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::imports::ImportResolver;
5 use crate::Namespace::*;
6 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy};
7 use crate::{CrateLint, ParentScope, ResolutionError, Resolver, Scope, ScopeSet, Weak};
8 use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment, ToNameBinding};
9 use rustc::middle::stability;
10 use rustc::session::parse::feature_err;
11 use rustc::session::Session;
12 use rustc::{lint, span_bug, ty};
13 use rustc_ast::ast::{self, Ident, NodeId};
14 use rustc_ast_pretty::pprust;
15 use rustc_attr::{self as attr, StabilityLevel};
16 use rustc_data_structures::fx::FxHashSet;
17 use rustc_expand::base::SyntaxExtension;
18 use rustc_expand::base::{self, Indeterminate, InvocationRes};
19 use rustc_expand::compile_declarative_macro;
20 use rustc_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
21 use rustc_feature::is_builtin_attr_name;
22 use rustc_hir::def::{self, DefKind, NonMacroAttrKind};
23 use rustc_hir::def_id;
24 use rustc_span::edition::Edition;
25 use rustc_span::hygiene::{self, ExpnData, ExpnId, ExpnKind};
26 use rustc_span::symbol::{kw, sym, Symbol};
27 use rustc_span::{Span, DUMMY_SP};
29 use rustc_data_structures::sync::Lrc;
30 use rustc_span::hygiene::{AstPass, MacroKind};
33 type Res = def::Res<NodeId>;
35 /// Binding produced by a `macro_rules` item.
36 /// Not modularized, can shadow previous `macro_rules` bindings, etc.
38 pub struct MacroRulesBinding<'a> {
39 crate binding: &'a NameBinding<'a>,
40 /// `macro_rules` scope into which the `macro_rules` item was planted.
41 crate parent_macro_rules_scope: MacroRulesScope<'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 `macro_rules` scopes too because they
49 /// can potentially expand into macro definitions.
50 #[derive(Copy, Clone, Debug)]
51 pub enum MacroRulesScope<'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 MacroRulesBinding<'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 {
70 let sub_ns = |kind| match kind {
71 MacroKind::Bang => SubNS::Bang,
72 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
74 let candidate = candidate.map(sub_ns);
75 let requirement = requirement.map(sub_ns);
76 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
77 candidate.is_none() || requirement.is_none() || candidate == requirement
80 // We don't want to format a path using pretty-printing,
81 // `format!("{}", path)`, because that tries to insert
82 // line-breaks and is slow.
83 fn fast_print_path(path: &ast::Path) -> Symbol {
84 if path.segments.len() == 1 {
85 return path.segments[0].ident.name;
87 let mut path_str = String::with_capacity(64);
88 for (i, segment) in path.segments.iter().enumerate() {
90 path_str.push_str("::");
92 if segment.ident.name != kw::PathRoot {
93 path_str.push_str(&segment.ident.as_str())
96 Symbol::intern(&path_str)
100 /// The code common between processing `#![register_tool]` and `#![register_attr]`.
101 fn registered_idents(
103 attrs: &[ast::Attribute],
106 ) -> FxHashSet<Ident> {
107 let mut registered = FxHashSet::default();
108 for attr in attr::filter_by_name(attrs, attr_name) {
109 for nested_meta in attr.meta_item_list().unwrap_or_default() {
110 match nested_meta.ident() {
112 if let Some(old_ident) = registered.replace(ident) {
113 let msg = format!("{} `{}` was already registered", descr, ident);
114 sess.struct_span_err(ident.span, &msg)
115 .span_label(old_ident.span, "already registered here")
120 let msg = format!("`{}` only accepts identifiers", attr_name);
121 let span = nested_meta.span();
122 sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
130 crate fn registered_attrs_and_tools(
132 attrs: &[ast::Attribute],
133 ) -> (FxHashSet<Ident>, FxHashSet<Ident>) {
134 let registered_attrs = registered_idents(sess, attrs, sym::register_attr, "attribute");
135 let mut registered_tools = registered_idents(sess, attrs, sym::register_tool, "tool");
136 // We implicitly add `rustfmt` and `clippy` to known tools,
137 // but it's not an error to register them explicitly.
