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, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex,
18 DefIndexAddressSpace};
19 use rustc::hir::def::{Def, Export, NonMacroAttrKind};
20 use rustc::hir::map::{self, DefCollector};
21 use rustc::{ty, lint};
22 use rustc::middle::cstore::CrateStore;
23 use syntax::ast::{self, Name, Ident};
25 use syntax::errors::DiagnosticBuilder;
26 use syntax::ext::base::{self, Determinacy, MultiModifier, MultiDecorator};
27 use syntax::ext::base::{MacroKind, SyntaxExtension, Resolver as SyntaxResolver};
28 use syntax::ext::expand::{AstFragment, Invocation, InvocationKind};
29 use syntax::ext::hygiene::{self, Mark};
30 use syntax::ext::tt::macro_rules;
31 use syntax::feature_gate::{self, feature_err, emit_feature_err, is_builtin_attr_name, GateIssue};
32 use syntax::feature_gate::EXPLAIN_DERIVE_UNDERSCORE;
33 use syntax::fold::{self, Folder};
34 use syntax::parse::parser::PathStyle;
35 use syntax::parse::token::{self, Token};
37 use syntax::symbol::{Symbol, keywords};
38 use syntax::tokenstream::{TokenStream, TokenTree, Delimited};
39 use syntax::util::lev_distance::find_best_match_for_name;
40 use syntax_pos::{Span, DUMMY_SP};
44 use rustc_data_structures::sync::Lrc;
47 pub struct InvocationData<'a> {
48 pub module: Cell<Module<'a>>,
49 pub def_index: DefIndex,
50 // The scope in which the invocation path is resolved.
51 pub legacy_scope: Cell<LegacyScope<'a>>,
52 // The smallest scope that includes this invocation's expansion,
53 // or `Empty` if this invocation has not been expanded yet.
54 pub expansion: Cell<LegacyScope<'a>>,
57 impl<'a> InvocationData<'a> {
58 pub fn root(graph_root: Module<'a>) -> Self {
60 module: Cell::new(graph_root),
61 def_index: CRATE_DEF_INDEX,
62 legacy_scope: Cell::new(LegacyScope::Empty),
63 expansion: Cell::new(LegacyScope::Empty),
68 #[derive(Copy, Clone)]
69 pub enum LegacyScope<'a> {
71 Invocation(&'a InvocationData<'a>), // The scope of the invocation, not including its expansion
72 Expansion(&'a InvocationData<'a>), // The scope of the invocation, including its expansion
73 Binding(&'a LegacyBinding<'a>),
76 pub struct LegacyBinding<'a> {
77 pub parent: Cell<LegacyScope<'a>>,
83 pub struct ProcMacError {
88 warn_msg: &'static str,
91 #[derive(Copy, Clone)]
92 pub enum MacroBinding<'a> {
93 Legacy(&'a LegacyBinding<'a>),
94 Global(&'a NameBinding<'a>),
95 Modern(&'a NameBinding<'a>),
98 impl<'a> MacroBinding<'a> {
99 pub fn span(self) -> Span {
101 MacroBinding::Legacy(binding) => binding.span,
102 MacroBinding::Global(binding) | MacroBinding::Modern(binding) => binding.span,
106 pub fn binding(self) -> &'a NameBinding<'a> {
108 MacroBinding::Global(binding) | MacroBinding::Modern(binding) => binding,
109 MacroBinding::Legacy(_) => panic!("unexpected MacroBinding::Legacy"),
113 pub fn def_ignoring_ambiguity(self) -> Def {
115 MacroBinding::Legacy(binding) => Def::Macro(binding.def_id, MacroKind::Bang),
116 MacroBinding::Global(binding) | MacroBinding::Modern(binding) =>
117 binding.def_ignoring_ambiguity(),
122 impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
123 fn next_node_id(&mut self) -> ast::NodeId {
124 self.session.next_node_id()
127 fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
128 let mark = Mark::fresh(Mark::root());
129 let module = self.module_map[&self.definitions.local_def_id(id)];
130 self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
131 module: Cell::new(module),
132 def_index: module.def_id().unwrap().index,
133 legacy_scope: Cell::new(LegacyScope::Empty),
134 expansion: Cell::new(LegacyScope::Empty),
139 fn eliminate_crate_var(&mut self, item: P<ast::Item>) -> P<ast::Item> {
140 struct EliminateCrateVar<'b, 'a: 'b, 'crateloader: 'a>(
141 &'b mut Resolver<'a, 'crateloader>, Span
144 impl<'a, 'b, 'crateloader> Folder for EliminateCrateVar<'a, 'b, 'crateloader> {
145 fn fold_path(&mut self, path: ast::Path) -> ast::Path {
146 match self.fold_qpath(None, path) {
147 (None, path) => path,
152 fn fold_qpath(&mut self, mut qself: Option<ast::QSelf>, mut path: ast::Path)
153 -> (Option<ast::QSelf>, ast::Path) {
154 qself = qself.map(|ast::QSelf { ty, path_span, position }| {
156 ty: self.fold_ty(ty),
157 path_span: self.new_span(path_span),
162 if path.segments[0].ident.name == keywords::DollarCrate.name() {
163 let module = self.0.resolve_crate_root(path.segments[0].ident);
164 path.segments[0].ident.name = keywords::CrateRoot.name();
165 if !module.is_local() {
166 let span = path.segments[0].ident.span;
