1 //! A bunch of methods and structures more or less related to resolving macros and
2 //! interface provided by `Resolver` to macro expander.
4 use crate::{AmbiguityError, AmbiguityKind, AmbiguityErrorMisc, Determinacy};
5 use crate::{CrateLint, Resolver, ResolutionError, Scope, ScopeSet, ParentScope, Weak};
6 use crate::{ModuleKind, NameBinding, PathResult, Segment, ToNameBinding};
7 use crate::{ModuleOrUniformRoot, KNOWN_TOOLS};
8 use crate::Namespace::*;
9 use crate::resolve_imports::ImportResolver;
10 use rustc::hir::def::{self, DefKind, NonMacroAttrKind};
11 use rustc::hir::def_id;
12 use rustc::middle::stability;
13 use rustc::{ty, lint, span_bug};
14 use syntax::ast::{self, NodeId, Ident};
15 use syntax::attr::StabilityLevel;
16 use syntax::edition::Edition;
17 use syntax::expand::SpecialDerives;
18 use syntax::feature_gate::{emit_feature_err, is_builtin_attr_name};
19 use syntax::feature_gate::GateIssue;
20 use syntax::print::pprust;
21 use syntax::symbol::{Symbol, kw, sym};
22 use syntax_expand::base::{self, InvocationRes, Indeterminate};
23 use syntax_expand::base::SyntaxExtension;
24 use syntax_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
25 use syntax_expand::compile_declarative_macro;
26 use syntax_pos::hygiene::{self, ExpnId, ExpnData, ExpnKind};
27 use syntax_pos::{Span, DUMMY_SP};
30 use rustc_data_structures::sync::Lrc;
31 use syntax_pos::hygiene::{MacroKind, AstPass};
33 type Res = def::Res<NodeId>;
35 /// Binding produced by a `macro_rules` item.
36 /// Not modularized, can shadow previous legacy bindings, etc.
38 pub struct LegacyBinding<'a> {
39 crate binding: &'a NameBinding<'a>,
40 /// Legacy scope into which the `macro_rules` item was planted.
41 crate parent_legacy_scope: LegacyScope<'a>,
45 /// The scope introduced by a `macro_rules!` macro.
46 /// This starts at the macro's definition and ends at the end of the macro's parent
47 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
48 /// Some macro invocations need to introduce legacy scopes too because they
49 /// can potentially expand into macro definitions.
50 #[derive(Copy, Clone, Debug)]
51 pub enum LegacyScope<'a> {
52 /// Empty "root" scope at the crate start containing no names.
54 /// The scope introduced by a `macro_rules!` macro definition.
55 Binding(&'a LegacyBinding<'a>),
56 /// The scope introduced by a macro invocation that can potentially
57 /// create a `macro_rules!` macro definition.
61 // Macro namespace is separated into two sub-namespaces, one for bang macros and
62 // one for attribute-like macros (attributes, derives).
63 // We ignore resolutions from one sub-namespace when searching names in scope for another.
64 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
66 enum SubNS { Bang, AttrLike }
67 let sub_ns = |kind| match kind {
68 MacroKind::Bang => SubNS::Bang,
69 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
71 let candidate = candidate.map(sub_ns);
72 let requirement = requirement.map(sub_ns);
73 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
74 candidate.is_none() || requirement.is_none() || candidate == requirement
77 // We don't want to format a path using pretty-printing,
78 // `format!("{}", path)`, because that tries to insert
79 // line-breaks and is slow.
80 fn fast_print_path(path: &ast::Path) -> Symbol {
81 if path.segments.len() == 1 {
82 return path.segments[0].ident.name
84 let mut path_str = String::with_capacity(64);
85 for (i, segment) in path.segments.iter().enumerate() {
87 path_str.push_str("::");
89 if segment.ident.name != kw::PathRoot {
90 path_str.push_str(&segment.ident.as_str())
93 Symbol::intern(&path_str)
97 impl<'a> base::Resolver for Resolver<'a> {
98 fn next_node_id(&mut self) -> NodeId {
99 self.session.next_node_id()
102 fn resolve_dollar_crates(&mut self) {
103 hygiene::update_dollar_crate_names(|ctxt| {
104 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
105 match self.resolve_crate_root(ident).kind {
106 ModuleKind::Def(.., name) if name != kw::Invalid => name,
112 fn visit_ast_fragment_with_placeholders(&mut self, expansion: ExpnId, fragment: &AstFragment) {
113 // Integrate the new AST fragment into all the definition and module structures.
114 // We are inside the `expansion` now, but other parent scope components are still the same.
115 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
116 let output_legacy_scope = self.build_reduced_graph(fragment, parent_scope);
117 self.output_legacy_scopes.insert(expansion, output_legacy_scope);
119 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
122 fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension) {
123 if self.builtin_macros.insert(ident.name, ext).is_some() {
124 self.session.span_err(ident.span,
125 &format!("built-in macro `{}` was already defined", ident));
129 // Create a new Expansion with a definition site of the provided module, or
130 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
131 fn expansion_for_ast_pass(
136 parent_module_id: Option<NodeId>,
138 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
139 ExpnKind::AstPass(pass),
141 self.session.edition(),
145 let parent_scope = if let Some(module_id) = parent_module_id {
146 let parent_def_id = self.definitions.local_def_id(module_id);
147 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id);
148 self.module_map[&parent_def_id]
150 self.definitions.add_parent_module_of_macro_def(
152 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
156 self.ast_transform_scopes.insert(expn_id, parent_scope);
160 fn resolve_imports(&mut self) {
161 ImportResolver { r: self }.resolve_imports()
164 fn resolve_macro_invocation(
165 &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
166 ) -> Result<InvocationRes, Indeterminate> {
167 let invoc_id = invoc.expansion_data.id;
168 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
169 Some(parent_scope) => *parent_scope,
171 // If there's no entry in the table, then we are resolving an eagerly expanded
172 // macro, which should inherit its parent scope from its eager expansion root -
173 // the macro that requested this eager expansion.
174 let parent_scope = *self.invocation_parent_scopes.get(&eager_expansion_root)
175 .expect("non-eager expansion without a parent scope");
176 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
181 let (path, kind, derives, after_derive) = match invoc.kind {
182 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
183 (&attr.path, MacroKind::Attr, self.arenas.alloc_ast_paths(derives), after_derive),
184 InvocationKind::Bang { ref mac, .. } =>
185 (&mac.path, MacroKind::Bang, &[][..], false),
186 InvocationKind::Derive { ref path, .. } =>
187 (path, MacroKind::Derive, &[][..], false),
188 InvocationKind::DeriveContainer { ref derives, .. } => {
189 // Block expansion of the container until we resolve all derives in it.
190 // This is required for two reasons:
191 // - Derive helper attributes are in scope for the item to which the `#[derive]`
192 // is applied, so they have to be produced by the container's expansion rather
193 // than by individual derives.
194 // - Derives in the container need to know whether one of them is a built-in `Copy`.
195 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
196 let mut exts = Vec::new();
197 for path in derives {
198 exts.push(match self.resolve_macro_path(
199 path, Some(MacroKind::Derive), &parent_scope, true, force
201 Ok((Some(ext), _)) => ext,
202 Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
203 Err(Determinacy::Undetermined) => return Err(Indeterminate),
206 return Ok(InvocationRes::DeriveContainer(exts));
210 // Derives are not included when `invocations` are collected, so we have to add them here.
211 let parent_scope = &ParentScope { derives, ..parent_scope };
212 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
214 let span = invoc.span();
215 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
217 if let Res::Def(_, def_id) = res {
219 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
221 self.macro_defs.insert(invoc_id, def_id);
222 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
223 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
226 match invoc.fragment_kind {
227 AstFragmentKind::Arms
228 | AstFragmentKind::Fields
229 | AstFragmentKind::FieldPats
230 | AstFragmentKind::GenericParams
231 | AstFragmentKind::Params
232 | AstFragmentKind::StructFields
233 | AstFragmentKind::Variants =>
235 if let Res::Def(..) = res {
236 self.session.span_err(
238 &format!("expected an inert attribute, found {} {}",
239 res.article(), res.descr()),
241 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
247 Ok(InvocationRes::Single(ext))
250 fn check_unused_macros(&self) {
251 for (&node_id, &span) in self.unused_macros.iter() {
252 self.session.buffer_lint(
253 lint::builtin::UNUSED_MACROS, node_id, span, "unused macro definition"
258 fn has_derives(&self, expn_id: ExpnId, derives: SpecialDerives) -> bool {
259 self.has_derives(expn_id, derives)
262 fn add_derives(&mut self, expn_id: ExpnId, derives: SpecialDerives) {
263 *self.special_derives.entry(expn_id).or_default() |= derives;
267 impl<'a> Resolver<'a> {
268 /// Resolve macro path with error reporting and recovery.
269 fn smart_resolve_macro_path(
273 parent_scope: &ParentScope<'a>,
275 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
276 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope,
278 Ok((Some(ext), res)) => (ext, res),
279 // Use dummy syntax extensions for unresolved macros for better recovery.
280 Ok((None, res)) => (self.dummy_ext(kind), res),
281 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
282 Err(Determinacy::Undetermined) => return Err(Indeterminate),
285 // Report errors and enforce feature gates for the resolved macro.
286 let features = self.session.features_untracked();
287 for segment in &path.segments {
288 if let Some(args) = &segment.args {
289 self.session.span_err(args.span(), "generic arguments in macro path");
291 if kind == MacroKind::Attr && !features.rustc_attrs &&
292 segment.ident.as_str().starts_with("rustc") {
294 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
296 &self.session.parse_sess,
306 Res::Def(DefKind::Macro(_), def_id) => {
307 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
308 self.unused_macros.remove(&node_id);
309 if self.proc_macro_stubs.contains(&node_id) {
310 self.session.span_err(
312 "can't use a procedural macro from the same crate that defines it",
317 Res::NonMacroAttr(..) | Res::Err => {}
318 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
321 self.check_stability_and_deprecation(&ext, path);
323 Ok(if ext.macro_kind() != kind {
324 let expected = kind.descr_expected();
325 let path_str = pprust::path_to_string(path);
326 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
327 self.session.struct_span_err(path.span, &msg)
328 .span_label(path.span, format!("not {} {}", kind.article(), expected))
330 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
331 (self.dummy_ext(kind), Res::Err)
337 pub fn resolve_macro_path(
340 kind: Option<MacroKind>,
341 parent_scope: &ParentScope<'a>,
344 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
345 let path_span = path.span;
346 let mut path = Segment::from_path(path);
348 // Possibly apply the macro helper hack
349 if kind == Some(MacroKind::Bang) && path.len() == 1 &&
350 path[0].ident.span.ctxt().outer_expn_data().local_inner_macros {
351 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
352 path.insert(0, Segment::from_ident(root));
355 let res = if path.len() > 1 {
356 let res = match self.resolve_path(&path, Some(MacroNS), parent_scope,
357 false, path_span, CrateLint::No) {
358 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
359 Ok(path_res.base_res())
361 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
362 PathResult::NonModule(..)
363 | PathResult::Indeterminate
364 | PathResult::Failed { .. } => Err(Determinacy::Determined),
365 PathResult::Module(..) => unreachable!(),
369 let kind = kind.expect("macro kind must be specified if tracing is enabled");
370 self.multi_segment_macro_resolutions
371 .push((path, path_span, kind, *parent_scope, res.ok()));
374 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
377 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
378 let binding = self.early_resolve_ident_in_lexical_scope(
379 path[0].ident, scope_set, parent_scope, false, force, path_span
381 if let Err(Determinacy::Undetermined) = binding {
382 return Err(Determinacy::Undetermined);
386 let kind = kind.expect("macro kind must be specified if tracing is enabled");
387 self.single_segment_macro_resolutions
388 .push((path[0].ident, kind, *parent_scope, binding.ok()));
391 let res = binding.map(|binding| binding.res());
392 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
396 res.map(|res| (self.get_macro(res), res))
399 // Resolve an identifier in lexical scope.
400 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
401 // expansion and import resolution (perhaps they can be merged in the future).
402 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
403 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
404 crate fn early_resolve_ident_in_lexical_scope(
408 parent_scope: &ParentScope<'a>,
412 ) -> Result<&'a NameBinding<'a>, Determinacy> {
413 bitflags::bitflags! {
415 const MACRO_RULES = 1 << 0;
416 const MODULE = 1 << 1;
417 const PRELUDE = 1 << 2;
418 const MISC_SUGGEST_CRATE = 1 << 3;
419 const MISC_SUGGEST_SELF = 1 << 4;
420 const MISC_FROM_PRELUDE = 1 << 5;
424 assert!(force || !record_used); // `record_used` implies `force`
426 // Make sure `self`, `super` etc produce an error when passed to here.
427 if orig_ident.is_path_segment_keyword() {
428 return Err(Determinacy::Determined);
431 let (ns, macro_kind, is_import) = match scope_set {
432 ScopeSet::All(ns, is_import) => (ns, None, is_import),
433 ScopeSet::AbsolutePath(ns) => (ns, None, false),
434 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
437 // This is *the* result, resolution from the scope closest to the resolved identifier.
438 // However, sometimes this result is "weak" because it comes from a glob import or
439 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
440 // mod m { ... } // solution in outer scope
442 // use prefix::*; // imports another `m` - innermost solution
443 // // weak, cannot shadow the outer `m`, need to report ambiguity error
446 // So we have to save the innermost solution and continue searching in outer scopes
447 // to detect potential ambiguities.
448 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
449 let mut determinacy = Determinacy::Determined;
451 // Go through all the scopes and try to resolve the name.
452 let break_result = self.visit_scopes(scope_set, parent_scope, orig_ident,
453 |this, scope, use_prelude, ident| {
454 let result = match scope {
455 Scope::DeriveHelpers => {
456 let mut result = Err(Determinacy::Determined);
457 for derive in parent_scope.derives {
458 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
459 match this.resolve_macro_path(derive, Some(MacroKind::Derive),
460 parent_scope, true, force) {
461 Ok((Some(ext), _)) => if ext.helper_attrs.contains(&ident.name) {
462 let binding = (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
463 ty::Visibility::Public, derive.span, ExpnId::root())
464 .to_name_binding(this.arenas);
465 result = Ok((binding, Flags::empty()));
468 Ok(_) | Err(Determinacy::Determined) => {}
469 Err(Determinacy::Undetermined) =>
470 result = Err(Determinacy::Undetermined),
475 Scope::MacroRules(legacy_scope) => match legacy_scope {
476 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
477 Ok((legacy_binding.binding, Flags::MACRO_RULES)),
478 LegacyScope::Invocation(invoc_id)
479 if !this.output_legacy_scopes.contains_key(&invoc_id) =>
480 Err(Determinacy::Undetermined),
481 _ => Err(Determinacy::Determined),
483 Scope::CrateRoot => {
484 let root_ident = Ident::new(kw::PathRoot, ident.span);
485 let root_module = this.resolve_crate_root(root_ident);
486 let binding = this.resolve_ident_in_module_ext(
487 ModuleOrUniformRoot::Module(root_module),
495 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
496 Err((Determinacy::Undetermined, Weak::No)) =>
497 return Some(Err(Determinacy::determined(force))),
498 Err((Determinacy::Undetermined, Weak::Yes)) =>
499 Err(Determinacy::Undetermined),
500 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
503 Scope::Module(module) => {
504 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
505 let binding = this.resolve_ident_in_module_unadjusted_ext(
506 ModuleOrUniformRoot::Module(module),
509 adjusted_parent_scope,
516 let misc_flags = if ptr::eq(module, this.graph_root) {
517 Flags::MISC_SUGGEST_CRATE
518 } else if module.is_normal() {
519 Flags::MISC_SUGGEST_SELF
523 Ok((binding, Flags::MODULE | misc_flags))
525 Err((Determinacy::Undetermined, Weak::No)) =>
526 return Some(Err(Determinacy::determined(force))),
527 Err((Determinacy::Undetermined, Weak::Yes)) =>
528 Err(Determinacy::Undetermined),
529 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
532 Scope::MacroUsePrelude => match this.macro_use_prelude.get(&ident.name).cloned() {
533 Some(binding) => Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE)),
534 None => Err(Determinacy::determined(
535 this.graph_root.unexpanded_invocations.borrow().is_empty()
538 Scope::BuiltinAttrs => if is_builtin_attr_name(ident.name) {
539 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Builtin),
540 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
541 .to_name_binding(this.arenas);
542 Ok((binding, Flags::PRELUDE))
544 Err(Determinacy::Determined)
546 Scope::LegacyPluginHelpers => if this.session.plugin_attributes.borrow().iter()
547 .any(|(name, _)| ident.name == *name) {
548 let binding = (Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
549 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
550 .to_name_binding(this.arenas);
551 Ok((binding, Flags::PRELUDE))
553 Err(Determinacy::Determined)
555 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
556 Some(binding) => Ok((binding, Flags::PRELUDE)),
557 None => Err(Determinacy::determined(
558 this.graph_root.unexpanded_invocations.borrow().is_empty()
561 Scope::ToolPrelude => if KNOWN_TOOLS.contains(&ident.name) {
562 let binding = (Res::ToolMod, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
563 .to_name_binding(this.arenas);
564 Ok((binding, Flags::PRELUDE))
566 Err(Determinacy::Determined)
568 Scope::StdLibPrelude => {
569 let mut result = Err(Determinacy::Determined);
570 if let Some(prelude) = this.prelude {
571 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
572 ModuleOrUniformRoot::Module(prelude),
579 if use_prelude || this.is_builtin_macro(binding.res()) {
580 result = Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE));
586 Scope::BuiltinTypes => match this.primitive_type_table.primitive_types
587 .get(&ident.name).cloned() {
589 let binding = (Res::PrimTy(prim_ty), ty::Visibility::Public,
590 DUMMY_SP, ExpnId::root()).to_name_binding(this.arenas);
591 Ok((binding, Flags::PRELUDE))
593 None => Err(Determinacy::Determined)
598 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
600 return Some(Ok(binding));
603 if let Some((innermost_binding, innermost_flags)) = innermost_result {
604 // Found another solution, if the first one was "weak", report an error.
605 let (res, innermost_res) = (binding.res(), innermost_binding.res());
606 if res != innermost_res {
607 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
608 let derive_helper = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
610 Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
612 let ambiguity_error_kind = if is_import {
613 Some(AmbiguityKind::Import)
614 } else if innermost_res == builtin || res == builtin {
615 Some(AmbiguityKind::BuiltinAttr)
616 } else if innermost_res == derive_helper || res == derive_helper {
617 Some(AmbiguityKind::DeriveHelper)
618 } else if innermost_res == legacy_helper &&
619 flags.contains(Flags::PRELUDE) ||
620 res == legacy_helper &&
621 innermost_flags.contains(Flags::PRELUDE) {
622 Some(AmbiguityKind::LegacyHelperVsPrelude)
623 } else if innermost_flags.contains(Flags::MACRO_RULES) &&
624 flags.contains(Flags::MODULE) &&
625 !this.disambiguate_legacy_vs_modern(innermost_binding,
627 flags.contains(Flags::MACRO_RULES) &&
628 innermost_flags.contains(Flags::MODULE) &&
629 !this.disambiguate_legacy_vs_modern(binding,
631 Some(AmbiguityKind::LegacyVsModern)
632 } else if innermost_binding.is_glob_import() {
633 Some(AmbiguityKind::GlobVsOuter)
634 } else if innermost_binding.may_appear_after(parent_scope.expansion,
636 Some(AmbiguityKind::MoreExpandedVsOuter)
640 if let Some(kind) = ambiguity_error_kind {
641 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
642 AmbiguityErrorMisc::SuggestCrate
643 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
644 AmbiguityErrorMisc::SuggestSelf
645 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
646 AmbiguityErrorMisc::FromPrelude
648 AmbiguityErrorMisc::None
650 this.ambiguity_errors.push(AmbiguityError {
653 b1: innermost_binding,
655 misc1: misc(innermost_flags),
658 return Some(Ok(innermost_binding));
662 // Found the first solution.
663 innermost_result = Some((binding, flags));
666 Ok(..) | Err(Determinacy::Determined) => {}
667 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
673 if let Some(break_result) = break_result {
677 // The first found solution was the only one, return it.
678 if let Some((binding, _)) = innermost_result {
682 let determinacy = Determinacy::determined(determinacy == Determinacy::Determined || force);
683 if determinacy == Determinacy::Determined && macro_kind == Some(MacroKind::Attr) &&
684 self.session.features_untracked().custom_attribute {
685 // For single-segment attributes interpret determinate "no resolution" as a custom
686 // attribute. (Lexical resolution implies the first segment and attr kind should imply
687 // the last segment, so we are certainly working with a single-segment attribute here.)
688 assert!(ns == MacroNS);
689 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Custom),
690 ty::Visibility::Public, orig_ident.span, ExpnId::root())
691 .to_name_binding(self.arenas);
698 crate fn finalize_macro_resolutions(&mut self) {
699 let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
700 initial_res: Option<Res>, res: Res| {
701 if let Some(initial_res) = initial_res {
702 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
703 // Make sure compilation does not succeed if preferred macro resolution
704 // has changed after the macro had been expanded. In theory all such
705 // situations should be reported as ambiguity errors, so this is a bug.
706 if initial_res == Res::NonMacroAttr(NonMacroAttrKind::Custom) {
707 // Yeah, legacy custom attributes are implemented using forced resolution
708 // (which is a best effort error recovery tool, basically), so we can't
709 // promise their resolution won't change later.
710 let msg = format!("inconsistent resolution for a macro: first {}, then {}",
711 initial_res.descr(), res.descr());
712 this.session.span_err(span, &msg);
714 span_bug!(span, "inconsistent resolution for a macro");
718 // It's possible that the macro was unresolved (indeterminate) and silently
719 // expanded into a dummy fragment for recovery during expansion.
720 // Now, post-expansion, the resolution may succeed, but we can't change the
721 // past and need to report an error.
722 // However, non-speculative `resolve_path` can successfully return private items
723 // even if speculative `resolve_path` returned nothing previously, so we skip this
724 // less informative error if the privacy error is reported elsewhere.
725 if this.privacy_errors.is_empty() {
726 let msg = format!("cannot determine resolution for the {} `{}`",
727 kind.descr(), Segment::names_to_string(path));
728 let msg_note = "import resolution is stuck, try simplifying macro imports";
729 this.session.struct_span_err(span, &msg).note(msg_note).emit();
734 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
735 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
736 // FIXME: Path resolution will ICE if segment IDs present.
737 for seg in &mut path { seg.id = None; }
738 match self.resolve_path(
739 &path, Some(MacroNS), &parent_scope, true, path_span, CrateLint::No
741 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
742 let res = path_res.base_res();
743 check_consistency(self, &path, path_span, kind, initial_res, res);
745 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
746 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
749 (path_span, format!("partially resolved path in {} {}",
750 kind.article(), kind.descr()))
752 self.report_error(span, ResolutionError::FailedToResolve {
757 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
761 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
762 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
763 match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
764 &parent_scope, true, true, ident.span) {
766 let initial_res = initial_binding.map(|initial_binding| {
767 self.record_use(ident, MacroNS, initial_binding, false);
768 initial_binding.res()
770 let res = binding.res();
771 let seg = Segment::from_ident(ident);
772 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
775 let expected = kind.descr_expected();
776 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
777 let mut err = self.session.struct_span_err(ident.span, &msg);
778 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
784 let builtin_attrs = mem::take(&mut self.builtin_attrs);
785 for (ident, parent_scope) in builtin_attrs {
786 let _ = self.early_resolve_ident_in_lexical_scope(
787 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
792 fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, path: &ast::Path) {
793 let span = path.span;
794 if let Some(stability) = &ext.stability {
795 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
796 let feature = stability.feature;
797 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
798 let node_id = ast::CRATE_NODE_ID;
800 |lint, span, msg: &_| self.session.buffer_lint(lint, node_id, span, msg);
801 stability::report_unstable(
802 self.session, feature, reason, issue, is_soft, span, soft_handler
806 if let Some(depr) = &stability.rustc_depr {
807 let path = pprust::path_to_string(path);
808 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
809 stability::early_report_deprecation(
810 self.session, &message, depr.suggestion, lint, span
814 if let Some(depr) = &ext.deprecation {
815 let path = pprust::path_to_string(&path);
816 let (message, lint) = stability::deprecation_message(depr, &path);
817 stability::early_report_deprecation(self.session, &message, None, lint, span);
821 fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
822 res: Option<Res>, span: Span) {
823 if let Some(Res::NonMacroAttr(kind)) = res {
824 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
825 let msg = format!("cannot use a {} through an import", kind.descr());
826 let mut err = self.session.struct_span_err(span, &msg);
827 if let Some(binding) = binding {
828 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
835 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
836 // Reserve some names that are not quite covered by the general check
837 // performed on `Resolver::builtin_attrs`.
838 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
839 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
840 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
841 self.session.span_err(
842 ident.span, &format!("name `{}` is reserved in attribute namespace", ident)
848 /// Compile the macro into a `SyntaxExtension` and possibly replace it with a pre-defined
849 /// extension partially or entirely for built-in macros and legacy plugin macros.
850 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
851 let mut result = compile_declarative_macro(
852 &self.session.parse_sess, self.session.features_untracked(), item, edition
855 if result.is_builtin {
856 // The macro was marked with `#[rustc_builtin_macro]`.
857 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
859 // The macro is a built-in, replace only the expander function.
860 result.kind = ext.kind;
862 // The macro is from a plugin, the in-source definition is dummy,
863 // take all the data from the resolver.
867 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
868 self.session.span_err(item.span, &msg);