacy> {
 283         let res = self.resolve_macro_to_res_inner(path, kind, parent_scope, trace, force);
 284
 285         // Report errors and enforce feature gates for the resolved macro.
 286         if res != Err(Determinacy::Undetermined) {
 287             // Do not report duplicated errors on every undetermined resolution.
 288             for segment in &path.segments {
 289                 if let Some(args) = &segment.args {
 290                     self.session.span_err(args.span(), "generic arguments in macro path");
 291                 }
 292             }
 293         }
 294
 295         let res = res?;
 296
 297         match res {
 298             Res::Def(DefKind::Macro(macro_kind), def_id) => {
 299                 self.unused_macros.remove(&def_id);
 300                 if macro_kind == MacroKind::ProcMacroStub {
 301                     let msg = "can't use a procedural macro from the same crate that defines it";
 302                     self.session.span_err(path.span, msg);
 303                     return Err(Determinacy::Determined);
 304                 }
 305             }
 306             Res::NonMacroAttr(attr_kind) => {
 307                 if kind == MacroKind::Attr {
 308                     let features = self.session.features_untracked();
 309                     if attr_kind == NonMacroAttrKind::Custom {
 310                         assert!(path.segments.len() == 1);
 311                         let name = path.segments[0].ident.as_str();
 312                         if name.starts_with("rustc_") {
 313                             if !features.rustc_attrs {
 314                                 let msg = "unless otherwise specified, attributes with the prefix \
 315                                            `rustc_` are reserved for internal compiler diagnostics";
 316                                 self.report_unknown_attribute(path.span, &name, msg,
 317                                                               sym::rustc_attrs);
 318                             }
 319                         } else if !features.custom_attribute {
 320                             let msg = format!("The attribute `{}` is currently unknown to the \
 321                                                compiler and may have meaning added to it in the \
 322                                                future", path);
 323                             self.report_unknown_attribute(
 324                                 path.span,
 325                                 &name,
 326                                 &msg,
 327                                 sym::custom_attribute,
 328                             );
 329                         }
 330                     }
 331                 } else {
 332                     // Not only attributes, but anything in macro namespace can result in
 333                     // `Res::NonMacroAttr` definition (e.g., `inline!()`), so we must report
 334                     // an error for those cases.
 335                     let msg = format!("expected a macro, found {}", res.descr());
 336                     self.session.span_err(path.span, &msg);
 337                     return Err(Determinacy::Determined);
 338                 }
 339             }
 340             Res::Err => {
 341                 return Err(Determinacy::Determined);
 342             }
 343             _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
 344         }
 345
 346         Ok((res, self.get_macro(res)))
 347     }
 348
 349     fn report_unknown_attribute(&self, span: Span, name: &str, msg: &str, feature: Symbol) {
 350         let mut err = feature_err(
 351             &self.session.parse_sess,
 352             feature,
 353             span,
 354             GateIssue::Language,
 355             &msg,
 356         );
 357
 358         let features = self.session.features_untracked();
 359
 360         let attr_candidates = BUILTIN_ATTRIBUTES
 361             .iter()
 362             .filter_map(|&(name, _, _, ref gate)| {
 363                 if name.as_str().starts_with("rustc_") && !features.rustc_attrs {
 364                     return None;
 365                 }
 366
 367                 match gate {
 368                     AttributeGate::Gated(Stability::Unstable, ..)
 369                         if self.session.opts.unstable_features.is_nightly_build() =>
 370                     {
 371                         Some(name)
 372                     }
 373                     AttributeGate::Gated(Stability::Deprecated(..), ..) => Some(name),
 374                     AttributeGate::Ungated => Some(name),
 375                     _ => None,
 376                 }
 377             })
 378             .chain(
 379                 // Add built-in macro attributes as well.