167 path.segments.insert(1, match module.kind {
168 ModuleKind::Def(_, name) => ast::PathSegment::from_ident(
169 ast::Ident::with_empty_ctxt(name).with_span_pos(span)
173 if let Some(qself) = &mut qself {
181 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
182 fold::noop_fold_mac(mac, self)
186 EliminateCrateVar(self, item.span).fold_item(item).expect_one("")
189 fn is_whitelisted_legacy_custom_derive(&self, name: Name) -> bool {
190 self.whitelisted_legacy_custom_derives.contains(&name)
193 fn visit_ast_fragment_with_placeholders(&mut self, mark: Mark, fragment: &AstFragment,
195 let invocation = self.invocations[&mark];
196 self.collect_def_ids(mark, invocation, fragment);
198 self.current_module = invocation.module.get();
199 self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
200 self.current_module.unresolved_invocations.borrow_mut().extend(derives);
201 for &derive in derives {
202 self.invocations.insert(derive, invocation);
204 let mut visitor = BuildReducedGraphVisitor {
206 legacy_scope: LegacyScope::Invocation(invocation),
209 fragment.visit_with(&mut visitor);
210 invocation.expansion.set(visitor.legacy_scope);
213 fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
215 krate: BUILTIN_MACROS_CRATE,
216 index: DefIndex::from_array_index(self.macro_map.len(),
217 DefIndexAddressSpace::Low),
219 let kind = ext.kind();
220 self.macro_map.insert(def_id, ext);
221 let binding = self.arenas.alloc_name_binding(NameBinding {
222 kind: NameBindingKind::Def(Def::Macro(def_id, kind), false),
224 vis: ty::Visibility::Invisible,
225 expansion: Mark::root(),
227 self.macro_prelude.insert(ident.name, binding);
230 fn resolve_imports(&mut self) {
231 ImportResolver { resolver: self }.resolve_imports()
234 // Resolves attribute and derive legacy macros from `#![plugin(..)]`.
235 fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>, allow_derive: bool)
236 -> Option<ast::Attribute> {
237 for i in 0..attrs.len() {
238 let name = attrs[i].name();
240 if self.session.plugin_attributes.borrow().iter()
241 .any(|&(ref attr_nm, _)| name == &**attr_nm) {
242 attr::mark_known(&attrs[i]);
245 match self.macro_prelude.get(&name).cloned() {
246 Some(binding) => match *binding.get_macro(self) {
247 MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
248 return Some(attrs.remove(i))
256 if !allow_derive { return None }
258 // Check for legacy derives
259 for i in 0..attrs.len() {
260 let name = attrs[i].name();
262 if name == "derive" {
263 let result = attrs[i].parse_list(&self.session.parse_sess, |parser| {
264 parser.parse_path_allowing_meta(PathStyle::Mod)
267 let mut traits = match result {
268 Ok(traits) => traits,
275 for j in 0..traits.len() {
276 if traits[j].segments.len() > 1 {
279 let trait_name = traits[j].segments[0].ident.name;
280 let legacy_name = Symbol::intern(&format!("derive_{}", trait_name));
281 if !self.macro_prelude.contains_key(&legacy_name) {
284 let span = traits.remove(j).span;
285 self.gate_legacy_custom_derive(legacy_name, span);
286 if traits.is_empty() {
289 let mut tokens = Vec::new();
290 for (j, path) in traits.iter().enumerate() {
292 tokens.push(TokenTree::Token(attrs[i].span, Token::Comma).into());
294 for (k, segment) in path.segments.iter().enumerate() {
296 tokens.push(TokenTree::Token(path.span, Token::ModSep).into());
298 let tok = Token::from_ast_ident(segment.ident);
299 tokens.push(TokenTree::Token(path.span, tok).into());
302 attrs[i].tokens = TokenTree::Delimited(attrs[i].span, Delimited {
304 tts: TokenStream::concat(tokens).into(),
307 return Some(ast::Attribute {
308 path: ast::Path::from_ident(Ident::new(legacy_name, span)),
309 tokens: TokenStream::empty(),
310 id: attr::mk_attr_id(),
311 style: ast::AttrStyle::Outer,
312 is_sugared_doc: false,
322 fn resolve_invoc(&mut self, invoc: &Invocation, scope: Mark, force: bool)
323 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
324 let def = match invoc.kind {
325 InvocationKind::Attr { attr: None, .. } => return Ok(None),
326 _ => self.resolve_invoc_to_def(invoc, scope, force)?,
328 if let Def::Macro(_, MacroKind::ProcMacroStub) = def {
329 self.report_proc_macro_stub(invoc.span());
330 return Err(Determinacy::Determined);
331 } else if let Def::NonMacroAttr(attr_kind) = def {
332 // Note that not only attributes, but anything in macro namespace can result in a
333 // `Def::NonMacroAttr` definition (e.g. `inline!()`), so we must report the error
334 // below for these cases.
