1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use {AmbiguityError, CrateLint, Resolver, ResolutionError, is_known_tool, resolve_error};
12 use {Module, ModuleKind, NameBinding, NameBindingKind, PathResult, ToNameBinding};
13 use ModuleOrUniformRoot;
14 use Namespace::{self, TypeNS, MacroNS};
15 use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
16 use resolve_imports::ImportResolver;
17 use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX, DefIndex,
18 CrateNum, DefIndexAddressSpace};
19 use rustc::hir::def::{Def, NonMacroAttrKind};
20 use rustc::hir::map::{self, DefCollector};
21 use rustc::{ty, lint};
22 use syntax::ast::{self, Name, Ident};
24 use syntax::errors::DiagnosticBuilder;
25 use syntax::ext::base::{self, Determinacy};
26 use syntax::ext::base::{MacroKind, SyntaxExtension, Resolver as SyntaxResolver};
27 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind, TogetherWith};
28 use syntax::ext::hygiene::{self, Mark};
29 use syntax::ext::tt::macro_rules;
30 use syntax::feature_gate::{self, feature_err, emit_feature_err, is_builtin_attr_name, GateIssue};
31 use syntax::feature_gate::EXPLAIN_DERIVE_UNDERSCORE;
32 use syntax::fold::{self, Folder};
33 use syntax::parse::parser::PathStyle;
34 use syntax::parse::token::{self, Token};
36 use syntax::symbol::{Symbol, keywords};
37 use syntax::tokenstream::{TokenStream, TokenTree, Delimited, DelimSpan};
38 use syntax::util::lev_distance::find_best_match_for_name;
39 use syntax_pos::{Span, DUMMY_SP};
40 use errors::Applicability;
44 use rustc_data_structures::sync::Lrc;
46 #[derive(Clone, Copy)]
47 crate struct FromPrelude(bool);
50 pub struct InvocationData<'a> {
52 /// Module in which the macro was invoked.
53 crate module: Cell<Module<'a>>,
54 /// Legacy scope in which the macro was invoked.
55 /// The invocation path is resolved in this scope.
56 crate parent_legacy_scope: Cell<LegacyScope<'a>>,
57 /// Legacy scope *produced* by expanding this macro invocation,
58 /// includes all the macro_rules items, other invocations, etc generated by it.
59 /// Set to the parent scope if the macro is not expanded yet (as if the macro produced nothing).
60 crate output_legacy_scope: Cell<LegacyScope<'a>>,
63 impl<'a> InvocationData<'a> {
64 pub fn root(graph_root: Module<'a>) -> Self {
66 module: Cell::new(graph_root),
67 def_index: CRATE_DEF_INDEX,
68 parent_legacy_scope: Cell::new(LegacyScope::Empty),
69 output_legacy_scope: Cell::new(LegacyScope::Empty),
74 /// Binding produced by a `macro_rules` item.
75 /// Not modularized, can shadow previous legacy bindings, etc.
76 pub struct LegacyBinding<'a> {
77 binding: &'a NameBinding<'a>,
78 /// Legacy scope into which the `macro_rules` item was planted.
79 parent_legacy_scope: LegacyScope<'a>,
83 /// Scope introduced by a `macro_rules!` macro.
84 /// Starts at the macro's definition and ends at the end of the macro's parent module
85 /// (named or unnamed), or even further if it escapes with `#[macro_use]`.
86 /// Some macro invocations need to introduce legacy scopes too because they
87 /// potentially can expand into macro definitions.
88 #[derive(Copy, Clone)]
89 pub enum LegacyScope<'a> {
90 /// Created when invocation data is allocated in the arena,
91 /// must be replaced with a proper scope later.
93 /// Empty "root" scope at the crate start containing no names.
95 /// Scope introduced by a `macro_rules!` macro definition.
96 Binding(&'a LegacyBinding<'a>),
97 /// Scope introduced by a macro invocation that can potentially
98 /// create a `macro_rules!` macro definition.
99 Invocation(&'a InvocationData<'a>),
102 /// Everything you need to resolve a macro path.
104 pub struct ParentScope<'a> {
105 crate module: Module<'a>,
106 crate expansion: Mark,
107 crate legacy: LegacyScope<'a>,
108 crate derives: Vec<ast::Path>,
111 // Macro namespace is separated into two sub-namespaces, one for bang macros and
112 // one for attribute-like macros (attributes, derives).
113 // We ignore resolutions from one sub-namespace when searching names in scope for another.
