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::ext::base::{self, InvocationRes, Indeterminate, SpecialDerives};
18 use syntax::ext::base::{MacroKind, SyntaxExtension};
19 use syntax::ext::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
20 use syntax::ext::hygiene::{self, ExpnId, ExpnData, ExpnKind};
21 use syntax::ext::compile_declarative_macro;
22 use syntax::feature_gate::{emit_feature_err, is_builtin_attr_name};
23 use syntax::feature_gate::GateIssue;
24 use syntax::print::pprust;
25 use syntax::symbol::{Symbol, kw, sym};
26 use syntax_pos::{Span, DUMMY_SP};
29 use rustc_data_structures::sync::Lrc;
30 use syntax_pos::hygiene::AstPass;
32 type Res = def::Res<NodeId>;
34 /// Binding produced by a `macro_rules` item.
35 /// Not modularized, can shadow previous legacy bindings, etc.
37 pub struct LegacyBinding<'a> {
38 crate binding: &'a NameBinding<'a>,
39 /// Legacy scope into which the `macro_rules` item was planted.
40 crate parent_legacy_scope: LegacyScope<'a>,
44 /// The scope introduced by a `macro_rules!` macro.
45 /// This starts at the macro's definition and ends at the end of the macro's parent
46 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
47 /// Some macro invocations need to introduce legacy scopes too because they
48 /// can potentially expand into macro definitions.
49 #[derive(Copy, Clone, Debug)]
50 pub enum LegacyScope<'a> {
51 /// Empty "root" scope at the crate start containing no names.
53 /// The scope introduced by a `macro_rules!` macro definition.
54 Binding(&'a LegacyBinding<'a>),
55 /// The scope introduced by a macro invocation that can potentially
56 /// create a `macro_rules!` macro definition.
60 // Macro namespace is separated into two sub-namespaces, one for bang macros and
61 // one for attribute-like macros (attributes, derives).
62 // We ignore resolutions from one sub-namespace when searching names in scope for another.
63 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
65 enum SubNS { Bang, AttrLike }
66 let sub_ns = |kind| match kind {
67 MacroKind::Bang => SubNS::Bang,
68 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
70 let candidate = candidate.map(sub_ns);
71 let requirement = requirement.map(sub_ns);
72 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
73 candidate.is_none() || requirement.is_none() || candidate == requirement
76 // We don't want to format a path using pretty-printing,
77 // `format!("{}", path)`, because that tries to insert
78 // line-breaks and is slow.
79 fn fast_print_path(path: &ast::Path) -> Symbol {
80 if path.segments.len() == 1 {
81 return path.segments[0].ident.name
83 let mut path_str = String::with_capacity(64);
84 for (i, segment) in path.segments.iter().enumerate() {
86 path_str.push_str("::");
88 if segment.ident.name != kw::PathRoot {
89 path_str.push_str(&segment.ident.as_str())
92 Symbol::intern(&path_str)
96 impl<'a> base::Resolver for Resolver<'a> {
97 fn next_node_id(&mut self) -> NodeId {
98 self.session.next_node_id()
101 fn resolve_dollar_crates(&mut self) {
102 hygiene::update_dollar_crate_names(|ctxt| {
103 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
104 match self.resolve_crate_root(ident).kind {
105 ModuleKind::Def(.., name) if name != kw::Invalid => name,
111 // FIXME: `extra_placeholders` should be included into the `fragment` as regular placeholders.
112 fn visit_ast_fragment_with_placeholders(
113 &mut self, expansion: ExpnId, fragment: &AstFragment, extra_placeholders: &[NodeId]
115 // Integrate the new AST fragment into all the definition and module structures.
116 // We are inside the `expansion` now, but other parent scope components are still the same.