336 if let InvocationKind::Attr { .. } = invoc.kind { true } else { false };
337 let path = invoc.path().expect("no path for non-macro attr");
339 NonMacroAttrKind::Tool | NonMacroAttrKind::DeriveHelper |
340 NonMacroAttrKind::Custom if is_attr_invoc => {
341 let features = self.session.features_untracked();
342 if attr_kind == NonMacroAttrKind::Tool &&
343 !features.tool_attributes {
344 feature_err(&self.session.parse_sess, "tool_attributes",
345 invoc.span(), GateIssue::Language,
346 "tool attributes are unstable").emit();
348 if attr_kind == NonMacroAttrKind::Custom {
349 assert!(path.segments.len() == 1);
350 let name = path.segments[0].ident.name.as_str();
351 if name.starts_with("rustc_") {
352 if !features.rustc_attrs {
353 let msg = "unless otherwise specified, attributes with the prefix \
354 `rustc_` are reserved for internal compiler diagnostics";
355 feature_err(&self.session.parse_sess, "rustc_attrs", invoc.span(),
356 GateIssue::Language, &msg).emit();
358 } else if name.starts_with("derive_") {
359 if !features.custom_derive {
360 feature_err(&self.session.parse_sess, "custom_derive", invoc.span(),
361 GateIssue::Language, EXPLAIN_DERIVE_UNDERSCORE).emit();
363 } else if !features.custom_attribute {
364 let msg = format!("The attribute `{}` is currently unknown to the \
365 compiler and may have meaning added to it in the \
367 feature_err(&self.session.parse_sess, "custom_attribute", invoc.span(),
368 GateIssue::Language, &msg).emit();
372 return Ok(Some(Lrc::new(SyntaxExtension::NonMacroAttr {
373 mark_used: attr_kind == NonMacroAttrKind::Tool,
377 self.report_non_macro_attr(path.span, def);
378 return Err(Determinacy::Determined);
382 let def_id = def.def_id();
384 self.macro_defs.insert(invoc.expansion_data.mark, def_id);
385 let normal_module_def_id =
386 self.macro_def_scope(invoc.expansion_data.mark).normal_ancestor_id;
387 self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
388 normal_module_def_id);
390 self.unused_macros.remove(&def_id);
391 let ext = self.get_macro(def);
392 invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
393 invoc.expansion_data.mark.set_is_builtin(def_id.krate == BUILTIN_MACROS_CRATE);
397 fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
398 -> Result<Lrc<SyntaxExtension>, Determinacy> {
399 self.resolve_macro_to_def(scope, path, kind, force).and_then(|def| {
400 if let Def::Macro(_, MacroKind::ProcMacroStub) = def {
401 self.report_proc_macro_stub(path.span);
402 return Err(Determinacy::Determined);
403 } else if let Def::NonMacroAttr(..) = def {
404 self.report_non_macro_attr(path.span, def);
405 return Err(Determinacy::Determined);
407 self.unused_macros.remove(&def.def_id());
408 Ok(self.get_macro(def))
412 fn check_unused_macros(&self) {
413 for did in self.unused_macros.iter() {
414 let id_span = match *self.macro_map[did] {
415 SyntaxExtension::NormalTT { def_info, .. } |
416 SyntaxExtension::DeclMacro { def_info, .. } => def_info,
419 if let Some((id, span)) = id_span {
420 let lint = lint::builtin::UNUSED_MACROS;
421 let msg = "unused macro definition";
422 self.session.buffer_lint(lint, id, span, msg);
424 bug!("attempted to create unused macro error, but span not available");
430 impl<'a, 'cl> Resolver<'a, 'cl> {
431 fn report_proc_macro_stub(&self, span: Span) {
432 self.session.span_err(span,
433 "can't use a procedural macro from the same crate that defines it");
436 fn report_non_macro_attr(&self, span: Span, def: Def) {
437 self.session.span_err(span, &format!("expected a macro, found {}", def.kind_name()));
440 fn resolve_invoc_to_def(&mut self, invoc: &Invocation, scope: Mark, force: bool)
441 -> Result<Def, Determinacy> {
442 let (attr, traits) = match invoc.kind {
443 InvocationKind::Attr { ref attr, ref traits, .. } => (attr, traits),
444 InvocationKind::Bang { ref mac, .. } => {
445 return self.resolve_macro_to_def(scope, &mac.node.path, MacroKind::Bang, force);
447 InvocationKind::Derive { ref path, .. } => {
448 return self.resolve_macro_to_def(scope, path, MacroKind::Derive, force);
452 let path = attr.as_ref().unwrap().path.clone();
453 let def = self.resolve_macro_to_def(scope, &path, MacroKind::Attr, force);
454 if let Ok(Def::NonMacroAttr(NonMacroAttrKind::Custom)) = def {} else {
458 // At this point we've found that the `attr` is determinately unresolved and thus can be
459 // interpreted as a custom attribute. Normally custom attributes are feature gated, but
460 // it may be a custom attribute whitelisted by a derive macro and they do not require
463 // So here we look through all of the derive annotations in scope and try to resolve them.