114 fn sub_namespace_mismatch(requirement: Option<MacroKind>, candidate: Option<MacroKind>) -> bool {
116 enum SubNS { Bang, AttrLike }
117 let sub_ns = |kind| match kind {
118 MacroKind::Bang => Some(SubNS::Bang),
119 MacroKind::Attr | MacroKind::Derive => Some(SubNS::AttrLike),
120 MacroKind::ProcMacroStub => None,
122 let requirement = requirement.and_then(|kind| sub_ns(kind));
123 let candidate = candidate.and_then(|kind| sub_ns(kind));
124 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
125 candidate.is_some() && requirement.is_some() && candidate != requirement
128 impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
129 fn next_node_id(&mut self) -> ast::NodeId {
130 self.session.next_node_id()
133 fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
134 let mark = Mark::fresh(Mark::root());
135 let module = self.module_map[&self.definitions.local_def_id(id)];
136 self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
137 module: Cell::new(module),
138 def_index: module.def_id().unwrap().index,
139 parent_legacy_scope: Cell::new(LegacyScope::Empty),
140 output_legacy_scope: Cell::new(LegacyScope::Empty),
145 fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> {
146 struct EliminateCrateVar<'b, 'a: 'b, 'crateloader: 'a>(
147 &'b mut Resolver<'a, 'crateloader>, Span
150 impl<'a, 'b, 'crateloader> Folder for EliminateCrateVar<'a, 'b, 'crateloader> {
151 fn fold_path(&mut self, path: ast::Path) -> ast::Path {
152 match self.fold_qpath(None, path) {
153 (None, path) => path,
158 fn fold_qpath(&mut self, mut qself: Option<ast::QSelf>, mut path: ast::Path)
159 -> (Option<ast::QSelf>, ast::Path) {
160 qself = qself.map(|ast::QSelf { ty, path_span, position }| {
162 ty: self.fold_ty(ty),
163 path_span: self.new_span(path_span),
168 if path.segments[0].ident.name == keywords::DollarCrate.name() {
169 let module = self.0.resolve_crate_root(path.segments[0].ident);
170 path.segments[0].ident.name = keywords::CrateRoot.name();
171 if !module.is_local() {
172 let span = path.segments[0].ident.span;
173 path.segments.insert(1, match module.kind {
174 ModuleKind::Def(_, name) => ast::PathSegment::from_ident(
175 ast::Ident::with_empty_ctxt(name).with_span_pos(span)
179 if let Some(qself) = &mut qself {
187 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
188 fold::noop_fold_mac(mac, self)
192 let ret = EliminateCrateVar(self, item.span).fold_item(item);
193 assert!(ret.len() == 1);
194 ret.into_iter().next().unwrap()
197 fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool {
198 self.whitelisted_legacy_custom_derives.contains(&name)
201 fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
203 let invocation = self.invocations[&mark];
204 self.collect_def_ids(mark, invocation, fragment);
206 self.current_module = invocation.module.get();
207 self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
208 self.current_module.unresolved_invocations.borrow_mut().extend(derives);
209 for &derive in derives {
210 self.invocations.insert(derive, invocation);
212 let mut visitor = BuildReducedGraphVisitor {
214 current_legacy_scope: invocation.parent_legacy_scope.get(),
217 fragment.visit_with(&mut visitor);
218 invocation.output_legacy_scope.set(visitor.current_legacy_scope);
221 fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
223 krate: CrateNum::BuiltinMacros,
224 index: DefIndex::from_array_index(self.macro_map.len(),
225 DefIndexAddressSpace::Low),
227 let kind = ext.kind();
228 self.macro_map.insert(def_id, ext);
229 let binding = self.arenas.alloc_name_binding(NameBinding {
230 kind: NameBindingKind::Def(Def::Macro(def_id, kind), false),
232 vis: ty::Visibility::Invisible,
233 expansion: Mark::root(),
235 if self.builtin_macros.insert(ident.name, binding).is_some() {
236 self.session.span_err(ident.span,
237 &format!("built-in macro `{}` was already defined", ident));
241 fn resolve_imports(&mut self) {
242 ImportResolver { resolver: self }.resolve_imports()
245 // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
246 fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>, allow_derive: bool)
247 -> Option<ast::Attribute> {
252 // Check for legacy derives
253 for i in 0..attrs.len() {
254 let name = attrs[i].name();
256 if name == "derive" {
257 let result = attrs[i].parse_list(&self.session.parse_sess, |parser| {
258 parser.parse_path_allowing_meta(PathStyle::Mod)
