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 rustc_feature::is_builtin_attr_name;
16 use syntax::ast::{self, NodeId, Ident};
17 use syntax::attr::{self, StabilityLevel};
18 use syntax::edition::Edition;
19 use syntax::feature_gate::feature_err;
20 use syntax::print::pprust;
21 use syntax_expand::base::{self, InvocationRes, Indeterminate};
22 use syntax_expand::base::SyntaxExtension;
23 use syntax_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationKind};
24 use syntax_expand::compile_declarative_macro;
25 use syntax_pos::hygiene::{self, ExpnId, ExpnData, ExpnKind};
26 use syntax_pos::symbol::{Symbol, kw, sym};
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)
97 /// The code common between processing `#![register_tool]` and `#![register_attr]`.
100 attrs: &[ast::Attribute],
103 ) -> FxHashSet<Ident> {
104 let mut registered = FxHashSet::default();
105 for attr in attr::filter_by_name(attrs, attr_name) {
106 for nested_meta in attr.meta_item_list().unwrap_or_default() {
107 match nested_meta.ident() {
108 Some(ident) => if let Some(old_ident) = registered.replace(ident) {
109 let msg = format!("{} `{}` was already registered", descr, ident);
110 sess.struct_span_err(ident.span, &msg)
111 .span_label(old_ident.span, "already registered here").emit();
114 let msg = format!("`{}` only accepts identifiers", attr_name);
115 let span = nested_meta.span();
116 sess.struct_span_err(span, &msg).span_label(span, "not an identifier").emit();
124 crate fn registered_attrs_and_tools(
126 attrs: &[ast::Attribute],
127 ) -> (FxHashSet<Ident>, FxHashSet<Ident>) {
128 let registered_attrs = registered_idents(sess, attrs, sym::register_attr, "attribute");
129 let mut registered_tools = registered_idents(sess, attrs, sym::register_tool, "tool");
130 // We implicitly add `rustfmt` and `clippy` to known tools,
131 // but it's not an error to register them explicitly.
132 let predefined_tools = [sym::clippy, sym::rustfmt];
133 registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
134 (registered_attrs, registered_tools)
137 impl<'a> base::Resolver for Resolver<'a> {
138 fn next_node_id(&mut self) -> NodeId {
142 fn resolve_dollar_crates(&mut self) {
143 hygiene::update_dollar_crate_names(|ctxt| {
144 let ident = Ident::new(kw::DollarCrate, DUMMY_SP.with_ctxt(ctxt));
145 match self.resolve_crate_root(ident).kind {
146 ModuleKind::Def(.., name) if name != kw::Invalid => name,
152 fn visit_ast_fragment_with_placeholders(&mut self, expansion: ExpnId, fragment: &AstFragment) {
153 // Integrate the new AST fragment into all the definition and module structures.
154 // We are inside the `expansion` now, but other parent scope components are still the same.
155 let parent_scope = ParentScope { expansion, ..self.invocation_parent_scopes[&expansion] };
156 let output_legacy_scope = self.build_reduced_graph(fragment, parent_scope);
157 self.output_legacy_scopes.insert(expansion, output_legacy_scope);
159 parent_scope.module.unexpanded_invocations.borrow_mut().remove(&expansion);
162 fn register_builtin_macro(&mut self, ident: ast::Ident, ext: SyntaxExtension) {
163 if self.builtin_macros.insert(ident.name, ext).is_some() {
164 self.session.span_err(ident.span,
165 &format!("built-in macro `{}` was already defined", ident));
169 // Create a new Expansion with a definition site of the provided module, or
170 // a fake empty `#[no_implicit_prelude]` module if no module is provided.