464 // If they themselves successfully resolve *and* one of the resolved derive macros
465 // whitelists this attribute's name, then this is a registered attribute and we can convert
466 // it from a "generic custom attrite" into a "known derive helper attribute".
467 enum ConvertToDeriveHelper { Yes, No, DontKnow }
468 let mut convert_to_derive_helper = ConvertToDeriveHelper::No;
469 let attr_name = path.segments[0].ident.name;
471 match self.resolve_macro(scope, path, MacroKind::Derive, force) {
472 Ok(ext) => if let SyntaxExtension::ProcMacroDerive(_, ref inert_attrs, _) = *ext {
473 if inert_attrs.contains(&attr_name) {
474 convert_to_derive_helper = ConvertToDeriveHelper::Yes;
478 Err(Determinacy::Undetermined) =>
479 convert_to_derive_helper = ConvertToDeriveHelper::DontKnow,
480 Err(Determinacy::Determined) => {}
484 match convert_to_derive_helper {
485 ConvertToDeriveHelper::Yes => Ok(Def::NonMacroAttr(NonMacroAttrKind::DeriveHelper)),
486 ConvertToDeriveHelper::No => def,
487 ConvertToDeriveHelper::DontKnow => Err(Determinacy::determined(force)),
491 fn resolve_macro_to_def(&mut self, scope: Mark, path: &ast::Path, kind: MacroKind, force: bool)
492 -> Result<Def, Determinacy> {
493 let def = self.resolve_macro_to_def_inner(scope, path, kind, force);
494 if def != Err(Determinacy::Undetermined) {
495 // Do not report duplicated errors on every undetermined resolution.
496 path.segments.iter().find(|segment| segment.args.is_some()).map(|segment| {
497 self.session.span_err(segment.args.as_ref().unwrap().span(),
498 "generic arguments in macro path");
501 if kind != MacroKind::Bang && path.segments.len() > 1 &&
502 def != Ok(Def::NonMacroAttr(NonMacroAttrKind::Tool)) {
503 if !self.session.features_untracked().proc_macro_path_invoc {
505 &self.session.parse_sess,
506 "proc_macro_path_invoc",
509 "paths of length greater than one in macro invocations are \
517 pub fn resolve_macro_to_def_inner(&mut self, scope: Mark, path: &ast::Path,
518 kind: MacroKind, force: bool)
519 -> Result<Def, Determinacy> {
520 let ast::Path { ref segments, span } = *path;
521 let mut path: Vec<_> = segments.iter().map(|seg| seg.ident).collect();
522 let invocation = self.invocations[&scope];
523 let module = invocation.module.get();
524 self.current_module = if module.is_trait() { module.parent.unwrap() } else { module };
526 // Possibly apply the macro helper hack
527 if self.use_extern_macros && kind == MacroKind::Bang && path.len() == 1 &&
528 path[0].span.ctxt().outer().expn_info().map_or(false, |info| info.local_inner_macros) {
529 let root = Ident::new(keywords::DollarCrate.name(), path[0].span);
530 path.insert(0, root);
534 if !self.use_extern_macros && self.gated_errors.insert(span) {
535 let msg = "non-ident macro paths are experimental";
536 let feature = "use_extern_macros";
537 emit_feature_err(&self.session.parse_sess, feature, span, GateIssue::Language, msg);
538 self.found_unresolved_macro = true;
539 return Err(Determinacy::Determined);
542 let res = self.resolve_path(None, &path, Some(MacroNS), false, span, CrateLint::No);
543 let def = match res {
544 PathResult::NonModule(path_res) => match path_res.base_def() {
545 Def::Err => Err(Determinacy::Determined),
547 if path_res.unresolved_segments() > 0 {
548 self.found_unresolved_macro = true;
549 self.session.span_err(span, "fail to resolve non-ident macro path");
550 Err(Determinacy::Determined)
556 PathResult::Module(..) => unreachable!(),
557 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
559 self.found_unresolved_macro = true;
560 Err(Determinacy::Determined)
563 self.current_module.nearest_item_scope().macro_resolutions.borrow_mut()
564 .push((path.into_boxed_slice(), span));
568 let legacy_resolution = self.resolve_legacy_scope(&invocation.legacy_scope, path[0], false);
569 let result = if let Some(MacroBinding::Legacy(binding)) = legacy_resolution {
570 Ok(Def::Macro(binding.def_id, MacroKind::Bang))
572 match self.resolve_lexical_macro_path_segment(path[0], MacroNS, false, force,
573 kind == MacroKind::Attr, span) {
574 Ok(binding) => Ok(binding.binding().def_ignoring_ambiguity()),
575 Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
576 Err(Determinacy::Determined) => {
577 self.found_unresolved_macro = true;
578 Err(Determinacy::Determined)
583 self.current_module.nearest_item_scope().legacy_macro_resolutions.borrow_mut()
584 .push((scope, path[0], kind, result.ok()));
589 // Resolve the initial segment of a non-global macro path
590 // (e.g. `foo` in `foo::bar!(); or `foo!();`).