261 let mut traits = match result {
262 Ok(traits) => traits,
269 for j in 0..traits.len() {
270 if traits[j].segments.len() > 1 {
273 let trait_name = traits[j].segments[0].ident.name;
274 let legacy_name = Symbol::intern(&format!("derive_{}", trait_name));
275 if !self.builtin_macros.contains_key(&legacy_name) {
278 let span = traits.remove(j).span;
279 self.gate_legacy_custom_derive(legacy_name, span);
280 if traits.is_empty() {
283 let mut tokens = Vec::new();
284 for (j, path) in traits.iter().enumerate() {
286 tokens.push(TokenTree::Token(attrs[i].span, Token::Comma).into());
288 for (k, segment) in path.segments.iter().enumerate() {
290 tokens.push(TokenTree::Token(path.span, Token::ModSep).into());
292 let tok = Token::from_ast_ident(segment.ident);
293 tokens.push(TokenTree::Token(path.span, tok).into());
296 let delim_span = DelimSpan::from_single(attrs[i].span);
297 attrs[i].tokens = TokenTree::Delimited(delim_span, Delimited {
299 tts: TokenStream::concat(tokens).into(),
302 return Some(ast::Attribute {
303 path: ast::Path::from_ident(Ident::new(legacy_name, span)),
304 tokens: TokenStream::empty(),
305 id: attr::mk_attr_id(),
306 style: ast::AttrStyle::Outer,
307 is_sugared_doc: false,
317 fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
318 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
319 let (path, kind, derives_in_scope, together_with) = match invoc.kind {
320 InvocationKind::Attr { attr: None, .. } =>
322 InvocationKind::Attr { attr: Some(ref attr), ref traits, together_with, .. } =>
323 (&attr.path, MacroKind::Attr, traits.clone(), together_with),
324 InvocationKind::Bang { ref mac, .. } =>
325 (&mac.node.path, MacroKind::Bang, Vec::new(), TogetherWith::None),
326 InvocationKind::Derive { ref path, .. } =>
327 (path, MacroKind::Derive, Vec::new(), TogetherWith::None),
330 let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
331 let (def, ext) = self.resolve_macro_to_def(path, kind, &parent_scope, force)?;
333 if let Def::Macro(def_id, _) = def {
334 match together_with {
335 TogetherWith::Derive =>
336 self.session.span_err(invoc.span(),
337 "macro attributes must be placed before `#[derive]`"),
338 TogetherWith::TestBench if !self.session.features_untracked().plugin =>
339 self.session.span_err(invoc.span(),
340 "macro attributes cannot be used together with `#[test]` or `#[bench]`"),
343 self.macro_defs.insert(invoc.expansion_data.mark, def_id);
344 let normal_module_def_id =
345 self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
346 self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
347 normal_module_def_id);
348 invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
349 invoc.expansion_data.mark.set_is_builtin(def_id.krate == CrateNum::BuiltinMacros);
355 fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
356 derives_in_scope: Vec<ast::Path>, force: bool)
357 -> Result<Lrc<SyntaxExtension>, Determinacy> {
358 let parent_scope = self.invoc_parent_scope(invoc_id, derives_in_scope);
359 Ok(self.resolve_macro_to_def(path, kind, &parent_scope, force)?.1)
362 fn check_unused_macros(&self) {
363 for did in self.unused_macros.iter() {
364 let id_span = match *self.macro_map[did] {
365 SyntaxExtension::NormalTT { def_info, .. } |
366 SyntaxExtension::DeclMacro { def_info, .. } => def_info,
369 if let Some((id, span)) = id_span {
370 let lint = lint::builtin::UNUSED_MACROS;
371 let msg = "unused macro definition";
372 self.session.buffer_lint(lint, id, span, msg);
374 bug!("attempted to create unused macro error, but span not available");
380 impl<'a, 'cl> Resolver<'a, 'cl> {
381 pub fn dummy_parent_scope(&mut self) -> ParentScope<'a> {
382 self.invoc_parent_scope(Mark::root(), Vec::new())
385 fn invoc_parent_scope(&mut self, invoc_id: Mark, derives: Vec<ast::Path>) -> ParentScope<'a> {
386 let invoc = self.invocations[&invoc_id];
388 module: invoc.module.get().nearest_item_scope(),
389 expansion: invoc_id.parent(),
390 legacy: invoc.parent_legacy_scope.get(),
395 fn resolve_macro_to_def(
399 parent_scope: &ParentScope<'a>,
401 ) -> Result<(Def, Lrc<SyntaxExtension>), Determinacy> {
402 let def = self.resolve_macro_to_def_inner(path, kind, parent_scope, force);
404 // Report errors and enforce feature gates for the resolved macro.
405 if def != Err(Determinacy::Undetermined) {
406 // Do not report duplicated errors on every undetermined resolution.