171 fn expansion_for_ast_pass(
176 parent_module_id: Option<NodeId>,
178 let expn_id = ExpnId::fresh(Some(ExpnData::allow_unstable(
179 ExpnKind::AstPass(pass),
181 self.session.edition(),
185 let parent_scope = if let Some(module_id) = parent_module_id {
186 let parent_def_id = self.definitions.local_def_id(module_id);
187 self.definitions.add_parent_module_of_macro_def(expn_id, parent_def_id);
188 self.module_map[&parent_def_id]
190 self.definitions.add_parent_module_of_macro_def(
192 def_id::DefId::local(def_id::CRATE_DEF_INDEX),
196 self.ast_transform_scopes.insert(expn_id, parent_scope);
200 fn resolve_imports(&mut self) {
201 ImportResolver { r: self }.resolve_imports()
204 fn resolve_macro_invocation(
205 &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
206 ) -> Result<InvocationRes, Indeterminate> {
207 let invoc_id = invoc.expansion_data.id;
208 let parent_scope = match self.invocation_parent_scopes.get(&invoc_id) {
209 Some(parent_scope) => *parent_scope,
211 // If there's no entry in the table, then we are resolving an eagerly expanded
212 // macro, which should inherit its parent scope from its eager expansion root -
213 // the macro that requested this eager expansion.
214 let parent_scope = *self.invocation_parent_scopes.get(&eager_expansion_root)
215 .expect("non-eager expansion without a parent scope");
216 self.invocation_parent_scopes.insert(invoc_id, parent_scope);
221 let (path, kind, derives, after_derive) = match invoc.kind {
222 InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
223 (&attr.get_normal_item().path,
225 self.arenas.alloc_ast_paths(derives),
227 InvocationKind::Bang { ref mac, .. } =>
228 (&mac.path, MacroKind::Bang, &[][..], false),
229 InvocationKind::Derive { ref path, .. } =>
230 (path, MacroKind::Derive, &[][..], false),
231 InvocationKind::DeriveContainer { ref derives, .. } => {
232 // Block expansion of the container until we resolve all derives in it.
233 // This is required for two reasons:
234 // - Derive helper attributes are in scope for the item to which the `#[derive]`
235 // is applied, so they have to be produced by the container's expansion rather
236 // than by individual derives.
237 // - Derives in the container need to know whether one of them is a built-in `Copy`.
238 // FIXME: Try to avoid repeated resolutions for derives here and in expansion.
239 let mut exts = Vec::new();
240 let mut helper_attrs = Vec::new();
241 for path in derives {
242 exts.push(match self.resolve_macro_path(
243 path, Some(MacroKind::Derive), &parent_scope, true, force
245 Ok((Some(ext), _)) => {
246 let span = path.segments.last().unwrap().ident.span.modern();
248 ext.helper_attrs.iter().map(|name| Ident::new(*name, span))
250 if ext.is_derive_copy {
251 self.add_derive_copy(invoc_id);
255 Ok(_) | Err(Determinacy::Determined) => self.dummy_ext(MacroKind::Derive),
256 Err(Determinacy::Undetermined) => return Err(Indeterminate),
259 self.helper_attrs.insert(invoc_id, helper_attrs);
260 return Ok(InvocationRes::DeriveContainer(exts));
264 // Derives are not included when `invocations` are collected, so we have to add them here.
265 let parent_scope = &ParentScope { derives, ..parent_scope };
266 let (ext, res) = self.smart_resolve_macro_path(path, kind, parent_scope, force)?;
268 let span = invoc.span();
269 invoc_id.set_expn_data(ext.expn_data(parent_scope.expansion, span, fast_print_path(path)));
271 if let Res::Def(_, def_id) = res {
273 self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
275 self.macro_defs.insert(invoc_id, def_id);
276 let normal_module_def_id = self.macro_def_scope(invoc_id).normal_ancestor_id;
277 self.definitions.add_parent_module_of_macro_def(invoc_id, normal_module_def_id);
280 match invoc.fragment_kind {
281 AstFragmentKind::Arms
282 | AstFragmentKind::Fields
283 | AstFragmentKind::FieldPats
284 | AstFragmentKind::GenericParams
285 | AstFragmentKind::Params
286 | AstFragmentKind::StructFields
287 | AstFragmentKind::Variants =>
289 if let Res::Def(..) = res {
290 self.session.span_err(
292 &format!("expected an inert attribute, found {} {}",
293 res.article(), res.descr()),
295 return Ok(InvocationRes::Single(self.dummy_ext(kind)));
301 Ok(InvocationRes::Single(ext))
304 fn check_unused_macros(&mut self) {
305 for (&node_id, &span) in self.unused_macros.iter() {
306 self.lint_buffer.buffer_lint(
307 lint::builtin::UNUSED_MACROS, node_id, span, "unused macro definition"
312 fn has_derive_copy(&self, expn_id: ExpnId) -> bool {
313 self.containers_deriving_copy.contains(&expn_id)
316 fn add_derive_copy(&mut self, expn_id: ExpnId) {
317 self.containers_deriving_copy.insert(expn_id);
321 impl<'a> Resolver<'a> {
322 /// Resolve macro path with error reporting and recovery.
