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::{AmbiguityError, AmbiguityKind, AmbiguityErrorMisc, Determinacy};
5 use crate::{CrateLint, Resolver, ResolutionError, Scope, ScopeSet, ParentScope, Weak};
6 use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment, ToNameBinding};
7 use crate::Namespace::*;
8 use crate::resolve_imports::ImportResolver;
9 use rustc::hir::def::{self, DefKind, NonMacroAttrKind};
10 use rustc::hir::def_id;
11 use rustc::middle::stability;
12 use rustc::session::Session;
13 use rustc::util::nodemap::FxHashSet;
14 use rustc::{ty, lint, span_bug};
15 use syntax::ast::{self, NodeId, Ident};
16 use syntax::attr::{self, StabilityLevel};
17 use syntax::edition::Edition;
18 use syntax::feature_gate::{emit_feature_err, is_builtin_attr_name};
19 use syntax::feature_gate::GateIssue;
20 use syntax::print::pprust;
21 use syntax::symbol::{Symbol, kw, sym};
22 use syntax_expand::base::{self, InvocationRes, Indeterminate};
23 use syntax_expand::base::SyntaxExtension;
24 use syntax_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
25 use syntax_expand::compile_declarative_macro;
26 use syntax_pos::hygiene::{self, ExpnId, ExpnData, ExpnKind};
27 use syntax_pos::{Span, DUMMY_SP};
30 use rustc_data_structures::sync::Lrc;
31 use syntax_pos::hygiene::{MacroKind, AstPass};
33 type Res = def::Res<NodeId>;
35 /// Binding produced by a `macro_rules` item.
36 /// Not modularized, can shadow previous legacy bindings, etc.
38 pub struct LegacyBinding<'a> {
39 crate binding: &'a NameBinding<'a>,
40 /// Legacy scope into which the `macro_rules` item was planted.
41 crate parent_legacy_scope: LegacyScope<'a>,
45 /// The scope introduced by a `macro_rules!` macro.
46 /// This starts at the macro's definition and ends at the end of the macro's parent
47 /// module (named or unnamed), or even further if it escapes with `#[macro_use]`.
48 /// Some macro invocations need to introduce legacy scopes too because they
49 /// can potentially expand into macro definitions.
50 #[derive(Copy, Clone, Debug)]
51 pub enum LegacyScope<'a> {
52 /// Empty "root" scope at the crate start containing no names.
54 /// The scope introduced by a `macro_rules!` macro definition.
55 Binding(&'a LegacyBinding<'a>),
56 /// The scope introduced by a macro invocation that can potentially
57 /// create a `macro_rules!` macro definition.
61 // Macro namespace is separated into two sub-namespaces, one for bang macros and
62 // one for attribute-like macros (attributes, derives).
63 // We ignore resolutions from one sub-namespace when searching names in scope for another.
64 fn sub_namespace_match(candidate: Option<MacroKind>, requirement: Option<MacroKind>) -> bool {
66 enum SubNS { Bang, AttrLike }
67 let sub_ns = |kind| match kind {
68 MacroKind::Bang => SubNS::Bang,
69 MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
71 let candidate = candidate.map(sub_ns);
72 let requirement = requirement.map(sub_ns);
73 // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
74 candidate.is_none() || requirement.is_none() || candidate == requirement
77 // We don't want to format a path using pretty-printing,
78 // `format!("{}", path)`, because that tries to insert
79 // line-breaks and is slow.
80 fn fast_print_path(path: &ast::Path) -> Symbol {
81 if path.segments.len() == 1 {
82 return path.segments[0].ident.name
84 let mut path_str = String::with_capacity(64);
85 for (i, segment) in path.segments.iter().enumerate() {
87 path_str.push_str("::");
89 if segment.ident.name != kw::PathRoot {
90 path_str.push_str(&segment.ident.as_str())
93 Symbol::intern(&path_str)
99 attrs: &[ast::Attribute],
102 ) -> FxHashSet<Ident> {
103 let mut registered = FxHashSet::default();
104 for attr in attr::filter_by_name(attrs, attr_name) {
105 for nested_meta in attr.meta_item_list().unwrap_or_default() {
106 match nested_meta.ident() {
107 Some(ident) => if let Some(old_ident) = registered.replace(ident) {
108 let msg = format!("{} `{}` was already registered", descr, ident);
109 sess.struct_span_err(ident.span, &msg)
110 .span_label(old_ident.span, "already registered here").emit();
113 let msg = format!("`{}` only accepts identifiers", attr_name);
114 let span = nested_meta.span();
115 sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
123 crate fn registered_attrs_and_tools(
125 attrs: &[ast::Attribute],
126 ) -> (FxHashSet<Ident>, FxHashSet<Ident>) {
127 let registered_attrs = registered_idents(sess, attrs, sym::register_attr, "attribute");
128 let mut registered_tools = registered_idents(sess, attrs, sym::register_tool, "tool");
129 // We implicitly add `rustfmt` and `clippy` to known tools,
130 // but it's not an error to register them explicitly.
131 let predefined_tools = [sym::clippy, sym::rustfmt];
132 registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
133 (registered_attrs, registered_tools)
136 impl<'a> base::Resolver for Resolver<'a> {
137 fn next_node_id(&mut self) -> NodeId {
138 self.session.next_node_id()
141 fn resolve_dollar_crates(&mut self) {
142 hygiene::update_dollar_crate_names(|ctxt| {
143 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
144 match self.resolve_crate_root(ident).kind {
145 ModuleKind::Def(.., name) if name != kw::Invalid => name,
151 fn visit_ast_fragment_with_placeholders(&mut self, expansion: ExpnId, fragment: &AstFragment) {
152 // Integrate the new AST fragment into all the definition and module structures.
153 // We are inside the `expansion` now, but other parent scope components are still the same.
154 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
155 let output_legacy_scope = self.build_reduced_graph(fragment, parent_scope);
156 self.output_legacy_scopes.insert(expansion, output_legacy_scope);
158 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
161 fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension) {
162 if self.builtin_macros.insert(ident.name, ext).is_some() {
163 self.session.span_err(ident.span,
164 &format!("built-in macro `{}` was already defined", ident));
168 // Create a new Expansion with a definition site of the provided module, or
169 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
170 fn expansion_for_ast_pass(
175 parent_module_id: Option<NodeId>,
177 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
178 ExpnKind::AstPass(pass),
180 self.session.edition(),
184 let parent_scope = if let Some(module_id) = parent_module_id {
185 let parent_def_id = self.definitions.local_def_id(module_id);
186 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id);
187 self.module_map[&parent_def_id]
189 self.definitions.add_parent_module_of_macro_def(
191 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
195 self.ast_transform_scopes.insert(expn_id, parent_scope);
199 fn resolve_imports(&mut self) {
200 ImportResolver { r: self }.resolve_imports()
203 fn resolve_macro_invocation(
204 &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
205 ) -> Result<InvocationRes, Indeterminate> {
206 let invoc_id = invoc.expansion_data.id;
207 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
208 Some(parent_scope) => *parent_scope,
210 // If there's no entry in the table, then we are resolving an eagerly expanded
211 // macro, which should inherit its parent scope from its eager expansion root -
212 // the macro that requested this eager expansion.
213 let parent_scope = *self.invocation_parent_scopes.get(&eager_expansion_root)
214 .expect("non-eager expansion without a parent scope");
215 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
220 let (path, kind, derives, after_derive) = match invoc.kind {
221 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
222 (&attr.get_normal_item().path,
224 self.arenas.alloc_ast_paths(derives),
226 InvocationKind::Bang { ref mac, .. } =>
227 (&mac.path, MacroKind::Bang, &[][..], false),
228 InvocationKind::Derive { ref path, .. } =>
229 (path, MacroKind::Derive, &[][..], false),
230 InvocationKind::DeriveContainer { ref derives, .. } => {
231 // Block expansion of the container until we resolve all derives in it.
232 // This is required for two reasons:
233 // - Derive helper attributes are in scope for the item to which the `#[derive]`
234 // is applied, so they have to be produced by the container's expansion rather
235 // than by individual derives.
236 // - Derives in the container need to know whether one of them is a built-in `Copy`.
237 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
238 let mut exts = Vec::new();
239 for path in derives {
240 exts.push(match self.resolve_macro_path(
241 path, Some(MacroKind::Derive), &parent_scope, true, force
243 Ok((Some(ext), _)) => ext,
244 Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
245 Err(Determinacy::Undetermined) => return Err(Indeterminate),
248 return Ok(InvocationRes::DeriveContainer(exts));
252 // Derives are not included when `invocations` are collected, so we have to add them here.
253 let parent_scope = &ParentScope { derives, ..parent_scope };
254 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
256 let span = invoc.span();
257 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
259 if let Res::Def(_, def_id) = res {
261 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
263 self.macro_defs.insert(invoc_id, def_id);
264 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
265 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
268 match invoc.fragment_kind {
269 AstFragmentKind::Arms
270 | AstFragmentKind::Fields
271 | AstFragmentKind::FieldPats
272 | AstFragmentKind::GenericParams
273 | AstFragmentKind::Params
274 | AstFragmentKind::StructFields
275 | AstFragmentKind::Variants =>
277 if let Res::Def(..) = res {
278 self.session.span_err(
280 &format!("expected an inert attribute, found {} {}",
281 res.article(), res.descr()),
283 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
289 Ok(InvocationRes::Single(ext))
292 fn check_unused_macros(&mut self) {
293 for (&node_id, &span) in self.unused_macros.iter() {
294 self.lint_buffer.buffer_lint(
295 lint::builtin::UNUSED_MACROS, node_id, span, "unused macro definition"
300 fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
301 self.containers_deriving_copy.contains(&expn_id)
304 fn add_derive_copy(&mut self, expn_id: ExpnId) {
305 self.containers_deriving_copy.insert(expn_id);
309 impl<'a> Resolver<'a> {
310 /// Resolve macro path with error reporting and recovery.
311 fn smart_resolve_macro_path(
315 parent_scope: &ParentScope<'a>,
317 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
318 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope,
320 Ok((Some(ext), res)) => (ext, res),
321 // Use dummy syntax extensions for unresolved macros for better recovery.
322 Ok((None, res)) => (self.dummy_ext(kind), res),
323 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
324 Err(Determinacy::Undetermined) => return Err(Indeterminate),
327 // Report errors and enforce feature gates for the resolved macro.
328 let features = self.session.features_untracked();
329 for segment in &path.segments {
330 if let Some(args) = &segment.args {
331 self.session.span_err(args.span(), "generic arguments in macro path");
333 if kind == MacroKind::Attr && !features.rustc_attrs &&
334 segment.ident.as_str().starts_with("rustc") {
336 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
338 &self.session.parse_sess,
348 Res::Def(DefKind::Macro(_), def_id) => {
349 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
350 self.unused_macros.remove(&node_id);
351 if self.proc_macro_stubs.contains(&node_id) {
352 self.session.span_err(
354 "can't use a procedural macro from the same crate that defines it",
359 Res::NonMacroAttr(..) | Res::Err => {}
360 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
363 self.check_stability_and_deprecation(&ext, path);
365 Ok(if ext.macro_kind() != kind {
366 let expected = kind.descr_expected();
367 let path_str = pprust::path_to_string(path);
368 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
369 self.session.struct_span_err(path.span, &msg)
370 .span_label(path.span, format!("not {} {}", kind.article(), expected))
372 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
373 (self.dummy_ext(kind), Res::Err)
379 pub fn resolve_macro_path(
382 kind: Option<MacroKind>,
383 parent_scope: &ParentScope<'a>,
386 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
387 let path_span = path.span;
388 let mut path = Segment::from_path(path);
390 // Possibly apply the macro helper hack
391 if kind == Some(MacroKind::Bang) && path.len() == 1 &&
392 path[0].ident.span.ctxt().outer_expn_data().local_inner_macros {
393 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
394 path.insert(0, Segment::from_ident(root));
397 let res = if path.len() > 1 {
398 let res = match self.resolve_path(&path, Some(MacroNS), parent_scope,
399 false, path_span, CrateLint::No) {
400 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
401 Ok(path_res.base_res())
403 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
404 PathResult::NonModule(..)
405 | PathResult::Indeterminate
406 | PathResult::Failed { .. } => Err(Determinacy::Determined),
407 PathResult::Module(..) => unreachable!(),
411 let kind = kind.expect("macro kind must be specified if tracing is enabled");
412 self.multi_segment_macro_resolutions
413 .push((path, path_span, kind, *parent_scope, res.ok()));
416 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
419 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
420 let binding = self.early_resolve_ident_in_lexical_scope(
421 path[0].ident, scope_set, parent_scope, false, force, path_span
423 if let Err(Determinacy::Undetermined) = binding {
424 return Err(Determinacy::Undetermined);
428 let kind = kind.expect("macro kind must be specified if tracing is enabled");
429 self.single_segment_macro_resolutions
430 .push((path[0].ident, kind, *parent_scope, binding.ok()));
433 let res = binding.map(|binding| binding.res());
434 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
438 res.map(|res| (self.get_macro(res), res))
441 // Resolve an identifier in lexical scope.
442 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
443 // expansion and import resolution (perhaps they can be merged in the future).
444 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
445 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
446 crate fn early_resolve_ident_in_lexical_scope(
450 parent_scope: &ParentScope<'a>,
454 ) -> Result<&'a NameBinding<'a>, Determinacy> {
455 bitflags::bitflags! {
457 const MACRO_RULES = 1 << 0;
458 const MODULE = 1 << 1;
459 const PRELUDE = 1 << 2;
460 const MISC_SUGGEST_CRATE = 1 << 3;
461 const MISC_SUGGEST_SELF = 1 << 4;
462 const MISC_FROM_PRELUDE = 1 << 5;
466 assert!(force || !record_used); // `record_used` implies `force`
468 // Make sure `self`, `super` etc produce an error when passed to here.
469 if orig_ident.is_path_segment_keyword() {
470 return Err(Determinacy::Determined);
473 let (ns, macro_kind, is_import) = match scope_set {
474 ScopeSet::All(ns, is_import) => (ns, None, is_import),
475 ScopeSet::AbsolutePath(ns) => (ns, None, false),
476 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
479 // This is *the* result, resolution from the scope closest to the resolved identifier.
480 // However, sometimes this result is "weak" because it comes from a glob import or
481 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
482 // mod m { ... } // solution in outer scope
484 // use prefix::*; // imports another `m` - innermost solution
485 // // weak, cannot shadow the outer `m`, need to report ambiguity error
488 // So we have to save the innermost solution and continue searching in outer scopes
489 // to detect potential ambiguities.
490 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
491 let mut determinacy = Determinacy::Determined;
493 // Go through all the scopes and try to resolve the name.
494 let break_result = self.visit_scopes(scope_set, parent_scope, orig_ident,
495 |this, scope, use_prelude, ident| {
496 let result = match scope {
497 Scope::DeriveHelpers => {
498 let mut result = Err(Determinacy::Determined);
499 for derive in parent_scope.derives {
500 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
501 match this.resolve_macro_path(derive, Some(MacroKind::Derive),
502 parent_scope, true, force) {
503 Ok((Some(ext), _)) => if ext.helper_attrs.contains(&ident.name) {
504 let binding = (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
505 ty::Visibility::Public, derive.span, ExpnId::root())
506 .to_name_binding(this.arenas);
507 result = Ok((binding, Flags::empty()));
510 Ok(_) | Err(Determinacy::Determined) => {}
511 Err(Determinacy::Undetermined) =>
512 result = Err(Determinacy::Undetermined),
517 Scope::MacroRules(legacy_scope) => match legacy_scope {
518 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
519 Ok((legacy_binding.binding, Flags::MACRO_RULES)),
520 LegacyScope::Invocation(invoc_id)
521 if !this.output_legacy_scopes.contains_key(&invoc_id) =>
522 Err(Determinacy::Undetermined),
523 _ => Err(Determinacy::Determined),
525 Scope::CrateRoot => {
526 let root_ident = Ident::new(kw::PathRoot, ident.span);
527 let root_module = this.resolve_crate_root(root_ident);
528 let binding = this.resolve_ident_in_module_ext(
529 ModuleOrUniformRoot::Module(root_module),
537 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
538 Err((Determinacy::Undetermined, Weak::No)) =>
539 return Some(Err(Determinacy::determined(force))),
540 Err((Determinacy::Undetermined, Weak::Yes)) =>
541 Err(Determinacy::Undetermined),
542 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
545 Scope::Module(module) => {
546 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
547 let binding = this.resolve_ident_in_module_unadjusted_ext(
548 ModuleOrUniformRoot::Module(module),
551 adjusted_parent_scope,
558 let misc_flags = if ptr::eq(module, this.graph_root) {
559 Flags::MISC_SUGGEST_CRATE
560 } else if module.is_normal() {
561 Flags::MISC_SUGGEST_SELF
565 Ok((binding, Flags::MODULE | misc_flags))
567 Err((Determinacy::Undetermined, Weak::No)) =>
568 return Some(Err(Determinacy::determined(force))),
569 Err((Determinacy::Undetermined, Weak::Yes)) =>
570 Err(Determinacy::Undetermined),
571 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
574 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
576 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Registered),
577 ty::Visibility::Public, ident.span, ExpnId::root())
578 .to_name_binding(this.arenas);
579 Ok((binding, Flags::PRELUDE))
581 None => Err(Determinacy::Determined)
583 Scope::MacroUsePrelude => match this.macro_use_prelude.get(&ident.name).cloned() {
584 Some(binding) => Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE)),
585 None => Err(Determinacy::determined(
586 this.graph_root.unexpanded_invocations.borrow().is_empty()
589 Scope::BuiltinAttrs => if is_builtin_attr_name(ident.name) {
590 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Builtin),
591 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
592 .to_name_binding(this.arenas);
593 Ok((binding, Flags::PRELUDE))
595 Err(Determinacy::Determined)
597 Scope::LegacyPluginHelpers => if this.session.plugin_attributes.borrow().iter()
598 .any(|(name, _)| ident.name == *name) {
599 let binding = (Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper),
600 ty::Visibility::Public, DUMMY_SP, ExpnId::root())
601 .to_name_binding(this.arenas);
602 Ok((binding, Flags::PRELUDE))
604 Err(Determinacy::Determined)
606 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
607 Some(binding) => Ok((binding, Flags::PRELUDE)),
608 None => Err(Determinacy::determined(
609 this.graph_root.unexpanded_invocations.borrow().is_empty()
612 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
614 let binding = (Res::ToolMod,
615 ty::Visibility::Public, ident.span, ExpnId::root())
616 .to_name_binding(this.arenas);
617 Ok((binding, Flags::PRELUDE))
619 None => Err(Determinacy::Determined)
621 Scope::StdLibPrelude => {
622 let mut result = Err(Determinacy::Determined);
623 if let Some(prelude) = this.prelude {
624 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
625 ModuleOrUniformRoot::Module(prelude),
632 if use_prelude || this.is_builtin_macro(binding.res()) {
633 result = Ok((binding, Flags::PRELUDE | Flags::MISC_FROM_PRELUDE));
639 Scope::BuiltinTypes => match this.primitive_type_table.primitive_types
640 .get(&ident.name).cloned() {
642 let binding = (Res::PrimTy(prim_ty), ty::Visibility::Public,
643 DUMMY_SP, ExpnId::root()).to_name_binding(this.arenas);
644 Ok((binding, Flags::PRELUDE))
646 None => Err(Determinacy::Determined)
651 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
653 return Some(Ok(binding));
656 if let Some((innermost_binding, innermost_flags)) = innermost_result {
657 // Found another solution, if the first one was "weak", report an error.
658 let (res, innermost_res) = (binding.res(), innermost_binding.res());
659 if res != innermost_res {
660 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
661 let derive_helper = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
663 Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
665 let ambiguity_error_kind = if is_import {
666 Some(AmbiguityKind::Import)
667 } else if innermost_res == builtin || res == builtin {
668 Some(AmbiguityKind::BuiltinAttr)
669 } else if innermost_res == derive_helper || res == derive_helper {
670 Some(AmbiguityKind::DeriveHelper)
671 } else if innermost_res == legacy_helper &&
672 flags.contains(Flags::PRELUDE) ||
673 res == legacy_helper &&
674 innermost_flags.contains(Flags::PRELUDE) {
675 Some(AmbiguityKind::LegacyHelperVsPrelude)
676 } else if innermost_flags.contains(Flags::MACRO_RULES) &&
677 flags.contains(Flags::MODULE) &&
678 !this.disambiguate_legacy_vs_modern(innermost_binding,
680 flags.contains(Flags::MACRO_RULES) &&
681 innermost_flags.contains(Flags::MODULE) &&
682 !this.disambiguate_legacy_vs_modern(binding,
684 Some(AmbiguityKind::LegacyVsModern)
685 } else if innermost_binding.is_glob_import() {
686 Some(AmbiguityKind::GlobVsOuter)
687 } else if innermost_binding.may_appear_after(parent_scope.expansion,
689 Some(AmbiguityKind::MoreExpandedVsOuter)
693 if let Some(kind) = ambiguity_error_kind {
694 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
695 AmbiguityErrorMisc::SuggestCrate
696 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
697 AmbiguityErrorMisc::SuggestSelf
698 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
699 AmbiguityErrorMisc::FromPrelude
701 AmbiguityErrorMisc::None
703 this.ambiguity_errors.push(AmbiguityError {
706 b1: innermost_binding,
708 misc1: misc(innermost_flags),
711 return Some(Ok(innermost_binding));
715 // Found the first solution.
716 innermost_result = Some((binding, flags));
719 Ok(..) | Err(Determinacy::Determined) => {}
720 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
726 if let Some(break_result) = break_result {
730 // The first found solution was the only one, return it.
731 if let Some((binding, _)) = innermost_result {
735 let determinacy = Determinacy::determined(determinacy == Determinacy::Determined || force);
736 if determinacy == Determinacy::Determined && macro_kind == Some(MacroKind::Attr) &&
737 self.session.features_untracked().custom_attribute {
738 // For single-segment attributes interpret determinate "no resolution" as a custom
739 // attribute. (Lexical resolution implies the first segment and attr kind should imply
740 // the last segment, so we are certainly working with a single-segment attribute here.)
741 assert!(ns == MacroNS);
742 let binding = (Res::NonMacroAttr(NonMacroAttrKind::Custom),
743 ty::Visibility::Public, orig_ident.span, ExpnId::root())
744 .to_name_binding(self.arenas);
751 crate fn finalize_macro_resolutions(&mut self) {
752 let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
753 initial_res: Option<Res>, res: Res| {
754 if let Some(initial_res) = initial_res {
755 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
756 // Make sure compilation does not succeed if preferred macro resolution
757 // has changed after the macro had been expanded. In theory all such
758 // situations should be reported as ambiguity errors, so this is a bug.
759 if initial_res == Res::NonMacroAttr(NonMacroAttrKind::Custom) {
760 // Yeah, legacy custom attributes are implemented using forced resolution
761 // (which is a best effort error recovery tool, basically), so we can't
762 // promise their resolution won't change later.
763 let msg = format!("inconsistent resolution for a macro: first {}, then {}",
764 initial_res.descr(), res.descr());
765 this.session.span_err(span, &msg);
767 span_bug!(span, "inconsistent resolution for a macro");
771 // It's possible that the macro was unresolved (indeterminate) and silently
772 // expanded into a dummy fragment for recovery during expansion.
773 // Now, post-expansion, the resolution may succeed, but we can't change the
774 // past and need to report an error.
775 // However, non-speculative `resolve_path` can successfully return private items
776 // even if speculative `resolve_path` returned nothing previously, so we skip this
777 // less informative error if the privacy error is reported elsewhere.
778 if this.privacy_errors.is_empty() {
779 let msg = format!("cannot determine resolution for the {} `{}`",
780 kind.descr(), Segment::names_to_string(path));
781 let msg_note = "import resolution is stuck, try simplifying macro imports";
782 this.session.struct_span_err(span, &msg).note(msg_note).emit();
787 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
788 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
789 // FIXME: Path resolution will ICE if segment IDs present.
790 for seg in &mut path { seg.id = None; }
791 match self.resolve_path(
792 &path, Some(MacroNS), &parent_scope, true, path_span, CrateLint::No
794 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
795 let res = path_res.base_res();
796 check_consistency(self, &path, path_span, kind, initial_res, res);
798 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
799 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
802 (path_span, format!("partially resolved path in {} {}",
803 kind.article(), kind.descr()))
805 self.report_error(span, ResolutionError::FailedToResolve {
810 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
814 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
815 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
816 match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
817 &parent_scope, true, true, ident.span) {
819 let initial_res = initial_binding.map(|initial_binding| {
820 self.record_use(ident, MacroNS, initial_binding, false);
821 initial_binding.res()
823 let res = binding.res();
824 let seg = Segment::from_ident(ident);
825 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
828 let expected = kind.descr_expected();
829 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
830 let mut err = self.session.struct_span_err(ident.span, &msg);
831 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
837 let builtin_attrs = mem::take(&mut self.builtin_attrs);
838 for (ident, parent_scope) in builtin_attrs {
839 let _ = self.early_resolve_ident_in_lexical_scope(
840 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
845 fn check_stability_and_deprecation(&mut self, ext: &SyntaxExtension, path: &ast::Path) {
846 let span = path.span;
847 if let Some(stability) = &ext.stability {
848 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
849 let feature = stability.feature;
850 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
851 let node_id = ast::CRATE_NODE_ID;
852 let lint_buffer = &mut self.lint_buffer;
853 let soft_handler = |lint, span, msg: &_| {
854 lint_buffer.buffer_lint(lint, node_id, span, msg)
856 stability::report_unstable(
857 self.session, feature, reason, issue, is_soft, span, soft_handler
861 if let Some(depr) = &stability.rustc_depr {
862 let path = pprust::path_to_string(path);
863 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
864 stability::early_report_deprecation(
865 &mut self.lint_buffer, &message, depr.suggestion, lint, span
869 if let Some(depr) = &ext.deprecation {
870 let path = pprust::path_to_string(&path);
871 let (message, lint) = stability::deprecation_message(depr, &path);
872 stability::early_report_deprecation(&mut self.lint_buffer, &message, None, lint, span);
876 fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
877 res: Option<Res>, span: Span) {
878 if let Some(Res::NonMacroAttr(kind)) = res {
879 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
880 let msg = format!("cannot use a {} through an import", kind.descr());
881 let mut err = self.session.struct_span_err(span, &msg);
882 if let Some(binding) = binding {
883 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
890 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
891 // Reserve some names that are not quite covered by the general check
892 // performed on `Resolver::builtin_attrs`.
893 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
894 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
895 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
896 self.session.span_err(
897 ident.span, &format!("name `{}` is reserved in attribute namespace", ident)
903 /// Compile the macro into a `SyntaxExtension` and possibly replace it with a pre-defined
904 /// extension partially or entirely for built-in macros and legacy plugin macros.
905 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
906 let mut result = compile_declarative_macro(
907 &self.session.parse_sess, self.session.features_untracked(), item, edition
910 if result.is_builtin {
911 // The macro was marked with `#[rustc_builtin_macro]`.
912 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
914 // The macro is a built-in, replace only the expander function.
915 result.kind = ext.kind;
917 // The macro is from a plugin, the in-source definition is dummy,
918 // take all the data from the resolver.
922 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
923 self.session.span_err(item.span, &msg);