407 for segment in &path.segments {
408 if let Some(args) = &segment.args {
409 self.session.span_err(args.span(), "generic arguments in macro path");
417 Def::Macro(def_id, macro_kind) => {
418 self.unused_macros.remove(&def_id);
419 if macro_kind == MacroKind::ProcMacroStub {
420 let msg = "can't use a procedural macro from the same crate that defines it";
421 self.session.span_err(path.span, msg);
422 return Err(Determinacy::Determined);
425 Def::NonMacroAttr(attr_kind) => {
426 if kind == MacroKind::Attr {
427 let features = self.session.features_untracked();
428 if attr_kind == NonMacroAttrKind::Custom {
429 assert!(path.segments.len() == 1);
430 let name = path.segments[0].ident.name.as_str();
431 if name.starts_with("rustc_") {
432 if !features.rustc_attrs {
433 let msg = "unless otherwise specified, attributes with the prefix \
434 `rustc_` are reserved for internal compiler diagnostics";
435 feature_err(&self.session.parse_sess, "rustc_attrs", path.span,
436 GateIssue::Language, &msg).emit();
438 } else if name.starts_with("derive_") {
439 if !features.custom_derive {
440 feature_err(&self.session.parse_sess, "custom_derive", path.span,
441 GateIssue::Language, EXPLAIN_DERIVE_UNDERSCORE).emit();
443 } else if !features.custom_attribute {
444 let msg = format!("The attribute `{}` is currently unknown to the \
445 compiler and may have meaning added to it in the \
447 feature_err(&self.session.parse_sess, "custom_attribute", path.span,
448 GateIssue::Language, &msg).emit();
452 // Not only attributes, but anything in macro namespace can result in
453 // `Def::NonMacroAttr` definition (e.g. `inline!()`), so we must report
454 // an error for those cases.
455 let msg = format!("expected a macro, found {}", def.kind_name());
456 self.session.span_err(path.span, &msg);
457 return Err(Determinacy::Determined);
460 _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
463 Ok((def, self.get_macro(def)))
466 pub fn resolve_macro_to_def_inner(
470 parent_scope: &ParentScope<'a>,
472 ) -> Result<Def, Determinacy> {
473 let ast::Path { ref segments, span } = *path;
474 let mut path: Vec<_> = segments.iter().map(|seg| seg.ident).collect();
476 // Possibly apply the macro helper hack
477 if kind == MacroKind::Bang && path.len() == 1 &&
478 path[0].span.ctxt().outer().expn_info().map_or(false, |info| info.local_inner_macros) {
479 let root = Ident::new(keywords::DollarCrate.name(), path[0].span);
480 path.insert(0, root);
484 let def = match self.resolve_path_with_parent_scope(None, &path, Some(MacroNS),
485 parent_scope, false, span,
487 PathResult::NonModule(path_res) => match path_res.base_def() {
488 Def::Err => Err(Determinacy::Determined),
490 if path_res.unresolved_segments() > 0 {
491 self.found_unresolved_macro = true;
492 self.session.span_err(span, "fail to resolve non-ident macro path");
493 Err(Determinacy::Determined)
499 PathResult::Module(..) => unreachable!(),
500 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
502 self.found_unresolved_macro = true;
503 Err(Determinacy::Determined)
506 parent_scope.module.macro_resolutions.borrow_mut()
507 .push((path.into_boxed_slice(), span));
511 let result = if let Some(legacy_binding) = self.resolve_legacy_scope(path[0], Some(kind),
512 parent_scope, false) {
513 Ok(legacy_binding.def())
515 match self.resolve_lexical_macro_path_segment(path[0], MacroNS, Some(kind),
516 parent_scope, false, force, span) {
517 Ok((binding, _)) => Ok(binding.def_ignoring_ambiguity()),
518 Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
519 Err(Determinacy::Determined) => {
520 self.found_unresolved_macro = true;
521 Err(Determinacy::Determined)
526 parent_scope.module.legacy_macro_resolutions.borrow_mut()
527 .push((path[0], kind, parent_scope.clone(), result.ok()));
532 // Resolve the initial segment of a non-global macro path
533 // (e.g. `foo` in `foo::bar!(); or `foo!();`).
534 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
535 // expansion and import resolution (perhaps they can be merged in the future).
536 crate fn resolve_lexical_macro_path_segment(
540 kind: Option<MacroKind>,
541 parent_scope: &ParentScope<'a>,
545 ) -> Result<(&'a NameBinding<'a>, FromPrelude), Determinacy> {
546 // General principles:
547 // 1. Not controlled (user-defined) names should have higher priority than controlled names
548 // built into the language or standard library. This way we can add new names into the
549 // language or standard library without breaking user code.
550 // 2. "Closed set" below means new names can appear after the current resolution attempt.
551 // Places to search (in order of decreasing priority):
553 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
554 // (open set, not controlled).
555 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
556 // (open, not controlled).
557 // 3. Extern prelude (closed, not controlled).
558 // 4. Tool modules (closed, controlled right now, but not in the future).
559 // 5. Standard library prelude (de-facto closed, controlled).
560 // 6. Language prelude (closed, controlled).
562 // 0. Derive helpers (open, not controlled). All ambiguities with other names
563 // are currently reported as errors. They should be higher in priority than preludes
564 // and probably even names in modules according to the "general principles" above. They
565 // also should be subject to restricted shadowing because are effectively produced by
566 // derives (you need to resolve the derive first to add helpers into scope), but they
567 // should be available before the derive is expanded for compatibility.
568 // It's mess in general, so we are being conservative for now.
