rustc_resolve/
macros.rs

1//! A bunch of methods and structures more or less related to resolving macros and
2//! interface provided by `Resolver` to macro expander.
3
4use std::cell::Cell;
5use std::mem;
6use std::sync::Arc;
7
8use rustc_ast::{self as ast, Crate, NodeId, attr};
9use rustc_ast_pretty::pprust;
10use rustc_attr_data_structures::{CfgEntry, StabilityLevel, StrippedCfgItem};
11use rustc_errors::{Applicability, DiagCtxtHandle, StashKey};
12use rustc_expand::base::{
13    Annotatable, DeriveResolution, Indeterminate, ResolverExpand, SyntaxExtension,
14    SyntaxExtensionKind,
15};
16use rustc_expand::compile_declarative_macro;
17use rustc_expand::expand::{
18    AstFragment, AstFragmentKind, Invocation, InvocationKind, SupportsMacroExpansion,
19};
20use rustc_hir::def::{self, DefKind, Namespace, NonMacroAttrKind};
21use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
22use rustc_middle::middle::stability;
23use rustc_middle::ty::{RegisteredTools, TyCtxt};
24use rustc_session::lint::BuiltinLintDiag;
25use rustc_session::lint::builtin::{
26    LEGACY_DERIVE_HELPERS, OUT_OF_SCOPE_MACRO_CALLS, UNKNOWN_DIAGNOSTIC_ATTRIBUTES,
27    UNUSED_MACRO_RULES, UNUSED_MACROS,
28};
29use rustc_session::parse::feature_err;
30use rustc_span::edit_distance::find_best_match_for_name;
31use rustc_span::edition::Edition;
32use rustc_span::hygiene::{self, AstPass, ExpnData, ExpnKind, LocalExpnId, MacroKind};
33use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
34
35use crate::Namespace::*;
36use crate::errors::{
37    self, AddAsNonDerive, CannotDetermineMacroResolution, CannotFindIdentInThisScope,
38    MacroExpectedFound, RemoveSurroundingDerive,
39};
40use crate::imports::Import;
41use crate::{
42    BindingKey, DeriveData, Determinacy, Finalize, InvocationParent, MacroData, ModuleKind,
43    ModuleOrUniformRoot, NameBinding, NameBindingKind, ParentScope, PathResult, ResolutionError,
44    Resolver, ScopeSet, Segment, Used,
45};
46
47type Res = def::Res<NodeId>;
48
49/// Binding produced by a `macro_rules` item.
50/// Not modularized, can shadow previous `macro_rules` bindings, etc.
51#[derive(Debug)]
52pub(crate) struct MacroRulesBinding<'ra> {
53    pub(crate) binding: NameBinding<'ra>,
54    /// `macro_rules` scope into which the `macro_rules` item was planted.
55    pub(crate) parent_macro_rules_scope: MacroRulesScopeRef<'ra>,
56    pub(crate) ident: Ident,
57}
58
59/// The scope introduced by a `macro_rules!` macro.
60/// This starts at the macro's definition and ends at the end of the macro's parent
61/// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
62/// Some macro invocations need to introduce `macro_rules` scopes too because they
63/// can potentially expand into macro definitions.
64#[derive(Copy, Clone, Debug)]
65pub(crate) enum MacroRulesScope<'ra> {
66    /// Empty "root" scope at the crate start containing no names.
67    Empty,
68    /// The scope introduced by a `macro_rules!` macro definition.
69    Binding(&'ra MacroRulesBinding<'ra>),
70    /// The scope introduced by a macro invocation that can potentially
71    /// create a `macro_rules!` macro definition.
72    Invocation(LocalExpnId),
73}
74
75/// `macro_rules!` scopes are always kept by reference and inside a cell.
76/// The reason is that we update scopes with value `MacroRulesScope::Invocation(invoc_id)`
77/// in-place after `invoc_id` gets expanded.
78/// This helps to avoid uncontrollable growth of `macro_rules!` scope chains,
79/// which usually grow linearly with the number of macro invocations
80/// in a module (including derives) and hurt performance.
81pub(crate) type MacroRulesScopeRef<'ra> = &'ra Cell<MacroRulesScope<'ra>>;
82
83/// Macro namespace is separated into two sub-namespaces, one for bang macros and
84/// one for attribute-like macros (attributes, derives).
85/// We ignore resolutions from one sub-namespace when searching names in scope for another.
86pub(crate) fn sub_namespace_match(
87    candidate: Option<MacroKind>,
88    requirement: Option<MacroKind>,
89) -> bool {
90    #[derive(PartialEq)]
91    enum SubNS {
92        Bang,
93        AttrLike,
94    }
95    let sub_ns = |kind| match kind {
96        MacroKind::Bang => SubNS::Bang,
97        MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
98    };
99    let candidate = candidate.map(sub_ns);
100    let requirement = requirement.map(sub_ns);
101    // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
102    candidate.is_none() || requirement.is_none() || candidate == requirement
103}
104
105// We don't want to format a path using pretty-printing,
106// `format!("{}", path)`, because that tries to insert
107// line-breaks and is slow.