117 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
118 let output_legacy_scope =
119 self.build_reduced_graph(fragment, extra_placeholders, parent_scope);
120 self.output_legacy_scopes.insert(expansion, output_legacy_scope);
122 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
125 fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension) {
126 if self.builtin_macros.insert(ident.name, ext).is_some() {
127 self.session.span_err(ident.span,
128 &format!("built-in macro `{}` was already defined", ident));
132 // Create a new Expansion with a definition site of the provided module, or
133 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
134 fn expansion_for_ast_pass(
139 parent_module_id: Option<NodeId>,
141 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
142 ExpnKind::AstPass(pass),
144 self.session.edition(),
148 let parent_scope = if let Some(module_id) = parent_module_id {
149 let parent_def_id = self.definitions.local_def_id(module_id);
150 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id);
151 self.module_map[&parent_def_id]
153 self.definitions.add_parent_module_of_macro_def(
155 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
159 self.ast_transform_scopes.insert(expn_id, parent_scope);
163 fn resolve_imports(&mut self) {
164 ImportResolver { r: self }.resolve_imports()
167 fn resolve_macro_invocation(
168 &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
169 ) -> Result<InvocationRes, Indeterminate> {
170 let invoc_id = invoc.expansion_data.id;
171 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
172 Some(parent_scope) => *parent_scope,
174 // If there's no entry in the table, then we are resolving an eagerly expanded
175 // macro, which should inherit its parent scope from its eager expansion root -
176 // the macro that requested this eager expansion.
177 let parent_scope = *self.invocation_parent_scopes.get(&eager_expansion_root)
178 .expect("non-eager expansion without a parent scope");
179 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
184 let (path, kind, derives, after_derive) = match invoc.kind {
185 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
186 (&attr.path, MacroKind::Attr, self.arenas.alloc_ast_paths(derives), after_derive),
187 InvocationKind::Bang { ref mac, .. } =>
188 (&mac.path, MacroKind::Bang, &[][..], false),
189 InvocationKind::Derive { ref path, .. } =>
190 (path, MacroKind::Derive, &[][..], false),
191 InvocationKind::DeriveContainer { ref derives, .. } => {
192 // Block expansion of the container until we resolve all derives in it.
193 // This is required for two reasons:
194 // - Derive helper attributes are in scope for the item to which the `#[derive]`
195 // is applied, so they have to be produced by the container's expansion rather
196 // than by individual derives.
197 // - Derives in the container need to know whether one of them is a built-in `Copy`.
198 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
199 let mut exts = Vec::new();
200 for path in derives {
201 exts.push(match self.resolve_macro_path(
202 path, Some(MacroKind::Derive), &parent_scope, true, force
204 Ok((Some(ext), _)) => ext,
205 Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
206 Err(Determinacy::Undetermined) => return Err(Indeterminate),
209 return Ok(InvocationRes::DeriveContainer(exts));
213 // Derives are not included when `invocations` are collected, so we have to add them here.
214 let parent_scope = &ParentScope { derives, ..parent_scope };
215 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
217 let span = invoc.span();
218 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
220 if let Res::Def(_, def_id) = res {
222 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
224 self.macro_defs.insert(invoc_id, def_id);
225 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
226 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
229 match invoc.fragment_kind {
230 AstFragmentKind::Arms
231 | AstFragmentKind::Fields
232 | AstFragmentKind::FieldPats
233 | AstFragmentKind::GenericParams
234 | AstFragmentKind::Params
235 | AstFragmentKind::StructFields
236 | AstFragmentKind::Variants =>
238 if let Res::Def(..) = res {
239 self.session.span_err(
241 &format!("expected an inert attribute, found {} {}",
242 res.article(), res.descr()),
244 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
250 Ok(InvocationRes::Single(ext))
253 fn check_unused_macros(&self) {
254 for (&node_id, &span) in self.unused_macros.iter() {
255 self.session.buffer_lint(
256 lint::builtin::UNUSED_MACROS, node_id, span, "unused macro definition"
261 fn has_derives(&self, expn_id: ExpnId, derives: SpecialDerives) -> bool {
262 self.has_derives(expn_id, derives)
265 fn add_derives(&mut self, expn_id: ExpnId, derives: SpecialDerives) {
266 *self.special_derives.entry(expn_id).or_default() |= derives;
270 impl<'a> Resolver<'a> {
271 /// Resolve macro path with error reporting and recovery.
272 fn smart_resolve_macro_path(
276 parent_scope: &ParentScope<'a>,
278 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
279 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope,
281 Ok((Some(ext), res)) => (ext, res),
282 // Use dummy syntax extensions for unresolved macros for better recovery.
283 Ok((None, res)) => (self.dummy_ext(kind), res),
284 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
285 Err(Determinacy::Undetermined) => return Err(Indeterminate),
288 // Report errors and enforce feature gates for the resolved macro.
289 let features = self.session.features_untracked();
290 for segment in &path.segments {
291 if let Some(args) = &segment.args {
292 self.session.span_err(args.span(), "generic arguments in macro path");
294 if kind == MacroKind::Attr && !features.rustc_attrs &&
295 segment.ident.as_str().starts_with("rustc") {
297 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
299 &self.session.parse_sess,
309 Res::Def(DefKind::Macro(_), def_id) => {
310 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
311 self.unused_macros.remove(&node_id);
312 if self.proc_macro_stubs.contains(&node_id) {
313 self.session.span_err(
315 "can't use a procedural macro from the same crate that defines it",
320 Res::NonMacroAttr(..) | Res::Err => {}
321 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
324 self.check_stability_and_deprecation(&ext, path);
326 Ok(if ext.macro_kind() != kind {
327 let expected = kind.descr_expected();
328 let path_str = pprust::path_to_string(path);
329 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
330 self.session.struct_span_err(path.span, &msg)
331 .span_label(path.span, format!("not {} {}", kind.article(), expected))
333 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
334 (self.dummy_ext(kind), Res::Err)
340 pub fn resolve_macro_path(
343 kind: Option<MacroKind>,
344 parent_scope: &ParentScope<'a>,
347 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
348 let path_span = path.span;
349 let mut path = Segment::from_path(path);
351 // Possibly apply the macro helper hack
352 if kind == Some(MacroKind::Bang) && path.len() == 1 &&
353 path[0].ident.span.ctxt().outer_expn_data().local_inner_macros {
354 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
355 path.insert(0, Segment::from_ident(root));
358 let res = if path.len() > 1 {
359 let res = match self.resolve_path(&path, Some(MacroNS), parent_scope,
360 false, path_span, CrateLint::No) {
361 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
362 Ok(path_res.base_res())
364 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
365 PathResult::NonModule(..)
366 | PathResult::Indeterminate
367 | PathResult::Failed { .. } => Err(Determinacy::Determined),
368 PathResult::Module(..) => unreachable!(),
372 let kind = kind.expect("macro kind must be specified if tracing is enabled");
373 self.multi_segment_macro_resolutions
374 .push((path, path_span, kind, *parent_scope, res.ok()));
377 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
380 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
381 let binding = self.early_resolve_ident_in_lexical_scope(
382 path[0].ident, scope_set, parent_scope, false, force, path_span
384 if let Err(Determinacy::Undetermined) = binding {
385 return Err(Determinacy::Undetermined);
389 let kind = kind.expect("macro kind must be specified if tracing is enabled");
390 self.single_segment_macro_resolutions
391 .push((path[0].ident, kind, *parent_scope, binding.ok()));
394 let res = binding.map(|binding| binding.res());
395 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
399 res.map(|res| (self.get_macro(res), res))
402 // Resolve an identifier in lexical scope.
403 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
404 // expansion and import resolution (perhaps they can be merged in the future).
405 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
406 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
407 crate fn early_resolve_ident_in_lexical_scope(
411 parent_scope: &ParentScope<'a>,
415 ) -> Result<&'a NameBinding<'a>, Determinacy> {
416 bitflags::bitflags! {
418 const MACRO_RULES = 1 << 0;
419 const MODULE = 1 << 1;
420 const PRELUDE = 1 << 2;
421 const MISC_SUGGEST_CRATE = 1 << 3;
422 const MISC_SUGGEST_SELF = 1 << 4;
423 const MISC_FROM_PRELUDE = 1 << 5;
427 assert!(force || !record_used); // `record_used` implies `force`
429 // Make sure `self`, `super` etc produce an error when passed to here.
430 if orig_ident.is_path_segment_keyword() {
431 return Err(Determinacy::Determined);
434 let (ns, macro_kind, is_import) = match scope_set {
435 ScopeSet::All(ns, is_import) => (ns, None, is_import),
436 ScopeSet::AbsolutePath(ns) => (ns, None, false),
437 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
440 // This is *the* result, resolution from the scope closest to the resolved identifier.
441 // However, sometimes this result is "weak" because it comes from a glob import or
442 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
443 // mod m { ... } // solution in outer scope
445 // use prefix::*; // imports another `m` - innermost solution
446 // // weak, cannot shadow the outer `m`, need to report ambiguity error
449 // So we have to save the innermost solution and continue searching in outer scopes
450 // to detect potential ambiguities.
451 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
452 let mut determinacy = Determinacy::Determined;
454 // Go through all the scopes and try to resolve the name.
455 let break_result = self.visit_scopes(scope_set, parent_scope, orig_ident,
456 |this, scope, use_prelude, ident| {
457 let result = match scope {
458 Scope::DeriveHelpers => {
459 let mut result = Err(Determinacy::Determined);
460 for derive in parent_scope.derives {
461 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
462 match this.resolve_macro_path(derive, Some(MacroKind::Derive),
463 parent_scope, true, force) {
464 Ok((Some(ext), _)) => if ext.helper_attrs.contains(&ident.name) {
465 let binding = (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
466 ty::Visibility::Public, derive.span, ExpnId::root())
467 .to_name_binding(this.arenas);
468 result = Ok((binding, Flags::empty()));
471 Ok(_) | Err(Determinacy::Determined) => {}
472 Err(Determinacy::Undetermined) =>
473 result = Err(Determinacy::Undetermined),
478 Scope::MacroRules(legacy_scope) => match legacy_scope {
479 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
480 Ok((legacy_binding.binding, Flags::MACRO_RULES)),
481 LegacyScope::Invocation(invoc_id)
482 if !this.output_legacy_scopes.contains_key(&invoc_id) =>
483 Err(Determinacy::Undetermined),
484 _ => Err(Determinacy::Determined),
486 Scope::CrateRoot => {
487 let root_ident = Ident::new(kw::PathRoot, ident.span);
488 let root_module = this.resolve_crate_root(root_ident);
489 let binding = this.resolve_ident_in_module_ext(
490 ModuleOrUniformRoot::Module(root_module),
498 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
499 Err((Determinacy::Undetermined, Weak::No)) =>
500 return Some(Err(Determinacy::determined(force))),
501 Err((Determinacy::Undetermined, Weak::Yes)) =>
502 Err(Determinacy::Undetermined),
503 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
506 Scope::Module(module) => {
507 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
508 let binding = this.resolve_ident_in_module_unadjusted_ext(
509 ModuleOrUniformRoot::Module(module),
512 adjusted_parent_scope,
519 let misc_flags = if ptr::eq(module, this.graph_root) {
520 Flags::MISC_SUGGEST_CRATE
521 } else if module.is_normal() {
522 Flags::MISC_SUGGEST_SELF
526 Ok((binding, Flags::MODULE | misc_flags))
528 Err((Determinacy::Undetermined, Weak::No)) =>
529 return Some(Err(Determinacy::determined(force))),
530 Err((Determinacy::Undetermined, Weak::Yes)) =>
531 Err(Determinacy::Undetermined),
532 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
535 Scope::MacroUsePrelude => match this.macro_use_prelude.get(&ident.name).cloned() {
536 Some(binding) => Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE)),
537 None => Err(Determinacy::determined(
538 this.graph_root.unexpanded_invocations.borrow().is_empty()
541 Scope::BuiltinAttrs => if is_builtin_attr_name(ident.name) {
542 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Builtin),
543 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
544 .to_name_binding(this.arenas);
545 Ok((binding, Flags::PRELUDE))
547 Err(Determinacy::Determined)
549 Scope::LegacyPluginHelpers => if this.session.plugin_attributes.borrow().iter()
550 .any(|(name, _)| ident.name == *name) {
551 let binding = (Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
552 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
553 .to_name_binding(this.arenas);
554 Ok((binding, Flags::PRELUDE))
556 Err(Determinacy::Determined)
558 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
559 Some(binding) => Ok((binding, Flags::PRELUDE)),
560 None => Err(Determinacy::determined(
561 this.graph_root.unexpanded_invocations.borrow().is_empty()
564 Scope::ToolPrelude => if KNOWN_TOOLS.contains(&ident.name) {
565 let binding = (Res::ToolMod, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
566 .to_name_binding(this.arenas);
567 Ok((binding, Flags::PRELUDE))
569 Err(Determinacy::Determined)
571 Scope::StdLibPrelude => {
572 let mut result = Err(Determinacy::Determined);
573 if let Some(prelude) = this.prelude {
574 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
575 ModuleOrUniformRoot::Module(prelude),
582 if use_prelude || this.is_builtin_macro(binding.res()) {
583 result = Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE));
589 Scope::BuiltinTypes => match this.primitive_type_table.primitive_types
590 .get(&ident.name).cloned() {
592 let binding = (Res::PrimTy(prim_ty), ty::Visibility::Public,
593 DUMMY_SP, ExpnId::root()).to_name_binding(this.arenas);
594 Ok((binding, Flags::PRELUDE))
596 None => Err(Determinacy::Determined)
601 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
603 return Some(Ok(binding));
606 if let Some((innermost_binding, innermost_flags)) = innermost_result {
607 // Found another solution, if the first one was "weak", report an error.
608 let (res, innermost_res) = (binding.res(), innermost_binding.res());
609 if res != innermost_res {
610 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
611 let derive_helper = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
613 Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
615 let ambiguity_error_kind = if is_import {
616 Some(AmbiguityKind::Import)
617 } else if innermost_res == builtin || res == builtin {
618 Some(AmbiguityKind::BuiltinAttr)
619 } else if innermost_res == derive_helper || res == derive_helper {
620 Some(AmbiguityKind::DeriveHelper)
621 } else if innermost_res == legacy_helper &&
622 flags.contains(Flags::PRELUDE) ||
623 res == legacy_helper &&
624 innermost_flags.contains(Flags::PRELUDE) {
625 Some(AmbiguityKind::LegacyHelperVsPrelude)
626 } else if innermost_flags.contains(Flags::MACRO_RULES) &&
627 flags.contains(Flags::MODULE) &&
628 !this.disambiguate_legacy_vs_modern(innermost_binding,
630 flags.contains(Flags::MACRO_RULES) &&
631 innermost_flags.contains(Flags::MODULE) &&
632 !this.disambiguate_legacy_vs_modern(binding,
634 Some(AmbiguityKind::LegacyVsModern)
635 } else if innermost_binding.is_glob_import() {
636 Some(AmbiguityKind::GlobVsOuter)
637 } else if innermost_binding.may_appear_after(parent_scope.expansion,
639 Some(AmbiguityKind::MoreExpandedVsOuter)
643 if let Some(kind) = ambiguity_error_kind {
644 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
645 AmbiguityErrorMisc::SuggestCrate
646 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
647 AmbiguityErrorMisc::SuggestSelf
648 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
649 AmbiguityErrorMisc::FromPrelude
651 AmbiguityErrorMisc::None
653 this.ambiguity_errors.push(AmbiguityError {
656 b1: innermost_binding,
658 misc1: misc(innermost_flags),
661 return Some(Ok(innermost_binding));
665 // Found the first solution.
666 innermost_result = Some((binding, flags));
669 Ok(..) | Err(Determinacy::Determined) => {}
670 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
676 if let Some(break_result) = break_result {
680 // The first found solution was the only one, return it.
681 if let Some((binding, _)) = innermost_result {
685 let determinacy = Determinacy::determined(determinacy == Determinacy::Determined || force);
686 if determinacy == Determinacy::Determined && macro_kind == Some(MacroKind::Attr) &&
687 self.session.features_untracked().custom_attribute {
688 // For single-segment attributes interpret determinate "no resolution" as a custom
689 // attribute. (Lexical resolution implies the first segment and attr kind should imply
690 // the last segment, so we are certainly working with a single-segment attribute here.)
691 assert!(ns == MacroNS);
692 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Custom),
693 ty::Visibility::Public, orig_ident.span, ExpnId::root())
694 .to_name_binding(self.arenas);
701 crate fn finalize_macro_resolutions(&mut self) {
702 let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
703 initial_res: Option<Res>, res: Res| {
704 if let Some(initial_res) = initial_res {
705 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
706 // Make sure compilation does not succeed if preferred macro resolution
707 // has changed after the macro had been expanded. In theory all such
708 // situations should be reported as ambiguity errors, so this is a bug.
709 if initial_res == Res::NonMacroAttr(NonMacroAttrKind::Custom) {
710 // Yeah, legacy custom attributes are implemented using forced resolution
711 // (which is a best effort error recovery tool, basically), so we can't
712 // promise their resolution won't change later.
713 let msg = format!("inconsistent resolution for a macro: first {}, then {}",
714 initial_res.descr(), res.descr());
715 this.session.span_err(span, &msg);
717 span_bug!(span, "inconsistent resolution for a macro");
721 // It's possible that the macro was unresolved (indeterminate) and silently
722 // expanded into a dummy fragment for recovery during expansion.
723 // Now, post-expansion, the resolution may succeed, but we can't change the
724 // past and need to report an error.
725 // However, non-speculative `resolve_path` can successfully return private items
726 // even if speculative `resolve_path` returned nothing previously, so we skip this
727 // less informative error if the privacy error is reported elsewhere.
728 if this.privacy_errors.is_empty() {
729 let msg = format!("cannot determine resolution for the {} `{}`",
730 kind.descr(), Segment::names_to_string(path));
731 let msg_note = "import resolution is stuck, try simplifying macro imports";
732 this.session.struct_span_err(span, &msg).note(msg_note).emit();
737 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
738 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
739 // FIXME: Path resolution will ICE if segment IDs present.
740 for seg in &mut path { seg.id = None; }
741 match self.resolve_path(
742 &path, Some(MacroNS), &parent_scope, true, path_span, CrateLint::No
744 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
745 let res = path_res.base_res();
746 check_consistency(self, &path, path_span, kind, initial_res, res);
748 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
749 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
752 (path_span, format!("partially resolved path in {} {}",
753 kind.article(), kind.descr()))
755 self.report_error(span, ResolutionError::FailedToResolve {
760 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
764 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
765 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
766 match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
767 &parent_scope, true, true, ident.span) {
769 let initial_res = initial_binding.map(|initial_binding| {
770 self.record_use(ident, MacroNS, initial_binding, false);
771 initial_binding.res()
773 let res = binding.res();
774 let seg = Segment::from_ident(ident);
775 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
778 let expected = kind.descr_expected();
779 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
780 let mut err = self.session.struct_span_err(ident.span, &msg);
781 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
787 let builtin_attrs = mem::take(&mut self.builtin_attrs);
788 for (ident, parent_scope) in builtin_attrs {
789 let _ = self.early_resolve_ident_in_lexical_scope(
790 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
795 fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, path: &ast::Path) {
796 let span = path.span;
797 if let Some(stability) = &ext.stability {
798 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
799 let feature = stability.feature;
800 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
801 let node_id = ast::CRATE_NODE_ID;
803 |lint, span, msg: &_| self.session.buffer_lint(lint, node_id, span, msg);
804 stability::report_unstable(
805 self.session, feature, reason, issue, is_soft, span, soft_handler
809 if let Some(depr) = &stability.rustc_depr {
810 let path = pprust::path_to_string(path);
811 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
812 stability::early_report_deprecation(
813 self.session, &message, depr.suggestion, lint, span
817 if let Some(depr) = &ext.deprecation {
818 let path = pprust::path_to_string(&path);
819 let (message, lint) = stability::deprecation_message(depr, &path);
820 stability::early_report_deprecation(self.session, &message, None, lint, span);
824 fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
825 res: Option<Res>, span: Span) {
826 if let Some(Res::NonMacroAttr(kind)) = res {
827 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
828 let msg = format!("cannot use a {} through an import", kind.descr());
829 let mut err = self.session.struct_span_err(span, &msg);
830 if let Some(binding) = binding {
831 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
838 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
839 // Reserve some names that are not quite covered by the general check
840 // performed on `Resolver::builtin_attrs`.
841 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
842 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
843 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
844 self.session.span_err(
845 ident.span, &format!("name `{}` is reserved in attribute namespace", ident)
851 /// Compile the macro into a `SyntaxExtension` and possibly replace it with a pre-defined
852 /// extension partially or entirely for built-in macros and legacy plugin macros.
853 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
854 let mut result = compile_declarative_macro(
855 &self.session.parse_sess, self.session.features_untracked(), item, edition
858 if result.is_builtin {
859 // The macro was marked with `#[rustc_builtin_macro]`.
860 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
862 // The macro is a built-in, replace only the expander function.
863 result.kind = ext.kind;
865 // The macro is from a plugin, the in-source definition is dummy,
866 // take all the data from the resolver.
870 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
871 self.session.span_err(item.span, &msg);