569 // 1. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
570 // (open, not controlled).
571 // 2. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
572 // 2a. User-defined prelude from macro-use
573 // (open, the open part is from macro expansions, not controlled).
574 // 2b. Standard library prelude is currently implemented as `macro-use` (closed, controlled)
575 // 3. Language prelude: builtin macros (closed, controlled, except for legacy plugins).
576 // 4. Language prelude: builtin attributes (closed, controlled).
577 // N (unordered). Derive helpers (open, not controlled). All ambiguities with other names
578 // are currently reported as errors. They should be higher in priority than preludes
579 // and maybe even names in modules according to the "general principles" above. They
580 // also should be subject to restricted shadowing because are effectively produced by
581 // derives (you need to resolve the derive first to add helpers into scope), but they
582 // should be available before the derive is expanded for compatibility.
583 // It's mess in general, so we are being conservative for now.
584 // N (unordered). Legacy plugin helpers (open, not controlled). Similar to derive helpers,
585 // but introduced by legacy plugins using `register_attribute`.
587 assert!(ns == TypeNS || ns == MacroNS);
588 assert!(force || !record_used); // `record_used` implies `force`
589 ident = ident.modern();
591 // This is *the* result, resolution from the scope closest to the resolved identifier.
592 // However, sometimes this result is "weak" because it comes from a glob import or
593 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
594 // mod m { ... } // solution in outer scope
596 // use prefix::*; // imports another `m` - innermost solution
597 // // weak, cannot shadow the outer `m`, need to report ambiguity error
600 // So we have to save the innermost solution and continue searching in outer scopes
601 // to detect potential ambiguities.
602 let mut innermost_result: Option<(&NameBinding, FromPrelude)> = None;
604 enum WhereToResolve<'a> {
617 // Go through all the scopes and try to resolve the name.
618 let mut where_to_resolve = WhereToResolve::DeriveHelpers;
619 let mut use_prelude = !parent_scope.module.no_implicit_prelude;
621 let result = match where_to_resolve {
622 WhereToResolve::Module(module) => {
623 let orig_current_module = mem::replace(&mut self.current_module, module);
624 let binding = self.resolve_ident_in_module_unadjusted(
625 ModuleOrUniformRoot::Module(module),
632 self.current_module = orig_current_module;
633 binding.map(|binding| (binding, FromPrelude(false)))
635 WhereToResolve::MacroUsePrelude => {
636 match self.macro_use_prelude.get(&ident.name).cloned() {
637 Some(binding) => Ok((binding, FromPrelude(true))),
638 None => Err(Determinacy::Determined),
641 WhereToResolve::BuiltinMacros => {
642 match self.builtin_macros.get(&ident.name).cloned() {
643 Some(binding) => Ok((binding, FromPrelude(true))),
644 None => Err(Determinacy::Determined),
647 WhereToResolve::BuiltinAttrs => {
648 if is_builtin_attr_name(ident.name) {
649 let binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
650 ty::Visibility::Public, ident.span, Mark::root())
651 .to_name_binding(self.arenas);
652 Ok((binding, FromPrelude(true)))
654 Err(Determinacy::Determined)
657 WhereToResolve::DeriveHelpers => {
658 let mut result = Err(Determinacy::Determined);
659 for derive in &parent_scope.derives {
660 let parent_scope = ParentScope { derives: Vec::new(), ..*parent_scope };
661 if let Ok((_, ext)) = self.resolve_macro_to_def(derive, MacroKind::Derive,
662 &parent_scope, force) {
663 if let SyntaxExtension::ProcMacroDerive(_, helper_attrs, _) = &*ext {
664 if helper_attrs.contains(&ident.name) {
666 (Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
667 ty::Visibility::Public, derive.span, Mark::root())
668 .to_name_binding(self.arenas);
669 result = Ok((binding, FromPrelude(false)));
677 WhereToResolve::LegacyPluginHelpers => {
678 if self.session.plugin_attributes.borrow().iter()
679 .any(|(name, _)| ident.name == &**name) {
680 let binding = (Def::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
681 ty::Visibility::Public, ident.span, Mark::root())
682 .to_name_binding(self.arenas);
683 Ok((binding, FromPrelude(false)))
685 Err(Determinacy::Determined)
688 WhereToResolve::ExternPrelude => {
689 if use_prelude && self.session.extern_prelude.contains(&ident.name) {
691 self.crate_loader.process_path_extern(ident.name, ident.span);
693 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
694 self.populate_module_if_necessary(crate_root);
696 let binding = (crate_root, ty::Visibility::Public,
697 ident.span, Mark::root()).to_name_binding(self.arenas);
698 Ok((binding, FromPrelude(true)))
700 Err(Determinacy::Determined)
703 WhereToResolve::ToolPrelude => {
704 if use_prelude && is_known_tool(ident.name) {
705 let binding = (Def::ToolMod, ty::Visibility::Public,
706 ident.span, Mark::root()).to_name_binding(self.arenas);
707 Ok((binding, FromPrelude(true)))
709 Err(Determinacy::Determined)
712 WhereToResolve::StdLibPrelude => {
713 let mut result = Err(Determinacy::Determined);
715 if let Some(prelude) = self.prelude {
716 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
717 ModuleOrUniformRoot::Module(prelude),
724 result = Ok((binding, FromPrelude(true)));
730 WhereToResolve::BuiltinTypes => {
731 if let Some(prim_ty) =
732 self.primitive_type_table.primitive_types.get(&ident.name).cloned() {
733 let binding = (Def::PrimTy(prim_ty), ty::Visibility::Public,
734 ident.span, Mark::root()).to_name_binding(self.arenas);
735 Ok((binding, FromPrelude(true)))
737 Err(Determinacy::Determined)
742 macro_rules! continue_search { () => {
743 where_to_resolve = match where_to_resolve {
744 WhereToResolve::Module(module) => {
745 match self.hygienic_lexical_parent(module, &mut ident.span) {
746 Some(parent_module) => WhereToResolve::Module(parent_module),
748 use_prelude = !module.no_implicit_prelude;
750 WhereToResolve::MacroUsePrelude
752 WhereToResolve::ExternPrelude
757 WhereToResolve::MacroUsePrelude => WhereToResolve::BuiltinMacros,
758 WhereToResolve::BuiltinMacros => WhereToResolve::BuiltinAttrs,
759 WhereToResolve::BuiltinAttrs => WhereToResolve::DeriveHelpers,
760 WhereToResolve::DeriveHelpers => WhereToResolve::LegacyPluginHelpers,
761 WhereToResolve::LegacyPluginHelpers => break, // nowhere else to search
762 WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
763 WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
764 WhereToResolve::StdLibPrelude => WhereToResolve::BuiltinTypes,
765 WhereToResolve::BuiltinTypes => break, // nowhere else to search
773 if sub_namespace_mismatch(kind, result.0.macro_kind()) {
781 if let Some(innermost_result) = innermost_result {
782 // Found another solution, if the first one was "weak", report an error.
783 let prohibit_ambiguities = |def| {
784 def == Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper) ||
785 def == Def::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper)
787 if result.0.def() != innermost_result.0.def() &&
788 (innermost_result.0.is_glob_import() ||
789 innermost_result.0.may_appear_after(parent_scope.expansion, result.0) ||
790 prohibit_ambiguities(innermost_result.0.def()) ||
791 prohibit_ambiguities(result.0.def())) {
792 self.ambiguity_errors.push(AmbiguityError {
794 b1: innermost_result.0,
797 return Ok(innermost_result);
800 // Found the first solution.
801 innermost_result = Some(result);
806 Err(Determinacy::Determined) => {
809 Err(Determinacy::Undetermined) => return Err(Determinacy::determined(force)),
813 // The first found solution was the only one, return it.
814 if let Some(innermost_result) = innermost_result {
815 return Ok(innermost_result);
818 let determinacy = Determinacy::determined(force);
819 if determinacy == Determinacy::Determined && kind == Some(MacroKind::Attr) {
820 // For single-segment attributes interpret determinate "no resolution" as a custom
821 // attribute. (Lexical resolution implies the first segment and attr kind should imply
822 // the last segment, so we are certainly working with a single-segment attribute here.)
823 assert!(ns == MacroNS);
824 let binding = (Def::NonMacroAttr(NonMacroAttrKind::Custom),
825 ty::Visibility::Public, ident.span, Mark::root())
826 .to_name_binding(self.arenas);
827 Ok((binding, FromPrelude(true)))
833 fn resolve_legacy_scope(
836 kind: Option<MacroKind>,
837 parent_scope: &ParentScope<'a>,
839 ) -> Option<&'a NameBinding<'a>> {
840 if sub_namespace_mismatch(kind, Some(MacroKind::Bang)) {
844 let ident = ident.modern();
846 // This is *the* result, resolution from the scope closest to the resolved identifier.
847 // However, sometimes this result is "weak" because it comes from a macro expansion,
848 // and in this case it cannot shadow names from outer scopes, e.g.
849 // macro_rules! m { ... } // solution in outer scope
851 // define_m!(); // generates another `macro_rules! m` - innermost solution
852 // // weak, cannot shadow the outer `m`, need to report ambiguity error
855 // So we have to save the innermost solution and continue searching in outer scopes
856 // to detect potential ambiguities.
857 let mut innermost_result: Option<&NameBinding> = None;
859 // Go through all the scopes and try to resolve the name.
860 let mut where_to_resolve = parent_scope.legacy;
862 let result = match where_to_resolve {
863 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
864 Some(legacy_binding.binding),
868 macro_rules! continue_search { () => {
869 where_to_resolve = match where_to_resolve {
870 LegacyScope::Empty => break, // nowhere else to search
871 LegacyScope::Binding(binding) => binding.parent_legacy_scope,
872 LegacyScope::Invocation(invocation) => invocation.output_legacy_scope.get(),
873 LegacyScope::Uninitialized => unreachable!(),
885 if let Some(innermost_result) = innermost_result {
886 // Found another solution, if the first one was "weak", report an error.
887 if result.def() != innermost_result.def() &&
888 innermost_result.may_appear_after(parent_scope.expansion, result) {
889 self.ambiguity_errors.push(AmbiguityError {
891 b1: innermost_result,
894 return Some(innermost_result);
897 // Found the first solution.
898 innermost_result = Some(result);
909 // The first found solution was the only one (or there was no solution at all), return it.
913 pub fn finalize_current_module_macro_resolutions(&mut self) {
914 let module = self.current_module;
915 for &(ref path, span) in module.macro_resolutions.borrow().iter() {
916 match self.resolve_path(None, &path, Some(MacroNS), true, span, CrateLint::No) {
917 PathResult::NonModule(_) => {},
918 PathResult::Failed(span, msg, _) => {
919 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
925 let legacy_macro_resolutions =
926 mem::replace(&mut *module.legacy_macro_resolutions.borrow_mut(), Vec::new());
927 for (ident, kind, parent_scope, def) in legacy_macro_resolutions {
928 let span = ident.span;
929 let legacy_resolution = self.resolve_legacy_scope(
930 ident, Some(kind), &parent_scope, true
932 let resolution = self.resolve_lexical_macro_path_segment(
933 ident, MacroNS, Some(kind), &parent_scope, true, true, span
936 let check_consistency = |this: &Self, new_def: Def| {
937 if let Some(def) = def {
938 if this.ambiguity_errors.is_empty() && new_def != def && new_def != Def::Err {
939 // Make sure compilation does not succeed if preferred macro resolution
940 // has changed after the macro had been expanded. In theory all such
941 // situations should be reported as ambiguity errors, so this is span-bug.
942 span_bug!(span, "inconsistent resolution for a macro");
945 // It's possible that the macro was unresolved (indeterminate) and silently
946 // expanded into a dummy fragment for recovery during expansion.
947 // Now, post-expansion, the resolution may succeed, but we can't change the
948 // past and need to report an error.
950 format!("cannot determine resolution for the {} `{}`", kind.descr(), ident);
951 let msg_note = "import resolution is stuck, try simplifying macro imports";
952 this.session.struct_span_err(span, &msg).note(msg_note).emit();
956 match (legacy_resolution, resolution) {
958 assert!(def.is_none());
959 let bang = if kind == MacroKind::Bang { "!" } else { "" };
961 format!("cannot find {} `{}{}` in this scope", kind.descr(), ident, bang);
962 let mut err = self.session.struct_span_err(span, &msg);
963 self.suggest_macro_name(&ident.as_str(), kind, &mut err, span);
966 (Some(legacy_binding), Ok((binding, FromPrelude(from_prelude))))
967 if legacy_binding.def() != binding.def_ignoring_ambiguity() &&
969 !self.disambiguate_legacy_vs_modern(legacy_binding, binding) ||
970 legacy_binding.may_appear_after(parent_scope.expansion, binding)) => {
971 self.report_ambiguity_error(ident, legacy_binding, binding);
973 // OK, non-macro-expanded legacy wins over prelude even if defs are different
974 // Also, non-macro-expanded legacy wins over modern from the same module
975 // Also, legacy and modern can co-exist if their defs are same
976 (Some(legacy_binding), Ok(_)) |
977 // OK, unambiguous resolution
978 (Some(legacy_binding), Err(_)) => {
979 check_consistency(self, legacy_binding.def());
981 // OK, unambiguous resolution
982 (None, Ok((binding, FromPrelude(from_prelude)))) => {
983 check_consistency(self, binding.def_ignoring_ambiguity());
985 self.record_use(ident, MacroNS, binding);
991 let builtin_attrs = mem::replace(&mut *module.builtin_attrs.borrow_mut(), Vec::new());
992 for (ident, parent_scope) in builtin_attrs {
993 let resolve_legacy = |this: &mut Self| this.resolve_legacy_scope(
994 ident, Some(MacroKind::Attr), &parent_scope, true
996 let resolve_modern = |this: &mut Self| this.resolve_lexical_macro_path_segment(
997 ident, MacroNS, Some(MacroKind::Attr), &parent_scope, true, true, ident.span
998 ).map(|(binding, _)| binding).ok();
1000 if let Some(binding) = resolve_legacy(self).or_else(|| resolve_modern(self)) {
1001 if binding.def_ignoring_ambiguity() !=
1002 Def::NonMacroAttr(NonMacroAttrKind::Builtin) {
1003 let builtin_binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
1004 ty::Visibility::Public, ident.span, Mark::root())
1005 .to_name_binding(self.arenas);
1006 self.report_ambiguity_error(ident, binding, builtin_binding);
1012 fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
1013 err: &mut DiagnosticBuilder<'a>, span: Span) {
1014 // First check if this is a locally-defined bang macro.