591 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
592 // expansion and import resolution (perhaps they can be merged in the future).
593 pub fn resolve_lexical_macro_path_segment(&mut self,
600 -> Result<MacroBinding<'a>, Determinacy> {
601 // General principles:
602 // 1. Not controlled (user-defined) names should have higher priority than controlled names
603 // built into the language or standard library. This way we can add new names into the
604 // language or standard library without breaking user code.
605 // 2. "Closed set" below means new names can appear after the current resolution attempt.
606 // Places to search (in order of decreasing priority):
608 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
609 // (open set, not controlled).
610 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
611 // (open, not controlled).
612 // 3. Extern prelude (closed, not controlled).
613 // 4. Tool modules (closed, controlled right now, but not in the future).
614 // 5. Standard library prelude (de-facto closed, controlled).
615 // 6. Language prelude (closed, controlled).
617 // 1. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
618 // (open, not controlled).
619 // 2. Macro prelude (language, standard library, user-defined legacy plugins lumped into
620 // one set) (open, the open part is from macro expansions, not controlled).
621 // 2a. User-defined prelude from macro-use
622 // (open, the open part is from macro expansions, not controlled).
623 // 2b. Standard library prelude, currently just a macro-use (closed, controlled)
624 // 2c. Language prelude, perhaps including builtin attributes
625 // (closed, controlled, except for legacy plugins).
626 // 3. Builtin attributes (closed, controlled).
628 assert!(ns == TypeNS || ns == MacroNS);
629 assert!(force || !record_used); // `record_used` implies `force`
630 ident = ident.modern();
632 // Names from inner scope that can't shadow names from outer scopes, e.g.
635 // use prefix::*; // if this imports another `m`, then it can't shadow the outer `m`
636 // // and we have and ambiguity error
639 // This includes names from globs and from macro expansions.
640 let mut potentially_ambiguous_result: Option<MacroBinding> = None;
642 enum WhereToResolve<'a> {
652 // Go through all the scopes and try to resolve the name.
653 let mut where_to_resolve = WhereToResolve::Module(self.current_module);
654 let mut use_prelude = !self.current_module.no_implicit_prelude;
656 let result = match where_to_resolve {
657 WhereToResolve::Module(module) => {
658 let orig_current_module = mem::replace(&mut self.current_module, module);
659 let binding = self.resolve_ident_in_module_unadjusted(
660 ModuleOrUniformRoot::Module(module),
667 self.current_module = orig_current_module;
668 binding.map(MacroBinding::Modern)
670 WhereToResolve::MacroPrelude => {
671 match self.macro_prelude.get(&ident.name).cloned() {
672 Some(binding) => Ok(MacroBinding::Global(binding)),
673 None => Err(Determinacy::Determined),
676 WhereToResolve::BuiltinAttrs => {
677 // FIXME: Only built-in attributes are not considered as candidates for
678 // non-attributes to fight off regressions on stable channel (#53205).
679 // We need to come up with some more principled approach instead.
680 if is_attr && is_builtin_attr_name(ident.name) {
681 let binding = (Def::NonMacroAttr(NonMacroAttrKind::Builtin),
682 ty::Visibility::Public, ident.span, Mark::root())
683 .to_name_binding(self.arenas);
684 Ok(MacroBinding::Global(binding))
686 Err(Determinacy::Determined)
689 WhereToResolve::ExternPrelude => {
690 if use_prelude && self.extern_prelude.contains(&ident.name) {
691 if !self.session.features_untracked().extern_prelude &&
692 !self.ignore_extern_prelude_feature {
693 feature_err(&self.session.parse_sess, "extern_prelude",
694 ident.span, GateIssue::Language,
695 "access to extern crates through prelude is experimental")
700 self.crate_loader.process_path_extern(ident.name, ident.span);
702 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
703 self.populate_module_if_necessary(crate_root);
705 let binding = (crate_root, ty::Visibility::Public,
706 ident.span, Mark::root()).to_name_binding(self.arenas);
707 Ok(MacroBinding::Global(binding))
709 Err(Determinacy::Determined)
712 WhereToResolve::ToolPrelude => {
713 if use_prelude && is_known_tool(ident.name) {
714 let binding = (Def::ToolMod, ty::Visibility::Public,
715 ident.span, Mark::root()).to_name_binding(self.arenas);
716 Ok(MacroBinding::Global(binding))
718 Err(Determinacy::Determined)
721 WhereToResolve::StdLibPrelude => {
722 let mut result = Err(Determinacy::Determined);
724 if let Some(prelude) = self.prelude {
725 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
726 ModuleOrUniformRoot::Module(prelude),
733 result = Ok(MacroBinding::Global(binding));
739 WhereToResolve::PrimitiveTypes => {
740 if let Some(prim_ty) =
741 self.primitive_type_table.primitive_types.get(&ident.name).cloned() {
742 let binding = (Def::PrimTy(prim_ty), ty::Visibility::Public,
743 ident.span, Mark::root()).to_name_binding(self.arenas);
744 Ok(MacroBinding::Global(binding))
746 Err(Determinacy::Determined)
751 macro_rules! continue_search { () => {