323 fn smart_resolve_macro_path(
327 parent_scope: &ParentScope<'a>,
329 ) -> Result<(Lrc<SyntaxExtension>, Res), Indeterminate> {
330 let (ext, res) = match self.resolve_macro_path(path, Some(kind), parent_scope,
332 Ok((Some(ext), res)) => (ext, res),
333 // Use dummy syntax extensions for unresolved macros for better recovery.
334 Ok((None, res)) => (self.dummy_ext(kind), res),
335 Err(Determinacy::Determined) => (self.dummy_ext(kind), Res::Err),
336 Err(Determinacy::Undetermined) => return Err(Indeterminate),
339 // Report errors and enforce feature gates for the resolved macro.
340 let features = self.session.features_untracked();
341 for segment in &path.segments {
342 if let Some(args) = &segment.args {
343 self.session.span_err(args.span(), "generic arguments in macro path");
345 if kind == MacroKind::Attr && !features.rustc_attrs &&
346 segment.ident.as_str().starts_with("rustc") {
348 "attributes starting with `rustc` are reserved for use by the `rustc` compiler";
349 feature_err(&self.session.parse_sess, sym::rustc_attrs, segment.ident.span, msg)
355 Res::Def(DefKind::Macro(_), def_id) => {
356 if let Some(node_id) = self.definitions.as_local_node_id(def_id) {
357 self.unused_macros.remove(&node_id);
358 if self.proc_macro_stubs.contains(&node_id) {
359 self.session.span_err(
361 "can't use a procedural macro from the same crate that defines it",
366 Res::NonMacroAttr(..) | Res::Err => {}
367 _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
370 self.check_stability_and_deprecation(&ext, path);
372 Ok(if ext.macro_kind() != kind {
373 let expected = kind.descr_expected();
374 let path_str = pprust::path_to_string(path);
375 let msg = format!("expected {}, found {} `{}`", expected, res.descr(), path_str);
376 self.session.struct_span_err(path.span, &msg)
377 .span_label(path.span, format!("not {} {}", kind.article(), expected))
379 // Use dummy syntax extensions for unexpected macro kinds for better recovery.
380 (self.dummy_ext(kind), Res::Err)
386 pub fn resolve_macro_path(
389 kind: Option<MacroKind>,
390 parent_scope: &ParentScope<'a>,
393 ) -> Result<(Option<Lrc<SyntaxExtension>>, Res), Determinacy> {
394 let path_span = path.span;
395 let mut path = Segment::from_path(path);
397 // Possibly apply the macro helper hack
398 if kind == Some(MacroKind::Bang) && path.len() == 1 &&
399 path[0].ident.span.ctxt().outer_expn_data().local_inner_macros {
400 let root = Ident::new(kw::DollarCrate, path[0].ident.span);
401 path.insert(0, Segment::from_ident(root));
