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::hir::def::{self, DefKind, NonMacroAttrKind};
10 use rustc::hir::def_id;
11 use rustc::middle::stability;
12 use rustc::session::Session;
13 use rustc::util::nodemap::FxHashSet;
14 use rustc::{lint, span_bug, ty};
15 use rustc_expand::base::SyntaxExtension;
16 use rustc_expand::base::{self, Indeterminate, InvocationRes};
17 use rustc_expand::compile_declarative_macro;
18 use rustc_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
19 use rustc_feature::is_builtin_attr_name;
20 use rustc_span::hygiene::{self, ExpnData, ExpnId, ExpnKind};
21 use rustc_span::symbol::{kw, sym, Symbol};
22 use rustc_span::{Span, DUMMY_SP};
23 use syntax::ast::{self, Ident, NodeId};
24 use syntax::attr::{self, StabilityLevel};
25 use syntax::edition::Edition;
26 use syntax::feature_gate::feature_err;
27 use syntax::print::pprust;
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 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 {
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_legacy_scope = self.build_reduced_graph(fragment, parent_scope);
163 self.output_legacy_scopes.insert(expansion, output_legacy_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), _)) => {
261 let span = path.segments.last().unwrap().ident.span.modern();
263 ext.helper_attrs.iter().map(|name| Ident::new(*name, span)),
265 if ext.is_derive_copy {
266 self.add_derive_copy(invoc_id);
270 Ok(_) | Err(Determinacy::Determined) => {
271 self.dummy_ext(MacroKind::Derive)
273 Err(Determinacy::Undetermined) => return Err(Indeterminate),
277 self.helper_attrs.insert(invoc_id, helper_attrs);
278 return Ok(InvocationRes::DeriveContainer(exts));
282 // Derives are not included when `invocations` are collected, so we have to add them here.
283 let parent_scope = &ParentScope { derives, ..parent_scope };
284 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
286 let span = invoc.span();
287 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
289 if let Res::Def(_, def_id) = res {
291 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
293 self.macro_defs.insert(invoc_id, def_id);
294 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
295 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
298 match invoc.fragment_kind {
299 AstFragmentKind::Arms
300 | AstFragmentKind::Fields
301 | AstFragmentKind::FieldPats
302 | AstFragmentKind::GenericParams
303 | AstFragmentKind::Params
304 | AstFragmentKind::StructFields
305 | AstFragmentKind::Variants => {
306 if let Res::Def(..) = res {
307 self.session.span_err(
310 "expected an inert attribute, found {} {}",
315 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
321 Ok(InvocationRes::Single(ext))
324 fn check_unused_macros(&mut self) {
325 for (&node_id, &span) in self.unused_macros.iter() {
326 self.lint_buffer.buffer_lint(
327 lint::builtin::UNUSED_MACROS,
330 "unused macro definition",
335 fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
336 self.containers_deriving_copy.contains(&expn_id)
339 fn add_derive_copy(&mut self, expn_id: ExpnId) {
340 self.containers_deriving_copy.insert(expn_id);
344 impl<'a> Resolver<'a> {
345 /// Resolve macro path with error reporting and recovery.
346 fn smart_resolve_macro_path(
350 parent_scope: &ParentScope<'a>,
352 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
353 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope, true, force)
355 Ok((Some(ext), res)) => (ext, res),
356 // Use dummy syntax extensions for unresolved macros for better recovery.
357 Ok((None, res)) => (self.dummy_ext(kind), res),
358 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
359 Err(Determinacy::Undetermined) => return Err(Indeterminate),
362 // Report errors and enforce feature gates for the resolved macro.
363 let features = self.session.features_untracked();
364 for segment in &path.segments {
365 if let Some(args) = &segment.args {
366 self.session.span_err(args.span(), "generic arguments in macro path");
368 if kind == MacroKind::Attr
369 && !features.rustc_attrs
370 && segment.ident.as_str().starts_with("rustc")
373 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
374 feature_err(&self.session.parse_sess, sym::rustc_attrs, segment.ident.span, msg)
380 Res::Def(DefKind::Macro(_), def_id) => {
381 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
382 self.unused_macros.remove(&node_id);
383 if self.proc_macro_stubs.contains(&node_id) {
384 self.session.span_err(
386 "can't use a procedural macro from the same crate that defines it",
391 Res::NonMacroAttr(..) | Res::Err => {}
392 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
395 self.check_stability_and_deprecation(&ext, path);
397 Ok(if ext.macro_kind() != kind {
398 let expected = kind.descr_expected();
399 let path_str = pprust::path_to_string(path);
400 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
402 .struct_span_err(path.span, &msg)
403 .span_label(path.span, format!("not {} {}", kind.article(), expected))
405 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
406 (self.dummy_ext(kind), Res::Err)
412 pub fn resolve_macro_path(
415 kind: Option<MacroKind>,
416 parent_scope: &ParentScope<'a>,
419 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
420 let path_span = path.span;
421 let mut path = Segment::from_path(path);
423 // Possibly apply the macro helper hack
424 if kind == Some(MacroKind::Bang)
426 && path[0].ident.span.ctxt().outer_expn_data().local_inner_macros
428 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
429 path.insert(0, Segment::from_ident(root));
432 let res = if path.len() > 1 {
433 let res = match self.resolve_path(
441 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
442 Ok(path_res.base_res())
444 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
445 PathResult::NonModule(..)
446 | PathResult::Indeterminate
447 | PathResult::Failed { .. } => Err(Determinacy::Determined),
448 PathResult::Module(..) => unreachable!(),
452 let kind = kind.expect("macro kind must be specified if tracing is enabled");
453 self.multi_segment_macro_resolutions.push((
462 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
465 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
466 let binding = self.early_resolve_ident_in_lexical_scope(
474 if let Err(Determinacy::Undetermined) = binding {
475 return Err(Determinacy::Undetermined);
479 let kind = kind.expect("macro kind must be specified if tracing is enabled");
480 self.single_segment_macro_resolutions.push((
488 let res = binding.map(|binding| binding.res());
489 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
493 res.map(|res| (self.get_macro(res), res))
496 // Resolve an identifier in lexical scope.
497 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
498 // expansion and import resolution (perhaps they can be merged in the future).
499 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
500 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
501 crate fn early_resolve_ident_in_lexical_scope(
505 parent_scope: &ParentScope<'a>,
509 ) -> Result<&'a NameBinding<'a>, Determinacy> {
510 bitflags::bitflags! {
512 const MACRO_RULES = 1 << 0;
513 const MODULE = 1 << 1;
514 const DERIVE_HELPER_COMPAT = 1 << 2;
515 const MISC_SUGGEST_CRATE = 1 << 3;
516 const MISC_SUGGEST_SELF = 1 << 4;
517 const MISC_FROM_PRELUDE = 1 << 5;
521 assert!(force || !record_used); // `record_used` implies `force`
523 // Make sure `self`, `super` etc produce an error when passed to here.
524 if orig_ident.is_path_segment_keyword() {
525 return Err(Determinacy::Determined);
528 let (ns, macro_kind, is_import) = match scope_set {
529 ScopeSet::All(ns, is_import) => (ns, None, is_import),
530 ScopeSet::AbsolutePath(ns) => (ns, None, false),
531 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
534 // This is *the* result, resolution from the scope closest to the resolved identifier.
535 // However, sometimes this result is "weak" because it comes from a glob import or
536 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
537 // mod m { ... } // solution in outer scope
539 // use prefix::*; // imports another `m` - innermost solution
540 // // weak, cannot shadow the outer `m`, need to report ambiguity error
543 // So we have to save the innermost solution and continue searching in outer scopes
544 // to detect potential ambiguities.
545 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
546 let mut determinacy = Determinacy::Determined;
548 // Go through all the scopes and try to resolve the name.
549 let break_result = self.visit_scopes(
553 |this, scope, use_prelude, ident| {
554 let ok = |res, span, arenas| {
556 (res, ty::Visibility::Public, span, ExpnId::root()).to_name_binding(arenas),
560 let result = match scope {
561 Scope::DeriveHelpers(expn_id) => {
562 if let Some(attr) = this
565 .and_then(|attrs| attrs.iter().rfind(|i| ident == **i))
568 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
569 ty::Visibility::Public,
573 .to_name_binding(this.arenas);
574 Ok((binding, Flags::empty()))
576 Err(Determinacy::Determined)
579 Scope::DeriveHelpersCompat => {
580 let mut result = Err(Determinacy::Determined);
581 for derive in parent_scope.derives {
582 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
583 match this.resolve_macro_path(
585 Some(MacroKind::Derive),
590 Ok((Some(ext), _)) => {
591 if ext.helper_attrs.contains(&ident.name) {
593 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
594 ty::Visibility::Public,
598 .to_name_binding(this.arenas);
599 result = Ok((binding, Flags::DERIVE_HELPER_COMPAT));
603 Ok(_) | Err(Determinacy::Determined) => {}
604 Err(Determinacy::Undetermined) => {
605 result = Err(Determinacy::Undetermined)
611 Scope::MacroRules(legacy_scope) => match legacy_scope {
612 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident => {
613 Ok((legacy_binding.binding, Flags::MACRO_RULES))
615 LegacyScope::Invocation(invoc_id)
616 if !this.output_legacy_scopes.contains_key(&invoc_id) =>
618 Err(Determinacy::Undetermined)
620 _ => Err(Determinacy::Determined),
622 Scope::CrateRoot => {
623 let root_ident = Ident::new(kw::PathRoot, ident.span);
624 let root_module = this.resolve_crate_root(root_ident);
625 let binding = this.resolve_ident_in_module_ext(
626 ModuleOrUniformRoot::Module(root_module),
634 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
635 Err((Determinacy::Undetermined, Weak::No)) => {
636 return Some(Err(Determinacy::determined(force)));
638 Err((Determinacy::Undetermined, Weak::Yes)) => {
639 Err(Determinacy::Undetermined)
641 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
644 Scope::Module(module) => {
645 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
646 let binding = this.resolve_ident_in_module_unadjusted_ext(
647 ModuleOrUniformRoot::Module(module),
650 adjusted_parent_scope,
657 let misc_flags = if ptr::eq(module, this.graph_root) {
658 Flags::MISC_SUGGEST_CRATE
659 } else if module.is_normal() {
660 Flags::MISC_SUGGEST_SELF
664 Ok((binding, Flags::MODULE | misc_flags))
666 Err((Determinacy::Undetermined, Weak::No)) => {
667 return Some(Err(Determinacy::determined(force)));
669 Err((Determinacy::Undetermined, Weak::Yes)) => {
670 Err(Determinacy::Undetermined)
672 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
675 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
677 Res::NonMacroAttr(NonMacroAttrKind::Registered),
681 None => Err(Determinacy::Determined),
683 Scope::MacroUsePrelude => {
684 match this.macro_use_prelude.get(&ident.name).cloned() {
685 Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)),
686 None => Err(Determinacy::determined(
687 this.graph_root.unexpanded_invocations.borrow().is_empty(),
691 Scope::BuiltinAttrs => {
692 if is_builtin_attr_name(ident.name) {
693 ok(Res::NonMacroAttr(NonMacroAttrKind::Builtin), DUMMY_SP, this.arenas)
695 Err(Determinacy::Determined)
698 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
699 Some(binding) => Ok((binding, Flags::empty())),
700 None => Err(Determinacy::determined(
701 this.graph_root.unexpanded_invocations.borrow().is_empty(),
704 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
705 Some(ident) => ok(Res::ToolMod, ident.span, this.arenas),
706 None => Err(Determinacy::Determined),
708 Scope::StdLibPrelude => {
709 let mut result = Err(Determinacy::Determined);
710 if let Some(prelude) = this.prelude {
711 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
712 ModuleOrUniformRoot::Module(prelude),
719 if use_prelude || this.is_builtin_macro(binding.res()) {
720 result = Ok((binding, Flags::MISC_FROM_PRELUDE));
726 Scope::BuiltinTypes => {
727 match this.primitive_type_table.primitive_types.get(&ident.name).cloned() {
728 Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas),
729 None => Err(Determinacy::Determined),
736 if sub_namespace_match(binding.macro_kind(), macro_kind) =>
739 return Some(Ok(binding));
742 if let Some((innermost_binding, innermost_flags)) = innermost_result {
743 // Found another solution, if the first one was "weak", report an error.
744 let (res, innermost_res) = (binding.res(), innermost_binding.res());
745 if res != innermost_res {
746 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
747 let is_derive_helper_compat = |res, flags: Flags| {
748 res == Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper)
749 && flags.contains(Flags::DERIVE_HELPER_COMPAT)
752 let ambiguity_error_kind = if is_import {
753 Some(AmbiguityKind::Import)
754 } else if innermost_res == builtin || res == builtin {
755 Some(AmbiguityKind::BuiltinAttr)
756 } else if is_derive_helper_compat(innermost_res, innermost_flags)
757 || is_derive_helper_compat(res, flags)
759 Some(AmbiguityKind::DeriveHelper)
760 } else if innermost_flags.contains(Flags::MACRO_RULES)
761 && flags.contains(Flags::MODULE)
763 .disambiguate_legacy_vs_modern(innermost_binding, binding)
764 || flags.contains(Flags::MACRO_RULES)
765 && innermost_flags.contains(Flags::MODULE)
766 && !this.disambiguate_legacy_vs_modern(
771 Some(AmbiguityKind::LegacyVsModern)
772 } else if innermost_binding.is_glob_import() {
773 Some(AmbiguityKind::GlobVsOuter)
774 } else if innermost_binding
775 .may_appear_after(parent_scope.expansion, binding)
777 Some(AmbiguityKind::MoreExpandedVsOuter)
781 if let Some(kind) = ambiguity_error_kind {
782 let misc = |f: Flags| {
783 if f.contains(Flags::MISC_SUGGEST_CRATE) {
784 AmbiguityErrorMisc::SuggestCrate
785 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
786 AmbiguityErrorMisc::SuggestSelf
787 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
788 AmbiguityErrorMisc::FromPrelude
790 AmbiguityErrorMisc::None
793 this.ambiguity_errors.push(AmbiguityError {
796 b1: innermost_binding,
798 misc1: misc(innermost_flags),
801 return Some(Ok(innermost_binding));
805 // Found the first solution.
806 innermost_result = Some((binding, flags));
809 Ok(..) | Err(Determinacy::Determined) => {}
810 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
817 if let Some(break_result) = break_result {
821 // The first found solution was the only one, return it.
822 if let Some((binding, _)) = innermost_result {
826 Err(Determinacy::determined(determinacy == Determinacy::Determined || force))
829 crate fn finalize_macro_resolutions(&mut self) {
830 let check_consistency = |this: &mut Self,
834 initial_res: Option<Res>,
836 if let Some(initial_res) = initial_res {
837 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
838 // Make sure compilation does not succeed if preferred macro resolution
839 // has changed after the macro had been expanded. In theory all such
840 // situations should be reported as ambiguity errors, so this is a bug.
841 span_bug!(span, "inconsistent resolution for a macro");
844 // It's possible that the macro was unresolved (indeterminate) and silently
845 // expanded into a dummy fragment for recovery during expansion.
846 // Now, post-expansion, the resolution may succeed, but we can't change the
847 // past and need to report an error.
848 // However, non-speculative `resolve_path` can successfully return private items
849 // even if speculative `resolve_path` returned nothing previously, so we skip this
850 // less informative error if the privacy error is reported elsewhere.
851 if this.privacy_errors.is_empty() {
853 "cannot determine resolution for the {} `{}`",
855 Segment::names_to_string(path)
857 let msg_note = "import resolution is stuck, try simplifying macro imports";
858 this.session.struct_span_err(span, &msg).note(msg_note).emit();
863 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
864 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
865 // FIXME: Path resolution will ICE if segment IDs present.
866 for seg in &mut path {
869 match self.resolve_path(
877 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
878 let res = path_res.base_res();
879 check_consistency(self, &path, path_span, kind, initial_res, res);
881 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
882 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
888 "partially resolved path in {} {}",
896 ResolutionError::FailedToResolve { label, suggestion: None },
899 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
903 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
904 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
905 match self.early_resolve_ident_in_lexical_scope(
907 ScopeSet::Macro(kind),
914 let initial_res = initial_binding.map(|initial_binding| {
915 self.record_use(ident, MacroNS, initial_binding, false);
916 initial_binding.res()
918 let res = binding.res();
919 let seg = Segment::from_ident(ident);
920 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
923 let expected = kind.descr_expected();
924 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
925 let mut err = self.session.struct_span_err(ident.span, &msg);
926 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
932 let builtin_attrs = mem::take(&mut self.builtin_attrs);
933 for (ident, parent_scope) in builtin_attrs {
934 let _ = self.early_resolve_ident_in_lexical_scope(
936 ScopeSet::Macro(MacroKind::Attr),
945 fn check_stability_and_deprecation(&mut self, ext: &SyntaxExtension, path: &ast::Path) {
946 let span = path.span;
947 if let Some(stability) = &ext.stability {
948 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
949 let feature = stability.feature;
950 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
951 let node_id = ast::CRATE_NODE_ID;
952 let lint_buffer = &mut self.lint_buffer;
954 |lint, span, msg: &_| lint_buffer.buffer_lint(lint, node_id, span, msg);
955 stability::report_unstable(
966 if let Some(depr) = &stability.rustc_depr {
967 let path = pprust::path_to_string(path);
968 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
969 stability::early_report_deprecation(
970 &mut self.lint_buffer,
978 if let Some(depr) = &ext.deprecation {
979 let path = pprust::path_to_string(&path);
980 let (message, lint) = stability::deprecation_message(depr, &path);
981 stability::early_report_deprecation(&mut self.lint_buffer, &message, None, lint, span);
985 fn prohibit_imported_non_macro_attrs(
987 binding: Option<&'a NameBinding<'a>>,
991 if let Some(Res::NonMacroAttr(kind)) = res {
992 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
994 format!("cannot use {} {} through an import", kind.article(), kind.descr());
995 let mut err = self.session.struct_span_err(span, &msg);
996 if let Some(binding) = binding {
997 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
1004 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
1005 // Reserve some names that are not quite covered by the general check
1006 // performed on `Resolver::builtin_attrs`.
1007 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
1008 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
1009 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
1010 self.session.span_err(
1012 &format!("name `{}` is reserved in attribute namespace", ident),
1018 /// Compile the macro into a `SyntaxExtension` and possibly replace
1019 /// its expander to a pre-defined one for built-in macros.
1020 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
1021 let mut result = compile_declarative_macro(
1022 &self.session.parse_sess,
1023 self.session.features_untracked(),
1028 if result.is_builtin {
1029 // The macro was marked with `#[rustc_builtin_macro]`.
1030 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
1031 // The macro is a built-in, replace its expander function
1032 // while still taking everything else from the source code.
1033 result.kind = ext.kind;
1035 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
1036 self.session.span_err(item.span, &msg);