752 where_to_resolve = match where_to_resolve {
753 WhereToResolve::Module(module) => {
754 match self.hygienic_lexical_parent(module, &mut ident.span) {
755 Some(parent_module) => WhereToResolve::Module(parent_module),
757 use_prelude = !module.no_implicit_prelude;
759 WhereToResolve::MacroPrelude
761 WhereToResolve::ExternPrelude
766 WhereToResolve::MacroPrelude => WhereToResolve::BuiltinAttrs,
767 WhereToResolve::BuiltinAttrs => break, // nowhere else to search
768 WhereToResolve::ExternPrelude => WhereToResolve::ToolPrelude,
769 WhereToResolve::ToolPrelude => WhereToResolve::StdLibPrelude,
770 WhereToResolve::StdLibPrelude => WhereToResolve::PrimitiveTypes,
771 WhereToResolve::PrimitiveTypes => break, // nowhere else to search
783 let binding = result.binding();
785 // Found a solution that is ambiguous with a previously found solution.
786 // Push an ambiguity error for later reporting and
787 // return something for better recovery.
788 if let Some(previous_result) = potentially_ambiguous_result {
789 if binding.def() != previous_result.binding().def() {
790 self.ambiguity_errors.push(AmbiguityError {
793 b1: previous_result.binding(),
797 return Ok(previous_result);
801 // Found a solution that's not an ambiguity yet, but is "suspicious" and
802 // can participate in ambiguities later on.
803 // Remember it and go search for other solutions in outer scopes.
804 if binding.is_glob_import() || binding.expansion != Mark::root() {
805 potentially_ambiguous_result = Some(result);
810 // Found a solution that can't be ambiguous, great success.
813 Err(Determinacy::Determined) => {
816 Err(Determinacy::Undetermined) => return Err(Determinacy::determined(force)),
820 // Previously found potentially ambiguous result turned out to not be ambiguous after all.
821 if let Some(previous_result) = potentially_ambiguous_result {
822 return Ok(previous_result);
825 let determinacy = Determinacy::determined(force);
826 if determinacy == Determinacy::Determined && is_attr {
827 // For single-segment attributes interpret determinate "no resolution" as a custom
828 // attribute. (Lexical resolution implies the first segment and is_attr should imply
829 // the last segment, so we are certainly working with a single-segment attribute here.)
830 assert!(ns == MacroNS);
831 let binding = (Def::NonMacroAttr(NonMacroAttrKind::Custom),
832 ty::Visibility::Public, ident.span, Mark::root())
833 .to_name_binding(self.arenas);
834 Ok(MacroBinding::Global(binding))
840 pub fn resolve_legacy_scope(&mut self,
841 mut scope: &'a Cell<LegacyScope<'a>>,
844 -> Option<MacroBinding<'a>> {
845 let ident = ident.modern();
846 let mut possible_time_travel = None;
847 let mut relative_depth: u32 = 0;
848 let mut binding = None;
851 LegacyScope::Empty => break,
852 LegacyScope::Expansion(invocation) => {
853 match invocation.expansion.get() {
854 LegacyScope::Invocation(_) => scope.set(invocation.legacy_scope.get()),
855 LegacyScope::Empty => {
856 if possible_time_travel.is_none() {
857 possible_time_travel = Some(scope);
859 scope = &invocation.legacy_scope;
863 scope = &invocation.expansion;
867 LegacyScope::Invocation(invocation) => {
868 relative_depth = relative_depth.saturating_sub(1);
869 scope = &invocation.legacy_scope;
871 LegacyScope::Binding(potential_binding) => {
872 if potential_binding.ident == ident {
873 if (!self.use_extern_macros || record_used) && relative_depth > 0 {
874 self.disallowed_shadowing.push(potential_binding);
876 binding = Some(potential_binding);
879 scope = &potential_binding.parent;
884 let binding = if let Some(binding) = binding {
885 MacroBinding::Legacy(binding)
886 } else if let Some(binding) = self.macro_prelude.get(&ident.name).cloned() {
887 if !self.use_extern_macros {
888 self.record_use(ident, MacroNS, binding, DUMMY_SP);
890 MacroBinding::Global(binding)
895 if !self.use_extern_macros {
896 if let Some(scope) = possible_time_travel {
897 // Check for disallowed shadowing later
898 self.lexical_macro_resolutions.push((ident, scope));
905 pub fn finalize_current_module_macro_resolutions(&mut self) {
906 let module = self.current_module;
907 for &(ref path, span) in module.macro_resolutions.borrow().iter() {
908 match self.resolve_path(None, &path, Some(MacroNS), true, span, CrateLint::No) {
909 PathResult::NonModule(_) => {},
910 PathResult::Failed(span, msg, _) => {
911 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
917 for &(mark, ident, kind, def) in module.legacy_macro_resolutions.borrow().iter() {
918 let span = ident.span;
919 let legacy_scope = &self.invocations[&mark].legacy_scope;
920 let legacy_resolution = self.resolve_legacy_scope(legacy_scope, ident, true);
921 let resolution = self.resolve_lexical_macro_path_segment(ident, MacroNS, true, true,
922 kind == MacroKind::Attr, span);
924 let check_consistency = |this: &Self, binding: MacroBinding| {
925 if let Some(def) = def {
926 if this.ambiguity_errors.is_empty() && this.disallowed_shadowing.is_empty() &&
927 binding.def_ignoring_ambiguity() != def {
928 // Make sure compilation does not succeed if preferred macro resolution
929 // has changed after the macro had been expanded. In theory all such
930 // situations should be reported as ambiguity errors, so this is span-bug.
931 span_bug!(span, "inconsistent resolution for a macro");
934 // It's possible that the macro was unresolved (indeterminate) and silently
935 // expanded into a dummy fragment for recovery during expansion.
936 // Now, post-expansion, the resolution may succeed, but we can't change the
937 // past and need to report an error.
939 format!("cannot determine resolution for the {} `{}`", kind.descr(), ident);
940 let msg_note = "import resolution is stuck, try simplifying macro imports";
941 this.session.struct_span_err(span, &msg).note(msg_note).emit();
945 match (legacy_resolution, resolution) {
946 (Some(MacroBinding::Legacy(legacy_binding)), Ok(MacroBinding::Modern(binding))) => {
947 if legacy_binding.def_id != binding.def_ignoring_ambiguity().def_id() {
948 let msg1 = format!("`{}` could refer to the macro defined here", ident);
950 format!("`{}` could also refer to the macro imported here", ident);
951 self.session.struct_span_err(span, &format!("`{}` is ambiguous", ident))
952 .span_note(legacy_binding.span, &msg1)
953 .span_note(binding.span, &msg2)
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(MacroBinding::Modern(_)), _) | (_, Ok(MacroBinding::Legacy(_))) => {
967 span_bug!(span, "impossible macro resolution result");
969 // OK, unambiguous resolution
970 (Some(binding), Err(_)) | (None, Ok(binding)) |
971 // OK, legacy wins over global even if their definitions are different
972 (Some(binding @ MacroBinding::Legacy(_)), Ok(MacroBinding::Global(_))) |
973 // OK, modern wins over global even if their definitions are different
974 (Some(MacroBinding::Global(_)), Ok(binding @ MacroBinding::Modern(_))) => {
975 check_consistency(self, binding);
977 (Some(MacroBinding::Global(binding1)), Ok(MacroBinding::Global(binding2))) => {
978 if binding1.def() != binding2.def() {
979 span_bug!(span, "mismatch between same global macro resolutions");
981 check_consistency(self, MacroBinding::Global(binding1));
983 self.record_use(ident, MacroNS, binding1, span);
984 self.err_if_macro_use_proc_macro(ident.name, span, binding1);
990 fn suggest_macro_name(&mut self, name: &str, kind: MacroKind,
991 err: &mut DiagnosticBuilder<'a>, span: Span) {
992 // First check if this is a locally-defined bang macro.
993 let suggestion = if let MacroKind::Bang = kind {
994 find_best_match_for_name(self.macro_names.iter().map(|ident| &ident.name), name, None)
997 // Then check global macros.
999 // FIXME: get_macro needs an &mut Resolver, can we do it without cloning?
1000 let macro_prelude = self.macro_prelude.clone();
1001 let names = macro_prelude.iter().filter_map(|(name, binding)| {
1002 if binding.get_macro(self).kind() == kind {
1008 find_best_match_for_name(names, name, None)
1009 // Then check modules.
1011 if !self.use_extern_macros {
1014 let is_macro = |def| {
1015 if let Def::Macro(_, def_kind) = def {
1021 let ident = Ident::new(Symbol::intern(name), span);
1022 self.lookup_typo_candidate(&[ident], MacroNS, is_macro, span)
1025 if let Some(suggestion) = suggestion {
1026 if suggestion != name {
1027 if let MacroKind::Bang = kind {
1028 err.span_suggestion(span, "you could try the macro", suggestion.to_string());
1030 err.span_suggestion(span, "try", suggestion.to_string());
1033 err.help("have you added the `#[macro_use]` on the module/import?");
1038 fn collect_def_ids(&mut self,
1040 invocation: &'a InvocationData<'a>,
1041 fragment: &AstFragment) {
1042 let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
1043 let InvocationData { def_index, .. } = *invocation;
1045 let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
1046 invocations.entry(invoc.mark).or_insert_with(|| {
1047 arenas.alloc_invocation_data(InvocationData {
1048 def_index: invoc.def_index,
1049 module: Cell::new(graph_root),
1050 expansion: Cell::new(LegacyScope::Empty),
1051 legacy_scope: Cell::new(LegacyScope::Empty),
1056 let mut def_collector = DefCollector::new(&mut self.definitions, mark);
1057 def_collector.visit_macro_invoc = Some(visit_macro_invoc);
1058 def_collector.with_parent(def_index, |def_collector| {
1059 fragment.visit_with(def_collector)
1063 pub fn define_macro(&mut self,
1066 legacy_scope: &mut LegacyScope<'a>) {
1067 self.local_macro_def_scopes.insert(item.id, self.current_module);
1068 let ident = item.ident;
1069 if ident.name == "macro_rules" {
1070 self.session.span_err(item.span, "user-defined macros may not be named `macro_rules`");
1073 let def_id = self.definitions.local_def_id(item.id);
1074 let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
1075 &self.session.features_untracked(),
1076 item, hygiene::default_edition()));
1077 self.macro_map.insert(def_id, ext);
1079 let def = match item.node { ast::ItemKind::MacroDef(ref def) => def, _ => unreachable!() };
1081 let ident = ident.modern();
1082 self.macro_names.insert(ident);
1083 *legacy_scope = LegacyScope::Binding(self.arenas.alloc_legacy_binding(LegacyBinding {
1084 parent: Cell::new(*legacy_scope), ident: ident, def_id: def_id, span: item.span,
1086 let def = Def::Macro(def_id, MacroKind::Bang);
1087 self.all_macros.insert(ident.name, def);
1088 if attr::contains_name(&item.attrs, "macro_export") {
1089 if self.use_extern_macros {
1090 let module = self.graph_root;
1091 let vis = ty::Visibility::Public;
1092 self.define(module, ident, MacroNS,
1093 (def, vis, item.span, expansion, IsMacroExport));
1095 self.macro_exports.push(Export {
1096 ident: ident.modern(),
1098 vis: ty::Visibility::Public,
1103 self.unused_macros.insert(def_id);
1106 let module = self.current_module;
1107 let def = Def::Macro(def_id, MacroKind::Bang);
1108 let vis = self.resolve_visibility(&item.vis);
1109 if vis != ty::Visibility::Public {
1110 self.unused_macros.insert(def_id);
1112 self.define(module, ident, MacroNS, (def, vis, item.span, expansion));
1116 /// Error if `ext` is a Macros 1.1 procedural macro being imported by `#[macro_use]`
1117 fn err_if_macro_use_proc_macro(&mut self, name: Name, use_span: Span,
1118 binding: &NameBinding<'a>) {
1119 let krate = binding.def().def_id().krate;
1121 // Plugin-based syntax extensions are exempt from this check
1122 if krate == BUILTIN_MACROS_CRATE { return; }
1124 let ext = binding.get_macro(self);
1127 // If `ext` is a procedural macro, check if we've already warned about it
1128 SyntaxExtension::AttrProcMacro(..) | SyntaxExtension::ProcMacro { .. } =>
1129 if !self.warned_proc_macros.insert(name) { return; },
1133 let warn_msg = match *ext {
1134 SyntaxExtension::AttrProcMacro(..) =>
1135 "attribute procedural macros cannot be imported with `#[macro_use]`",
1136 SyntaxExtension::ProcMacro { .. } =>
1137 "procedural macros cannot be imported with `#[macro_use]`",
1141 let def_id = self.current_module.normal_ancestor_id;
1142 let node_id = self.definitions.as_local_node_id(def_id).unwrap();
1144 self.proc_mac_errors.push(ProcMacError {
1145 crate_name: self.cstore.crate_name_untracked(krate),
1153 pub fn report_proc_macro_import(&mut self, krate: &ast::Crate) {
1154 for err in self.proc_mac_errors.drain(..) {
1155 let (span, found_use) = ::UsePlacementFinder::check(krate, err.module);
1157 if let Some(span) = span {
1158 let found_use = if found_use { "" } else { "\n" };
1159 self.session.struct_span_err(err.use_span, err.warn_msg)
1162 "instead, import the procedural macro like any other item",
1163 format!("use {}::{};{}", err.crate_name, err.name, found_use),
1166 self.session.struct_span_err(err.use_span, err.warn_msg)
1167 .help(&format!("instead, import the procedural macro like any other item: \
1168 `use {}::{};`", err.crate_name, err.name))
1174 fn gate_legacy_custom_derive(&mut self, name: Symbol, span: Span) {
1175 if !self.session.features_untracked().custom_derive {
1176 let sess = &self.session.parse_sess;
1177 let explain = feature_gate::EXPLAIN_CUSTOM_DERIVE;
1178 emit_feature_err(sess, "custom_derive", span, GateIssue::Language, explain);
1179 } else if !self.is_whitelisted_legacy_custom_derive(name) {
1180 self.session.span_warn(span, feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE);