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, DeriveData, ParentScope, ResolutionError, Resolver, Scope, ScopeSet, Weak};
8 use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment, ToNameBinding};
9 use rustc_ast::{self as ast, Inline, ItemKind, ModKind, 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::intern::Interned;
15 use rustc_data_structures::sync::Lrc;
16 use rustc_errors::struct_span_err;
17 use rustc_expand::base::{Annotatable, DeriveResolutions, Indeterminate, ResolverExpand};
18 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
19 use rustc_expand::compile_declarative_macro;
20 use rustc_expand::expand::{AstFragment, Invocation, InvocationKind, SupportsMacroExpansion};
21 use rustc_feature::is_builtin_attr_name;
22 use rustc_hir::def::{self, DefKind, NonMacroAttrKind};
23 use rustc_hir::def_id::{CrateNum, LocalDefId};
24 use rustc_hir::PrimTy;
25 use rustc_middle::middle::stability;
26 use rustc_middle::ty::{self, RegisteredTools};
27 use rustc_session::lint::builtin::{LEGACY_DERIVE_HELPERS, PROC_MACRO_DERIVE_RESOLUTION_FALLBACK};
28 use rustc_session::lint::builtin::{SOFT_UNSTABLE, UNUSED_MACROS};
29 use rustc_session::lint::BuiltinLintDiagnostics;
30 use rustc_session::parse::feature_err;
31 use rustc_session::Session;
32 use rustc_span::edition::Edition;
33 use rustc_span::hygiene::{self, ExpnData, ExpnKind, LocalExpnId};
34 use rustc_span::hygiene::{AstPass, MacroKind};
35 use rustc_span::symbol::{kw, sym, Ident, Symbol};
36 use rustc_span::{Span, DUMMY_SP};
40 type Res = def::Res<NodeId>;
42 /// Binding produced by a `macro_rules` item.
43 /// Not modularized, can shadow previous `macro_rules` bindings, etc.
45 pub struct MacroRulesBinding<'a> {
46 crate binding: &'a NameBinding<'a>,
47 /// `macro_rules` scope into which the `macro_rules` item was planted.
48 crate parent_macro_rules_scope: MacroRulesScopeRef<'a>,
52 /// The scope introduced by a `macro_rules!` macro.
53 /// This starts at the macro's definition and ends at the end of the macro's parent
54 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
55 /// Some macro invocations need to introduce `macro_rules` scopes too because they
56 /// can potentially expand into macro definitions.
57 #[derive(Copy, Clone, Debug)]
58 pub enum MacroRulesScope<'a> {
59 /// Empty "root" scope at the crate start containing no names.
61 /// The scope introduced by a `macro_rules!` macro definition.
62 Binding(&'a MacroRulesBinding<'a>),
63 /// The scope introduced by a macro invocation that can potentially
64 /// create a `macro_rules!` macro definition.
65 Invocation(LocalExpnId),
68 /// `macro_rules!` scopes are always kept by reference and inside a cell.
69 /// The reason is that we update scopes with value `MacroRulesScope::Invocation(invoc_id)`
70 /// in-place after `invoc_id` gets expanded.
71 /// This helps to avoid uncontrollable growth of `macro_rules!` scope chains,
72 /// which usually grow lineraly with the number of macro invocations
73 /// in a module (including derives) and hurt performance.
74 pub(crate) type MacroRulesScopeRef<'a> = Interned<'a, Cell<MacroRulesScope<'a>>>;
76 // Macro namespace is separated into two sub-namespaces, one for bang macros and
77 // one for attribute-like macros (attributes, derives).
78 // We ignore resolutions from one sub-namespace when searching names in scope for another.
79 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
85 let sub_ns = |kind| match kind {
86 MacroKind::Bang => SubNS::Bang,
87 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
89 let candidate = candidate.map(sub_ns);
90 let requirement = requirement.map(sub_ns);
91 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
92 candidate.is_none() || requirement.is_none() || candidate == requirement
95 // We don't want to format a path using pretty-printing,
96 // `format!("{}", path)`, because that tries to insert
97 // line-breaks and is slow.
98 fn fast_print_path(path: &ast::Path) -> Symbol {
99 if path.segments.len() == 1 {
100 path.segments[0].ident.name
102 let mut path_str = String::with_capacity(64);
103 for (i, segment) in path.segments.iter().enumerate() {
105 path_str.push_str("::");
107 if segment.ident.name != kw::PathRoot {
108 path_str.push_str(segment.ident.as_str())
111 Symbol::intern(&path_str)
115 /// The code common between processing `#![register_tool]` and `#![register_attr]`.
116 fn registered_idents(
118 attrs: &[ast::Attribute],
121 ) -> FxHashSet<Ident> {
122 let mut registered = FxHashSet::default();
123 for attr in sess.filter_by_name(attrs, attr_name) {
124 for nested_meta in attr.meta_item_list().unwrap_or_default() {
125 match nested_meta.ident() {
127 if let Some(old_ident) = registered.replace(ident) {
128 let msg = format!("{} `{}` was already registered", descr, ident);
129 sess.struct_span_err(ident.span, &msg)
130 .span_label(old_ident.span, "already registered here")
135 let msg = format!("`{}` only accepts identifiers", attr_name);
136 let span = nested_meta.span();
137 sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
145 crate fn registered_attrs_and_tools(
147 attrs: &[ast::Attribute],
148 ) -> (FxHashSet<Ident>, FxHashSet<Ident>) {
149 let registered_attrs = registered_idents(sess, attrs, sym::register_attr, "attribute");
150 let mut registered_tools = registered_idents(sess, attrs, sym::register_tool, "tool");
151 // We implicitly add `rustfmt` and `clippy` to known tools,
152 // but it's not an error to register them explicitly.
153 let predefined_tools = [sym::clippy, sym::rustfmt];
154 registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
155 (registered_attrs, registered_tools)
158 // Some feature gates for inner attributes are reported as lints for backward compatibility.
159 fn soft_custom_inner_attributes_gate(path: &ast::Path, invoc: &Invocation) -> bool {
160 match &path.segments[..] {
162 [seg] if seg.ident.name == sym::test => return true,
163 // `#![rustfmt::skip]` on out-of-line modules
164 [seg1, seg2] if seg1.ident.name == sym::rustfmt && seg2.ident.name == sym::skip => {
165 if let InvocationKind::Attr { item, .. } = &invoc.kind {
166 if let Annotatable::Item(item) = item {
167 if let ItemKind::Mod(_, ModKind::Loaded(_, Inline::No, _)) = item.kind {
178 impl<'a> ResolverExpand for Resolver<'a> {
179 fn next_node_id(&mut self) -> NodeId {
183 fn invocation_parent(&self, id: LocalExpnId) -> LocalDefId {
184 self.invocation_parents[&id].0
187 fn resolve_dollar_crates(&mut self) {
188 hygiene::update_dollar_crate_names(|ctxt| {
189 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
190 match self.resolve_crate_root(ident).kind {
191 ModuleKind::Def(.., name) if name != kw::Empty => name,
197 fn visit_ast_fragment_with_placeholders(
199 expansion: LocalExpnId,
200 fragment: &AstFragment,
202 // Integrate the new AST fragment into all the definition and module structures.
203 // We are inside the `expansion` now, but other parent scope components are still the same.
204 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
205 let output_macro_rules_scope = self.build_reduced_graph(fragment, parent_scope);
206 self.output_macro_rules_scopes.insert(expansion, output_macro_rules_scope);
208 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
211 fn register_builtin_macro(&mut self, name: Symbol, ext: SyntaxExtensionKind) {
212 if self.builtin_macros.insert(name, BuiltinMacroState::NotYetSeen(ext)).is_some() {
215 .bug(&format!("built-in macro `{}` was already registered", name));
219 // Create a new Expansion with a definition site of the provided module, or
220 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
221 fn expansion_for_ast_pass(
226 parent_module_id: Option<NodeId>,
229 parent_module_id.map(|module_id| self.local_def_id(module_id).to_def_id());
230 let expn_id = LocalExpnId::fresh(
231 ExpnData::allow_unstable(
232 ExpnKind::AstPass(pass),
234 self.session.edition(),
239 self.create_stable_hashing_context(),
243 parent_module.map_or(self.empty_module, |def_id| self.expect_module(def_id));
244 self.ast_transform_scopes.insert(expn_id, parent_scope);
249 fn resolve_imports(&mut self) {
250 ImportResolver { r: self }.resolve_imports()
253 fn resolve_macro_invocation(
256 eager_expansion_root: LocalExpnId,
258 ) -> Result<Lrc<SyntaxExtension>, Indeterminate> {
259 let invoc_id = invoc.expansion_data.id;
260 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
261 Some(parent_scope) => *parent_scope,
263 // If there's no entry in the table, then we are resolving an eagerly expanded
264 // macro, which should inherit its parent scope from its eager expansion root -
265 // the macro that requested this eager expansion.
266 let parent_scope = *self
267 .invocation_parent_scopes
268 .get(&eager_expansion_root)
269 .expect("non-eager expansion without a parent scope");
270 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
275 let (path, kind, inner_attr, derives) = match invoc.kind {
276 InvocationKind::Attr { ref attr, ref derives, .. } => (
277 &attr.get_normal_item().path,
279 attr.style == ast::AttrStyle::Inner,
280 self.arenas.alloc_ast_paths(derives),
282 InvocationKind::Bang { ref mac, .. } => (&mac.path, MacroKind::Bang, false, &[][..]),
283 InvocationKind::Derive { ref path, .. } => (path, MacroKind::Derive, false, &[][..]),
286 // Derives are not included when `invocations` are collected, so we have to add them here.
287 let parent_scope = &ParentScope { derives, ..parent_scope };
288 let supports_macro_expansion = invoc.fragment_kind.supports_macro_expansion();
289 let node_id = invoc.expansion_data.lint_node_id;
290 let (ext, res) = self.smart_resolve_macro_path(
293 supports_macro_expansion,
298 soft_custom_inner_attributes_gate(path, invoc),
301 let span = invoc.span();
302 let def_id = res.opt_def_id();
303 invoc_id.set_expn_data(
305 parent_scope.expansion,
307 fast_print_path(path),
309 def_id.map(|def_id| self.macro_def_scope(def_id).nearest_parent_mod()),
311 self.create_stable_hashing_context(),
317 fn check_unused_macros(&mut self) {
318 for (_, &(node_id, ident)) in self.unused_macros.iter() {
319 self.lint_buffer.buffer_lint(
323 &format!("unused macro definition: `{}`", ident.as_str()),
328 fn has_derive_copy(&self, expn_id: LocalExpnId) -> bool {
329 self.containers_deriving_copy.contains(&expn_id)
334 expn_id: LocalExpnId,
336 derive_paths: &dyn Fn() -> DeriveResolutions,
337 ) -> Result<(), Indeterminate> {
338 // Block expansion of the container until we resolve all derives in it.
339 // This is required for two reasons:
340 // - Derive helper attributes are in scope for the item to which the `#[derive]`
341 // is applied, so they have to be produced by the container's expansion rather
342 // than by individual derives.
343 // - Derives in the container need to know whether one of them is a built-in `Copy`.
344 // Temporarily take the data to avoid borrow checker conflicts.
345 let mut derive_data = mem::take(&mut self.derive_data);
346 let entry = derive_data.entry(expn_id).or_insert_with(|| DeriveData {
347 resolutions: derive_paths(),
348 helper_attrs: Vec::new(),
349 has_derive_copy: false,
351 let parent_scope = self.invocation_parent_scopes[&expn_id];
352 for (i, (path, _, opt_ext)) in entry.resolutions.iter_mut().enumerate() {
353 if opt_ext.is_none() {
355 match self.resolve_macro_path(
357 Some(MacroKind::Derive),
362 Ok((Some(ext), _)) => {
363 if !ext.helper_attrs.is_empty() {
364 let last_seg = path.segments.last().unwrap();
365 let span = last_seg.ident.span.normalize_to_macros_2_0();
366 entry.helper_attrs.extend(
369 .map(|name| (i, Ident::new(*name, span))),
372 entry.has_derive_copy |= ext.builtin_name == Some(sym::Copy);
375 Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
376 Err(Determinacy::Undetermined) => {
377 assert!(self.derive_data.is_empty());
378 self.derive_data = derive_data;
379 return Err(Indeterminate);
385 // Sort helpers in a stable way independent from the derive resolution order.
386 entry.helper_attrs.sort_by_key(|(i, _)| *i);
388 .insert(expn_id, entry.helper_attrs.iter().map(|(_, ident)| *ident).collect());
389 // Mark this derive as having `Copy` either if it has `Copy` itself or if its parent derive
390 // has `Copy`, to support cases like `#[derive(Clone, Copy)] #[derive(Debug)]`.