108fn fast_print_path(path: &ast::Path) -> Symbol {
109    if let [segment] = path.segments.as_slice() {
110        segment.ident.name
111    } else {
112        let mut path_str = String::with_capacity(64);
113        for (i, segment) in path.segments.iter().enumerate() {
114            if i != 0 {
115                path_str.push_str("::");
116            }
117            if segment.ident.name != kw::PathRoot {
118                path_str.push_str(segment.ident.as_str())
119            }
120        }
121        Symbol::intern(&path_str)
122    }
123}
124
125pub(crate) fn registered_tools(tcx: TyCtxt<'_>, (): ()) -> RegisteredTools {
126    let (_, pre_configured_attrs) = &*tcx.crate_for_resolver(()).borrow();
127    registered_tools_ast(tcx.dcx(), pre_configured_attrs)
128}
129
130pub fn registered_tools_ast(
131    dcx: DiagCtxtHandle<'_>,
132    pre_configured_attrs: &[ast::Attribute],
133) -> RegisteredTools {
134    let mut registered_tools = RegisteredTools::default();
135    for attr in attr::filter_by_name(pre_configured_attrs, sym::register_tool) {
136        for meta_item_inner in attr.meta_item_list().unwrap_or_default() {
137            match meta_item_inner.ident() {
138                Some(ident) => {
139                    if let Some(old_ident) = registered_tools.replace(ident) {
140                        dcx.emit_err(errors::ToolWasAlreadyRegistered {
141                            span: ident.span,
142                            tool: ident,
143                            old_ident_span: old_ident.span,
144                        });
145                    }
146                }
147                None => {
148                    dcx.emit_err(errors::ToolOnlyAcceptsIdentifiers {
149                        span: meta_item_inner.span(),
150                        tool: sym::register_tool,
151                    });
152                }
153            }
154        }
155    }
156    // We implicitly add `rustfmt`, `clippy`, `diagnostic`, `miri` and `rust_analyzer` to known
157    // tools, but it's not an error to register them explicitly.
158    let predefined_tools =
159        [sym::clippy, sym::rustfmt, sym::diagnostic, sym::miri, sym::rust_analyzer];
160    registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
161    registered_tools
162}
163
164impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
165    fn next_node_id(&mut self) -> NodeId {
166        self.next_node_id()
167    }
168
169    fn invocation_parent(&self, id: LocalExpnId) -> LocalDefId {
170        self.invocation_parents[&id].parent_def
171    }
172
173    fn resolve_dollar_crates(&self) {
174        hygiene::update_dollar_crate_names(|ctxt| {
175            let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
176            match self.resolve_crate_root(ident).kind {
177                ModuleKind::Def(.., name) if let Some(name) = name => name,
178                _ => kw::Crate,
179            }
180        });
181    }
182
183    fn visit_ast_fragment_with_placeholders(
184        &mut self,
185        expansion: LocalExpnId,
186        fragment: &AstFragment,
187    ) {
188        // Integrate the new AST fragment into all the definition and module structures.
189        // We are inside the `expansion` now, but other parent scope components are still the same.
190        let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
191        let output_macro_rules_scope = self.build_reduced_graph(fragment, parent_scope);
192        self.output_macro_rules_scopes.insert(expansion, output_macro_rules_scope);
193
194        parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
195        if let Some(unexpanded_invocations) =
196            self.impl_unexpanded_invocations.get_mut(&self.invocation_parent(expansion))
197        {
198            unexpanded_invocations.remove(&expansion);
199        }
200    }
201
202    fn register_builtin_macro(&mut self, name: Symbol, ext: SyntaxExtensionKind) {
203        if self.builtin_macros.insert(name, ext).is_some() {
204            self.dcx().bug(format!("built-in macro `{name}` was already registered"));
205        }
206    }
207
208    // Create a new Expansion with a definition site of the provided module, or
209    // a fake empty `#[no_implicit_prelude]` module if no module is provided.
210    fn expansion_for_ast_pass(
211        &mut self,
212        call_site: Span,
213        pass: AstPass,
214        features: &[Symbol],
215        parent_module_id: Option<NodeId>,
216    ) -> LocalExpnId {
217        let parent_module =
218            parent_module_id.map(|module_id| self.local_def_id(module_id).to_def_id());
219        let expn_id = LocalExpnId::fresh(
220            ExpnData::allow_unstable(
221                ExpnKind::AstPass(pass),
222                call_site,
223                self.tcx.sess.edition(),
224                features.into(),
225                None,
226                parent_module,
227            ),
228            self.create_stable_hashing_context(),
229        );
230
231        let parent_scope =
232            parent_module.map_or(self.empty_module, |def_id| self.expect_module(def_id));
233        self.ast_transform_scopes.insert(expn_id, parent_scope);
234
235        expn_id
236    }
237
238    fn resolve_imports(&mut self) {
239        self.resolve_imports()
240    }
241
242    fn resolve_macro_invocation(
243        &mut self,
244        invoc: &Invocation,
245        eager_expansion_root: LocalExpnId,
246        force: bool,
247    ) -> Result<Arc<SyntaxExtension>, Indeterminate> {
248        let invoc_id = invoc.expansion_data.id;
249        let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
250            Some(parent_scope) => *parent_scope,
251            None => {
252                // If there's no entry in the table, then we are resolving an eagerly expanded
253                // macro, which should inherit its parent scope from its eager expansion root -
254                // the macro that requested this eager expansion.
255                let parent_scope = *self
256                    .invocation_parent_scopes
257                    .get(&eager_expansion_root)
258                    .expect("non-eager expansion without a parent scope");
259                self.invocation_parent_scopes.insert(invoc_id, parent_scope);
260                parent_scope
261            }
262        };
263
264        let (mut derives, mut inner_attr, mut deleg_impl) = (&[][..], false, None);
265        let (path, kind) = match invoc.kind {
266            InvocationKind::Attr { ref attr, derives: ref attr_derives, .. } => {
267                derives = self.arenas.alloc_ast_paths(attr_derives);
268                inner_attr = attr.style == ast::AttrStyle::Inner;
269                (&attr.get_normal_item().path, MacroKind::Attr)
270            }
271            InvocationKind::Bang { ref mac, .. } => (&mac.path, MacroKind::Bang),
272            InvocationKind::Derive { ref path, .. } => (path, MacroKind::Derive),
273            InvocationKind::GlobDelegation { ref item, .. } => {
274                let ast::AssocItemKind::DelegationMac(deleg) = &item.kind else { unreachable!() };
275                deleg_impl = Some(self.invocation_parent(invoc_id));
276                // It is sufficient to consider glob delegation a bang macro for now.
277                (&deleg.prefix, MacroKind::Bang)
278            }
279        };
280
281        // Derives are not included when `invocations` are collected, so we have to add them here.
282        let parent_scope = &ParentScope { derives, ..parent_scope };
283        let supports_macro_expansion = invoc.fragment_kind.supports_macro_expansion();
284        let node_id = invoc.expansion_data.lint_node_id;
285        // This is a heuristic, but it's good enough for the lint.
286        let looks_like_invoc_in_mod_inert_attr = self
287            .invocation_parents
288            .get(&invoc_id)
289            .or_else(|| self.invocation_parents.get(&eager_expansion_root))
290            .filter(|&&InvocationParent { parent_def: mod_def_id, in_attr, .. }| {
291                in_attr
292                    && invoc.fragment_kind == AstFragmentKind::Expr
293                    && self.tcx.def_kind(mod_def_id) == DefKind::Mod
294            })
295            .map(|&InvocationParent { parent_def: mod_def_id, .. }| mod_def_id);
296        let sugg_span = match &invoc.kind {
297            InvocationKind::Attr { item: Annotatable::Item(item), .. }
298                if !item.span.from_expansion() =>
299            {
300                Some(item.span.shrink_to_lo())
301            }
302            _ => None,
303        };
304        let (ext, res) = self.smart_resolve_macro_path(
305            path,
306            kind,
307            supports_macro_expansion,
308            inner_attr,
309            parent_scope,
310            node_id,
311            force,
312            deleg_impl,
313            looks_like_invoc_in_mod_inert_attr,
314            sugg_span,
315        )?;
316
317        let span = invoc.span();
318        let def_id = if deleg_impl.is_some() { None } else { res.opt_def_id() };
319        invoc_id.set_expn_data(
320            ext.expn_data(
321                parent_scope.expansion,
322                span,
323                fast_print_path(path),
324                def_id,
325                def_id.map(|def_id| self.macro_def_scope(def_id).nearest_parent_mod()),
326            ),
327            self.create_stable_hashing_context(),
328        );
329
330        Ok(ext)
331    }
332
333    fn record_macro_rule_usage(&mut self, id: NodeId, rule_i: usize) {
334        if let Some(rules) = self.unused_macro_rules.get_mut(&id) {
335            rules.remove(rule_i);
336        }
337    }
338
339    fn check_unused_macros(&mut self) {
340        for (_, &(node_id, ident)) in self.unused_macros.iter() {
341            self.lint_buffer.buffer_lint(
342                UNUSED_MACROS,
343                node_id,
344                ident.span,
345                BuiltinLintDiag::UnusedMacroDefinition(ident.name),
346            );
347            // Do not report unused individual rules if the entire macro is unused
348            self.unused_macro_rules.swap_remove(&node_id);
349        }
350
351        for (&node_id, unused_arms) in self.unused_macro_rules.iter() {
352            if unused_arms.is_empty() {
353                continue;
354            }
355            let def_id = self.local_def_id(node_id);
356            let m = &self.local_macro_map[&def_id];
357            let SyntaxExtensionKind::LegacyBang(ref ext) = m.ext.kind else {
358                continue;
359            };
360            for arm_i in unused_arms.iter() {
361                if let Some((ident, rule_span)) = ext.get_unused_rule(arm_i) {
362                    self.lint_buffer.buffer_lint(
363                        UNUSED_MACRO_RULES,
364                        node_id,
365                        rule_span,
366                        BuiltinLintDiag::MacroRuleNeverUsed(arm_i, ident.name),
367                    );
368                }
369            }
370        }
371    }
372
373    fn has_derive_copy(&self, expn_id: LocalExpnId) -> bool {
374        self.containers_deriving_copy.contains(&expn_id)
375    }
376
377    fn resolve_derives(
378        &mut self,
379        expn_id: LocalExpnId,
380        force: bool,
381        derive_paths: &dyn Fn() -> Vec<DeriveResolution>,
382    ) -> Result<(), Indeterminate> {
383        // Block expansion of the container until we resolve all derives in it.
384        // This is required for two reasons:
385        // - Derive helper attributes are in scope for the item to which the `#[derive]`
386        //   is applied, so they have to be produced by the container's expansion rather
387        //   than by individual derives.
388        // - Derives in the container need to know whether one of them is a built-in `Copy`.
389        // Temporarily take the data to avoid borrow checker conflicts.
390        let mut derive_data = mem::take(&mut self.derive_data);
391        let entry = derive_data.entry(expn_id).or_insert_with(|| DeriveData {
392            resolutions: derive_paths(),
393            helper_attrs: Vec::new(),
394            has_derive_copy: false,
395        });
396        let parent_scope = self.invocation_parent_scopes[&expn_id];
397        for (i, resolution) in entry.resolutions.iter_mut().enumerate() {
398            if resolution.exts.is_none() {
399                resolution.exts = Some(
400                    match self.resolve_macro_path(
401                        &resolution.path,
402                        Some(MacroKind::Derive),
403                        &parent_scope,
404                        true,
405                        force,
406                        None,
407                        None,
408                    ) {
409                        Ok((Some(ext), _)) => {
410                            if !ext.helper_attrs.is_empty() {
411                                let last_seg = resolution.path.segments.last().unwrap();
412                                let span = last_seg.ident.span.normalize_to_macros_2_0();
413                                entry.helper_attrs.extend(
414                                    ext.helper_attrs
415                                        .iter()
416                                        .map(|name| (i, Ident::new(*name, span))),
417                                );
418                            }
419                            entry.has_derive_copy |= ext.builtin_name == Some(sym::Copy);
420                            ext
421                        }
422                        Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
423                        Err(Determinacy::Undetermined) => {
424                            assert!(self.derive_data.is_empty());
425                            self.derive_data = derive_data;
426                            return Err(Indeterminate);
427                        }
428                    },
429                );
430            }
431        }
432        // Sort helpers in a stable way independent from the derive resolution order.
433        entry.helper_attrs.sort_by_key(|(i, _)| *i);
434        let helper_attrs = entry
435            .helper_attrs
436            .iter()
437            .map(|(_, ident)| {
438                let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
439                let binding = self.arenas.new_pub_res_binding(res, ident.span, expn_id);
440                (*ident, binding)
441            })
442            .collect();
443        self.helper_attrs.insert(expn_id, helper_attrs);
444        // Mark this derive as having `Copy` either if it has `Copy` itself or if its parent derive
445        // has `Copy`, to support cases like `#[derive(Clone, Copy)] #[derive(Debug)]`.
446        if entry.has_derive_copy || self.has_derive_copy(parent_scope.expansion) {
447            self.containers_deriving_copy.insert(expn_id);
448        }
449        assert!(self.derive_data.is_empty());
450        self.derive_data = derive_data;
451        Ok(())
452    }
453
454    fn take_derive_resolutions(&mut self, expn_id: LocalExpnId) -> Option<Vec<DeriveResolution>> {
455        self.derive_data.remove(&expn_id).map(|data| data.resolutions)
456    }
457
458    // The function that implements the resolution logic of `#[cfg_accessible(path)]`.
459    // Returns true if the path can certainly be resolved in one of three namespaces,
460    // returns false if the path certainly cannot be resolved in any of the three namespaces.
461    // Returns `Indeterminate` if we cannot give a certain answer yet.
462    fn cfg_accessible(
463        &mut self,
464        expn_id: LocalExpnId,
465        path: &ast::Path,
466    ) -> Result<bool, Indeterminate> {
467        self.path_accessible(expn_id, path, &[TypeNS, ValueNS, MacroNS])
468    }
469
470    fn macro_accessible(
471        &mut self,
472        expn_id: LocalExpnId,
473        path: &ast::Path,
474    ) -> Result<bool, Indeterminate> {
475        self.path_accessible(expn_id, path, &[MacroNS])
476    }
477
478    fn get_proc_macro_quoted_span(&self, krate: CrateNum, id: usize) -> Span {
479        self.cstore().get_proc_macro_quoted_span_untracked(krate, id, self.tcx.sess)
480    }
481
482    fn declare_proc_macro(&mut self, id: NodeId) {
483        self.proc_macros.push(self.local_def_id(id))
484    }
485
486    fn append_stripped_cfg_item(
487        &mut self,
488        parent_node: NodeId,
489        ident: Ident,
490        cfg: CfgEntry,
491        cfg_span: Span,
492    ) {
493        self.stripped_cfg_items.push(StrippedCfgItem {
494            parent_module: parent_node,
495            ident,
496            cfg: (cfg, cfg_span),
497        });
498    }
499
500    fn registered_tools(&self) -> &RegisteredTools {
501        self.registered_tools
502    }
503
504    fn register_glob_delegation(&mut self, invoc_id: LocalExpnId) {
505        self.glob_delegation_invoc_ids.insert(invoc_id);
506    }
507
508    fn glob_delegation_suffixes(
509        &mut self,
510        trait_def_id: DefId,
511        impl_def_id: LocalDefId,
512    ) -> Result<Vec<(Ident, Option<Ident>)>, Indeterminate> {
513        let target_trait = self.expect_module(trait_def_id);
514        if !target_trait.unexpanded_invocations.borrow().is_empty() {
515            return Err(Indeterminate);
516        }
517        // FIXME: Instead of waiting try generating all trait methods, and pruning
518        // the shadowed ones a bit later, e.g. when all macro expansion completes.
519        // Pros: expansion will be stuck less (but only in exotic cases), the implementation may be
520        // less hacky.
521        // Cons: More code is generated just to be deleted later, deleting already created `DefId`s
522        // may be nontrivial.
523        if let Some(unexpanded_invocations) = self.impl_unexpanded_invocations.get(&impl_def_id)
524            && !unexpanded_invocations.is_empty()
525        {
526            return Err(Indeterminate);
527        }
528
529        let mut idents = Vec::new();
530        target_trait.for_each_child(self, |this, ident, ns, _binding| {
531            // FIXME: Adjust hygiene for idents from globs, like for glob imports.
532            if let Some(overriding_keys) = this.impl_binding_keys.get(&impl_def_id)
533                && overriding_keys.contains(&BindingKey::new(ident, ns))
534            {
535                // The name is overridden, do not produce it from the glob delegation.
536            } else {
537                idents.push((ident, None));
538            }
539        });
540        Ok(idents)
541    }
542
543    fn insert_impl_trait_name(&mut self, id: NodeId, name: Symbol) {
544        self.impl_trait_names.insert(id, name);
545    }
546}
547
548impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
549    /// Resolve macro path with error reporting and recovery.
550    /// Uses dummy syntax extensions for unresolved macros or macros with unexpected resolutions
551    /// for better error recovery.
552    fn smart_resolve_macro_path(
553        &mut self,
554        path: &ast::Path,
555        kind: MacroKind,
556        supports_macro_expansion: SupportsMacroExpansion,
557        inner_attr: bool,
558        parent_scope: &ParentScope<'ra>,
559        node_id: NodeId,
560        force: bool,
561        deleg_impl: Option<LocalDefId>,
562        invoc_in_mod_inert_attr: Option<LocalDefId>,
563        suggestion_span: Option<Span>,
564    ) -> Result<(Arc<SyntaxExtension>, Res), Indeterminate> {
565        let (ext, res) = match self.resolve_macro_or_delegation_path(
566            path,
567            Some(kind),
568            parent_scope,
569            true,
570            force,
571            deleg_impl,
572            invoc_in_mod_inert_attr.map(|def_id| (def_id, node_id)),
573            None,
574            suggestion_span,
575        ) {
576            Ok((Some(ext), res)) => (ext, res),
577            Ok((None, res)) => (self.dummy_ext(kind), res),
578            Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
579            Err(Determinacy::Undetermined) => return Err(Indeterminate),
580        };
581
582        // Everything below is irrelevant to glob delegation, take a shortcut.
583        if deleg_impl.is_some() {
584            if !matches!(res, Res::Err | Res::Def(DefKind::Trait, _)) {
585                self.dcx().emit_err(MacroExpectedFound {
586                    span: path.span,
587                    expected: "trait",
588                    article: "a",
589                    found: res.descr(),
590                    macro_path: &pprust::path_to_string(path),
591                    remove_surrounding_derive: None,
592                    add_as_non_derive: None,
593                });
594                return Ok((self.dummy_ext(kind), Res::Err));
595            }
596
597            return Ok((ext, res));
598        }
599
600        // Report errors for the resolved macro.
601        for segment in &path.segments {
602            if let Some(args) = &segment.args {
603                self.dcx().emit_err(errors::GenericArgumentsInMacroPath { span: args.span() });
604            }
605            if kind == MacroKind::Attr && segment.ident.as_str().starts_with("rustc") {
606                self.dcx().emit_err(errors::AttributesStartingWithRustcAreReserved {
607                    span: segment.ident.span,
608                });
609            }
610        }
611
612        match res {
613            Res::Def(DefKind::Macro(_), def_id) => {
614                if let Some(def_id) = def_id.as_local() {
615                    self.unused_macros.swap_remove(&def_id);
616                    if self.proc_macro_stubs.contains(&def_id) {
617                        self.dcx().emit_err(errors::ProcMacroSameCrate {
618                            span: path.span,
619                            is_test: self.tcx.sess.is_test_crate(),
620                        });
621                    }
622                }
623            }
624            Res::NonMacroAttr(..) | Res::Err => {}
625            _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
626        };
627
628        self.check_stability_and_deprecation(&ext, path, node_id);
629
630        let unexpected_res = if ext.macro_kind() != kind {
631            Some((kind.article(), kind.descr_expected()))
632        } else if matches!(res, Res::Def(..)) {
633            match supports_macro_expansion {
634                SupportsMacroExpansion::No => Some(("a", "non-macro attribute")),
635                SupportsMacroExpansion::Yes { supports_inner_attrs } => {
636                    if inner_attr && !supports_inner_attrs {
637                        Some(("a", "non-macro inner attribute"))
638                    } else {
639                        None
640                    }
641                }
642            }
643        } else {
644            None
645        };
646        if let Some((article, expected)) = unexpected_res {
647            let path_str = pprust::path_to_string(path);
648
649            let mut err = MacroExpectedFound {
650                span: path.span,
651                expected,
652                article,
653                found: res.descr(),
654                macro_path: &path_str,
655                remove_surrounding_derive: None,
656                add_as_non_derive: None,
657            };
658
659            // Suggest moving the macro out of the derive() if the macro isn't Derive
660            if !path.span.from_expansion()
661                && kind == MacroKind::Derive
662                && ext.macro_kind() != MacroKind::Derive
663            {
664                err.remove_surrounding_derive = Some(RemoveSurroundingDerive { span: path.span });
665                err.add_as_non_derive = Some(AddAsNonDerive { macro_path: &path_str });
666            }
667
668            self.dcx().emit_err(err);
669
670            return Ok((self.dummy_ext(kind), Res::Err));
671        }
672
673        // We are trying to avoid reporting this error if other related errors were reported.
674        if res != Res::Err && inner_attr && !self.tcx.features().custom_inner_attributes() {
675            let is_macro = match res {
676                Res::Def(..) => true,
677                Res::NonMacroAttr(..) => false,
678                _ => unreachable!(),
679            };
680            let msg = if is_macro {
681                "inner macro attributes are unstable"
682            } else {
683                "custom inner attributes are unstable"
684            };
685            feature_err(&self.tcx.sess, sym::custom_inner_attributes, path.span, msg).emit();
686        }
687
688        if res == Res::NonMacroAttr(NonMacroAttrKind::Tool)
689            && let [namespace, attribute, ..] = &*path.segments
690            && namespace.ident.name == sym::diagnostic
691            && ![sym::on_unimplemented, sym::do_not_recommend].contains(&attribute.ident.name)
692        {
693            let typo_name = find_best_match_for_name(
694                &[sym::on_unimplemented, sym::do_not_recommend],
695                attribute.ident.name,
696                Some(5),
697            );
698
699            self.tcx.sess.psess.buffer_lint(
700                UNKNOWN_DIAGNOSTIC_ATTRIBUTES,
701                attribute.span(),
702                node_id,
703                BuiltinLintDiag::UnknownDiagnosticAttribute { span: attribute.span(), typo_name },
704            );
705        }
706
707        Ok((ext, res))
708    }
709
710    pub(crate) fn resolve_macro_path(
711        &mut self,
712        path: &ast::Path,
713        kind: Option<MacroKind>,
714        parent_scope: &ParentScope<'ra>,
715        trace: bool,
716        force: bool,
717        ignore_import: Option<Import<'ra>>,
718        suggestion_span: Option<Span>,
719    ) -> Result<(Option<Arc<SyntaxExtension>>, Res), Determinacy> {
720        self.resolve_macro_or_delegation_path(
721            path,
722            kind,
723            parent_scope,
724            trace,
725            force,
726            None,
727            None,
728            ignore_import,
729            suggestion_span,
730        )
731    }
732
733    fn resolve_macro_or_delegation_path(
734        &mut self,
735        ast_path: &ast::Path,
736        kind: Option<MacroKind>,
737        parent_scope: &ParentScope<'ra>,
738        trace: bool,
739        force: bool,
740        deleg_impl: Option<LocalDefId>,
741        invoc_in_mod_inert_attr: Option<(LocalDefId, NodeId)>,
742        ignore_import: Option<Import<'ra>>,
743        suggestion_span: Option<Span>,
744    ) -> Result<(Option<Arc<SyntaxExtension>>, Res), Determinacy> {
745        let path_span = ast_path.span;
746        let mut path = Segment::from_path(ast_path);
747
748        // Possibly apply the macro helper hack
749        if deleg_impl.is_none()
750            && kind == Some(MacroKind::Bang)
751            && let [segment] = path.as_slice()
752            && segment.ident.span.ctxt().outer_expn_data().local_inner_macros
753        {
754            let root = Ident::new(kw::DollarCrate, segment.ident.span);
755            path.insert(0, Segment::from_ident(root));
756        }
757
758        let res = if deleg_impl.is_some() || path.len() > 1 {
759            let ns = if deleg_impl.is_some() { TypeNS } else { MacroNS };
760            let res = match self.maybe_resolve_path(&path, Some(ns), parent_scope, ignore_import) {
761                PathResult::NonModule(path_res) if let Some(res) = path_res.full_res() => Ok(res),
762                PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
763                PathResult::NonModule(..)
764                | PathResult::Indeterminate
765                | PathResult::Failed { .. } => Err(Determinacy::Determined),
766                PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
767                    Ok(module.res().unwrap())
768                }
769                PathResult::Module(..) => unreachable!(),
770            };
771
772            if trace {
773                let kind = kind.expect("macro kind must be specified if tracing is enabled");
774                self.multi_segment_macro_resolutions.push((
775                    path,
776                    path_span,
777                    kind,
778                    *parent_scope,
779                    res.ok(),
780                    ns,
781                ));
782            }
783
784            self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
785            res
786        } else {
787            let scope_set = kind.map_or(ScopeSet::All(MacroNS), ScopeSet::Macro);
788            let binding = self.early_resolve_ident_in_lexical_scope(
789                path[0].ident,
790                scope_set,
791                parent_scope,
792                None,
793                force,
794                None,
795                None,
796            );
797            if let Err(Determinacy::Undetermined) = binding {
798                return Err(Determinacy::Undetermined);
799            }
800
801            if trace {
802                let kind = kind.expect("macro kind must be specified if tracing is enabled");
803                self.single_segment_macro_resolutions.push((
804                    path[0].ident,
805                    kind,
806                    *parent_scope,
807                    binding.ok(),
808                    suggestion_span,
809                ));
810            }
811
812            let res = binding.map(|binding| binding.res());
813            self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
814            self.report_out_of_scope_macro_calls(
815                ast_path,
816                parent_scope,
817                invoc_in_mod_inert_attr,
818                binding.ok(),
819            );
820            res
821        };
822
823        let res = res?;
824        let ext = match deleg_impl {
825            Some(impl_def_id) => match res {
826                def::Res::Def(DefKind::Trait, def_id) => {
827                    let edition = self.tcx.sess.edition();
828                    Some(Arc::new(SyntaxExtension::glob_delegation(def_id, impl_def_id, edition)))
829                }
830                _ => None,
831            },
832            None => self.get_macro(res).map(|macro_data| Arc::clone(&macro_data.ext)),
833        };
834        Ok((ext, res))
835    }
836
837    pub(crate) fn finalize_macro_resolutions(&mut self, krate: &Crate) {
838        let check_consistency = |this: &Self,
839                                 path: &[Segment],
840                                 span,
841                                 kind: MacroKind,
842                                 initial_res: Option<Res>,
843                                 res: Res| {
844            if let Some(initial_res) = initial_res {
845                if res != initial_res {
846                    // Make sure compilation does not succeed if preferred macro resolution
847                    // has changed after the macro had been expanded. In theory all such
848                    // situations should be reported as errors, so this is a bug.
849                    this.dcx().span_delayed_bug(span, "inconsistent resolution for a macro");
850                }
851            } else if this.tcx.dcx().has_errors().is_none() && this.privacy_errors.is_empty() {
852                // It's possible that the macro was unresolved (indeterminate) and silently
853                // expanded into a dummy fragment for recovery during expansion.
854                // Now, post-expansion, the resolution may succeed, but we can't change the
855                // past and need to report an error.
856                // However, non-speculative `resolve_path` can successfully return private items
857                // even if speculative `resolve_path` returned nothing previously, so we skip this
858                // less informative error if no other error is reported elsewhere.
859
860                let err = this.dcx().create_err(CannotDetermineMacroResolution {
861                    span,
862                    kind: kind.descr(),
863                    path: Segment::names_to_string(path),
864                });
865                err.stash(span, StashKey::UndeterminedMacroResolution);
866            }
867        };
868
869        let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
870        for (mut path, path_span, kind, parent_scope, initial_res, ns) in macro_resolutions {
871            // FIXME: Path resolution will ICE if segment IDs present.
872            for seg in &mut path {
873                seg.id = None;
874            }
875            match self.resolve_path(
876                &path,
877                Some(ns),
878                &parent_scope,
879                Some(Finalize::new(ast::CRATE_NODE_ID, path_span)),
880                None,
881                None,
882            ) {
883                PathResult::NonModule(path_res) if let Some(res) = path_res.full_res() => {
884                    check_consistency(self, &path, path_span, kind, initial_res, res)
885                }
886                // This may be a trait for glob delegation expansions.
887                PathResult::Module(ModuleOrUniformRoot::Module(module)) => check_consistency(
888                    self,
889                    &path,
890                    path_span,
891                    kind,
892                    initial_res,
893                    module.res().unwrap(),
894                ),
895                path_res @ (PathResult::NonModule(..) | PathResult::Failed { .. }) => {
896                    let mut suggestion = None;
897                    let (span, label, module, segment) =
898                        if let PathResult::Failed { span, label, module, segment_name, .. } =
899                            path_res
900                        {
901                            // try to suggest if it's not a macro, maybe a function
902                            if let PathResult::NonModule(partial_res) =
903                                self.maybe_resolve_path(&path, Some(ValueNS), &parent_scope, None)
904                                && partial_res.unresolved_segments() == 0
905                            {
906                                let sm = self.tcx.sess.source_map();
907                                let exclamation_span = sm.next_point(span);
908                                suggestion = Some((
909                                    vec![(exclamation_span, "".to_string())],
910                                    format!(
911                                        "{} is not a macro, but a {}, try to remove `!`",
912                                        Segment::names_to_string(&path),
913                                        partial_res.base_res().descr()
914                                    ),
915                                    Applicability::MaybeIncorrect,
916                                ));
917                            }
918                            (span, label, module, segment_name)
919                        } else {
920                            (
921                                path_span,
922                                format!(
923                                    "partially resolved path in {} {}",
924                                    kind.article(),
925                                    kind.descr()
926                                ),
927                                None,
928                                path.last().map(|segment| segment.ident.name).unwrap(),
929                            )
930                        };
931                    self.report_error(
932                        span,
933                        ResolutionError::FailedToResolve {
934                            segment: Some(segment),
935                            label,
936                            suggestion,
937                            module,
938                        },
939                    );
940                }
941                PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
942            }
943        }
944
945        let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
946        for (ident, kind, parent_scope, initial_binding, sugg_span) in macro_resolutions {
947            match self.early_resolve_ident_in_lexical_scope(
948                ident,
949                ScopeSet::Macro(kind),
950                &parent_scope,
951                Some(Finalize::new(ast::CRATE_NODE_ID, ident.span)),
952                true,
953                None,
954                None,
955            ) {
956                Ok(binding) => {
957                    let initial_res = initial_binding.map(|initial_binding| {
958                        self.record_use(ident, initial_binding, Used::Other);
959                        initial_binding.res()
960                    });
961                    let res = binding.res();
962                    let seg = Segment::from_ident(ident);
963                    check_consistency(self, &[seg], ident.span, kind, initial_res, res);
964                    if res == Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat) {
965                        let node_id = self
966                            .invocation_parents
967                            .get(&parent_scope.expansion)
968                            .map_or(ast::CRATE_NODE_ID, |parent| {
969                                self.def_id_to_node_id(parent.parent_def)
970                            });
971                        self.lint_buffer.buffer_lint(
972                            LEGACY_DERIVE_HELPERS,
973                            node_id,
974                            ident.span,
975                            BuiltinLintDiag::LegacyDeriveHelpers(binding.span),
976                        );
977                    }
978                }
979                Err(..) => {
980                    let expected = kind.descr_expected();
981
982                    let mut err = self.dcx().create_err(CannotFindIdentInThisScope {
983                        span: ident.span,
984                        expected,
985                        ident,
986                    });
987                    self.unresolved_macro_suggestions(
988                        &mut err,
989                        kind,
990                        &parent_scope,
991                        ident,
992                        krate,
993                        sugg_span,
994                    );
995                    err.emit();
996                }
997            }
998        }
999
1000        let builtin_attrs = mem::take(&mut self.builtin_attrs);
1001        for (ident, parent_scope) in builtin_attrs {
1002            let _ = self.early_resolve_ident_in_lexical_scope(
1003                ident,
1004                ScopeSet::Macro(MacroKind::Attr),
1005                &parent_scope,
1006                Some(Finalize::new(ast::CRATE_NODE_ID, ident.span)),
1007                true,
1008                None,
1009                None,
1010            );
1011        }
1012    }
1013
1014    fn check_stability_and_deprecation(
1015        &mut self,
1016        ext: &SyntaxExtension,
1017        path: &ast::Path,
1018        node_id: NodeId,
1019    ) {
1020        let span = path.span;
1021        if let Some(stability) = &ext.stability {
1022            if let StabilityLevel::Unstable { reason, issue, is_soft, implied_by, .. } =
1023                stability.level
1024            {
1025                let feature = stability.feature;
1026
1027                let is_allowed =
1028                    |feature| self.tcx.features().enabled(feature) || span.allows_unstable(feature);
1029                let allowed_by_implication = implied_by.is_some_and(|feature| is_allowed(feature));
1030                if !is_allowed(feature) && !allowed_by_implication {
1031                    let lint_buffer = &mut self.lint_buffer;
1032                    let soft_handler = |lint, span, msg: String| {
1033                        lint_buffer.buffer_lint(
1034                            lint,
1035                            node_id,
1036                            span,
1037                            BuiltinLintDiag::UnstableFeature(
1038                                // FIXME make this translatable
1039                                msg.into(),
1040                            ),
1041                        )
1042                    };
1043                    stability::report_unstable(
1044                        self.tcx.sess,
1045                        feature,
1046                        reason.to_opt_reason(),
1047                        issue,
1048                        None,
1049                        is_soft,
1050                        span,
1051                        soft_handler,
1052                        stability::UnstableKind::Regular,
1053                    );
1054                }
1055            }
1056        }
1057        if let Some(depr) = &ext.deprecation {
1058            let path = pprust::path_to_string(path);
1059            stability::early_report_macro_deprecation(
1060                &mut self.lint_buffer,
1061                depr,
1062                span,
1063                node_id,
1064                path,
1065            );
1066        }
1067    }
1068
1069    fn prohibit_imported_non_macro_attrs(
1070        &self,
1071        binding: Option<NameBinding<'ra>>,
1072        res: Option<Res>,
1073        span: Span,
1074    ) {
1075        if let Some(Res::NonMacroAttr(kind)) = res {
1076            if kind != NonMacroAttrKind::Tool && binding.is_none_or(|b| b.is_import()) {
1077                let binding_span = binding.map(|binding| binding.span);
1078                self.dcx().emit_err(errors::CannotUseThroughAnImport {
1079                    span,
1080                    article: kind.article(),
1081                    descr: kind.descr(),
1082                    binding_span,
1083                });
1084            }
1085        }
1086    }
1087
1088    fn report_out_of_scope_macro_calls(
1089        &mut self,
1090        path: &ast::Path,
1091        parent_scope: &ParentScope<'ra>,
1092        invoc_in_mod_inert_attr: Option<(LocalDefId, NodeId)>,
1093        binding: Option<NameBinding<'ra>>,
1094    ) {
1095        if let Some((mod_def_id, node_id)) = invoc_in_mod_inert_attr
1096            && let Some(binding) = binding
1097            // This is a `macro_rules` itself, not some import.
1098            && let NameBindingKind::Res(res) = binding.kind
1099            && let Res::Def(DefKind::Macro(MacroKind::Bang), def_id) = res
1100            // And the `macro_rules` is defined inside the attribute's module,
1101            // so it cannot be in scope unless imported.
1102            && self.tcx.is_descendant_of(def_id, mod_def_id.to_def_id())
1103        {
1104            // Try to resolve our ident ignoring `macro_rules` scopes.
1105            // If such resolution is successful and gives the same result
1106            // (e.g. if the macro is re-imported), then silence the lint.
1107            let no_macro_rules = self.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty);
1108            let fallback_binding = self.early_resolve_ident_in_lexical_scope(
1109                path.segments[0].ident,
1110                ScopeSet::Macro(MacroKind::Bang),
1111                &ParentScope { macro_rules: no_macro_rules, ..*parent_scope },
1112                None,
1113                false,
1114                None,
1115                None,
1116            );
1117            if fallback_binding.ok().and_then(|b| b.res().opt_def_id()) != Some(def_id) {
1118                let location = match parent_scope.module.kind {
1119                    ModuleKind::Def(kind, def_id, name) => {
1120                        if let Some(name) = name {
1121                            format!("{} `{name}`", kind.descr(def_id))
1122                        } else {
1123                            "the crate root".to_string()
1124                        }
1125                    }
1126                    ModuleKind::Block => "this scope".to_string(),
1127                };
1128                self.tcx.sess.psess.buffer_lint(
1129                    OUT_OF_SCOPE_MACRO_CALLS,
1130                    path.span,
1131                    node_id,
1132                    BuiltinLintDiag::OutOfScopeMacroCalls {
1133                        span: path.span,
1134                        path: pprust::path_to_string(path),
1135                        location,
1136                    },
1137                );
1138            }
1139        }
1140    }
1141
1142    pub(crate) fn check_reserved_macro_name(&self, ident: Ident, res: Res) {
1143        // Reserve some names that are not quite covered by the general check
1144        // performed on `Resolver::builtin_attrs`.
1145        if ident.name == sym::cfg || ident.name == sym::cfg_attr {
1146            let macro_kind = self.get_macro(res).map(|macro_data| macro_data.ext.macro_kind());
1147            if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
1148                self.dcx()
1149                    .emit_err(errors::NameReservedInAttributeNamespace { span: ident.span, ident });
1150            }
1151        }
1152    }
1153
1154    /// Compile the macro into a `SyntaxExtension` and its rule spans.
1155    ///
1156    /// Possibly replace its expander to a pre-defined one for built-in macros.
1157    pub(crate) fn compile_macro(
1158        &self,
1159        macro_def: &ast::MacroDef,
1160        ident: Ident,
1161        attrs: &[rustc_hir::Attribute],
1162        span: Span,
1163        node_id: NodeId,
1164        edition: Edition,
1165    ) -> MacroData {
1166        let (mut ext, mut nrules) = compile_declarative_macro(
1167            self.tcx.sess,
1168            self.tcx.features(),
1169            macro_def,
1170            ident,
1171            attrs,
1172            span,
1173            node_id,
1174            edition,
1175        );
1176
1177        if let Some(builtin_name) = ext.builtin_name {
1178            // The macro was marked with `#[rustc_builtin_macro]`.
1179            if let Some(builtin_ext_kind) = self.builtin_macros.get(&builtin_name) {
1180                // The macro is a built-in, replace its expander function
1181                // while still taking everything else from the source code.
1182                ext.kind = builtin_ext_kind.clone();
1183                nrules = 0;
1184            } else {
1185                self.dcx().emit_err(errors::CannotFindBuiltinMacroWithName { span, ident });
1186            }
1187        }
1188
1189        MacroData { ext: Arc::new(ext), nrules, macro_rules: macro_def.macro_rules }
1190    }
1191
1192    fn path_accessible(
1193        &mut self,
1194        expn_id: LocalExpnId,
1195        path: &ast::Path,
1196        namespaces: &[Namespace],
1197    ) -> Result<bool, Indeterminate> {
1198        let span = path.span;
1199        let path = &Segment::from_path(path);
1200        let parent_scope = self.invocation_parent_scopes[&expn_id];
1201
1202        let mut indeterminate = false;
1203        for ns in namespaces {
1204            match self.maybe_resolve_path(path, Some(*ns), &parent_scope, None) {
1205                PathResult::Module(ModuleOrUniformRoot::Module(_)) => return Ok(true),
1206                PathResult::NonModule(partial_res) if partial_res.unresolved_segments() == 0 => {
1207                    return Ok(true);
1208                }
1209                PathResult::NonModule(..) |
1210                // HACK(Urgau): This shouldn't be necessary
1211                PathResult::Failed { is_error_from_last_segment: false, .. } => {
1212                    self.dcx()
1213                        .emit_err(errors::CfgAccessibleUnsure { span });
1214
1215                    // If we get a partially resolved NonModule in one namespace, we should get the
1216                    // same result in any other namespaces, so we can return early.
1217                    return Ok(false);
1218                }
1219                PathResult::Indeterminate => indeterminate = true,
1220                // We can only be sure that a path doesn't exist after having tested all the
1221                // possibilities, only at that time we can return false.
1222                PathResult::Failed { .. } => {}
1223                PathResult::Module(_) => panic!("unexpected path resolution"),
1224            }
1225        }
1226
1227        if indeterminate {
1228            return Err(Indeterminate);
1229        }
1230
1231        Ok(false)
1232    }
1233}