src/librustc_resolve/macros.rs

   1 use {AmbiguityError, AmbiguityKind, AmbiguityErrorMisc};
   2 use {CrateLint, Resolver, ResolutionError, ScopeSet, Weak};
   3 use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult, Segment, ToNameBinding};
   4 use {is_known_tool, resolve_error};
   5 use ModuleOrUniformRoot;
   6 use Namespace::*;
   7 use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
   8 use resolve_imports::ImportResolver;
   9 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX, DefIndex,
  10                          CrateNum, DefIndexAddressSpace};
  11 use rustc::hir::def::{Def, NonMacroAttrKind};
  12 use rustc::hir::map::{self, DefCollector};
  13 use rustc::{ty, lint};
  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::{Annotatable, MacroKind, SyntaxExtension};
  19 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
  20 use syntax::ext::hygiene::{self, Mark};
  21 use syntax::ext::tt::macro_rules;
  22 use syntax::feature_gate::{feature_err, is_builtin_attr_name, GateIssue};
  23 use syntax::symbol::{Symbol, keywords};
  24 use syntax::visit::Visitor;
  25 use syntax::util::lev_distance::find_best_match_for_name;
  26 use syntax_pos::{Span, DUMMY_SP};
  27 use errors::Applicability;
  28
  29 use std::cell::Cell;
  30 use std::{mem, ptr};
  31 use rustc_data_structures::sync::Lrc;
  32
  33 #[derive(Clone, Debug)]
  34 pub struct InvocationData<'a> {
  35     def_index: DefIndex,
  36     /// Module in which the macro was invoked.
  37     crate module: Cell<Module<'a>>,
  38     /// Legacy scope in which the macro was invoked.
  39     /// The invocation path is resolved in this scope.
  40     crate parent_legacy_scope: Cell<LegacyScope<'a>>,
  41     /// Legacy scope *produced* by expanding this macro invocation,
  42     /// includes all the macro_rules items, other invocations, etc generated by it.
  43     /// `None` if the macro is not expanded yet.
  44     crate output_legacy_scope: Cell<Option<LegacyScope<'a>>>,
  45 }
  46
  47 impl<'a> InvocationData<'a> {
  48     pub fn root(graph_root: Module<'a>) -> Self {
  49         InvocationData {
  50             module: Cell::new(graph_root),
  51             def_index: CRATE_DEF_INDEX,
  52             parent_legacy_scope: Cell::new(LegacyScope::Empty),
  53             output_legacy_scope: Cell::new(Some(LegacyScope::Empty)),
  54         }
  55     }
  56 }
  57
  58 /// Binding produced by a `macro_rules` item.
  59 /// Not modularized, can shadow previous legacy bindings, etc.
  60 #[derive(Debug)]
  61 pub struct LegacyBinding<'a> {
  62     binding: &'a NameBinding<'a>,
  63     /// Legacy scope into which the `macro_rules` item was planted.
  64     parent_legacy_scope: LegacyScope<'a>,
  65     ident: Ident,
  66 }
  67
  68 /// Scope introduced by a `macro_rules!` macro.
  69 /// Starts at the macro's definition and ends at the end of the macro's parent module
  70 /// (named or unnamed), or even further if it escapes with `#[macro_use]`.
  71 /// Some macro invocations need to introduce legacy scopes too because they
  72 /// potentially can expand into macro definitions.
  73 #[derive(Copy, Clone, Debug)]
  74 pub enum LegacyScope<'a> {
  75     /// Created when invocation data is allocated in the arena,
  76     /// must be replaced with a proper scope later.
  77     Uninitialized,
  78     /// Empty "root" scope at the crate start containing no names.
  79     Empty,
  80     /// Scope introduced by a `macro_rules!` macro definition.
  81     Binding(&'a LegacyBinding<'a>),
  82     /// Scope introduced by a macro invocation that can potentially
  83     /// create a `macro_rules!` macro definition.
  84     Invocation(&'a InvocationData<'a>),
  85 }
  86
  87 /// Everything you need to resolve a macro or import path.
  88 #[derive(Clone, Debug)]
  89 pub struct ParentScope<'a> {
  90     crate module: Module<'a>,
  91     crate expansion: Mark,
  92     crate legacy: LegacyScope<'a>,
  93     crate derives: Vec<ast::Path>,
  94 }
  95
  96 // Macro namespace is separated into two sub-namespaces, one for bang macros and
  97 // one for attribute-like macros (attributes, derives).
  98 // We ignore resolutions from one sub-namespace when searching names in scope for another.
  99 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
 100     #[derive(PartialEq)]
 101     enum SubNS { Bang, AttrLike }
 102     let sub_ns = |kind| match kind {
 103         MacroKind::Bang => Some(SubNS::Bang),
 104         MacroKind::Attr | MacroKind::Derive => Some(SubNS::AttrLike),
 105         MacroKind::ProcMacroStub => None,
 106     };
 107     let requirement = requirement.and_then(|kind| sub_ns(kind));
 108     let candidate = candidate.and_then(|kind| sub_ns(kind));
 109     // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
 110     candidate.is_none() || requirement.is_none() || candidate == requirement
 111 }
 112
 113 impl<'a> base::Resolver for Resolver<'a> {
 114     fn next_node_id(&mut self) -> ast::NodeId {
 115         self.session.next_node_id()
 116     }
 117
 118     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
 119         let mark = Mark::fresh(Mark::root());
 120         let module = self.module_map[&self.definitions.local_def_id(id)];
 121         self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
 122             module: Cell::new(module),
 123             def_index: module.def_id().unwrap().index,
 124             parent_legacy_scope: Cell::new(LegacyScope::Empty),
 125             output_legacy_scope: Cell::new(Some(LegacyScope::Empty)),
 126         }));
 127         mark
 128     }
 129
 130     fn resolve_dollar_crates(&mut self, annotatable: &Annotatable) {
 131         pub struct ResolveDollarCrates<'a, 'b: 'a> {
 132             pub resolver: &'a mut Resolver<'b>,
 133         }
 134         impl<'a> Visitor<'a> for ResolveDollarCrates<'a, '_> {
 135             fn visit_ident(&mut self, ident: Ident) {
 136                 if ident.name == keywords::DollarCrate.name() {
 137                     let name = match self.resolver.resolve_crate_root(ident).kind {
 138                         ModuleKind::Def(_, name) if name != keywords::Invalid.name() => name,
 139                         _ => keywords::Crate.name(),
 140                     };
 141                     ident.span.ctxt().set_dollar_crate_name(name);
 142                 }
 143             }
 144             fn visit_mac(&mut self, _: &ast::Mac) {}
 145         }
 146
 147         annotatable.visit_with(&mut ResolveDollarCrates { resolver: self });
 148     }
 149
 150     fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
 151                                             derives: &[Mark]) {
 152         let invocation = self.invocations[&mark];
 153         self.collect_def_ids(mark, invocation, fragment);
 154
 155         self.current_module = invocation.module.get();
 156         self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
 157         self.current_module.unresolved_invocations.borrow_mut().extend(derives);
 158         self.invocations.extend(derives.iter().map(|&derive| (derive, invocation)));
 159         let mut visitor = BuildReducedGraphVisitor {
 160             resolver: self,
 161             current_legacy_scope: invocation.parent_legacy_scope.get(),
 162             expansion: mark,
 163         };
 164         fragment.visit_with(&mut visitor);
 165         invocation.output_legacy_scope.set(Some(visitor.current_legacy_scope));
 166     }
 167
 168     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
 169         let def_id = DefId {
 170             krate: CrateNum::BuiltinMacros,
 171             index: DefIndex::from_array_index(self.macro_map.len(),
 172                                               DefIndexAddressSpace::Low),
 173         };
 174         let kind = ext.kind();
 175         self.macro_map.insert(def_id, ext);
 176         let binding = self.arenas.alloc_name_binding(NameBinding {
 177             kind: NameBindingKind::Def(Def::Macro(def_id, kind), false),
 178             ambiguity: None,
 179             span: DUMMY_SP,
 180             vis: ty::Visibility::Public,
 181             expansion: Mark::root(),
 182         });
 183         if self.builtin_macros.insert(ident.name, binding).is_some() {
 184             self.session.span_err(ident.span,
 185                                   &format!("built-in macro `{}` was already defined", ident));
 186         }
 187     }
 188
 189     fn resolve_imports(&mut self) {
 190         ImportResolver { resolver: self }.resolve_imports()
 191     }
 192
 193     fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
 194                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
 195         let (path, kind, derives_in_scope, after_derive) = match invoc.kind {
 196             InvocationKind::Attr { attr: None, .. } =>
 197                 return Ok(None),
 198             InvocationKind::Attr { attr: Some(ref attr), ref traits, after_derive, .. } =>
 199                 (&attr.path, MacroKind::Attr, traits.clone(), after_derive),
 200             InvocationKind::Bang { ref mac, .. } =>
 201                 (&mac.node.path, MacroKind::Bang, Vec::new(), false),
 202             InvocationKind::Derive { ref path, .. } =>
 203                 (path, MacroKind::Derive, Vec::new(), false),
 204         };
 205
 206         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 207         let (def, ext) = match self.resolve_macro_to_def(path, kind, &parent_scope, true, force) {
 208             Ok((def, ext)) => (def, ext),
 209             Err(Determinacy::Determined) if kind == MacroKind::Attr => {
 210                 // Replace unresolved attributes with used inert attributes for better recovery.
 211                 return Ok(Some(Lrc::new(SyntaxExtension::NonMacroAttr { mark_used: true })));
 212             }
 213             Err(determinacy) => return Err(determinacy),
 214         };
 215
 216         if let Def::Macro(def_id, _) = def {
 217             if after_derive {
 218                 self.session.span_err(invoc.span(),
 219                                       "macro attributes must be placed before `#[derive]`");
 220             }
 221             self.macro_defs.insert(invoc.expansion_data.mark, def_id);
 222             let normal_module_def_id =
 223                 self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
 224             self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
 225                                                             normal_module_def_id);
 226             invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
 227         }
 228
 229         Ok(Some(ext))
 230     }
 231
 232     fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
 233                           derives_in_scope: Vec<ast::Path>, force: bool)
 234                           -> Result<Lrc<SyntaxExtension>, Determinacy> {
 235         let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
 236         Ok(self.resolve_macro_to_def(path, kind, &parent_scope, false, force)?.1)
 237     }
 238
 239     fn check_unused_macros(&self) {
 240         for did in self.unused_macros.iter() {
 241             let id_span = match *self.macro_map[did] {
 242                 SyntaxExtension::NormalTT { def_info, .. } |
 243                 SyntaxExtension::DeclMacro { def_info, .. } => def_info,
 244                 _ => None,
 245             };
 246             if let Some((id, span)) = id_span {
 247                 let lint = lint::builtin::UNUSED_MACROS;
 248                 let msg = "unused macro definition";
 249                 self.session.buffer_lint(lint, id, span, msg);
 250             } else {
 251                 bug!("attempted to create unused macro error, but span not available");
 252             }
 253         }
 254     }
 255 }
 256
 257 impl<'a> Resolver<'a> {
 258     pub fn dummy_parent_scope(&self) -> ParentScope<'a> {
 259         self.invoc_parent_scope(Mark::root(), Vec::new())
 260     }
 261
 262     fn invoc_parent_scope(&self, invoc_id: Mark, derives: Vec<ast::Path>) -> ParentScope<'a> {
 263         let invoc = self.invocations[&invoc_id];
 264         ParentScope {
 265             module: invoc.module.get().nearest_item_scope(),
 266             expansion: invoc_id.parent(),
 267             legacy: invoc.parent_legacy_scope.get(),
 268             derives,
 269         }
 270     }
 271
 272     fn resolve_macro_to_def(
 273         &mut self,
 274         path: &ast::Path,
 275         kind: MacroKind,
 276         parent_scope: &ParentScope<'a>,
 277         trace: bool,
 278         force: bool,
 279     ) -> Result<(Def, Lrc<SyntaxExtension>), Determinacy> {
 280         let def = self.resolve_macro_to_def_inner(path, kind, parent_scope, trace, force);
 281
 282         // Report errors and enforce feature gates for the resolved macro.
 283         if def != Err(Determinacy::Undetermined) {
 284             // Do not report duplicated errors on every undetermined resolution.
 285             for segment in &path.segments {
 286                 if let Some(args) = &segment.args {
 287                     self.session.span_err(args.span(), "generic arguments in macro path");
 288                 }
 289             }
 290         }
 291
 292         let def = def?;
 293
 294         match def {
 295             Def::Macro(def_id, macro_kind) => {
 296                 self.unused_macros.remove(&def_id);
 297                 if macro_kind == MacroKind::ProcMacroStub {
 298                     let msg = "can't use a procedural macro from the same crate that defines it";
 299                     self.session.span_err(path.span, msg);
 300                     return Err(Determinacy::Determined);
 301                 }
 302             }
 303             Def::NonMacroAttr(attr_kind) => {
 304                 if kind == MacroKind::Attr {
 305                     let features = self.session.features_untracked();
 306                     if attr_kind == NonMacroAttrKind::Custom {
 307                         assert!(path.segments.len() == 1);
 308                         let name = path.segments[0].ident.as_str();
 309                         if name.starts_with("rustc_") {
 310                             if !features.rustc_attrs {
 311                                 let msg = "unless otherwise specified, attributes with the prefix \
 312                                            `rustc_` are reserved for internal compiler diagnostics";
 313                                 feature_err(&self.session.parse_sess, "rustc_attrs", path.span,
 314                                             GateIssue::Language, &msg).emit();
 315                             }
 316                         } else if !features.custom_attribute {
 317                             let msg = format!("The attribute `{}` is currently unknown to the \
 318                                                compiler and may have meaning added to it in the \
 319                                                future", path);
 320                             feature_err(&self.session.parse_sess, "custom_attribute", path.span,
 321                                         GateIssue::Language, &msg).emit();
 322                         }
 323                     }
 324                 } else {
 325                     // Not only attributes, but anything in macro namespace can result in
 326                     // `Def::NonMacroAttr` definition (e.g., `inline!()`), so we must report
 327                     // an error for those cases.
 328                     let msg = format!("expected a macro, found {}", def.kind_name());
 329                     self.session.span_err(path.span, &msg);
 330                     return Err(Determinacy::Determined);
 331                 }
 332             }
 333             Def::Err => {
 334                 return Err(Determinacy::Determined);
 335             }
 336             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 337         }
 338
 339         Ok((def, self.get_macro(def)))
 340     }
 341
 342     pub fn resolve_macro_to_def_inner(
 343         &mut self,
 344         path: &ast::Path,
 345         kind: MacroKind,
 346         parent_scope: &ParentScope<'a>,
 347         trace: bool,
 348         force: bool,
 349     ) -> Result<Def, Determinacy> {
 350         let path_span = path.span;
 351         let mut path = Segment::from_path(path);
 352
 353         // Possibly apply the macro helper hack
 354         if kind == MacroKind::Bang && path.len() == 1 &&
 355            path[0].ident.span.ctxt().outer().expn_info()
 356                .map_or(false, |info| info.local_inner_macros) {
 357             let root = Ident::new(keywords::DollarCrate.name(), path[0].ident.span);
 358             path.insert(0, Segment::from_ident(root));
 359         }
 360
 361         if path.len() > 1 {
 362             let def = match self.resolve_path(&path, Some(MacroNS), parent_scope,
 363                                               false, path_span, CrateLint::No) {
 364                 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
 365                     Ok(path_res.base_def())
 366                 }
 367                 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
 368                 PathResult::NonModule(..) | PathResult::Indeterminate | PathResult::Failed(..) => {
 369                     Err(Determinacy::Determined)
 370                 }
 371                 PathResult::Module(..) => unreachable!(),
 372             };
 373
 374             if trace {
 375                 parent_scope.module.multi_segment_macro_resolutions.borrow_mut()
 376                     .push((path, path_span, kind, parent_scope.clone(), def.ok()));
 377             }
 378
 379             def
 380         } else {
 381             let binding = self.early_resolve_ident_in_lexical_scope(
 382                 path[0].ident, ScopeSet::Macro(kind), parent_scope, false, force, path_span
 383             );
 384             if let Err(Determinacy::Undetermined) = binding {
 385                 return Err(Determinacy::Undetermined);
 386             }
 387
 388             if trace {
 389                 parent_scope.module.single_segment_macro_resolutions.borrow_mut()
 390                     .push((path[0].ident, kind, parent_scope.clone(), binding.ok()));
 391             }
 392
 393             binding.map(|binding| binding.def())
 394         }
 395     }
 396
 397     // Resolve an identifier in lexical scope.
 398     // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
 399     // expansion and import resolution (perhaps they can be merged in the future).
 400     // The function is used for resolving initial segments of macro paths (e.g., `foo` in
 401     // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
 402     crate fn early_resolve_ident_in_lexical_scope(
 403         &mut self,
 404         orig_ident: Ident,
 405         scope_set: ScopeSet,
 406         parent_scope: &ParentScope<'a>,
 407         record_used: bool,
 408         force: bool,
 409         path_span: Span,
 410     ) -> Result<&'a NameBinding<'a>, Determinacy> {
 411         // General principles:
 412         // 1. Not controlled (user-defined) names should have higher priority than controlled names
 413         //    built into the language or standard library. This way we can add new names into the
 414         //    language or standard library without breaking user code.
 415         // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
 416         // Places to search (in order of decreasing priority):
 417         // (Type NS)
 418         // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
 419         //    (open set, not controlled).
 420         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 421         //    (open, not controlled).
 422         // 3. Extern prelude (closed, not controlled).
 423         // 4. Tool modules (closed, controlled right now, but not in the future).
 424         // 5. Standard library prelude (de-facto closed, controlled).
 425         // 6. Language prelude (closed, controlled).
 426         // (Value NS)
 427         // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
 428         //    (open set, not controlled).
 429         // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 430         //    (open, not controlled).
 431         // 3. Standard library prelude (de-facto closed, controlled).
 432         // (Macro NS)
 433         // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
 434         //    are currently reported as errors. They should be higher in priority than preludes
 435         //    and probably even names in modules according to the "general principles" above. They
 436         //    also should be subject to restricted shadowing because are effectively produced by
 437         //    derives (you need to resolve the derive first to add helpers into scope), but they
 438         //    should be available before the derive is expanded for compatibility.
 439         //    It's mess in general, so we are being conservative for now.
 440         // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
 441         //    priority than prelude macros, but create ambiguities with macros in modules.
 442         // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
 443         //    (open, not controlled). Have higher priority than prelude macros, but create
 444         //    ambiguities with `macro_rules`.
 445         // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
 446         // 4a. User-defined prelude from macro-use
 447         //    (open, the open part is from macro expansions, not controlled).
 448         // 4b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
 449         // 5. Language prelude: builtin macros (closed, controlled, except for legacy plugins).
 450         // 6. Language prelude: builtin attributes (closed, controlled).
 451         // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
 452         //    but introduced by legacy plugins using `register_attribute`. Priority is somewhere
 453         //    in prelude, not sure where exactly (creates ambiguities with any other prelude names).
 454
 455         enum WhereToResolve<'a> {
 456             DeriveHelpers,
 457             MacroRules(LegacyScope<'a>),
 458             CrateRoot,
 459             Module(Module<'a>),
 460             MacroUsePrelude,
 461             BuiltinMacros,
 462             BuiltinAttrs,
 463             LegacyPluginHelpers,
 464             ExternPrelude,
 465             ToolPrelude,
 466             StdLibPrelude,
 467             BuiltinTypes,
 468         }
 469
 470         bitflags! {
 471             struct Flags: u8 {
 472                 const MACRO_RULES        = 1 << 0;
 473                 const MODULE             = 1 << 1;
 474                 const PRELUDE            = 1 << 2;
 475                 const MISC_SUGGEST_CRATE = 1 << 3;
 476                 const MISC_SUGGEST_SELF  = 1 << 4;
 477                 const MISC_FROM_PRELUDE  = 1 << 5;
 478             }
 479         }
 480
 481         assert!(force || !record_used); // `record_used` implies `force`
 482         let mut ident = orig_ident.modern();
 483
 484         // Make sure `self`, `super` etc produce an error when passed to here.
 485         if ident.is_path_segment_keyword() {
 486             return Err(Determinacy::Determined);
 487         }
 488
 489         // This is *the* result, resolution from the scope closest to the resolved identifier.
 490         // However, sometimes this result is "weak" because it comes from a glob import or
 491         // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
 492         // mod m { ... } // solution in outer scope
 493         // {
 494         //     use prefix::*; // imports another `m` - innermost solution
 495         //                    // weak, cannot shadow the outer `m`, need to report ambiguity error
 496         //     m::mac!();
 497         // }
 498         // So we have to save the innermost solution and continue searching in outer scopes
 499         // to detect potential ambiguities.
 500         let mut innermost_result: Option<(&NameBinding, Flags)> = None;
 501
 502         // Go through all the scopes and try to resolve the name.
 503         let rust_2015 = orig_ident.span.rust_2015();
 504         let (ns, macro_kind, is_import, is_absolute_path) = match scope_set {
 505             ScopeSet::Import(ns) => (ns, None, true, false),
 506             ScopeSet::AbsolutePath(ns) => (ns, None, false, true),
 507             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false, false),
 508             ScopeSet::Module => (TypeNS, None, false, false),
 509         };
 510         let mut where_to_resolve = match ns {
 511             _ if is_absolute_path || is_import && rust_2015 => WhereToResolve::CrateRoot,
 512             TypeNS | ValueNS => WhereToResolve::Module(parent_scope.module),
 513             MacroNS => WhereToResolve::DeriveHelpers,
 514         };
 515         let mut use_prelude = !parent_scope.module.no_implicit_prelude;
 516         let mut determinacy = Determinacy::Determined;
 517         loop {
 518             let result = match where_to_resolve {
 519                 WhereToResolve::DeriveHelpers => {
 520                     let mut result = Err(Determinacy::Determined);
 521                     for derive in &parent_scope.derives {
 522                         let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
 523                         match self.resolve_macro_to_def(derive, MacroKind::Derive,
 524                                                         &parent_scope, true, force) {
 525                             Ok((_, ext)) => {
 526                                 if let SyntaxExtension::ProcMacroDerive(_, helpers, _) = &*ext {
 527                                     if helpers.contains(&ident.name) {
 528                                         let binding =
 529                                             (Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
 530                                             ty::Visibility::Public, derive.span, Mark::root())
 531                                             .to_name_binding(self.arenas);
 532                                         result = Ok((binding, Flags::empty()));
 533                                         break;
 534                                     }
 535                                 }
 536                             }
 537                             Err(Determinacy::Determined) => {}
 538                             Err(Determinacy::Undetermined) =>
 539                                 result = Err(Determinacy::Undetermined),
 540                         }
 541                     }
 542                     result
 543                 }
 544                 WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 545                     LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
 546                         Ok((legacy_binding.binding, Flags::MACRO_RULES)),
 547                     LegacyScope::Invocation(invoc) if invoc.output_legacy_scope.get().is_none() =>
 548                         Err(Determinacy::Undetermined),
 549                     _ => Err(Determinacy::Determined),
 550                 }
 551                 WhereToResolve::CrateRoot => {
 552                     let root_ident = Ident::new(keywords::PathRoot.name(), orig_ident.span);
 553                     let root_module = self.resolve_crate_root(root_ident);
 554                     let binding = self.resolve_ident_in_module_ext(
 555                         ModuleOrUniformRoot::Module(root_module),
 556                         orig_ident,
 557                         ns,
 558                         None,
 559                         record_used,
 560                         path_span,
 561                     );
 562                     match binding {
 563                         Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
 564                         Err((Determinacy::Undetermined, Weak::No)) =>
 565                             return Err(Determinacy::determined(force)),
 566                         Err((Determinacy::Undetermined, Weak::Yes)) =>
 567                             Err(Determinacy::Undetermined),
 568                         Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
 569                     }
 570                 }
 571                 WhereToResolve::Module(module) => {
 572                     let orig_current_module = mem::replace(&mut self.current_module, module);
 573                     let binding = self.resolve_ident_in_module_unadjusted_ext(
 574                         ModuleOrUniformRoot::Module(module),
 575                         ident,
 576                         ns,
 577                         None,
 578                         true,
 579                         record_used,
 580                         path_span,
 581                     );
 582                     self.current_module = orig_current_module;
 583                     match binding {
 584                         Ok(binding) => {
 585                             let misc_flags = if ptr::eq(module, self.graph_root) {
 586                                 Flags::MISC_SUGGEST_CRATE
 587                             } else if module.is_normal() {
 588                                 Flags::MISC_SUGGEST_SELF
 589                             } else {
 590                                 Flags::empty()
 591                             };
 592                             Ok((binding, Flags::MODULE | misc_flags))
 593                         }
 594                         Err((Determinacy::Undetermined, Weak::No)) =>
 595                             return Err(Determinacy::determined(force)),
 596                         Err((Determinacy::Undetermined, Weak::Yes)) =>
 597                             Err(Determinacy::Undetermined),
 598                         Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
 599                     }
 600                 }
 601                 WhereToResolve::MacroUsePrelude => {
 602                     if use_prelude || rust_2015 {
 603                         match self.macro_use_prelude.get(&ident.name).cloned() {
 604                             Some(binding) =>
 605                                 Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE)),
 606                             None => Err(Determinacy::determined(
 607                                 self.graph_root.unresolved_invocations.borrow().is_empty()
 608                             ))
 609                         }
 610                     } else {
 611                         Err(Determinacy::Determined)
 612                     }
 613                 }
 614                 WhereToResolve::BuiltinMacros => {
 615                     match self.builtin_macros.get(&ident.name).cloned() {
 616                         Some(binding) => Ok((binding, Flags::PRELUDE)),
 617                         None => Err(Determinacy::Determined),
 618                     }
 619                 }
 620                 WhereToResolve::BuiltinAttrs => {
 621                     if is_builtin_attr_name(ident.name) {
 622                         let binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
 623                                        ty::Visibility::Public, DUMMY_SP, Mark::root())
 624                                        .to_name_binding(self.arenas);
 625                         Ok((binding, Flags::PRELUDE))
 626                     } else {
 627                         Err(Determinacy::Determined)
 628                     }
 629                 }
 630                 WhereToResolve::LegacyPluginHelpers => {
 631                     if (use_prelude || rust_2015) &&
 632                        self.session.plugin_attributes.borrow().iter()
 633                                                      .any(|(name, _)| ident.name == &**name) {
 634                         let binding = (Def::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
 635                                        ty::Visibility::Public, DUMMY_SP, Mark::root())
 636                                        .to_name_binding(self.arenas);
 637                         Ok((binding, Flags::PRELUDE))
 638                     } else {
 639                         Err(Determinacy::Determined)
 640                     }
 641                 }
 642                 WhereToResolve::ExternPrelude => {
 643                     if use_prelude || is_absolute_path {
 644                         match self.extern_prelude_get(ident, !record_used) {
 645                             Some(binding) => Ok((binding, Flags::PRELUDE)),
 646                             None => Err(Determinacy::determined(
 647                                 self.graph_root.unresolved_invocations.borrow().is_empty()
 648                             )),
 649                         }
 650                     } else {
 651                         Err(Determinacy::Determined)
 652                     }
 653                 }
 654                 WhereToResolve::ToolPrelude => {
 655                     if use_prelude && is_known_tool(ident.name) {
 656                         let binding = (Def::ToolMod, ty::Visibility::Public,
 657                                        DUMMY_SP, Mark::root()).to_name_binding(self.arenas);
 658                         Ok((binding, Flags::PRELUDE))
 659                     } else {
 660                         Err(Determinacy::Determined)
 661                     }
 662                 }
 663                 WhereToResolve::StdLibPrelude => {
 664                     let mut result = Err(Determinacy::Determined);
 665                     if use_prelude {
 666                         if let Some(prelude) = self.prelude {
 667                             if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
 668                                 ModuleOrUniformRoot::Module(prelude),
 669                                 ident,
 670                                 ns,
 671                                 false,
 672                                 path_span,
 673                             ) {
 674                                 result = Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE));
 675                             }
 676                         }
 677                     }
 678                     result
 679                 }
 680                 WhereToResolve::BuiltinTypes => {
 681                     match self.primitive_type_table.primitive_types.get(&ident.name).cloned() {
 682                         Some(prim_ty) => {
 683                             let binding = (Def::PrimTy(prim_ty), ty::Visibility::Public,
 684                                            DUMMY_SP, Mark::root()).to_name_binding(self.arenas);
 685                             Ok((binding, Flags::PRELUDE))
 686                         }
 687                         None => Err(Determinacy::Determined)
 688                     }
 689                 }
 690             };
 691
 692             match result {
 693                 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
 694                     if !record_used {
 695                         return Ok(binding);
 696                     }
 697
 698                     if let Some((innermost_binding, innermost_flags)) = innermost_result {
 699                         // Found another solution, if the first one was "weak", report an error.
 700                         let (def, innermost_def) = (binding.def(), innermost_binding.def());
 701                         if def != innermost_def {
 702                             let builtin = Def::NonMacroAttr(NonMacroAttrKind::Builtin);
 703                             let derive_helper = Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
 704                             let legacy_helper =
 705                                 Def::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
 706
 707                             let ambiguity_error_kind = if is_import {
 708                                 Some(AmbiguityKind::Import)
 709                             } else if is_absolute_path {
 710                                 Some(AmbiguityKind::AbsolutePath)
 711                             } else if innermost_def == builtin || def == builtin {
 712                                 Some(AmbiguityKind::BuiltinAttr)
 713                             } else if innermost_def == derive_helper || def == derive_helper {
 714                                 Some(AmbiguityKind::DeriveHelper)
 715                             } else if innermost_def == legacy_helper &&
 716                                       flags.contains(Flags::PRELUDE) ||
 717                                       def == legacy_helper &&
 718                                       innermost_flags.contains(Flags::PRELUDE) {
 719                                 Some(AmbiguityKind::LegacyHelperVsPrelude)
 720                             } else if innermost_flags.contains(Flags::MACRO_RULES) &&
 721                                       flags.contains(Flags::MODULE) &&
 722                                       !self.disambiguate_legacy_vs_modern(innermost_binding,
 723                                                                           binding) ||
 724                                       flags.contains(Flags::MACRO_RULES) &&
 725                                       innermost_flags.contains(Flags::MODULE) &&
 726                                       !self.disambiguate_legacy_vs_modern(binding,
 727                                                                           innermost_binding) {
 728                                 Some(AmbiguityKind::LegacyVsModern)
 729                             } else if innermost_binding.is_glob_import() {
 730                                 Some(AmbiguityKind::GlobVsOuter)
 731                             } else if innermost_binding.may_appear_after(parent_scope.expansion,
 732                                                                          binding) {
 733                                 Some(AmbiguityKind::MoreExpandedVsOuter)
 734                             } else {
 735                                 None
 736                             };
 737                             if let Some(kind) = ambiguity_error_kind {
 738                                 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
 739                                     AmbiguityErrorMisc::SuggestCrate
 740                                 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
 741                                     AmbiguityErrorMisc::SuggestSelf
 742                                 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
 743                                     AmbiguityErrorMisc::FromPrelude
 744                                 } else {
 745                                     AmbiguityErrorMisc::None
 746                                 };
 747                                 self.ambiguity_errors.push(AmbiguityError {
 748                                     kind,
 749                                     ident: orig_ident,
 750                                     b1: innermost_binding,
 751                                     b2: binding,
 752                                     misc1: misc(innermost_flags),
 753                                     misc2: misc(flags),
 754                                 });
 755                                 return Ok(innermost_binding);
 756                             }
 757                         }
 758                     } else {
 759                         // Found the first solution.
 760                         innermost_result = Some((binding, flags));
 761                     }
 762                 }
 763                 Ok(..) | Err(Determinacy::Determined) => {}
 764                 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
 765             }
 766
 767             where_to_resolve = match where_to_resolve {
 768                 WhereToResolve::DeriveHelpers =>
 769                     WhereToResolve::MacroRules(parent_scope.legacy),
 770                 WhereToResolve::MacroRules(legacy_scope) => match legacy_scope {
 771                     LegacyScope::Binding(binding) => WhereToResolve::MacroRules(
 772                         binding.parent_legacy_scope
 773                     ),
 774                     LegacyScope::Invocation(invoc) => WhereToResolve::MacroRules(
 775                         invoc.output_legacy_scope.get().unwrap_or(invoc.parent_legacy_scope.get())
 776                     ),
 777                     LegacyScope::Empty => WhereToResolve::Module(parent_scope.module),
 778                     LegacyScope::Uninitialized => unreachable!(),
 779                 }
 780                 WhereToResolve::CrateRoot if is_import => match ns {
 781                     TypeNS | ValueNS => WhereToResolve::Module(parent_scope.module),
 782                     MacroNS => WhereToResolve::DeriveHelpers,
 783                 }
 784                 WhereToResolve::CrateRoot if is_absolute_path => match ns {
 785                     TypeNS => {
 786                         ident.span.adjust(Mark::root());
 787                         WhereToResolve::ExternPrelude
 788                     }
 789                     ValueNS | MacroNS => break,
 790                 }
 791                 WhereToResolve::CrateRoot => unreachable!(),
 792                 WhereToResolve::Module(module) => {
 793                     match self.hygienic_lexical_parent(module, &mut ident.span) {
 794                         Some(parent_module) => WhereToResolve::Module(parent_module),
 795                         None => {
 796                             use_prelude = !module.no_implicit_prelude;
 797                             match ns {
 798                                 TypeNS => WhereToResolve::ExternPrelude,
 799                                 ValueNS => WhereToResolve::StdLibPrelude,
 800                                 MacroNS => WhereToResolve::MacroUsePrelude,
 801                             }
 802                         }
 803                     }
 804                 }
 805                 WhereToResolve::MacroUsePrelude => WhereToResolve::BuiltinMacros,
 806                 WhereToResolve::BuiltinMacros => WhereToResolve::BuiltinAttrs,
 807                 WhereToResolve::BuiltinAttrs => WhereToResolve::LegacyPluginHelpers,
 808                 WhereToResolve::LegacyPluginHelpers => break, // nowhere else to search
 809                 WhereToResolve::ExternPrelude if is_absolute_path => break,
 810                 WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
 811                 WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
 812                 WhereToResolve::StdLibPrelude => match ns {
 813                     TypeNS => WhereToResolve::BuiltinTypes,
 814                     ValueNS => break, // nowhere else to search
 815                     MacroNS => unreachable!(),
 816                 }
 817                 WhereToResolve::BuiltinTypes => break, // nowhere else to search
 818             };
 819
 820             continue;
 821         }
 822
 823         // The first found solution was the only one, return it.
 824         if let Some((binding, flags)) = innermost_result {
 825             // We get to here only if there's no ambiguity, in ambiguous cases an error will
 826             // be reported anyway, so there's no reason to report an additional feature error.
 827             // The `binding` can actually be introduced by something other than `--extern`,
 828             // but its `Def` should coincide with a crate passed with `--extern`
 829             // (otherwise there would be ambiguity) and we can skip feature error in this case.
 830             'ok: {
 831                 if !is_import || self.session.features_untracked().uniform_paths {
 832                     break 'ok;
 833                 }
 834                 if ns == TypeNS && use_prelude && self.extern_prelude_get(ident, true).is_some() {
 835                     break 'ok;
 836                 }
 837                 if rust_2015 {
 838                     let root_ident = Ident::new(keywords::PathRoot.name(), orig_ident.span);
 839                     let root_module = self.resolve_crate_root(root_ident);
 840                     if self.resolve_ident_in_module_ext(ModuleOrUniformRoot::Module(root_module),
 841                                                         orig_ident, ns, None, false, path_span)
 842                                                         .is_ok() {
 843                         break 'ok;
 844                     }
 845                 }
 846
 847                 let msg = "imports can only refer to extern crate names \
 848                            passed with `--extern` on stable channel";
 849                 let mut err = feature_err(&self.session.parse_sess, "uniform_paths",
 850                                           ident.span, GateIssue::Language, msg);
 851
 852                 let what = self.binding_description(binding, ident,
 853                                                     flags.contains(Flags::MISC_FROM_PRELUDE));
 854                 let note_msg = format!("this import refers to {what}", what = what);
 855                 let label_span = if binding.span.is_dummy() {
 856                     err.note(&note_msg);
 857                     ident.span
 858                 } else {
 859                     err.span_note(binding.span, &note_msg);
 860                     binding.span
 861                 };
 862                 err.span_label(label_span, "not an extern crate passed with `--extern`");
 863                 err.emit();
 864             }
 865
 866             return Ok(binding);
 867         }
 868
 869         let determinacy = Determinacy::determined(determinacy == Determinacy::Determined || force);
 870         if determinacy == Determinacy::Determined && macro_kind == Some(MacroKind::Attr) {
 871             // For single-segment attributes interpret determinate "no resolution" as a custom
 872             // attribute. (Lexical resolution implies the first segment and attr kind should imply
 873             // the last segment, so we are certainly working with a single-segment attribute here.)
 874             assert!(ns == MacroNS);
 875             let binding = (Def::NonMacroAttr(NonMacroAttrKind::Custom),
 876                            ty::Visibility::Public, ident.span, Mark::root())
 877                            .to_name_binding(self.arenas);
 878             Ok(binding)
 879         } else {
 880             Err(determinacy)
 881         }
 882     }
 883
 884     pub fn finalize_current_module_macro_resolutions(&mut self) {
 885         let module = self.current_module;
 886
 887         let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
 888                                  initial_def: Option<Def>, def: Def| {
 889             if let Some(initial_def) = initial_def {
 890                 if def != initial_def && def != Def::Err && this.ambiguity_errors.is_empty() {
 891                     // Make sure compilation does not succeed if preferred macro resolution
 892                     // has changed after the macro had been expanded. In theory all such
 893                     // situations should be reported as ambiguity errors, so this is a bug.
 894                     if initial_def == Def::NonMacroAttr(NonMacroAttrKind::Custom) {
 895                         // Yeah, legacy custom attributes are implemented using forced resolution
 896                         // (which is a best effort error recovery tool, basically), so we can't
 897                         // promise their resolution won't change later.
 898                         let msg = format!("inconsistent resolution for a macro: first {}, then {}",
 899                                           initial_def.kind_name(), def.kind_name());
 900                         this.session.span_err(span, &msg);
 901                     } else {
 902                         span_bug!(span, "inconsistent resolution for a macro");
 903                     }
 904                 }
 905             } else {
 906                 // It's possible that the macro was unresolved (indeterminate) and silently
 907                 // expanded into a dummy fragment for recovery during expansion.
 908                 // Now, post-expansion, the resolution may succeed, but we can't change the
 909                 // past and need to report an error.
 910                 // However, non-speculative `resolve_path` can successfully return private items
 911                 // even if speculative `resolve_path` returned nothing previously, so we skip this
 912                 // less informative error if the privacy error is reported elsewhere.
 913                 if this.privacy_errors.is_empty() {
 914                     let msg = format!("cannot determine resolution for the {} `{}`",
 915                                         kind.descr(), Segment::names_to_string(path));
 916                     let msg_note = "import resolution is stuck, try simplifying macro imports";
 917                     this.session.struct_span_err(span, &msg).note(msg_note).emit();
 918                 }
 919             }
 920         };
 921
 922         let macro_resolutions =
 923             mem::replace(&mut *module.multi_segment_macro_resolutions.borrow_mut(), Vec::new());
 924         for (mut path, path_span, kind, parent_scope, initial_def) in macro_resolutions {
 925             // FIXME: Path resolution will ICE if segment IDs present.
 926             for seg in &mut path { seg.id = None; }
 927             match self.resolve_path(&path, Some(MacroNS), &parent_scope,
 928                                     true, path_span, CrateLint::No) {
 929                 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
 930                     let def = path_res.base_def();
 931                     check_consistency(self, &path, path_span, kind, initial_def, def);
 932                 }
 933                 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed(..) => {
 934                     let (span, msg) = if let PathResult::Failed(span, msg, ..) = path_res {
 935                         (span, msg)
 936                     } else {
 937                         (path_span, format!("partially resolved path in {} {}",
 938                                             kind.article(), kind.descr()))
 939                     };
 940                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
 941                 }
 942                 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
 943             }
 944         }
 945
 946         let macro_resolutions =
 947             mem::replace(&mut *module.single_segment_macro_resolutions.borrow_mut(), Vec::new());
 948         for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
 949             match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
 950                                                             &parent_scope, true, true, ident.span) {
 951                 Ok(binding) => {
 952                     let initial_def = initial_binding.map(|initial_binding| {
 953                         self.record_use(ident, MacroNS, initial_binding, false);
 954                         initial_binding.def()
 955                     });
 956                     let def = binding.def();
 957                     let seg = Segment::from_ident(ident);
 958                     check_consistency(self, &[seg], ident.span, kind, initial_def, def);
 959                 }
 960                 Err(..) => {
 961                     assert!(initial_binding.is_none());
 962                     let bang = if kind == MacroKind::Bang { "!" } else { "" };
 963                     let msg =
 964                         format!("cannot find {} `{}{}` in this scope", kind.descr(), ident, bang);
 965                     let mut err = self.session.struct_span_err(ident.span, &msg);
 966                     self.suggest_macro_name(&ident.as_str(), kind, &mut err, ident.span);
 967                     err.emit();
 968                 }
 969             }
 970         }
 971
 972         let builtin_attrs = mem::replace(&mut *module.builtin_attrs.borrow_mut(), Vec::new());
 973         for (ident, parent_scope) in builtin_attrs {
 974             let _ = self.early_resolve_ident_in_lexical_scope(
 975                 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
 976             );
 977         }
 978     }
 979
 980     fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
 981                           err: &mut DiagnosticBuilder<'a>, span: Span) {
 982         // First check if this is a locally-defined bang macro.
 983         let suggestion = if let MacroKind::Bang = kind {
 984             find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None)
 985         } else {
 986             None
 987         // Then check global macros.
 988         }.or_else(|| {
 989             let names = self.builtin_macros.iter().chain(self.macro_use_prelude.iter())
 990                                                   .filter_map(|(name, binding)| {
 991                 if binding.macro_kind() == Some(kind) { Some(name) } else { None }
 992             });
 993             find_best_match_for_name(names, name, None)
 994         // Then check modules.
 995         }).or_else(|| {
 996             let is_macro = |def| {
 997                 if let Def::Macro(_, def_kind) = def {
 998                     def_kind == kind
 999                 } else {
1000                     false
1001                 }
1002             };
1003             let ident = Ident::new(Symbol::intern(name), span);
1004             self.lookup_typo_candidate(&[Segment::from_ident(ident)], MacroNS, is_macro, span)
1005         });
1006
1007         if let Some(suggestion) = suggestion {
1008             if suggestion != name {
1009                 if let MacroKind::Bang = kind {
1010                     err.span_suggestion_with_applicability(
1011                         span,
1012                         "you could try the macro",
1013                         suggestion.to_string(),
1014                         Applicability::MaybeIncorrect
1015                     );
1016                 } else {
1017                     err.span_suggestion_with_applicability(
1018                         span,
1019                         "try",
1020                         suggestion.to_string(),
1021                         Applicability::MaybeIncorrect
1022                     );
1023                 }
1024             } else {
1025                 err.help("have you added the `#[macro_use]` on the module/import?");
1026             }
1027         }
1028     }
1029
1030     fn collect_def_ids(&mut self,
1031                        mark: Mark,
1032                        invocation: &'a InvocationData<'a>,
1033                        fragment: &AstFragment) {
1034         let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
1035         let InvocationData { def_index, .. } = *invocation;
1036
1037         let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
1038             invocations.entry(invoc.mark).or_insert_with(|| {
1039                 arenas.alloc_invocation_data(InvocationData {
1040                     def_index: invoc.def_index,
1041                     module: Cell::new(graph_root),
1042                     parent_legacy_scope: Cell::new(LegacyScope::Uninitialized),
1043                     output_legacy_scope: Cell::new(None),
1044                 })
1045             });
1046         };
1047
1048         let mut def_collector = DefCollector::new(&mut self.definitions, mark);
1049         def_collector.visit_macro_invoc = Some(visit_macro_invoc);
1050         def_collector.with_parent(def_index, |def_collector| {
1051             fragment.visit_with(def_collector)
1052         });
1053     }
1054
1055     pub fn define_macro(&mut self,
1056                         item: &ast::Item,
1057                         expansion: Mark,
1058                         current_legacy_scope: &mut LegacyScope<'a>) {
1059         self.local_macro_def_scopes.insert(item.id, self.current_module);
1060         let ident = item.ident;
1061         if ident.name == "macro_rules" {
1062             self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
1063         }
1064
1065         let def_id = self.definitions.local_def_id(item.id);
1066         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
1067                                                &self.session.features_untracked(),
1068                                                item, hygiene::default_edition()));
1069         self.macro_map.insert(def_id, ext);
1070
1071         let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
1072         if def.legacy {
1073             let ident = ident.modern();
1074             self.macro_names.insert(ident);
1075             let def = Def::Macro(def_id, MacroKind::Bang);
1076             let is_macro_export = attr::contains_name(&item.attrs, "macro_export");
1077             let vis = if is_macro_export {
1078                 ty::Visibility::Public
1079             } else {
1080                 ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))
1081             };
1082             let binding = (def, vis, item.span, expansion).to_name_binding(self.arenas);
1083             self.set_binding_parent_module(binding, self.current_module);
1084             let legacy_binding = self.arenas.alloc_legacy_binding(LegacyBinding {
1085                 parent_legacy_scope: *current_legacy_scope, binding, ident
1086             });
1087             *current_legacy_scope = LegacyScope::Binding(legacy_binding);
1088             self.all_macros.insert(ident.name, def);
1089             if is_macro_export {
1090                 let module = self.graph_root;
1091                 self.define(module, ident, MacroNS,
1092                             (def, vis, item.span, expansion, IsMacroExport));
1093             } else {
1094                 if !attr::contains_name(&item.attrs, "rustc_doc_only_macro") {
1095                     self.check_reserved_macro_name(ident, MacroNS);
1096                 }
1097                 self.unused_macros.insert(def_id);
1098             }
1099         } else {
1100             let module = self.current_module;
1101             let def = Def::Macro(def_id, MacroKind::Bang);
1102             let vis = self.resolve_visibility(&item.vis);
1103             if vis != ty::Visibility::Public {
1104                 self.unused_macros.insert(def_id);
1105             }
1106             self.define(module, ident, MacroNS, (def, vis, item.span, expansion));
1107         }
1108     }
1109 }