391 if entry.has_derive_copy || self.has_derive_copy(parent_scope.expansion) {
392 self.containers_deriving_copy.insert(expn_id);
394 assert!(self.derive_data.is_empty());
395 self.derive_data = derive_data;
399 fn take_derive_resolutions(&mut self, expn_id: LocalExpnId) -> Option<DeriveResolutions> {
400 self.derive_data.remove(&expn_id).map(|data| data.resolutions)
403 // The function that implements the resolution logic of `#[cfg_accessible(path)]`.
404 // Returns true if the path can certainly be resolved in one of three namespaces,
405 // returns false if the path certainly cannot be resolved in any of the three namespaces.
406 // Returns `Indeterminate` if we cannot give a certain answer yet.
409 expn_id: LocalExpnId,
411 ) -> Result<bool, Indeterminate> {
412 let span = path.span;
413 let path = &Segment::from_path(path);
414 let parent_scope = self.invocation_parent_scopes[&expn_id];
416 let mut indeterminate = false;
417 for ns in [TypeNS, ValueNS, MacroNS].iter().copied() {
418 match self.resolve_path(path, Some(ns), &parent_scope, false, span, CrateLint::No) {
419 PathResult::Module(ModuleOrUniformRoot::Module(_)) => return Ok(true),
420 PathResult::NonModule(partial_res) if partial_res.unresolved_segments() == 0 => {
423 PathResult::Indeterminate => indeterminate = true,
424 // FIXME: `resolve_path` is not ready to report partially resolved paths
425 // correctly, so we just report an error if the path was reported as unresolved.
426 // This needs to be fixed for `cfg_accessible` to be useful.
427 PathResult::NonModule(..) | PathResult::Failed { .. } => {}
428 PathResult::Module(_) => panic!("unexpected path resolution"),
433 return Err(Indeterminate);
437 .struct_span_err(span, "not sure whether the path is accessible or not")
438 .span_note(span, "`cfg_accessible` is not fully implemented")
443 fn get_proc_macro_quoted_span(&self, krate: CrateNum, id: usize) -> Span {
444 self.crate_loader.cstore().get_proc_macro_quoted_span_untracked(krate, id, self.session)
447 fn declare_proc_macro(&mut self, id: NodeId) {
448 self.proc_macros.push(id)
451 fn registered_tools(&self) -> &RegisteredTools {
452 &self.registered_tools
456 impl<'a> Resolver<'a> {
457 /// Resolve macro path with error reporting and recovery.
458 /// Uses dummy syntax extensions for unresolved macros or macros with unexpected resolutions
459 /// for better error recovery.
460 fn smart_resolve_macro_path(
464 supports_macro_expansion: SupportsMacroExpansion,
466 parent_scope: &ParentScope<'a>,
469 soft_custom_inner_attributes_gate: bool,
470 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
471 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope, true, force)
473 Ok((Some(ext), res)) => (ext, res),
474 Ok((None, res)) => (self.dummy_ext(kind), res),
475 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
476 Err(Determinacy::Undetermined) => return Err(Indeterminate),
479 // Report errors for the resolved macro.
480 for segment in &path.segments {
481 if let Some(args) = &segment.args {
482 self.session.span_err(args.span(), "generic arguments in macro path");
484 if kind == MacroKind::Attr && segment.ident.as_str().starts_with("rustc") {
485 self.session.span_err(
487 "attributes starting with `rustc` are reserved for use by the `rustc` compiler",
493 Res::Def(DefKind::Macro(_), def_id) => {
494 if let Some(def_id) = def_id.as_local() {
495 self.unused_macros.remove(&def_id);
496 if self.proc_macro_stubs.contains(&def_id) {
497 self.session.span_err(
499 "can't use a procedural macro from the same crate that defines it",
504 Res::NonMacroAttr(..) | Res::Err => {}
505 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
508 self.check_stability_and_deprecation(&ext, path, node_id);
510 let unexpected_res = if ext.macro_kind() != kind {
511 Some((kind.article(), kind.descr_expected()))
512 } else if matches!(res, Res::Def(..)) {
513 match supports_macro_expansion {
514 SupportsMacroExpansion::No => Some(("a", "non-macro attribute")),
515 SupportsMacroExpansion::Yes { supports_inner_attrs } => {
516 if inner_attr && !supports_inner_attrs {
517 Some(("a", "non-macro inner attribute"))
526 if let Some((article, expected)) = unexpected_res {
527 let path_str = pprust::path_to_string(path);
528 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
530 .struct_span_err(path.span, &msg)
531 .span_label(path.span, format!("not {} {}", article, expected))
533 return Ok((self.dummy_ext(kind), Res::Err));
536 // We are trying to avoid reporting this error if other related errors were reported.
539 && !self.session.features_untracked().custom_inner_attributes
541 let msg = match res {
542 Res::Def(..) => "inner macro attributes are unstable",
543 Res::NonMacroAttr(..) => "custom inner attributes are unstable",
546 if soft_custom_inner_attributes_gate {
547 self.session.parse_sess.buffer_lint(SOFT_UNSTABLE, path.span, node_id, msg);
549 feature_err(&self.session.parse_sess, sym::custom_inner_attributes, path.span, msg)
557 pub fn resolve_macro_path(
560 kind: Option<MacroKind>,
561 parent_scope: &ParentScope<'a>,
564 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
565 let path_span = path.span;
566 let mut path = Segment::from_path(path);
568 // Possibly apply the macro helper hack
569 if kind == Some(MacroKind::Bang)
571 && path[0].ident.span.ctxt().outer_expn_data().local_inner_macros
573 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
574 path.insert(0, Segment::from_ident(root));
577 let res = if path.len() > 1 {
578 let res = match self.resolve_path(
586 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
587 Ok(path_res.base_res())
589 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
590 PathResult::NonModule(..)
591 | PathResult::Indeterminate
592 | PathResult::Failed { .. } => Err(Determinacy::Determined),
593 PathResult::Module(..) => unreachable!(),
597 let kind = kind.expect("macro kind must be specified if tracing is enabled");
598 self.multi_segment_macro_resolutions.push((
607 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
610 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
611 let binding = self.early_resolve_ident_in_lexical_scope(
619 if let Err(Determinacy::Undetermined) = binding {
620 return Err(Determinacy::Undetermined);
624 let kind = kind.expect("macro kind must be specified if tracing is enabled");
625 self.single_segment_macro_resolutions.push((
633 let res = binding.map(|binding| binding.res());
634 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
638 res.map(|res| (self.get_macro(res), res))
641 // Resolve an identifier in lexical scope.
642 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
643 // expansion and import resolution (perhaps they can be merged in the future).
644 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
645 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
646 crate fn early_resolve_ident_in_lexical_scope(
649 scope_set: ScopeSet<'a>,
650 parent_scope: &ParentScope<'a>,
654 ) -> Result<&'a NameBinding<'a>, Determinacy> {
655 bitflags::bitflags! {
657 const MACRO_RULES = 1 << 0;
658 const MODULE = 1 << 1;
659 const MISC_SUGGEST_CRATE = 1 << 2;
660 const MISC_SUGGEST_SELF = 1 << 3;
661 const MISC_FROM_PRELUDE = 1 << 4;
665 assert!(force || !record_used); // `record_used` implies `force`
667 // Make sure `self`, `super` etc produce an error when passed to here.
668 if orig_ident.is_path_segment_keyword() {
669 return Err(Determinacy::Determined);
672 let (ns, macro_kind, is_import) = match scope_set {
673 ScopeSet::All(ns, is_import) => (ns, None, is_import),
674 ScopeSet::AbsolutePath(ns) => (ns, None, false),
675 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
676 ScopeSet::Late(ns, ..) => (ns, None, false),
679 // This is *the* result, resolution from the scope closest to the resolved identifier.
680 // However, sometimes this result is "weak" because it comes from a glob import or
681 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
682 // mod m { ... } // solution in outer scope
684 // use prefix::*; // imports another `m` - innermost solution
685 // // weak, cannot shadow the outer `m`, need to report ambiguity error
688 // So we have to save the innermost solution and continue searching in outer scopes
689 // to detect potential ambiguities.
690 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
691 let mut determinacy = Determinacy::Determined;
693 // Go through all the scopes and try to resolve the name.
694 let break_result = self.visit_scopes(
697 orig_ident.span.ctxt(),
698 |this, scope, use_prelude, ctxt| {
699 let ident = Ident::new(orig_ident.name, orig_ident.span.with_ctxt(ctxt));
700 let ok = |res, span, arenas| {
702 (res, ty::Visibility::Public, span, LocalExpnId::ROOT)
703 .to_name_binding(arenas),
707 let result = match scope {
708 Scope::DeriveHelpers(expn_id) => {
709 if let Some(attr) = this
712 .and_then(|attrs| attrs.iter().rfind(|i| ident == **i))
715 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
716 ty::Visibility::Public,
720 .to_name_binding(this.arenas);
721 Ok((binding, Flags::empty()))
723 Err(Determinacy::Determined)
726 Scope::DeriveHelpersCompat => {
727 let mut result = Err(Determinacy::Determined);
728 for derive in parent_scope.derives {
729 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
730 match this.resolve_macro_path(
732 Some(MacroKind::Derive),
737 Ok((Some(ext), _)) => {
738 if ext.helper_attrs.contains(&ident.name) {
740 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat),
747 Ok(_) | Err(Determinacy::Determined) => {}
748 Err(Determinacy::Undetermined) => {
749 result = Err(Determinacy::Undetermined)
755 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
756 MacroRulesScope::Binding(macro_rules_binding)
757 if ident == macro_rules_binding.ident =>
759 Ok((macro_rules_binding.binding, Flags::MACRO_RULES))
761 MacroRulesScope::Invocation(_) => Err(Determinacy::Undetermined),
762 _ => Err(Determinacy::Determined),
764 Scope::CrateRoot => {
765 let root_ident = Ident::new(kw::PathRoot, ident.span);
766 let root_module = this.resolve_crate_root(root_ident);
767 let binding = this.resolve_ident_in_module_ext(
768 ModuleOrUniformRoot::Module(root_module),
776 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
777 Err((Determinacy::Undetermined, Weak::No)) => {
778 return Some(Err(Determinacy::determined(force)));
780 Err((Determinacy::Undetermined, Weak::Yes)) => {
781 Err(Determinacy::Undetermined)
783 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
786 Scope::Module(module, derive_fallback_lint_id) => {
787 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
788 let binding = this.resolve_ident_in_module_unadjusted_ext(
789 ModuleOrUniformRoot::Module(module),
792 adjusted_parent_scope,
793 !matches!(scope_set, ScopeSet::Late(..)),
799 if let Some(lint_id) = derive_fallback_lint_id {
800 this.lint_buffer.buffer_lint_with_diagnostic(
801 PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
805 "cannot find {} `{}` in this scope",
809 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(
814 let misc_flags = if ptr::eq(module, this.graph_root) {
815 Flags::MISC_SUGGEST_CRATE
816 } else if module.is_normal() {
817 Flags::MISC_SUGGEST_SELF
821 Ok((binding, Flags::MODULE | misc_flags))
823 Err((Determinacy::Undetermined, Weak::No)) => {
824 return Some(Err(Determinacy::determined(force)));
826 Err((Determinacy::Undetermined, Weak::Yes)) => {
827 Err(Determinacy::Undetermined)
829 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
832 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
834 Res::NonMacroAttr(NonMacroAttrKind::Registered),
838 None => Err(Determinacy::Determined),
840 Scope::MacroUsePrelude => {
841 match this.macro_use_prelude.get(&ident.name).cloned() {
842 Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)),
843 None => Err(Determinacy::determined(
844 this.graph_root.unexpanded_invocations.borrow().is_empty(),
848 Scope::BuiltinAttrs => {
849 if is_builtin_attr_name(ident.name) {
851 Res::NonMacroAttr(NonMacroAttrKind::Builtin(ident.name)),
856 Err(Determinacy::Determined)
859 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
860 Some(binding) => Ok((binding, Flags::empty())),
861 None => Err(Determinacy::determined(
862 this.graph_root.unexpanded_invocations.borrow().is_empty(),
865 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
866 Some(ident) => ok(Res::ToolMod, ident.span, this.arenas),
867 None => Err(Determinacy::Determined),
869 Scope::StdLibPrelude => {
870 let mut result = Err(Determinacy::Determined);
871 if let Some(prelude) = this.prelude {
872 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
873 ModuleOrUniformRoot::Module(prelude),
880 if use_prelude || this.is_builtin_macro(binding.res()) {
881 result = Ok((binding, Flags::MISC_FROM_PRELUDE));
887 Scope::BuiltinTypes => match PrimTy::from_name(ident.name) {
888 Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas),
889 None => Err(Determinacy::Determined),
895 if sub_namespace_match(binding.macro_kind(), macro_kind) =>
897 if !record_used || matches!(scope_set, ScopeSet::Late(..)) {
898 return Some(Ok(binding));
901 if let Some((innermost_binding, innermost_flags)) = innermost_result {
902 // Found another solution, if the first one was "weak", report an error.
903 let (res, innermost_res) = (binding.res(), innermost_binding.res());
904 if res != innermost_res {
905 let is_builtin = |res| {
906 matches!(res, Res::NonMacroAttr(NonMacroAttrKind::Builtin(..)))
909 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
910 let derive_helper_compat =
911 Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
913 let ambiguity_error_kind = if is_import {
914 Some(AmbiguityKind::Import)
915 } else if is_builtin(innermost_res) || is_builtin(res) {
916 Some(AmbiguityKind::BuiltinAttr)
917 } else if innermost_res == derive_helper_compat
918 || res == derive_helper_compat && innermost_res != derive_helper
920 Some(AmbiguityKind::DeriveHelper)
921 } else if innermost_flags.contains(Flags::MACRO_RULES)
922 && flags.contains(Flags::MODULE)
923 && !this.disambiguate_macro_rules_vs_modularized(
927 || flags.contains(Flags::MACRO_RULES)
928 && innermost_flags.contains(Flags::MODULE)
929 && !this.disambiguate_macro_rules_vs_modularized(
934 Some(AmbiguityKind::MacroRulesVsModularized)
935 } else if innermost_binding.is_glob_import() {
936 Some(AmbiguityKind::GlobVsOuter)
937 } else if innermost_binding
938 .may_appear_after(parent_scope.expansion, binding)
940 Some(AmbiguityKind::MoreExpandedVsOuter)
944 if let Some(kind) = ambiguity_error_kind {
945 let misc = |f: Flags| {
946 if f.contains(Flags::MISC_SUGGEST_CRATE) {
947 AmbiguityErrorMisc::SuggestCrate
948 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
949 AmbiguityErrorMisc::SuggestSelf
950 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
951 AmbiguityErrorMisc::FromPrelude
953 AmbiguityErrorMisc::None
956 this.ambiguity_errors.push(AmbiguityError {
959 b1: innermost_binding,
961 misc1: misc(innermost_flags),
964 return Some(Ok(innermost_binding));
968 // Found the first solution.
969 innermost_result = Some((binding, flags));
972 Ok(..) | Err(Determinacy::Determined) => {}
973 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined,
980 if let Some(break_result) = break_result {
984 // The first found solution was the only one, return it.
985 if let Some((binding, _)) = innermost_result {
989 Err(Determinacy::determined(determinacy == Determinacy::Determined || force))
992 crate fn finalize_macro_resolutions(&mut self) {
993 let check_consistency = |this: &mut Self,
997 initial_res: Option<Res>,
999 if let Some(initial_res) = initial_res {
1000 if res != initial_res {
1001 // Make sure compilation does not succeed if preferred macro resolution
1002 // has changed after the macro had been expanded. In theory all such
1003 // situations should be reported as errors, so this is a bug.
1004 this.session.delay_span_bug(span, "inconsistent resolution for a macro");
1007 // It's possible that the macro was unresolved (indeterminate) and silently
1008 // expanded into a dummy fragment for recovery during expansion.
1009 // Now, post-expansion, the resolution may succeed, but we can't change the
1010 // past and need to report an error.
1011 // However, non-speculative `resolve_path` can successfully return private items
1012 // even if speculative `resolve_path` returned nothing previously, so we skip this
1013 // less informative error if the privacy error is reported elsewhere.
1014 if this.privacy_errors.is_empty() {
1016 "cannot determine resolution for the {} `{}`",
1018 Segment::names_to_string(path)
1020 let msg_note = "import resolution is stuck, try simplifying macro imports";
1021 this.session.struct_span_err(span, &msg).note(msg_note).emit();
1026 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
1027 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
1028 // FIXME: Path resolution will ICE if segment IDs present.
1029 for seg in &mut path {
1032 match self.resolve_path(
1040 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
1041 let res = path_res.base_res();
1042 check_consistency(self, &path, path_span, kind, initial_res, res);
1044 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
1045 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
1051 "partially resolved path in {} {}",
1059 ResolutionError::FailedToResolve { label, suggestion: None },
1062 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
1066 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
1067 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
1068 match self.early_resolve_ident_in_lexical_scope(
1070 ScopeSet::Macro(kind),
1077 let initial_res = initial_binding.map(|initial_binding| {
1078 self.record_use(ident, initial_binding, false);
1079 initial_binding.res()
1081 let res = binding.res();
1082 let seg = Segment::from_ident(ident);
1083 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
1084 if res == Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat) {
1087 .get(&parent_scope.expansion)
1088 .map_or(ast::CRATE_NODE_ID, |id| self.def_id_to_node_id[id.0]);
1089 self.lint_buffer.buffer_lint_with_diagnostic(
1090 LEGACY_DERIVE_HELPERS,
1093 "derive helper attribute is used before it is introduced",
1094 BuiltinLintDiagnostics::LegacyDeriveHelpers(binding.span),
1099 let expected = kind.descr_expected();
1100 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
1101 let mut err = self.session.struct_span_err(ident.span, &msg);
1102 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
1108 let builtin_attrs = mem::take(&mut self.builtin_attrs);
1109 for (ident, parent_scope) in builtin_attrs {
1110 let _ = self.early_resolve_ident_in_lexical_scope(
1112 ScopeSet::Macro(MacroKind::Attr),
1121 fn check_stability_and_deprecation(
1123 ext: &SyntaxExtension,
1127 let span = path.span;
1128 if let Some(stability) = &ext.stability {
1129 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
1130 let feature = stability.feature;
1131 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
1132 let lint_buffer = &mut self.lint_buffer;
1134 |lint, span, msg: &_| lint_buffer.buffer_lint(lint, node_id, span, msg);
1135 stability::report_unstable(
1148 if let Some(depr) = &ext.deprecation {
1149 let path = pprust::path_to_string(&path);
1150 let (message, lint) = stability::deprecation_message_and_lint(depr, "macro", &path);
1151 stability::early_report_deprecation(
1152 &mut self.lint_buffer,
1162 fn prohibit_imported_non_macro_attrs(
1164 binding: Option<&'a NameBinding<'a>>,
1168 if let Some(Res::NonMacroAttr(kind)) = res {
1169 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
1171 format!("cannot use {} {} through an import", kind.article(), kind.descr());
1172 let mut err = self.session.struct_span_err(span, &msg);
1173 if let Some(binding) = binding {
1174 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
1181 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
1182 // Reserve some names that are not quite covered by the general check
1183 // performed on `Resolver::builtin_attrs`.
1184 if ident.name == sym::cfg || ident.name == sym::cfg_attr {
1185 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
1186 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
1187 self.session.span_err(
1189 &format!("name `{}` is reserved in attribute namespace", ident),
1195 /// Compile the macro into a `SyntaxExtension` and possibly replace
1196 /// its expander to a pre-defined one for built-in macros.
1197 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
1198 let mut result = compile_declarative_macro(
1200 self.session.features_untracked(),
1205 if let Some(builtin_name) = result.builtin_name {
1206 // The macro was marked with `#[rustc_builtin_macro]`.
1207 if let Some(builtin_macro) = self.builtin_macros.get_mut(&builtin_name) {
1208 // The macro is a built-in, replace its expander function
1209 // while still taking everything else from the source code.
1210 // If we already loaded this builtin macro, give a better error message than 'no such builtin macro'.
1211 match mem::replace(builtin_macro, BuiltinMacroState::AlreadySeen(item.span)) {
1212 BuiltinMacroState::NotYetSeen(ext) => {
1214 if item.id != ast::DUMMY_NODE_ID {
1215 self.builtin_macro_kinds
1216 .insert(self.local_def_id(item.id), result.macro_kind());
1219 BuiltinMacroState::AlreadySeen(span) => {
1224 "attempted to define built-in macro more than once"
1226 .span_note(span, "previously defined here")
1231 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
1232 self.session.span_err(item.span, &msg);