138 let predefined_tools = [sym::clippy, sym::rustfmt];
139 registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
140 (registered_attrs, registered_tools)
143 impl<'a> base::Resolver for Resolver<'a> {
144 fn next_node_id(&mut self) -> NodeId {
148 fn resolve_dollar_crates(&mut self) {
149 hygiene::update_dollar_crate_names(|ctxt| {
150 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
151 match self.resolve_crate_root(ident).kind {
152 ModuleKind::Def(.., name) if name != kw::Invalid => name,
158 fn visit_ast_fragment_with_placeholders(&mut self, expansion: ExpnId, fragment: &AstFragment) {
159 // Integrate the new AST fragment into all the definition and module structures.
160 // We are inside the `expansion` now, but other parent scope components are still the same.
161 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
162 let output_macro_rules_scope = self.build_reduced_graph(fragment, parent_scope);
163 self.output_macro_rules_scopes.insert(expansion, output_macro_rules_scope);
165 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
168 fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension) {
169 if self.builtin_macros.insert(ident.name, ext).is_some() {
171 .span_err(ident.span, &format!("built-in macro `{}` was already defined", ident));
175 // Create a new Expansion with a definition site of the provided module, or
176 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
177 fn expansion_for_ast_pass(
182 parent_module_id: Option<NodeId>,
184 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
185 ExpnKind::AstPass(pass),
187 self.session.edition(),
191 let parent_scope = if let Some(module_id) = parent_module_id {
192 let parent_def_id = self.definitions.local_def_id(module_id);
193 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id);
194 self.module_map[&parent_def_id]
196 self.definitions.add_parent_module_of_macro_def(
198 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
202 self.ast_transform_scopes.insert(expn_id, parent_scope);
206 fn resolve_imports(&mut self) {
207 ImportResolver { r: self }.resolve_imports()
210 fn resolve_macro_invocation(
213 eager_expansion_root: ExpnId,
215 ) -> Result<InvocationRes, Indeterminate> {
216 let invoc_id = invoc.expansion_data.id;
217 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
218 Some(parent_scope) => *parent_scope,
220 // If there's no entry in the table, then we are resolving an eagerly expanded
221 // macro, which should inherit its parent scope from its eager expansion root -
222 // the macro that requested this eager expansion.
223 let parent_scope = *self
224 .invocation_parent_scopes
225 .get(&eager_expansion_root)
226 .expect("non-eager expansion without a parent scope");
227 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
232 let (path, kind, derives, after_derive) = match invoc.kind {
233 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } => (
234 &attr.get_normal_item().path,
236 self.arenas.alloc_ast_paths(derives),
239 InvocationKind::Bang { ref mac, .. } => (&mac.path, MacroKind::Bang, &[][..], false),
240 InvocationKind::Derive { ref path, .. } => (path, MacroKind::Derive, &[][..], false),
241 InvocationKind::DeriveContainer { ref derives, .. } => {
242 // Block expansion of the container until we resolve all derives in it.
243 // This is required for two reasons:
244 // - Derive helper attributes are in scope for the item to which the `#[derive]`
245 // is applied, so they have to be produced by the container's expansion rather
246 // than by individual derives.
247 // - Derives in the container need to know whether one of them is a built-in `Copy`.
248 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
249 let mut exts = Vec::new();
250 let mut helper_attrs = Vec::new();
251 for path in derives {
253 match self.resolve_macro_path(
255 Some(MacroKind::Derive),
260 Ok((Some(ext), _)) => {
267 .normalize_to_macros_2_0();
269 ext.helper_attrs.iter().map(|name| Ident::new(*name, span)),
271 if ext.is_derive_copy {
272 self.add_derive_copy(invoc_id);
276 Ok(_) | Err(Determinacy::Determined) => {
277 self.dummy_ext(MacroKind::Derive)
279 Err(Determinacy::Undetermined) => return Err(Indeterminate),
283 self.helper_attrs.insert(invoc_id, helper_attrs);
284 return Ok(InvocationRes::DeriveContainer(exts));
288 // Derives are not included when `invocations` are collected, so we have to add them here.
289 let parent_scope = &ParentScope { derives, ..parent_scope };
290 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
292 let span = invoc.span();
293 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
295 if let Res::Def(_, def_id) = res {
297 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
299 self.macro_defs.insert(invoc_id, def_id);
300 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
301 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
304 match invoc.fragment_kind {
305 AstFragmentKind::Arms
306 | AstFragmentKind::Fields
307 | AstFragmentKind::FieldPats
308 | AstFragmentKind::GenericParams
309 | AstFragmentKind::Params
310 | AstFragmentKind::StructFields
311 | AstFragmentKind::Variants => {
312 if let Res::Def(..) = res {
313 self.session.span_err(
316 "expected an inert attribute, found {} {}",
321 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
327 Ok(InvocationRes::Single(ext))
330 fn check_unused_macros(&mut self) {
331 for (&node_id, &span) in self.unused_macros.iter() {
332 self.lint_buffer.buffer_lint(
333 lint::builtin::UNUSED_MACROS,
336 "unused macro definition",
341 fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
342 self.containers_deriving_copy.contains(&expn_id)
345 fn add_derive_copy(&mut self, expn_id: ExpnId) {
346 self.containers_deriving_copy.insert(expn_id);
350 impl<'a> Resolver<'a> {
351 /// Resolve macro path with error reporting and recovery.
352 fn smart_resolve_macro_path(
356 parent_scope: &ParentScope<'a>,
358 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
359 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope, true, force)
361 Ok((Some(ext), res)) => (ext, res),
362 // Use dummy syntax extensions for unresolved macros for better recovery.
363 Ok((None, res)) => (self.dummy_ext(kind), res),
364 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
365 Err(Determinacy::Undetermined) => return Err(Indeterminate),
368 // Report errors and enforce feature gates for the resolved macro.
369 let features = self.session.features_untracked();
370 for segment in &path.segments {
371 if let Some(args) = &segment.args {
372 self.session.span_err(args.span(), "generic arguments in macro path");
374 if kind == MacroKind::Attr
375 && !features.rustc_attrs
376 && segment.ident.as_str().starts_with("rustc")
379 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
380 feature_err(&self.session.parse_sess, sym::rustc_attrs, segment.ident.span, msg)
386 Res::Def(DefKind::Macro(_), def_id) => {
387 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
388 self.unused_macros.remove(&node_id);
389 if self.proc_macro_stubs.contains(&node_id) {
390 self.session.span_err(
392 "can't use a procedural macro from the same crate that defines it",
397 Res::NonMacroAttr(..) | Res::Err => {}
398 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
401 self.check_stability_and_deprecation(&ext, path);
403 Ok(if ext.macro_kind() != kind {
404 let expected = kind.descr_expected();
405 let path_str = pprust::path_to_string(path);
406 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
408 .struct_span_err(path.span, &msg)
409 .span_label(path.span, format!("not {} {}", kind.article(), expected))
411 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
412 (self.dummy_ext(kind), Res::Err)
418 pub fn resolve_macro_path(
421 kind: Option<MacroKind>,
422 parent_scope: &ParentScope<'a>,
425 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
426 let path_span = path.span;
427 let mut path = Segment::from_path(path);
429 // Possibly apply the macro helper hack
430 if kind == Some(MacroKind::Bang)
432 && path[0].ident.span.ctxt().outer_expn_data().local_inner_macros
434 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
435 path.insert(0, Segment::from_ident(root));
438 let res = if path.len() > 1 {
439 let res = match self.resolve_path(
447 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
448 Ok(path_res.base_res())
450 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
451 PathResult::NonModule(..)
452 | PathResult::Indeterminate
453 | PathResult::Failed { .. } => Err(Determinacy::Determined),
454 PathResult::Module(..) => unreachable!(),
458 let kind = kind.expect("macro kind must be specified if tracing is enabled");
459 self.multi_segment_macro_resolutions.push((
468 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
471 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
472 let binding = self.early_resolve_ident_in_lexical_scope(
480 if let Err(Determinacy::Undetermined) = binding {
481 return Err(Determinacy::Undetermined);
485 let kind = kind.expect("macro kind must be specified if tracing is enabled");
486 self.single_segment_macro_resolutions.push((
494 let res = binding.map(|binding| binding.res());
495 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
499 res.map(|res| (self.get_macro(res), res))
502 // Resolve an identifier in lexical scope.
503 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
504 // expansion and import resolution (perhaps they can be merged in the future).
505 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
506 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
507 crate fn early_resolve_ident_in_lexical_scope(
511 parent_scope: &ParentScope<'a>,
515 ) -> Result<&'a NameBinding<'a>, Determinacy> {
516 bitflags::bitflags! {
518 const MACRO_RULES = 1 << 0;
519 const MODULE = 1 << 1;
520 const DERIVE_HELPER_COMPAT = 1 << 2;
521 const MISC_SUGGEST_CRATE = 1 << 3;
522 const MISC_SUGGEST_SELF = 1 << 4;
523 const MISC_FROM_PRELUDE = 1 << 5;
527 assert!(force || !record_used); // `record_used` implies `force`
529 // Make sure `self`, `super` etc produce an error when passed to here.
530 if orig_ident.is_path_segment_keyword() {
531 return Err(Determinacy::Determined);
534 let (ns, macro_kind, is_import) = match scope_set {
535 ScopeSet::All(ns, is_import) => (ns, None, is_import),
536 ScopeSet::AbsolutePath(ns) => (ns, None, false),
537 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
540 // This is *the* result, resolution from the scope closest to the resolved identifier.
541 // However, sometimes this result is "weak" because it comes from a glob import or
542 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
543 // mod m { ... } // solution in outer scope
545 // use prefix::*; // imports another `m` - innermost solution
546 // // weak, cannot shadow the outer `m`, need to report ambiguity error
549 // So we have to save the innermost solution and continue searching in outer scopes
550 // to detect potential ambiguities.
551 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
552 let mut determinacy = Determinacy::Determined;
554 // Go through all the scopes and try to resolve the name.
555 let break_result = self.visit_scopes(
559 |this, scope, use_prelude, ident| {
560 let ok = |res, span, arenas| {
562 (res, ty::Visibility::Public, span, ExpnId::root()).to_name_binding(arenas),
566 let result = match scope {
567 Scope::DeriveHelpers(expn_id) => {
568 if let Some(attr) = this
571 .and_then(|attrs| attrs.iter().rfind(|i| ident == **i))
574 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
575 ty::Visibility::Public,
579 .to_name_binding(this.arenas);
580 Ok((binding, Flags::empty()))
582 Err(Determinacy::Determined)
585 Scope::DeriveHelpersCompat => {
586 let mut result = Err(Determinacy::Determined);
587 for derive in parent_scope.derives {
588 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
589 match this.resolve_macro_path(
591 Some(MacroKind::Derive),
596 Ok((Some(ext), _)) => {
597 if ext.helper_attrs.contains(&ident.name) {
599 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
600 ty::Visibility::Public,
604 .to_name_binding(this.arenas);
605 result = Ok((binding, Flags::DERIVE_HELPER_COMPAT));
609 Ok(_) | Err(Determinacy::Determined) => {}
610 Err(Determinacy::Undetermined) => {
611 result = Err(Determinacy::Undetermined)
617 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope {
618 MacroRulesScope::Binding(macro_rules_binding)
619 if ident == macro_rules_binding.ident =>
621 Ok((macro_rules_binding.binding, Flags::MACRO_RULES))
623 MacroRulesScope::Invocation(invoc_id)
624 if !this.output_macro_rules_scopes.contains_key(&invoc_id) =>
626 Err(Determinacy::Undetermined)
628 _ => Err(Determinacy::Determined),
630 Scope::CrateRoot => {
631 let root_ident = Ident::new(kw::PathRoot, ident.span);
632 let root_module = this.resolve_crate_root(root_ident);
633 let binding = this.resolve_ident_in_module_ext(
634 ModuleOrUniformRoot::Module(root_module),
642 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
643 Err((Determinacy::Undetermined, Weak::No)) => {
644 return Some(Err(Determinacy::determined(force)));
646 Err((Determinacy::Undetermined, Weak::Yes)) => {
647 Err(Determinacy::Undetermined)
649 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
652 Scope::Module(module) => {
653 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
654 let binding = this.resolve_ident_in_module_unadjusted_ext(
655 ModuleOrUniformRoot::Module(module),
658 adjusted_parent_scope,
665 let misc_flags = if ptr::eq(module, this.graph_root) {
666 Flags::MISC_SUGGEST_CRATE
667 } else if module.is_normal() {
668 Flags::MISC_SUGGEST_SELF
672 Ok((binding, Flags::MODULE | misc_flags))
674 Err((Determinacy::Undetermined, Weak::No)) => {
675 return Some(Err(Determinacy::determined(force)));
677 Err((Determinacy::Undetermined, Weak::Yes)) => {
678 Err(Determinacy::Undetermined)
680 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
683 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
685 Res::NonMacroAttr(NonMacroAttrKind::Registered),
689 None => Err(Determinacy::Determined),
691 Scope::MacroUsePrelude => {
692 match this.macro_use_prelude.get(&ident.name).cloned() {
693 Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)),
694 None => Err(Determinacy::determined(
695 this.graph_root.unexpanded_invocations.borrow().is_empty(),
699 Scope::BuiltinAttrs => {
700 if is_builtin_attr_name(ident.name) {
701 ok(Res::NonMacroAttr(NonMacroAttrKind::Builtin), DUMMY_SP, this.arenas)
703 Err(Determinacy::Determined)
706 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
707 Some(binding) => Ok((binding, Flags::empty())),
708 None => Err(Determinacy::determined(
709 this.graph_root.unexpanded_invocations.borrow().is_empty(),
712 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
713 Some(ident) => ok(Res::ToolMod, ident.span, this.arenas),
714 None => Err(Determinacy::Determined),
716 Scope::StdLibPrelude => {
717 let mut result = Err(Determinacy::Determined);
718 if let Some(prelude) = this.prelude {
719 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
720 ModuleOrUniformRoot::Module(prelude),
727 if use_prelude || this.is_builtin_macro(binding.res()) {
728 result = Ok((binding, Flags::MISC_FROM_PRELUDE));
734 Scope::BuiltinTypes => {
735 match this.primitive_type_table.primitive_types.get(&ident.name).cloned() {
736 Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas),
737 None => Err(Determinacy::Determined),
744 if sub_namespace_match(binding.macro_kind(), macro_kind) =>
747 return Some(Ok(binding));
750 if let Some((innermost_binding, innermost_flags)) = innermost_result {
751 // Found another solution, if the first one was "weak", report an error.
752 let (res, innermost_res) = (binding.res(), innermost_binding.res());
753 if res != innermost_res {
754 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
755 let is_derive_helper_compat = |res, flags: Flags| {
756 res == Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper)
757 && flags.contains(Flags::DERIVE_HELPER_COMPAT)
760 let ambiguity_error_kind = if is_import {
761 Some(AmbiguityKind::Import)
762 } else if innermost_res == builtin || res == builtin {
763 Some(AmbiguityKind::BuiltinAttr)
764 } else if is_derive_helper_compat(innermost_res, innermost_flags)
765 || is_derive_helper_compat(res, flags)
767 Some(AmbiguityKind::DeriveHelper)
768 } else if innermost_flags.contains(Flags::MACRO_RULES)
769 && flags.contains(Flags::MODULE)
770 && !this.disambiguate_macro_rules_vs_modularized(
774 || flags.contains(Flags::MACRO_RULES)
775 && innermost_flags.contains(Flags::MODULE)
776 && !this.disambiguate_macro_rules_vs_modularized(
781 Some(AmbiguityKind::MacroRulesVsModularized)
782 } else if innermost_binding.is_glob_import() {
783 Some(AmbiguityKind::GlobVsOuter)
784 } else if innermost_binding
785 .may_appear_after(parent_scope.expansion, binding)
787 Some(AmbiguityKind::MoreExpandedVsOuter)
791 if let Some(kind) = ambiguity_error_kind {
792 let misc = |f: Flags| {
793 if f.contains(Flags::MISC_SUGGEST_CRATE) {
794 AmbiguityErrorMisc::SuggestCrate
795 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
796 AmbiguityErrorMisc::SuggestSelf
797 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
798 AmbiguityErrorMisc::FromPrelude
800 AmbiguityErrorMisc::None
803 this.ambiguity_errors.push(AmbiguityError {
806 b1: innermost_binding,
808 misc1: misc(innermost_flags),
811 return Some(Ok(innermost_binding));
815 // Found the first solution.
816 innermost_result = Some((binding, flags));
819 Ok(..) | Err(Determinacy::Determined) => {}
820 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
827 if let Some(break_result) = break_result {
831 // The first found solution was the only one, return it.
832 if let Some((binding, _)) = innermost_result {
836 Err(Determinacy::determined(determinacy == Determinacy::Determined || force))
839 crate fn finalize_macro_resolutions(&mut self) {
840 let check_consistency = |this: &mut Self,
844 initial_res: Option<Res>,
846 if let Some(initial_res) = initial_res {
847 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
848 // Make sure compilation does not succeed if preferred macro resolution
849 // has changed after the macro had been expanded. In theory all such
850 // situations should be reported as ambiguity errors, so this is a bug.
851 span_bug!(span, "inconsistent resolution for a macro");
854 // It's possible that the macro was unresolved (indeterminate) and silently
855 // expanded into a dummy fragment for recovery during expansion.
856 // Now, post-expansion, the resolution may succeed, but we can't change the
857 // past and need to report an error.
858 // However, non-speculative `resolve_path` can successfully return private items
859 // even if speculative `resolve_path` returned nothing previously, so we skip this
860 // less informative error if the privacy error is reported elsewhere.
861 if this.privacy_errors.is_empty() {
863 "cannot determine resolution for the {} `{}`",
865 Segment::names_to_string(path)
867 let msg_note = "import resolution is stuck, try simplifying macro imports";
868 this.session.struct_span_err(span, &msg).note(msg_note).emit();
873 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
874 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
875 // FIXME: Path resolution will ICE if segment IDs present.
876 for seg in &mut path {
879 match self.resolve_path(
887 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
888 let res = path_res.base_res();
889 check_consistency(self, &path, path_span, kind, initial_res, res);
891 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
892 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
898 "partially resolved path in {} {}",
906 ResolutionError::FailedToResolve { label, suggestion: None },
909 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
913 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
914 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
915 match self.early_resolve_ident_in_lexical_scope(
917 ScopeSet::Macro(kind),
924 let initial_res = initial_binding.map(|initial_binding| {
925 self.record_use(ident, MacroNS, initial_binding, false);
926 initial_binding.res()
928 let res = binding.res();
929 let seg = Segment::from_ident(ident);
930 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
933 let expected = kind.descr_expected();
934 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
935 let mut err = self.session.struct_span_err(ident.span, &msg);
936 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
942 let builtin_attrs = mem::take(&mut self.builtin_attrs);
943 for (ident, parent_scope) in builtin_attrs {
944 let _ = self.early_resolve_ident_in_lexical_scope(
946 ScopeSet::Macro(MacroKind::Attr),
955 fn check_stability_and_deprecation(&mut self, ext: &SyntaxExtension, path: &ast::Path) {
956 let span = path.span;
957 if let Some(stability) = &ext.stability {
958 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
959 let feature = stability.feature;
960 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
961 let node_id = ast::CRATE_NODE_ID;
962 let lint_buffer = &mut self.lint_buffer;
964 |lint, span, msg: &_| lint_buffer.buffer_lint(lint, node_id, span, msg);
965 stability::report_unstable(
976 if let Some(depr) = &stability.rustc_depr {
977 let path = pprust::path_to_string(path);
978 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
979 stability::early_report_deprecation(
980 &mut self.lint_buffer,
988 if let Some(depr) = &ext.deprecation {
989 let path = pprust::path_to_string(&path);
990 let (message, lint) = stability::deprecation_message(depr, &path);
991 stability::early_report_deprecation(&mut self.lint_buffer, &message, None, lint, span);
995 fn prohibit_imported_non_macro_attrs(
997 binding: Option<&'a NameBinding<'a>>,
1001 if let Some(Res::NonMacroAttr(kind)) = res {
1002 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
1004 format!("cannot use {} {} through an import", kind.article(), kind.descr());
1005 let mut err = self.session.struct_span_err(span, &msg);
1006 if let Some(binding) = binding {
1007 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
1014 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
1015 // Reserve some names that are not quite covered by the general check
1016 // performed on `Resolver::builtin_attrs`.
1017 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
1018 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
1019 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
1020 self.session.span_err(
1022 &format!("name `{}` is reserved in attribute namespace", ident),
1028 /// Compile the macro into a `SyntaxExtension` and possibly replace
1029 /// its expander to a pre-defined one for built-in macros.
1030 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
1031 let mut result = compile_declarative_macro(
1032 &self.session.parse_sess,
1033 self.session.features_untracked(),
1038 if result.is_builtin {
1039 // The macro was marked with `#[rustc_builtin_macro]`.
1040 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
1041 // The macro is a built-in, replace its expander function
1042 // while still taking everything else from the source code.
1043 result.kind = ext.kind;
1045 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
1046 self.session.span_err(item.span, &msg);