1015 let suggestion = if let MacroKind::Bang = kind {
1016 find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None)
1019 // Then check global macros.
1021 let names = self.builtin_macros.iter().chain(self.macro_use_prelude.iter())
1022 .filter_map(|(name, binding)| {
1023 if binding.macro_kind() == Some(kind) { Some(name) } else { None }
1025 find_best_match_for_name(names, name, None)
1026 // Then check modules.
1028 let is_macro = |def| {
1029 if let Def::Macro(_, def_kind) = def {
1035 let ident = Ident::new(Symbol::intern(name), span);
1036 self.lookup_typo_candidate(&[ident], MacroNS, is_macro, span)
1039 if let Some(suggestion) = suggestion {
1040 if suggestion != name {
1041 if let MacroKind::Bang = kind {
1042 err.span_suggestion_with_applicability(
1044 "you could try the macro",
1045 suggestion.to_string(),
1046 Applicability::MaybeIncorrect
1049 err.span_suggestion_with_applicability(
1052 suggestion.to_string(),
1053 Applicability::MaybeIncorrect
1057 err.help("have you added the `#[macro_use]` on the module/import?");
1062 fn collect_def_ids(&mut self,
1064 invocation: &'a InvocationData<'a>,
1065 fragment: &AstFragment) {
1066 let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
1067 let InvocationData { def_index, .. } = *invocation;
1069 let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
1070 invocations.entry(invoc.mark).or_insert_with(|| {
1071 arenas.alloc_invocation_data(InvocationData {
1072 def_index: invoc.def_index,
1073 module: Cell::new(graph_root),
1074 parent_legacy_scope: Cell::new(LegacyScope::Uninitialized),
1075 output_legacy_scope: Cell::new(LegacyScope::Uninitialized),
1080 let mut def_collector = DefCollector::new(&mut self.definitions, mark);
1081 def_collector.visit_macro_invoc = Some(visit_macro_invoc);
1082 def_collector.with_parent(def_index, |def_collector| {
1083 fragment.visit_with(def_collector)
1087 pub fn define_macro(&mut self,
1090 current_legacy_scope: &mut LegacyScope<'a>) {
1091 self.local_macro_def_scopes.insert(item.id, self.current_module);
1092 let ident = item.ident;
1093 if ident.name == "macro_rules" {
1094 self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
1097 let def_id = self.definitions.local_def_id(item.id);
1098 let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
1099 &self.session.features_untracked(),
1100 item, hygiene::default_edition()));
1101 self.macro_map.insert(def_id, ext);
1103 let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
1105 let ident = ident.modern();
1106 self.macro_names.insert(ident);
1107 let def = Def::Macro(def_id, MacroKind::Bang);
1108 let vis = ty::Visibility::Invisible; // Doesn't matter for legacy bindings
1109 let binding = (def, vis, item.span, expansion).to_name_binding(self.arenas);
1110 self.set_binding_parent_module(binding, self.current_module);
1111 let legacy_binding = self.arenas.alloc_legacy_binding(LegacyBinding {
1112 parent_legacy_scope: *current_legacy_scope, binding, ident
1114 *current_legacy_scope = LegacyScope::Binding(legacy_binding);
1115 self.all_macros.insert(ident.name, def);
1116 if attr::contains_name(&item.attrs, "macro_export") {
1117 let module = self.graph_root;
1118 let vis = ty::Visibility::Public;
1119 self.define(module, ident, MacroNS,
1120 (def, vis, item.span, expansion, IsMacroExport));
1122 if !attr::contains_name(&item.attrs, "rustc_doc_only_macro") {
1123 self.check_reserved_macro_name(ident, MacroNS);
1125 self.unused_macros.insert(def_id);
1128 let module = self.current_module;
1129 let def = Def::Macro(def_id, MacroKind::Bang);
1130 let vis = self.resolve_visibility(&item.vis);
1131 if vis != ty::Visibility::Public {
1132 self.unused_macros.insert(def_id);
1134 self.define(module, ident, MacroNS, (def, vis, item.span, expansion));
1138 fn gate_legacy_custom_derive(&mut self, name: Symbol, span: Span) {
1139 if !self.session.features_untracked().custom_derive {
1140 let sess = &self.session.parse_sess;
1141 let explain = feature_gate::EXPLAIN_CUSTOM_DERIVE;
1142 emit_feature_err(sess, "custom_derive", span, GateIssue::Language, explain);
1143 } else if !self.is_whitelisted_legacy_custom_derive(name) {
1144 self.session.span_warn(span, feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE);