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, BuiltinMacroState, Determinacy};
7 use crate::{CrateLint, ParentScope, ResolutionError, Resolver, Scope, ScopeSet, Weak};
8 use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment, ToNameBinding};
9 use rustc_ast::{self as ast, NodeId};
10 use rustc_ast_lowering::ResolverAstLowering;
11 use rustc_ast_pretty::pprust;
12 use rustc_attr::StabilityLevel;
13 use rustc_data_structures::fx::FxHashSet;
14 use rustc_data_structures::ptr_key::PtrKey;
15 use rustc_data_structures::sync::Lrc;
16 use rustc_errors::struct_span_err;
17 use rustc_expand::base::{Indeterminate, InvocationRes, ResolverExpand};
18 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
19 use rustc_expand::compile_declarative_macro;
20 use rustc_expand::expand::{AstFragment, 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_middle::middle::stability;
26 use rustc_session::lint::builtin::{SOFT_UNSTABLE, UNUSED_MACROS};
27 use rustc_session::parse::feature_err;
28 use rustc_session::Session;
29 use rustc_span::edition::Edition;
30 use rustc_span::hygiene::{self, ExpnData, ExpnId, ExpnKind};
31 use rustc_span::hygiene::{AstPass, MacroKind};
32 use rustc_span::symbol::{kw, sym, Ident, Symbol};
33 use rustc_span::{Span, DUMMY_SP};
37 type Res = def::Res<NodeId>;
39 /// Binding produced by a `macro_rules` item.
40 /// Not modularized, can shadow previous `macro_rules` bindings, etc.
42 pub struct MacroRulesBinding<'a> {
43 crate binding: &'a NameBinding<'a>,
44 /// `macro_rules` scope into which the `macro_rules` item was planted.
45 crate parent_macro_rules_scope: MacroRulesScopeRef<'a>,
49 /// The scope introduced by a `macro_rules!` macro.
50 /// This starts at the macro's definition and ends at the end of the macro's parent
51 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
52 /// Some macro invocations need to introduce `macro_rules` scopes too because they
53 /// can potentially expand into macro definitions.
54 #[derive(Copy, Clone, Debug)]
55 pub enum MacroRulesScope<'a> {
56 /// Empty "root" scope at the crate start containing no names.
58 /// The scope introduced by a `macro_rules!` macro definition.
59 Binding(&'a MacroRulesBinding<'a>),
60 /// The scope introduced by a macro invocation that can potentially
61 /// create a `macro_rules!` macro definition.
65 /// `macro_rules!` scopes are always kept by reference and inside a cell.
66 /// The reason is that we update scopes with value `MacroRulesScope::Invocation(invoc_id)`
67 /// in-place after `invoc_id` gets expanded.
68 /// This helps to avoid uncontrollable growth of `macro_rules!` scope chains,
69 /// which usually grow lineraly with the number of macro invocations
70 /// in a module (including derives) and hurt performance.
71 pub(crate) type MacroRulesScopeRef<'a> = PtrKey<'a, Cell<MacroRulesScope<'a>>>;
73 // Macro namespace is separated into two sub-namespaces, one for bang macros and
74 // one for attribute-like macros (attributes, derives).
75 // We ignore resolutions from one sub-namespace when searching names in scope for another.
76 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
82 let sub_ns = |kind| match kind {
83 MacroKind::Bang => SubNS::Bang,
84 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
86 let candidate = candidate.map(sub_ns);
87 let requirement = requirement.map(sub_ns);
88 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
89 candidate.is_none() || requirement.is_none() || candidate == requirement
92 // We don't want to format a path using pretty-printing,
93 // `format!("{}", path)`, because that tries to insert
94 // line-breaks and is slow.
95 fn fast_print_path(path: &ast::Path) -> Symbol {
96 if path.segments.len() == 1 {
97 path.segments[0].ident.name
99 let mut path_str = String::with_capacity(64);
100 for (i, segment) in path.segments.iter().enumerate() {
102 path_str.push_str("::");
104 if segment.ident.name != kw::PathRoot {
105 path_str.push_str(&segment.ident.as_str())
108 Symbol::intern(&path_str)
112 /// The code common between processing `#![register_tool]` and `#![register_attr]`.
113 fn registered_idents(
115 attrs: &[ast::Attribute],
118 ) -> FxHashSet<Ident> {
119 let mut registered = FxHashSet::default();
120 for attr in sess.filter_by_name(attrs, attr_name) {
121 for nested_meta in attr.meta_item_list().unwrap_or_default() {
122 match nested_meta.ident() {
124 if let Some(old_ident) = registered.replace(ident) {
125 let msg = format!("{} `{}` was already registered", descr, ident);
126 sess.struct_span_err(ident.span, &msg)
127 .span_label(old_ident.span, "already registered here")
132 let msg = format!("`{}` only accepts identifiers", attr_name);
133 let span = nested_meta.span();
134 sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
142 crate fn registered_attrs_and_tools(
144 attrs: &[ast::Attribute],
145 ) -> (FxHashSet<Ident>, FxHashSet<Ident>) {
146 let registered_attrs = registered_idents(sess, attrs, sym::register_attr, "attribute");
147 let mut registered_tools = registered_idents(sess, attrs, sym::register_tool, "tool");
148 // We implicitly add `rustfmt` and `clippy` to known tools,
149 // but it's not an error to register them explicitly.
150 let predefined_tools = [sym::clippy, sym::rustfmt];
151 registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
152 (registered_attrs, registered_tools)
155 impl<'a> ResolverExpand for Resolver<'a> {
156 fn next_node_id(&mut self) -> NodeId {
160 fn resolve_dollar_crates(&mut self) {
161 hygiene::update_dollar_crate_names(|ctxt| {
162 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
163 match self.resolve_crate_root(ident).kind {
164 ModuleKind::Def(.., name) if name != kw::Empty => name,
170 fn visit_ast_fragment_with_placeholders(&mut self, expansion: ExpnId, fragment: &AstFragment) {
171 // Integrate the new AST fragment into all the definition and module structures.
172 // We are inside the `expansion` now, but other parent scope components are still the same.
173 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
174 let output_macro_rules_scope = self.build_reduced_graph(fragment, parent_scope);
175 self.output_macro_rules_scopes.insert(expansion, output_macro_rules_scope);
177 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
180 fn register_builtin_macro(&mut self, name: Symbol, ext: SyntaxExtensionKind) {
181 if self.builtin_macros.insert(name, BuiltinMacroState::NotYetSeen(ext)).is_some() {
184 .bug(&format!("built-in macro `{}` was already registered", name));
188 // Create a new Expansion with a definition site of the provided module, or
189 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
190 fn expansion_for_ast_pass(
195 parent_module_id: Option<NodeId>,
197 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
198 ExpnKind::AstPass(pass),
200 self.session.edition(),
205 let parent_scope = if let Some(module_id) = parent_module_id {
206 let parent_def_id = self.local_def_id(module_id);
207 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id.to_def_id());
208 self.module_map[&parent_def_id]
210 self.definitions.add_parent_module_of_macro_def(
212 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
216 self.ast_transform_scopes.insert(expn_id, parent_scope);
220 fn resolve_imports(&mut self) {
221 ImportResolver { r: self }.resolve_imports()
224 fn resolve_macro_invocation(
227 eager_expansion_root: ExpnId,
229 ) -> Result<InvocationRes, Indeterminate> {
230 let invoc_id = invoc.expansion_data.id;
231 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
232 Some(parent_scope) => *parent_scope,
234 // If there's no entry in the table, then we are resolving an eagerly expanded
235 // macro, which should inherit its parent scope from its eager expansion root -
236 // the macro that requested this eager expansion.
237 let parent_scope = *self
238 .invocation_parent_scopes
239 .get(&eager_expansion_root)
240 .expect("non-eager expansion without a parent scope");
241 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
246 let (path, kind, inner_attr, derives, after_derive) = match invoc.kind {
247 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } => (
248 &attr.get_normal_item().path,
250 attr.style == ast::AttrStyle::Inner,
251 self.arenas.alloc_ast_paths(derives),
254 InvocationKind::Bang { ref mac, .. } => {
255 (&mac.path, MacroKind::Bang, false, &[][..], false)
257 InvocationKind::Derive { ref path, .. } => {
258 (path, MacroKind::Derive, false, &[][..], false)
260 InvocationKind::DeriveContainer { ref derives, .. } => {
261 // Block expansion of the container until we resolve all derives in it.
262 // This is required for two reasons:
263 // - Derive helper attributes are in scope for the item to which the `#[derive]`
264 // is applied, so they have to be produced by the container's expansion rather
265 // than by individual derives.
266 // - Derives in the container need to know whether one of them is a built-in `Copy`.
267 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
268 let mut exts = Vec::new();
269 let mut helper_attrs = Vec::new();
270 for path in derives {
272 match self.resolve_macro_path(
274 Some(MacroKind::Derive),
279 Ok((Some(ext), _)) => {
286 .normalize_to_macros_2_0();
288 ext.helper_attrs.iter().map(|name| Ident::new(*name, span)),
290 if ext.builtin_name == Some(sym::Copy) {
291 self.containers_deriving_copy.insert(invoc_id);
295 Ok(_) | Err(Determinacy::Determined) => {
296 self.dummy_ext(MacroKind::Derive)
298 Err(Determinacy::Undetermined) => return Err(Indeterminate),
302 self.helper_attrs.insert(invoc_id, helper_attrs);
303 return Ok(InvocationRes::DeriveContainer(exts));
307 // Derives are not included when `invocations` are collected, so we have to add them here.
308 let parent_scope = &ParentScope { derives, ..parent_scope };
309 let require_inert = !invoc.fragment_kind.supports_macro_expansion();
310 let node_id = self.lint_node_id(eager_expansion_root);
311 let (ext, res) = self.smart_resolve_macro_path(
321 let span = invoc.span();
322 invoc_id.set_expn_data(ext.expn_data(
323 parent_scope.expansion,
325 fast_print_path(path),
329 if let Res::Def(_, _) = res {
331 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
333 let normal_module_def_id = self.macro_def_scope(invoc_id).nearest_parent_mod;
334 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
337 Ok(InvocationRes::Single(ext))
340 fn check_unused_macros(&mut self) {
341 for (_, &(node_id, span)) in self.unused_macros.iter() {
342 self.lint_buffer.buffer_lint(UNUSED_MACROS, node_id, span, "unused macro definition");
346 fn lint_node_id(&mut self, expn_id: ExpnId) -> NodeId {
347 // FIXME - make this more precise. This currently returns the NodeId of the
348 // nearest closing item - we should try to return the closest parent of the ExpnId
349 self.invocation_parents
351 .map_or(ast::CRATE_NODE_ID, |id| self.def_id_to_node_id[*id])
354 fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
355 self.containers_deriving_copy.contains(&expn_id)
358 // The function that implements the resolution logic of `#[cfg_accessible(path)]`.
359 // Returns true if the path can certainly be resolved in one of three namespaces,
360 // returns false if the path certainly cannot be resolved in any of the three namespaces.
361 // Returns `Indeterminate` if we cannot give a certain answer yet.
362 fn cfg_accessible(&mut self, expn_id: ExpnId, path: &ast::Path) -> Result<bool, Indeterminate> {
363 let span = path.span;
364 let path = &Segment::from_path(path);
365 let parent_scope = self.invocation_parent_scopes[&expn_id];
367 let mut indeterminate = false;
368 for ns in [TypeNS, ValueNS, MacroNS].iter().copied() {
369 match self.resolve_path(path, Some(ns), &parent_scope, false, span, CrateLint::No) {
370 PathResult::Module(ModuleOrUniformRoot::Module(_)) => return Ok(true),
371 PathResult::NonModule(partial_res) if partial_res.unresolved_segments() == 0 => {
374 PathResult::Indeterminate => indeterminate = true,
375 // FIXME: `resolve_path` is not ready to report partially resolved paths
376 // correctly, so we just report an error if the path was reported as unresolved.
377 // This needs to be fixed for `cfg_accessible` to be useful.
378 PathResult::NonModule(..) | PathResult::Failed { .. } => {}
379 PathResult::Module(_) => panic!("unexpected path resolution"),
384 return Err(Indeterminate);
388 .struct_span_err(span, "not sure whether the path is accessible or not")
389 .span_note(span, "`cfg_accessible` is not fully implemented")
395 impl<'a> Resolver<'a> {
396 /// Resolve macro path with error reporting and recovery.
397 /// Uses dummy syntax extensions for unresolved macros or macros with unexpected resolutions
398 /// for better error recovery.
399 fn smart_resolve_macro_path(
405 parent_scope: &ParentScope<'a>,
408 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
409 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope, true, force)
411 Ok((Some(ext), res)) => (ext, res),
412 Ok((None, res)) => (self.dummy_ext(kind), res),
413 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
414 Err(Determinacy::Undetermined) => return Err(Indeterminate),
417 // Report errors for the resolved macro.
418 for segment in &path.segments {
419 if let Some(args) = &segment.args {
420 self.session.span_err(args.span(), "generic arguments in macro path");
422 if kind == MacroKind::Attr && segment.ident.as_str().starts_with("rustc") {
423 self.session.span_err(
425 "attributes starting with `rustc` are reserved for use by the `rustc` compiler",
431 Res::Def(DefKind::Macro(_), def_id) => {
432 if let Some(def_id) = def_id.as_local() {
433 self.unused_macros.remove(&def_id);
434 if self.proc_macro_stubs.contains(&def_id) {
435 self.session.span_err(
437 "can't use a procedural macro from the same crate that defines it",
442 Res::NonMacroAttr(..) | Res::Err => {}
443 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
446 self.check_stability_and_deprecation(&ext, path, node_id);
448 let unexpected_res = if ext.macro_kind() != kind {
449 Some((kind.article(), kind.descr_expected()))
450 } else if require_inert && matches!(res, Res::Def(..)) {
451 Some(("a", "non-macro attribute"))
455 if let Some((article, expected)) = unexpected_res {
456 let path_str = pprust::path_to_string(path);
457 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
459 .struct_span_err(path.span, &msg)
460 .span_label(path.span, format!("not {} {}", article, expected))
462 return Ok((self.dummy_ext(kind), Res::Err));
465 // We are trying to avoid reporting this error if other related errors were reported.
468 && !self.session.features_untracked().custom_inner_attributes
470 let msg = match res {
471 Res::Def(..) => "inner macro attributes are unstable",
472 Res::NonMacroAttr(..) => "custom inner attributes are unstable",
475 if path == &sym::test {
476 self.session.parse_sess.buffer_lint(SOFT_UNSTABLE, path.span, node_id, msg);
478 feature_err(&self.session.parse_sess, sym::custom_inner_attributes, path.span, msg)
486 pub fn resolve_macro_path(
489 kind: Option<MacroKind>,
490 parent_scope: &ParentScope<'a>,
493 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
494 let path_span = path.span;
495 let mut path = Segment::from_path(path);
497 // Possibly apply the macro helper hack
498 if kind == Some(MacroKind::Bang)
500 && path[0].ident.span.ctxt().outer_expn_data().local_inner_macros
502 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
503 path.insert(0, Segment::from_ident(root));
506 let res = if path.len() > 1 {
507 let res = match self.resolve_path(
515 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
516 Ok(path_res.base_res())
518 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
519 PathResult::NonModule(..)
520 | PathResult::Indeterminate
521 | PathResult::Failed { .. } => Err(Determinacy::Determined),
522 PathResult::Module(..) => unreachable!(),
526 let kind = kind.expect("macro kind must be specified if tracing is enabled");
527 self.multi_segment_macro_resolutions.push((
536 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
539 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
540 let binding = self.early_resolve_ident_in_lexical_scope(
548 if let Err(Determinacy::Undetermined) = binding {
549 return Err(Determinacy::Undetermined);
553 let kind = kind.expect("macro kind must be specified if tracing is enabled");
554 self.single_segment_macro_resolutions.push((
562 let res = binding.map(|binding| binding.res());
563 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
567 res.map(|res| (self.get_macro(res), res))
570 // Resolve an identifier in lexical scope.
571 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
572 // expansion and import resolution (perhaps they can be merged in the future).
573 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
574 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
575 crate fn early_resolve_ident_in_lexical_scope(
579 parent_scope: &ParentScope<'a>,
583 ) -> Result<&'a NameBinding<'a>, Determinacy> {
584 bitflags::bitflags! {
586 const MACRO_RULES = 1 << 0;
587 const MODULE = 1 << 1;
588 const MISC_SUGGEST_CRATE = 1 << 2;
589 const MISC_SUGGEST_SELF = 1 << 3;
590 const MISC_FROM_PRELUDE = 1 << 4;
594 assert!(force || !record_used); // `record_used` implies `force`
596 // Make sure `self`, `super` etc produce an error when passed to here.
597 if orig_ident.is_path_segment_keyword() {
598 return Err(Determinacy::Determined);
601 let (ns, macro_kind, is_import) = match scope_set {
602 ScopeSet::All(ns, is_import) => (ns, None, is_import),
603 ScopeSet::AbsolutePath(ns) => (ns, None, false),
604 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
607 // This is *the* result, resolution from the scope closest to the resolved identifier.
608 // However, sometimes this result is "weak" because it comes from a glob import or
609 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
610 // mod m { ... } // solution in outer scope
612 // use prefix::*; // imports another `m` - innermost solution
613 // // weak, cannot shadow the outer `m`, need to report ambiguity error
616 // So we have to save the innermost solution and continue searching in outer scopes
617 // to detect potential ambiguities.
618 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
619 let mut determinacy = Determinacy::Determined;
621 // Go through all the scopes and try to resolve the name.
622 let break_result = self.visit_scopes(
625 orig_ident.span.ctxt(),
626 |this, scope, use_prelude, ctxt| {
627 let ident = Ident::new(orig_ident.name, orig_ident.span.with_ctxt(ctxt));
628 let ok = |res, span, arenas| {
630 (res, ty::Visibility::Public, span, ExpnId::root()).to_name_binding(arenas),
634 let result = match scope {
635 Scope::DeriveHelpers(expn_id) => {
636 if let Some(attr) = this
639 .and_then(|attrs| attrs.iter().rfind(|i| ident == **i))
642 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
643 ty::Visibility::Public,
647 .to_name_binding(this.arenas);
648 Ok((binding, Flags::empty()))
650 Err(Determinacy::Determined)
653 Scope::DeriveHelpersCompat => {
654 let mut result = Err(Determinacy::Determined);
655 for derive in parent_scope.derives {
656 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
657 match this.resolve_macro_path(
659 Some(MacroKind::Derive),
664 Ok((Some(ext), _)) => {
665 if ext.helper_attrs.contains(&ident.name) {
667 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat),
674 Ok(_) | Err(Determinacy::Determined) => {}
675 Err(Determinacy::Undetermined) => {
676 result = Err(Determinacy::Undetermined)
682 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
683 MacroRulesScope::Binding(macro_rules_binding)
684 if ident == macro_rules_binding.ident =>
686 Ok((macro_rules_binding.binding, Flags::MACRO_RULES))
688 MacroRulesScope::Invocation(_) => Err(Determinacy::Undetermined),
689 _ => Err(Determinacy::Determined),
691 Scope::CrateRoot => {
692 let root_ident = Ident::new(kw::PathRoot, ident.span);
693 let root_module = this.resolve_crate_root(root_ident);
694 let binding = this.resolve_ident_in_module_ext(
695 ModuleOrUniformRoot::Module(root_module),
703 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
704 Err((Determinacy::Undetermined, Weak::No)) => {
705 return Some(Err(Determinacy::determined(force)));
707 Err((Determinacy::Undetermined, Weak::Yes)) => {
708 Err(Determinacy::Undetermined)
710 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
713 Scope::Module(module) => {
714 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
715 let binding = this.resolve_ident_in_module_unadjusted_ext(
716 ModuleOrUniformRoot::Module(module),
719 adjusted_parent_scope,
726 let misc_flags = if ptr::eq(module, this.graph_root) {
727 Flags::MISC_SUGGEST_CRATE
728 } else if module.is_normal() {
729 Flags::MISC_SUGGEST_SELF
733 Ok((binding, Flags::MODULE | misc_flags))
735 Err((Determinacy::Undetermined, Weak::No)) => {
736 return Some(Err(Determinacy::determined(force)));
738 Err((Determinacy::Undetermined, Weak::Yes)) => {
739 Err(Determinacy::Undetermined)
741 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
744 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
746 Res::NonMacroAttr(NonMacroAttrKind::Registered),
750 None => Err(Determinacy::Determined),
752 Scope::MacroUsePrelude => {
753 match this.macro_use_prelude.get(&ident.name).cloned() {
754 Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)),
755 None => Err(Determinacy::determined(
756 this.graph_root.unexpanded_invocations.borrow().is_empty(),
760 Scope::BuiltinAttrs => {
761 if is_builtin_attr_name(ident.name) {
763 Res::NonMacroAttr(NonMacroAttrKind::Builtin(ident.name)),
768 Err(Determinacy::Determined)
771 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
772 Some(binding) => Ok((binding, Flags::empty())),
773 None => Err(Determinacy::determined(
774 this.graph_root.unexpanded_invocations.borrow().is_empty(),
777 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
778 Some(ident) => ok(Res::ToolMod, ident.span, this.arenas),
779 None => Err(Determinacy::Determined),
781 Scope::StdLibPrelude => {
782 let mut result = Err(Determinacy::Determined);
783 if let Some(prelude) = this.prelude {
784 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
785 ModuleOrUniformRoot::Module(prelude),
792 if use_prelude || this.is_builtin_macro(binding.res()) {
793 result = Ok((binding, Flags::MISC_FROM_PRELUDE));
799 Scope::BuiltinTypes => {
800 match this.primitive_type_table.primitive_types.get(&ident.name).cloned() {
801 Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas),
802 None => Err(Determinacy::Determined),
809 if sub_namespace_match(binding.macro_kind(), macro_kind) =>
812 return Some(Ok(binding));
815 if let Some((innermost_binding, innermost_flags)) = innermost_result {
816 // Found another solution, if the first one was "weak", report an error.
817 let (res, innermost_res) = (binding.res(), innermost_binding.res());
818 if res != innermost_res {
819 let is_builtin = |res| {
820 matches!(res, Res::NonMacroAttr(NonMacroAttrKind::Builtin(..)))
822 let derive_helper_compat =
823 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
825 let ambiguity_error_kind = if is_import {
826 Some(AmbiguityKind::Import)
827 } else if is_builtin(innermost_res) || is_builtin(res) {
828 Some(AmbiguityKind::BuiltinAttr)
829 } else if innermost_res == derive_helper_compat
830 || res == derive_helper_compat
832 Some(AmbiguityKind::DeriveHelper)
833 } else if innermost_flags.contains(Flags::MACRO_RULES)
834 && flags.contains(Flags::MODULE)
835 && !this.disambiguate_macro_rules_vs_modularized(
839 || flags.contains(Flags::MACRO_RULES)
840 && innermost_flags.contains(Flags::MODULE)
841 && !this.disambiguate_macro_rules_vs_modularized(
846 Some(AmbiguityKind::MacroRulesVsModularized)
847 } else if innermost_binding.is_glob_import() {
848 Some(AmbiguityKind::GlobVsOuter)
849 } else if innermost_binding
850 .may_appear_after(parent_scope.expansion, binding)
852 Some(AmbiguityKind::MoreExpandedVsOuter)
856 if let Some(kind) = ambiguity_error_kind {
857 let misc = |f: Flags| {
858 if f.contains(Flags::MISC_SUGGEST_CRATE) {
859 AmbiguityErrorMisc::SuggestCrate
860 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
861 AmbiguityErrorMisc::SuggestSelf
862 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
863 AmbiguityErrorMisc::FromPrelude
865 AmbiguityErrorMisc::None
868 this.ambiguity_errors.push(AmbiguityError {
871 b1: innermost_binding,
873 misc1: misc(innermost_flags),
876 return Some(Ok(innermost_binding));
880 // Found the first solution.
881 innermost_result = Some((binding, flags));
884 Ok(..) | Err(Determinacy::Determined) => {}
885 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
892 if let Some(break_result) = break_result {
896 // The first found solution was the only one, return it.
897 if let Some((binding, _)) = innermost_result {
901 Err(Determinacy::determined(determinacy == Determinacy::Determined || force))
904 crate fn finalize_macro_resolutions(&mut self) {
905 let check_consistency = |this: &mut Self,
909 initial_res: Option<Res>,
911 if let Some(initial_res) = initial_res {
912 if res != initial_res {
913 // Make sure compilation does not succeed if preferred macro resolution
914 // has changed after the macro had been expanded. In theory all such
915 // situations should be reported as errors, so this is a bug.
916 this.session.delay_span_bug(span, "inconsistent resolution for a macro");
919 // It's possible that the macro was unresolved (indeterminate) and silently
920 // expanded into a dummy fragment for recovery during expansion.
921 // Now, post-expansion, the resolution may succeed, but we can't change the
922 // past and need to report an error.
923 // However, non-speculative `resolve_path` can successfully return private items
924 // even if speculative `resolve_path` returned nothing previously, so we skip this
925 // less informative error if the privacy error is reported elsewhere.
926 if this.privacy_errors.is_empty() {
928 "cannot determine resolution for the {} `{}`",
930 Segment::names_to_string(path)
932 let msg_note = "import resolution is stuck, try simplifying macro imports";
933 this.session.struct_span_err(span, &msg).note(msg_note).emit();
938 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
939 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
940 // FIXME: Path resolution will ICE if segment IDs present.
941 for seg in &mut path {
944 match self.resolve_path(
952 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
953 let res = path_res.base_res();
954 check_consistency(self, &path, path_span, kind, initial_res, res);
956 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
957 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
963 "partially resolved path in {} {}",
971 ResolutionError::FailedToResolve { label, suggestion: None },
974 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
978 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
979 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
980 match self.early_resolve_ident_in_lexical_scope(
982 ScopeSet::Macro(kind),
989 let initial_res = initial_binding.map(|initial_binding| {
990 self.record_use(ident, MacroNS, initial_binding, false);
991 initial_binding.res()
993 let res = binding.res();
994 let seg = Segment::from_ident(ident);
995 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
998 let expected = kind.descr_expected();
999 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
1000 let mut err = self.session.struct_span_err(ident.span, &msg);
1001 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
1007 let builtin_attrs = mem::take(&mut self.builtin_attrs);
1008 for (ident, parent_scope) in builtin_attrs {
1009 let _ = self.early_resolve_ident_in_lexical_scope(
1011 ScopeSet::Macro(MacroKind::Attr),
1020 fn check_stability_and_deprecation(
1022 ext: &SyntaxExtension,
1026 let span = path.span;
1027 if let Some(stability) = &ext.stability {
1028 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
1029 let feature = stability.feature;
1030 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
1031 let lint_buffer = &mut self.lint_buffer;
1033 |lint, span, msg: &_| lint_buffer.buffer_lint(lint, node_id, span, msg);
1034 stability::report_unstable(
1046 if let Some(depr) = &ext.deprecation {
1047 let path = pprust::path_to_string(&path);
1048 let (message, lint) = stability::deprecation_message(depr, "macro", &path);
1049 stability::early_report_deprecation(
1050 &mut self.lint_buffer,
1060 fn prohibit_imported_non_macro_attrs(
1062 binding: Option<&'a NameBinding<'a>>,
1066 if let Some(Res::NonMacroAttr(kind)) = res {
1067 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
1069 format!("cannot use {} {} through an import", kind.article(), kind.descr());
1070 let mut err = self.session.struct_span_err(span, &msg);
1071 if let Some(binding) = binding {
1072 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
1079 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
1080 // Reserve some names that are not quite covered by the general check
1081 // performed on `Resolver::builtin_attrs`.
1082 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
1083 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
1084 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
1085 self.session.span_err(
1087 &format!("name `{}` is reserved in attribute namespace", ident),
1093 /// Compile the macro into a `SyntaxExtension` and possibly replace
1094 /// its expander to a pre-defined one for built-in macros.
1095 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
1096 let mut result = compile_declarative_macro(
1098 self.session.features_untracked(),
1103 if let Some(builtin_name) = result.builtin_name {
1104 // The macro was marked with `#[rustc_builtin_macro]`.
1105 if let Some(builtin_macro) = self.builtin_macros.get_mut(&builtin_name) {
1106 // The macro is a built-in, replace its expander function
1107 // while still taking everything else from the source code.
1108 // If we already loaded this builtin macro, give a better error message than 'no such builtin macro'.
1109 match mem::replace(builtin_macro, BuiltinMacroState::AlreadySeen(item.span)) {
1110 BuiltinMacroState::NotYetSeen(ext) => result.kind = ext,
1111 BuiltinMacroState::AlreadySeen(span) => {
1116 "attempted to define built-in macro more than once"
1118 .span_note(span, "previously defined here")
1123 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
1124 self.session.span_err(item.span, &msg);