 380                 self.builtin_macros.iter().filter_map(|(name, binding)| {
 381                     match binding.macro_kind() {
 382                         Some(MacroKind::Attr) => Some(*name),
 383                         _ => None,
 384                     }
 385                 }),
 386             )
 387             .collect::<Vec<_>>();
 388
 389         let lev_suggestion = find_best_match_for_name(attr_candidates.iter(), &name, None);
 390
 391         if let Some(suggestion) = lev_suggestion {
 392             err.span_suggestion(
 393                 span,
 394                 "a built-in attribute with a similar name exists",
 395                 suggestion.to_string(),
 396                 Applicability::MaybeIncorrect,
 397             );
 398         }
 399
 400         err.emit();
 401     }
 402
 403     pub fn resolve_macro_to_res_inner(
 404         &mut self,
 405         path: &ast::Path,
 406         kind: MacroKind,
 407         parent_scope: &ParentScope<'a>,
 408         trace: bool,
 409         force: bool,
 410     ) -> Result<Res, Determinacy> {
 411         let path_span = path.span;
 412         let mut path = Segment::from_path(path);
 413
 414         // Possibly apply the macro helper hack
 415         if kind == MacroKind::Bang && path.len() == 1 &&
 416            path[0].ident.span.ctxt().outer_expn_info()
 417                .map_or(false, |info| info.local_inner_macros) {
 418             let root = Ident::new(kw::DollarCrate, path[0].ident.span);
 419             path.insert(0, Segment::from_ident(root));
 420         }
 421
 422         if path.len() > 1 {
 423             let res = match self.resolve_path(&path, Some(MacroNS), parent_scope,
 424                                               false, path_span, CrateLint::No) {
 425                 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
 426                     Ok(path_res.base_res())
 427                 }
 428                 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
 429                 PathResult::NonModule(..)
 430                 | PathResult::Indeterminate
 431                 | PathResult::Failed { .. } => Err(Determinacy::Determined),
 432                 PathResult::Module(..) => unreachable!(),
 433             };
 434
 435             if trace {
 436                 parent_scope.module.multi_segment_macro_resolutions.borrow_mut()
 437                     .push((path, path_span, kind, parent_scope.clone(), res.ok()));
 438             }
 439
 440             self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
 441             res
 442         } else {
 443             let binding = self.early_resolve_ident_in_lexical_scope(
 444                 path[0].ident, ScopeSet::Macro(kind), parent_scope, false, force, path_span
 445             );
 446             if let Err(Determinacy::Undetermined) = binding {
 447                 return Err(Determinacy::Undetermined);
 448             }
 449
 450             if trace {
 451                 parent_scope.module.single_segment_macro_resolutions.borrow_mut()
 452                     .push((path[0].ident, kind, parent_scope.clone(), binding.ok()));
 453             }
 454
 455             let res = binding.map(|binding| binding.res());
 456             self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
 457             res
 458         }
 459     }
 460
 461     // Resolve an identifier in lexical scope.
 462     // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
 463     // expansion and import resolution (perhaps they can be merged in the future).
 464     // The function is used for resolving initial segments of macro paths (e.g., `foo` in
 465     // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
 466     crate fn early_resolve_ident_in_lexical_scope(
 467         &mut self,
 468         orig_ident: Ident,
 469         scope_set: ScopeSet,
 470         parent_scope: &ParentScope<'a>,
 471         record_used: bool,
 472         force: bool,
 473         path_span: Span,
 474     ) -> Result<&'a NameBinding<'a>, Determinacy> {
 475         // General principles:
 476         // 1. Not controlled (user-defined) names should have higher priority than controlled names
 477         //    built into the language or standard library. This way we can add new names into the
 478         //    language or standard library without breaking user code.
 479         // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
 480         // Places to search (in order of decreasing priority):
 481         // (Type NS)
 482         // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
 483         //    (open set, not controlled).
 484         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 485         //    (open, not controlled).
 486         // 3. Extern prelude (closed, not controlled).
 487         // 4. Tool modules (closed, controlled right now, but not in the future).
 488         // 5. Standard library prelude (de-facto closed, controlled).
 489         // 6. Language prelude (closed, controlled).
 490         // (Value NS)
 491         // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
 492         //    (open set, not controlled).
 493         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 494         //    (open, not controlled).
 495         // 3. Standard library prelude (de-facto closed, controlled).
 496         // (Macro NS)
 497         // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
 498         //    are currently reported as errors. They should be higher in priority than preludes
 499         //    and probably even names in modules according to the "general principles" above. They
 500         //    also should be subject to restricted shadowing because are effectively produced by
 501         //    derives (you need to resolve the derive first to add helpers into scope), but they
 502         //    should be available before the derive is expanded for compatibility.
 503         //    It's mess in general, so we are being conservative for now.
 504         // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
 505         //    priority than prelude macros, but create ambiguities with macros in modules.
 506         // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 507         //    (open, not controlled). Have higher priority than prelude macros, but create
 508         //    ambiguities with `macro_rules`.
 509         // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
 510         // 4a. User-defined prelude from macro-use
 511         //    (open, the open part is from macro expansions, not controlled).
 512         // 4b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
 513         // 5. Language prelude: builtin macros (closed, controlled, except for legacy plugins).
 514         // 6. Language prelude: builtin attributes (closed, controlled).
 515         // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
 516         //    but introduced by legacy plugins using `register_attribute`. Priority is somewhere
 517         //    in prelude, not sure where exactly (creates ambiguities with any other prelude names).
 518
 519         enum WhereToResolve<'a> {
 520             DeriveHelpers,
 521             MacroRules(LegacyScope<'a>),
 522             CrateRoot,
 523             Module(Module<'a>),
 524             MacroUsePrelude,
 525             BuiltinMacros,
 526             BuiltinAttrs,
 527             LegacyPluginHelpers,
 528             ExternPrelude,
 529             ToolPrelude,
 530             StdLibPrelude,
 531             BuiltinTypes,
 532         }
 533
 534         bitflags::bitflags! {
 535             struct Flags: u8 {
 536                 const MACRO_RULES        = 1 << 0;
 537                 const MODULE             = 1 << 1;
 538                 const PRELUDE            = 1 << 2;
 539                 const MISC_SUGGEST_CRATE = 1 << 3;
 540                 const MISC_SUGGEST_SELF  = 1 << 4;
 541                 const MISC_FROM_PRELUDE  = 1 << 5;
 542             }
 543         }
 544
 545         assert!(force || !record_used); // `record_used` implies `force`
 546         let mut ident = orig_ident.modern();
 547
 548         // Make sure `self`, `super` etc produce an error when passed to here.
 549         if ident.is_path_segment_keyword() {
 550             return Err(Determinacy::Determined);
 551         }
 552
 553         // This is *the* result, resolution from the scope closest to the resolved identifier.
 554         // However, sometimes this result is "weak" because it comes from a glob import or
 555         // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
 556         // mod m { ... } // solution in outer scope
 557         // {
 558         //     use prefix::*; // imports another `m` - innermost solution
 559         //                    // weak, cannot shadow the outer `m`, need to report ambiguity error
 560         //     m::mac!();
 561         // }
 562         // So we have to save the innermost solution and continue searching in outer scopes
 563         // to detect potential ambiguities.
 564         let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
 565
 566         // Go through all the scopes and try to resolve the name.
 567         let rust_2015 = orig_ident.span.rust_2015();
 568         let (ns, macro_kind, is_import, is_absolute_path) = match scope_set {
 569             ScopeSet::Import(ns) => (ns, None, true, false),
 570             ScopeSet::AbsolutePath(ns) => (ns, None, false, true),
 571             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false, false),
 572             ScopeSet::Module => (TypeNS, None, false, false),
 573         };
 574         let mut where_to_resolve = match ns {
 575             _ if is_absolute_path => WhereToResolve::CrateRoot,
 576             TypeNS | ValueNS => WhereToResolve::Module(parent_scope.module),
 577             MacroNS => WhereToResolve::DeriveHelpers,
 578         };
 579         let mut use_prelude = !parent_scope.module.no_implicit_prelude;
 580         let mut determinacy = Determinacy::Determined;
 581         loop {
 582             let result = match where_to_resolve {
 583                 WhereToResolve::DeriveHelpers => {
 584                     let mut result = Err(Determinacy::Determined);
 585                     for derive in &parent_scope.derives {
 586                         let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
 587                         match self.resolve_macro_to_res(derive, MacroKind::Derive,
 588                                                         &parent_scope, true, force) {
 589                             Ok((_, ext)) => {
 590                                 if let SyntaxExtension::ProcMacroDerive(_, helpers, _) = &*ext {
 591                                     if helpers.contains(&ident.name) {
 592                                         let binding =
 593                                             (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
 594                                             ty::Visibility::Public, derive.span, Mark::root())
 595                                             .to_name_binding(self.arenas);
 596                                         result = Ok((binding, Flags::empty()));
 597                                         break;
 598                                     }
 599                                 }
 600                             }
 601                             Err(Determinacy::Determined) => {}
 602                             Err(Determinacy::Undetermined) =>
 603                                 result = Err(Determinacy::Undetermined),
 604                         }
 605                     }
 606                     result
 607                 }
 608                 WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 609                     LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
 610                         Ok((legacy_binding.binding, Flags::MACRO_RULES)),
 611                     LegacyScope::Invocation(invoc) if invoc.output_legacy_scope.get().is_none() =>
 612                         Err(Determinacy::Undetermined),
 613                     _ => Err(Determinacy::Determined),
 614                 }
 615                 WhereToResolve::CrateRoot => {
 616                     let root_ident = Ident::new(kw::PathRoot, orig_ident.span);
 617                     let root_module = self.resolve_crate_root(root_ident);
 618                     let binding = self.resolve_ident_in_module_ext(
 619                         ModuleOrUniformRoot::Module(root_module),
 620                         orig_ident,
 621                         ns,
 622                         None,
 623                         record_used,
 624                         path_span,
 625                     );
 626                     match binding {
 627                         Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
 628                         Err((Determinacy::Undetermined, Weak::No)) =>
 629                             return Err(Determinacy::determined(force)),
 630                         Err((Determinacy::Undetermined, Weak::Yes)) =>
 631                             Err(Determinacy::Undetermined),
 632                         Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
 633                     }
 634                 }
 635                 WhereToResolve::Module(module) => {
 636                     let orig_current_module = mem::replace(&mut self.current_module, module);
 637                     let binding = self.resolve_ident_in_module_unadjusted_ext(
 638                         ModuleOrUniformRoot::Module(module),
 639                         ident,
 640                         ns,
 641                         None,
 642                         true,
 643                         record_used,
 644                         path_span,
 645                     );
 646                     self.current_module = orig_current_module;
 647                     match binding {
 648                         Ok(binding) => {
 649                             let misc_flags = if ptr::eq(module, self.graph_root) {
 650                                 Flags::MISC_SUGGEST_CRATE
 651                             } else if module.is_normal() {
 652                                 Flags::MISC_SUGGEST_SELF
 653                             } else {
 654                                 Flags::empty()
 655                             };
 656                             Ok((binding, Flags::MODULE | misc_flags))
 657                         }
 658                         Err((Determinacy::Undetermined, Weak::No)) =>
 659                             return Err(Determinacy::determined(force)),
 660                         Err((Determinacy::Undetermined, Weak::Yes)) =>
 661                             Err(Determinacy::Undetermined),
 662                         Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
 663                     }
 664                 }
 665                 WhereToResolve::MacroUsePrelude => {
 666                     if use_prelude || rust_2015 {
 667                         match self.macro_use_prelude.get(&ident.name).cloned() {
 668                             Some(binding) =>
 669                                 Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE)),
 670                             None => Err(Determinacy::determined(
 671                                 self.graph_root.unresolved_invocations.borrow().is_empty()
 672                             ))
 673                         }
 674                     } else {
 675                         Err(Determinacy::Determined)
 676                     }
 677                 }
 678                 WhereToResolve::BuiltinMacros => {
 679                     match self.builtin_macros.get(&ident.name).cloned() {
 680                         Some(binding) => Ok((binding, Flags::PRELUDE)),
 681                         None => Err(Determinacy::Determined),
 682                     }
 683                 }
 684                 WhereToResolve::BuiltinAttrs => {
 685                     if is_builtin_attr_name(ident.name) {
 686                         let binding = (Res::NonMacroAttr(NonMacroAttrKind::Builtin),
 687                                        ty::Visibility::Public, DUMMY_SP, Mark::root())
 688                                        .to_name_binding(self.arenas);
 689                         Ok((binding, Flags::PRELUDE))
 690                     } else {
 691                         Err(Determinacy::Determined)
 692                     }
 693                 }
 694                 WhereToResolve::LegacyPluginHelpers => {
 695                     if (use_prelude || rust_2015) &&
 696                        self.session.plugin_attributes.borrow().iter()
 697                                                      .any(|(name, _)| ident.name == *name) {
 698                         let binding = (Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
 699                                        ty::Visibility::Public, DUMMY_SP, Mark::root())
 700                                        .to_name_binding(self.arenas);
 701                         Ok((binding, Flags::PRELUDE))
 702                     } else {
 703                         Err(Determinacy::Determined)
 704                     }
 705                 }
 706                 WhereToResolve::ExternPrelude => {
 707                     if use_prelude || is_absolute_path {
 708                         match self.extern_prelude_get(ident, !record_used) {
 709                             Some(binding) => Ok((binding, Flags::PRELUDE)),
 710                             None => Err(Determinacy::determined(
 711                                 self.graph_root.unresolved_invocations.borrow().is_empty()
 712                             )),
 713                         }
 714                     } else {
 715                         Err(Determinacy::Determined)
 716                     }
 717                 }
 718                 WhereToResolve::ToolPrelude => {
 719                     if use_prelude && is_known_tool(ident.name) {
 720                         let binding = (Res::ToolMod, ty::Visibility::Public,
 721                                        DUMMY_SP, Mark::root()).to_name_binding(self.arenas);
 722                         Ok((binding, Flags::PRELUDE))
 723                     } else {
 724                         Err(Determinacy::Determined)
 725                     }
 726                 }
 727                 WhereToResolve::StdLibPrelude => {
 728                     let mut result = Err(Determinacy::Determined);
 729                     if use_prelude {
 730                         if let Some(prelude) = self.prelude {
 731                             if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
 732                                 ModuleOrUniformRoot::Module(prelude),
 733                                 ident,
 734                                 ns,
 735                                 false,
 736                                 path_span,
 737                             ) {
 738                                 result = Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE));
 739                             }
 740                         }
 741                     }
 742                     result
 743                 }
 744                 WhereToResolve::BuiltinTypes => {
 745                     match self.primitive_type_table.primitive_types.get(&ident.name).cloned() {
 746                         Some(prim_ty) => {
 747                             let binding = (Res::PrimTy(prim_ty), ty::Visibility::Public,
 748                                            DUMMY_SP, Mark::root()).to_name_binding(self.arenas);
 749                             Ok((binding, Flags::PRELUDE))
 750                         }
 751                         None => Err(Determinacy::Determined)
 752                     }
 753                 }
 754             };
 755
 756             match result {
 757                 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
 758                     if !record_used {
 759                         return Ok(binding);
 760                     }
 761
 762                     if let Some((innermost_binding, innermost_flags)) = innermost_result {
 763                         // Found another solution, if the first one was "weak", report an error.
 764                         let (res, innermost_res) = (binding.res(), innermost_binding.res());
 765                         if res != innermost_res {
 766                             let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
 767                             let derive_helper = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
 768                             let legacy_helper =
 769                                 Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
 770
 771                             let ambiguity_error_kind = if is_import {
 772                                 Some(AmbiguityKind::Import)
 773                             } else if innermost_res == builtin || res == builtin {
 774                                 Some(AmbiguityKind::BuiltinAttr)
 775                             } else if innermost_res == derive_helper || res == derive_helper {
 776                                 Some(AmbiguityKind::DeriveHelper)
 777                             } else if innermost_res == legacy_helper &&
 778                                       flags.contains(Flags::PRELUDE) ||
 779                                       res == legacy_helper &&
 780                                       innermost_flags.contains(Flags::PRELUDE) {
 781                                 Some(AmbiguityKind::LegacyHelperVsPrelude)
 782                             } else if innermost_flags.contains(Flags::MACRO_RULES) &&
 783                                       flags.contains(Flags::MODULE) &&
 784                                       !self.disambiguate_legacy_vs_modern(innermost_binding,
 785                                                                           binding) ||
 786                                       flags.contains(Flags::MACRO_RULES) &&
 787                                       innermost_flags.contains(Flags::MODULE) &&
 788                                       !self.disambiguate_legacy_vs_modern(binding,
 789                                                                           innermost_binding) {
 790                                 Some(AmbiguityKind::LegacyVsModern)
 791                             } else if innermost_binding.is_glob_import() {
 792                                 Some(AmbiguityKind::GlobVsOuter)
 793                             } else if innermost_binding.may_appear_after(parent_scope.expansion,
 794                                                                          binding) {
 795                                 Some(AmbiguityKind::MoreExpandedVsOuter)
 796                             } else {
 797                                 None
 798                             };
 799                             if let Some(kind) = ambiguity_error_kind {
 800                                 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
 801                                     AmbiguityErrorMisc::SuggestCrate
 802                                 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
 803                                     AmbiguityErrorMisc::SuggestSelf
 804                                 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
 805                                     AmbiguityErrorMisc::FromPrelude
 806                                 } else {
 807                                     AmbiguityErrorMisc::None
 808                                 };
 809                                 self.ambiguity_errors.push(AmbiguityError {
 810                                     kind,
 811                                     ident: orig_ident,
 812                                     b1: innermost_binding,
 813                                     b2: binding,
 814                                     misc1: misc(innermost_flags),
 815                                     misc2: misc(flags),
 816                                 });
 817                                 return Ok(innermost_binding);
 818                             }
 819                         }
 820                     } else {
 821                         // Found the first solution.
 822                         innermost_result = Some((binding, flags));
 823                     }
 824                 }
 825                 Ok(..) | Err(Determinacy::Determined) => {}
 826                 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
 827             }
 828
 829             where_to_resolve = match where_to_resolve {
 830                 WhereToResolve::DeriveHelpers =>
 831                     WhereToResolve::MacroRules(parent_scope.legacy),
 832                 WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 833                     LegacyScope::Binding(binding) => WhereToResolve::MacroRules(
 834                         binding.parent_legacy_scope
 835                     ),
 836                     LegacyScope::Invocation(invoc) => WhereToResolve::MacroRules(
 837                         invoc.output_legacy_scope.get().unwrap_or(invoc.parent_legacy_scope.get())
 838                     ),
 839                     LegacyScope::Empty => WhereToResolve::Module(parent_scope.module),
 840                     LegacyScope::Uninitialized => unreachable!(),
 841                 }
 842                 WhereToResolve::CrateRoot => match ns {
 843                     TypeNS => {
 844                         ident.span.adjust(Mark::root());
 845                         WhereToResolve::ExternPrelude
 846                     }
 847                     ValueNS | MacroNS => break,
 848                 }
 849                 WhereToResolve::Module(module) => {
 850                     match self.hygienic_lexical_parent(module, &mut ident.span) {
 851                         Some(parent_module) => WhereToResolve::Module(parent_module),
 852                         None => {
 853                             use_prelude = !module.no_implicit_prelude;
 854                             match ns {
 855                                 TypeNS => WhereToResolve::ExternPrelude,
 856                                 ValueNS => WhereToResolve::StdLibPrelude,
 857                                 MacroNS => WhereToResolve::MacroUsePrelude,
 858                             }
 859                         }
 860                     }
 861                 }
 862                 WhereToResolve::MacroUsePrelude => WhereToResolve::BuiltinMacros,
 863                 WhereToResolve::BuiltinMacros => WhereToResolve::BuiltinAttrs,
 864                 WhereToResolve::BuiltinAttrs => WhereToResolve::LegacyPluginHelpers,
 865                 WhereToResolve::LegacyPluginHelpers => break, // nowhere else to search
 866                 WhereToResolve::ExternPrelude if is_absolute_path => break,
 867                 WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
 868                 WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
 869                 WhereToResolve::StdLibPrelude => match ns {
 870                     TypeNS => WhereToResolve::BuiltinTypes,
 871                     ValueNS => break, // nowhere else to search
 872                     MacroNS => unreachable!(),
 873                 }
 874                 WhereToResolve::BuiltinTypes => break, // nowhere else to search
 875             };
 876
 877             continue;
 878         }
 879
 880         // The first found solution was the only one, return it.
 881         if let Some((binding, _)) = innermost_result {
 882             return Ok(binding);
 883         }
 884
 885         let determinacy = Determinacy::determined(determinacy == Determinacy::Determined || force);
 886         if determinacy == Determinacy::Determined && macro_kind == Some(MacroKind::Attr) {
 887             // For single-segment attributes interpret determinate "no resolution" as a custom
 888             // attribute. (Lexical resolution implies the first segment and attr kind should imply
 889             // the last segment, so we are certainly working with a single-segment attribute here.)
 890             assert!(ns == MacroNS);
 891             let binding = (Res::NonMacroAttr(NonMacroAttrKind::Custom),
 892                            ty::Visibility::Public, ident.span, Mark::root())
 893                            .to_name_binding(self.arenas);
 894             Ok(binding)
 895         } else {
 896             Err(determinacy)
 897         }
 898     }
 899
 900     pub fn finalize_current_module_macro_resolutions(&mut self) {
 901         let module = self.current_module;
 902
 903         let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
 904                                  initial_res: Option<Res>, res: Res| {
 905             if let Some(initial_res) = initial_res {
 906                 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
 907                     // Make sure compilation does not succeed if preferred macro resolution
 908                     // has changed after the macro had been expanded. In theory all such
 909                     // situations should be reported as ambiguity errors, so this is a bug.
 910                     if initial_res == Res::NonMacroAttr(NonMacroAttrKind::Custom) {
 911                         // Yeah, legacy custom attributes are implemented using forced resolution
 912                         // (which is a best effort error recovery tool, basically), so we can't
 913                         // promise their resolution won't change later.
 914                         let msg = format!("inconsistent resolution for a macro: first {}, then {}",
 915                                           initial_res.descr(), res.descr());
 916                         this.session.span_err(span, &msg);
 917                     } else {
 918                         span_bug!(span, "inconsistent resolution for a macro");
 919                     }
 920                 }
 921             } else {
 922                 // It's possible that the macro was unresolved (indeterminate) and silently
 923                 // expanded into a dummy fragment for recovery during expansion.
 924                 // Now, post-expansion, the resolution may succeed, but we can't change the
 925                 // past and need to report an error.
 926                 // However, non-speculative `resolve_path` can successfully return private items
 927                 // even if speculative `resolve_path` returned nothing previously, so we skip this
 928                 // less informative error if the privacy error is reported elsewhere.
 929                 if this.privacy_errors.is_empty() {
 930                     let msg = format!("cannot determine resolution for the {} `{}`",
 931                                         kind.descr(), Segment::names_to_string(path));
 932                     let msg_note = "import resolution is stuck, try simplifying macro imports";
 933                     this.session.struct_span_err(span, &msg).note(msg_note).emit();
 934                 }
 935             }
 936         };
 937
 938         let macro_resolutions =
 939             mem::replace(&mut *module.multi_segment_macro_resolutions.borrow_mut(), Vec::new());
 940         for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
 941             // FIXME: Path resolution will ICE if segment IDs present.
 942             for seg in &mut path { seg.id = None; }
 943             match self.resolve_path(&path, Some(MacroNS), &parent_scope,
 944                                     true, path_span, CrateLint::No) {
 945                 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
 946                     let res = path_res.base_res();
 947                     check_consistency(self, &path, path_span, kind, initial_res, res);
 948                 }
 949                 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
 950                     let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
 951                         (span, label)
 952                     } else {
 953                         (path_span, format!("partially resolved path in {} {}",
 954                                             kind.article(), kind.descr()))
 955                     };
 956                     resolve_error(self, span, ResolutionError::FailedToResolve {
 957                         label,
 958                         suggestion: None
 959                     });
 960                 }
 961                 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
 962             }
 963         }
 964
 965         let macro_resolutions =
 966             mem::replace(&mut *module.single_segment_macro_resolutions.borrow_mut(), Vec::new());
 967         for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
 968             match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
 969                                                             &parent_scope, true, true, ident.span) {
 970                 Ok(binding) => {
 971                     let initial_res = initial_binding.map(|initial_binding| {
 972                         self.record_use(ident, MacroNS, initial_binding, false);
 973                         initial_binding.res()
 974                     });
 975                     let res = binding.res();
 976                     let seg = Segment::from_ident(ident);
 977                     check_consistency(self, &[seg], ident.span, kind, initial_res, res);
 978                 }
 979                 Err(..) => {
 980                     assert!(initial_binding.is_none());
 981                     let bang = if kind == MacroKind::Bang { "!" } else { "" };
 982                     let msg =
 983                         format!("cannot find {} `{}{}` in this scope", kind.descr(), ident, bang);
 984                     let mut err = self.session.struct_span_err(ident.span, &msg);
 985                     self.suggest_macro_name(ident.name, kind, &mut err, ident.span);
 986                     err.emit();
 987                 }
 988             }
 989         }
 990
 991         let builtin_attrs = mem::replace(&mut *module.builtin_attrs.borrow_mut(), Vec::new());
 992         for (ident, parent_scope) in builtin_attrs {
 993             let _ = self.early_resolve_ident_in_lexical_scope(
 994                 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
 995             );
 996         }
 997     }
 998
 999     fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
1000                                          res: Option<Res>, span: Span) {
1001         if let Some(Res::NonMacroAttr(kind)) = res {
1002             if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
1003                 let msg = format!("cannot use a {} through an import", kind.descr());
1004                 let mut err = self.session.struct_span_err(span, &msg);
1005                 if let Some(binding) = binding {
1006                     err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
1007                 }
1008                 err.emit();
1009             }
1010         }
1011     }
1012
1013     fn suggest_macro_name(&mut self, name: Symbol, kind: MacroKind,
1014                           err: &mut DiagnosticBuilder<'a>, span: Span) {
1015         // First check if this is a locally-defined bang macro.
1016         let suggestion = if let MacroKind::Bang = kind {
1017             find_best_match_for_name(
1018                 self.macro_names.iter().map(|ident| &ident.name), &name.as_str(), None)
1019         } else {
1020             None
1021         // Then check global macros.
1022         }.or_else(|| {
1023             let names = self.builtin_macros.iter().chain(self.macro_use_prelude.iter())
1024                                                   .filter_map(|(name, binding)| {
1025                 if binding.macro_kind() == Some(kind) { Some(name) } else { None }
1026             });
1027             find_best_match_for_name(names, &name.as_str(), None)
1028         // Then check modules.
1029         }).or_else(|| {
1030             let is_macro = |res| {
1031                 if let Res::Def(DefKind::Macro(def_kind), _) = res {
1032                     def_kind == kind
1033                 } else {
1034                     false
1035                 }
1036             };
1037             let ident = Ident::new(name, span);
1038             self.lookup_typo_candidate(&[Segment::from_ident(ident)], MacroNS, is_macro, span)
1039                 .map(|suggestion| suggestion.candidate)
1040         });
1041
1042         if let Some(suggestion) = suggestion {
1043             if suggestion != name {
1044                 if let MacroKind::Bang = kind {
1045                     err.span_suggestion(
1046                         span,
1047                         "you could try the macro",
1048                         suggestion.to_string(),
1049                         Applicability::MaybeIncorrect
1050                     );
1051                 } else {
1052                     err.span_suggestion(
1053                         span,
1054                         "try",
1055                         suggestion.to_string(),
1056                         Applicability::MaybeIncorrect
1057                     );
1058                 }
1059             } else {
1060                 err.help("have you added the `#[macro_use]` on the module/import?");
1061             }
1062         }
1063     }
1064
1065     fn collect_def_ids(&mut self,
1066                        mark: Mark,
1067                        invocation: &'a InvocationData<'a>,
1068                        fragment: &AstFragment) {
1069         let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
1070         let InvocationData { def_index, .. } = *invocation;
1071
1072         let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
1073             invocations.entry(invoc.mark).or_insert_with(|| {
1074                 arenas.alloc_invocation_data(InvocationData {
1075                     def_index: invoc.def_index,
1076                     module: Cell::new(graph_root),
1077                     parent_legacy_scope: Cell::new(LegacyScope::Uninitialized),
1078                     output_legacy_scope: Cell::new(None),
1079                 })
1080             });
1081         };
1082
1083         let mut def_collector = DefCollector::new(&mut self.definitions, mark);
1084         def_collector.visit_macro_invoc = Some(visit_macro_invoc);
1085         def_collector.with_parent(def_index, |def_collector| {
1086             fragment.visit_with(def_collector)
1087         });
1088     }
1089
1090     pub fn define_macro(&mut self,
1091                         item: &ast::Item,
1092                         expansion: Mark,
1093                         current_legacy_scope: &mut LegacyScope<'a>) {
1094         self.local_macro_def_scopes.insert(item.id, self.current_module);
1095         let ident = item.ident;
1096         if ident.name == sym::macro_rules {
1097             self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
1098         }
1099
1100         let def_id = self.definitions.local_def_id(item.id);
1101         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
1102                                                &self.session.features_untracked(),
1103                                                item, self.session.edition()));
1104         self.macro_map.insert(def_id, ext);
1105
1106         let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
1107         if def.legacy {
1108             let ident = ident.modern();
1109             self.macro_names.insert(ident);
1110             let res = Res::Def(DefKind::Macro(MacroKind::Bang), def_id);
1111             let is_macro_export = attr::contains_name(&item.attrs, sym::macro_export);
1112             let vis = if is_macro_export {
1113                 ty::Visibility::Public
1114             } else {
1115                 ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))
1116             };
1117             let binding = (res, vis, item.span, expansion).to_name_binding(self.arenas);
1118             self.set_binding_parent_module(binding, self.current_module);
1119             let legacy_binding = self.arenas.alloc_legacy_binding(LegacyBinding {
1120                 parent_legacy_scope: *current_legacy_scope, binding, ident
1121             });
1122             *current_legacy_scope = LegacyScope::Binding(legacy_binding);
1123             self.all_macros.insert(ident.name, res);
1124             if is_macro_export {
1125                 let module = self.graph_root;
1126                 self.define(module, ident, MacroNS,
1127                             (res, vis, item.span, expansion, IsMacroExport));
1128             } else {
1129                 if !attr::contains_name(&item.attrs, sym::rustc_doc_only_macro) {
1130                     self.check_reserved_macro_name(ident, MacroNS);
1131                 }
1132                 self.unused_macros.insert(def_id);
1133             }
1134         } else {
1135             let module = self.current_module;
1136             let res = Res::Def(DefKind::Macro(MacroKind::Bang), def_id);
1137             let vis = self.resolve_visibility(&item.vis);
1138             if vis != ty::Visibility::Public {
1139                 self.unused_macros.insert(def_id);
1140             }
1141             self.define(module, ident, MacroNS, (res, vis, item.span, expansion));
1142         }
1143     }
1144 }