404 let res = if path.len() > 1 {
405 let res = match self.resolve_path(&path, Some(MacroNS), parent_scope,
406 false, path_span, CrateLint::No) {
407 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
408 Ok(path_res.base_res())
410 PathResult::Indeterminate if !force => return Err(Determinacy::Undetermined),
411 PathResult::NonModule(..)
412 | PathResult::Indeterminate
413 | PathResult::Failed { .. } => Err(Determinacy::Determined),
414 PathResult::Module(..) => unreachable!(),
418 let kind = kind.expect("macro kind must be specified if tracing is enabled");
419 self.multi_segment_macro_resolutions
420 .push((path, path_span, kind, *parent_scope, res.ok()));
423 self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
426 let scope_set = kind.map_or(ScopeSet::All(MacroNS, false), ScopeSet::Macro);
427 let binding = self.early_resolve_ident_in_lexical_scope(
428 path[0].ident, scope_set, parent_scope, false, force, path_span
430 if let Err(Determinacy::Undetermined) = binding {
431 return Err(Determinacy::Undetermined);
435 let kind = kind.expect("macro kind must be specified if tracing is enabled");
436 self.single_segment_macro_resolutions
437 .push((path[0].ident, kind, *parent_scope, binding.ok()));
440 let res = binding.map(|binding| binding.res());
441 self.prohibit_imported_non_macro_attrs(binding.ok(), res.ok(), path_span);
445 res.map(|res| (self.get_macro(res), res))
448 // Resolve an identifier in lexical scope.
449 // This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
450 // expansion and import resolution (perhaps they can be merged in the future).
451 // The function is used for resolving initial segments of macro paths (e.g., `foo` in
452 // `foo::bar!(); or `foo!();`) and also for import paths on 2018 edition.
453 crate fn early_resolve_ident_in_lexical_scope(
457 parent_scope: &ParentScope<'a>,
461 ) -> Result<&'a NameBinding<'a>, Determinacy> {
462 bitflags::bitflags! {
464 const MACRO_RULES = 1 << 0;
465 const MODULE = 1 << 1;
466 const DERIVE_HELPER_COMPAT = 1 << 2;
467 const MISC_SUGGEST_CRATE = 1 << 3;
468 const MISC_SUGGEST_SELF = 1 << 4;
469 const MISC_FROM_PRELUDE = 1 << 5;
473 assert!(force || !record_used); // `record_used` implies `force`
475 // Make sure `self`, `super` etc produce an error when passed to here.
476 if orig_ident.is_path_segment_keyword() {
477 return Err(Determinacy::Determined);
480 let (ns, macro_kind, is_import) = match scope_set {
481 ScopeSet::All(ns, is_import) => (ns, None, is_import),
482 ScopeSet::AbsolutePath(ns) => (ns, None, false),
483 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
486 // This is *the* result, resolution from the scope closest to the resolved identifier.
487 // However, sometimes this result is "weak" because it comes from a glob import or
488 // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g.
489 // mod m { ... } // solution in outer scope
491 // use prefix::*; // imports another `m` - innermost solution
492 // // weak, cannot shadow the outer `m`, need to report ambiguity error
495 // So we have to save the innermost solution and continue searching in outer scopes
496 // to detect potential ambiguities.
497 let mut innermost_result: Option<(&NameBinding<'_>, Flags)> = None;
498 let mut determinacy = Determinacy::Determined;
500 // Go through all the scopes and try to resolve the name.
501 let break_result = self.visit_scopes(scope_set, parent_scope, orig_ident,
502 |this, scope, use_prelude, ident| {
503 let ok = |res, span, arenas| Ok((
504 (res, ty::Visibility::Public, span, ExpnId::root()).to_name_binding(arenas),
507 let result = match scope {
508 Scope::DeriveHelpers(expn_id) => {
509 if let Some(attr) = this.helper_attrs.get(&expn_id).and_then(|attrs| {
510 attrs.iter().rfind(|i| ident == **i)
512 let binding = (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
513 ty::Visibility::Public, attr.span, expn_id)
514 .to_name_binding(this.arenas);
515 Ok((binding, Flags::empty()))
517 Err(Determinacy::Determined)
520 Scope::DeriveHelpersCompat => {
521 let mut result = Err(Determinacy::Determined);
522 for derive in parent_scope.derives {
523 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
524 match this.resolve_macro_path(derive, Some(MacroKind::Derive),
525 parent_scope, true, force) {
526 Ok((Some(ext), _)) => if ext.helper_attrs.contains(&ident.name) {
527 let binding = (Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper),
528 ty::Visibility::Public, derive.span, ExpnId::root())
529 .to_name_binding(this.arenas);
530 result = Ok((binding, Flags::DERIVE_HELPER_COMPAT));
533 Ok(_) | Err(Determinacy::Determined) => {}
534 Err(Determinacy::Undetermined) =>
535 result = Err(Determinacy::Undetermined),
540 Scope::MacroRules(legacy_scope) => match legacy_scope {
541 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
542 Ok((legacy_binding.binding, Flags::MACRO_RULES)),
543 LegacyScope::Invocation(invoc_id)
544 if !this.output_legacy_scopes.contains_key(&invoc_id) =>
545 Err(Determinacy::Undetermined),
546 _ => Err(Determinacy::Determined),
548 Scope::CrateRoot => {
549 let root_ident = Ident::new(kw::PathRoot, ident.span);
550 let root_module = this.resolve_crate_root(root_ident);
551 let binding = this.resolve_ident_in_module_ext(
552 ModuleOrUniformRoot::Module(root_module),
560 Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)),
561 Err((Determinacy::Undetermined, Weak::No)) =>
562 return Some(Err(Determinacy::determined(force))),
563 Err((Determinacy::Undetermined, Weak::Yes)) =>
564 Err(Determinacy::Undetermined),
565 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
568 Scope::Module(module) => {
569 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
570 let binding = this.resolve_ident_in_module_unadjusted_ext(
571 ModuleOrUniformRoot::Module(module),
574 adjusted_parent_scope,
581 let misc_flags = if ptr::eq(module, this.graph_root) {
582 Flags::MISC_SUGGEST_CRATE
583 } else if module.is_normal() {
584 Flags::MISC_SUGGEST_SELF
588 Ok((binding, Flags::MODULE | misc_flags))
590 Err((Determinacy::Undetermined, Weak::No)) =>
591 return Some(Err(Determinacy::determined(force))),
592 Err((Determinacy::Undetermined, Weak::Yes)) =>
593 Err(Determinacy::Undetermined),
594 Err((Determinacy::Determined, _)) => Err(Determinacy::Determined),
597 Scope::RegisteredAttrs => match this.registered_attrs.get(&ident).cloned() {
599 Res::NonMacroAttr(NonMacroAttrKind::Registered), ident.span, this.arenas
601 None => Err(Determinacy::Determined)
603 Scope::MacroUsePrelude => match this.macro_use_prelude.get(&ident.name).cloned() {
604 Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)),
605 None => Err(Determinacy::determined(
606 this.graph_root.unexpanded_invocations.borrow().is_empty()
609 Scope::BuiltinAttrs => if is_builtin_attr_name(ident.name) {
610 ok(Res::NonMacroAttr(NonMacroAttrKind::Builtin), DUMMY_SP, this.arenas)
612 Err(Determinacy::Determined)
614 Scope::ExternPrelude => match this.extern_prelude_get(ident, !record_used) {
615 Some(binding) => Ok((binding, Flags::empty())),
616 None => Err(Determinacy::determined(
617 this.graph_root.unexpanded_invocations.borrow().is_empty()
620 Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() {
621 Some(ident) => ok(Res::ToolMod, ident.span, this.arenas),
622 None => Err(Determinacy::Determined)
624 Scope::StdLibPrelude => {
625 let mut result = Err(Determinacy::Determined);
626 if let Some(prelude) = this.prelude {
627 if let Ok(binding) = this.resolve_ident_in_module_unadjusted(
628 ModuleOrUniformRoot::Module(prelude),
635 if use_prelude || this.is_builtin_macro(binding.res()) {
636 result = Ok((binding, Flags::MISC_FROM_PRELUDE));
642 Scope::BuiltinTypes => match this.primitive_type_table.primitive_types
643 .get(&ident.name).cloned() {
644 Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas),
645 None => Err(Determinacy::Determined)
650 Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => {
652 return Some(Ok(binding));
655 if let Some((innermost_binding, innermost_flags)) = innermost_result {
656 // Found another solution, if the first one was "weak", report an error.
657 let (res, innermost_res) = (binding.res(), innermost_binding.res());
658 if res != innermost_res {
659 let builtin = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
660 let is_derive_helper_compat = |res, flags: Flags| {
661 res == Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper) &&
662 flags.contains(Flags::DERIVE_HELPER_COMPAT)
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 is_derive_helper_compat(innermost_res, innermost_flags) ||
670 is_derive_helper_compat(res, flags) {
671 Some(AmbiguityKind::DeriveHelper)
672 } else if innermost_flags.contains(Flags::MACRO_RULES) &&
673 flags.contains(Flags::MODULE) &&
674 !this.disambiguate_legacy_vs_modern(innermost_binding,
676 flags.contains(Flags::MACRO_RULES) &&
677 innermost_flags.contains(Flags::MODULE) &&
678 !this.disambiguate_legacy_vs_modern(binding,
680 Some(AmbiguityKind::LegacyVsModern)
681 } else if innermost_binding.is_glob_import() {
682 Some(AmbiguityKind::GlobVsOuter)
683 } else if innermost_binding.may_appear_after(parent_scope.expansion,
685 Some(AmbiguityKind::MoreExpandedVsOuter)
689 if let Some(kind) = ambiguity_error_kind {
690 let misc = |f: Flags| if f.contains(Flags::MISC_SUGGEST_CRATE) {
691 AmbiguityErrorMisc::SuggestCrate
692 } else if f.contains(Flags::MISC_SUGGEST_SELF) {
693 AmbiguityErrorMisc::SuggestSelf
694 } else if f.contains(Flags::MISC_FROM_PRELUDE) {
695 AmbiguityErrorMisc::FromPrelude
697 AmbiguityErrorMisc::None
699 this.ambiguity_errors.push(AmbiguityError {
702 b1: innermost_binding,
704 misc1: misc(innermost_flags),
707 return Some(Ok(innermost_binding));
711 // Found the first solution.
712 innermost_result = Some((binding, flags));
715 Ok(..) | Err(Determinacy::Determined) => {}
716 Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined
722 if let Some(break_result) = break_result {
726 // The first found solution was the only one, return it.
727 if let Some((binding, _)) = innermost_result {
731 Err(Determinacy::determined(determinacy == Determinacy::Determined || force))
734 crate fn finalize_macro_resolutions(&mut self) {
735 let check_consistency = |this: &mut Self, path: &[Segment], span, kind: MacroKind,
736 initial_res: Option<Res>, res: Res| {
737 if let Some(initial_res) = initial_res {
738 if res != initial_res && res != Res::Err && this.ambiguity_errors.is_empty() {
739 // Make sure compilation does not succeed if preferred macro resolution
740 // has changed after the macro had been expanded. In theory all such
741 // situations should be reported as ambiguity errors, so this is a bug.
742 span_bug!(span, "inconsistent resolution for a macro");
745 // It's possible that the macro was unresolved (indeterminate) and silently
746 // expanded into a dummy fragment for recovery during expansion.
747 // Now, post-expansion, the resolution may succeed, but we can't change the
748 // past and need to report an error.
749 // However, non-speculative `resolve_path` can successfully return private items
750 // even if speculative `resolve_path` returned nothing previously, so we skip this
751 // less informative error if the privacy error is reported elsewhere.
752 if this.privacy_errors.is_empty() {
753 let msg = format!("cannot determine resolution for the {} `{}`",
754 kind.descr(), Segment::names_to_string(path));
755 let msg_note = "import resolution is stuck, try simplifying macro imports";
756 this.session.struct_span_err(span, &msg).note(msg_note).emit();
761 let macro_resolutions = mem::take(&mut self.multi_segment_macro_resolutions);
762 for (mut path, path_span, kind, parent_scope, initial_res) in macro_resolutions {
763 // FIXME: Path resolution will ICE if segment IDs present.
764 for seg in &mut path { seg.id = None; }
765 match self.resolve_path(
766 &path, Some(MacroNS), &parent_scope, true, path_span, CrateLint::No
768 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
769 let res = path_res.base_res();
770 check_consistency(self, &path, path_span, kind, initial_res, res);
772 path_res @ PathResult::NonModule(..) | path_res @ PathResult::Failed { .. } => {
773 let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
776 (path_span, format!("partially resolved path in {} {}",
777 kind.article(), kind.descr()))
779 self.report_error(span, ResolutionError::FailedToResolve {
784 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
788 let macro_resolutions = mem::take(&mut self.single_segment_macro_resolutions);
789 for (ident, kind, parent_scope, initial_binding) in macro_resolutions {
790 match self.early_resolve_ident_in_lexical_scope(ident, ScopeSet::Macro(kind),
791 &parent_scope, true, true, ident.span) {
793 let initial_res = initial_binding.map(|initial_binding| {
794 self.record_use(ident, MacroNS, initial_binding, false);
795 initial_binding.res()
797 let res = binding.res();
798 let seg = Segment::from_ident(ident);
799 check_consistency(self, &[seg], ident.span, kind, initial_res, res);
802 let expected = kind.descr_expected();
803 let msg = format!("cannot find {} `{}` in this scope", expected, ident);
804 let mut err = self.session.struct_span_err(ident.span, &msg);
805 self.unresolved_macro_suggestions(&mut err, kind, &parent_scope, ident);
811 let builtin_attrs = mem::take(&mut self.builtin_attrs);
812 for (ident, parent_scope) in builtin_attrs {
813 let _ = self.early_resolve_ident_in_lexical_scope(
814 ident, ScopeSet::Macro(MacroKind::Attr), &parent_scope, true, true, ident.span
819 fn check_stability_and_deprecation(&mut self, ext: &SyntaxExtension, path: &ast::Path) {
820 let span = path.span;
821 if let Some(stability) = &ext.stability {
822 if let StabilityLevel::Unstable { reason, issue, is_soft } = stability.level {
823 let feature = stability.feature;
824 if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
825 let node_id = ast::CRATE_NODE_ID;
826 let lint_buffer = &mut self.lint_buffer;
827 let soft_handler = |lint, span, msg: &_| {
828 lint_buffer.buffer_lint(lint, node_id, span, msg)
830 stability::report_unstable(
831 self.session, feature, reason, issue, is_soft, span, soft_handler
835 if let Some(depr) = &stability.rustc_depr {
836 let path = pprust::path_to_string(path);
837 let (message, lint) = stability::rustc_deprecation_message(depr, &path);
838 stability::early_report_deprecation(
839 &mut self.lint_buffer, &message, depr.suggestion, lint, span
843 if let Some(depr) = &ext.deprecation {
844 let path = pprust::path_to_string(&path);
845 let (message, lint) = stability::deprecation_message(depr, &path);
846 stability::early_report_deprecation(&mut self.lint_buffer, &message, None, lint, span);
850 fn prohibit_imported_non_macro_attrs(&self, binding: Option<&'a NameBinding<'a>>,
851 res: Option<Res>, span: Span) {
852 if let Some(Res::NonMacroAttr(kind)) = res {
853 if kind != NonMacroAttrKind::Tool && binding.map_or(true, |b| b.is_import()) {
855 format!("cannot use {} {} through an import", kind.article(), kind.descr());
856 let mut err = self.session.struct_span_err(span, &msg);
857 if let Some(binding) = binding {
858 err.span_note(binding.span, &format!("the {} imported here", kind.descr()));
865 crate fn check_reserved_macro_name(&mut self, ident: Ident, res: Res) {
866 // Reserve some names that are not quite covered by the general check
867 // performed on `Resolver::builtin_attrs`.
868 if ident.name == sym::cfg || ident.name == sym::cfg_attr || ident.name == sym::derive {
869 let macro_kind = self.get_macro(res).map(|ext| ext.macro_kind());
870 if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
871 self.session.span_err(
872 ident.span, &format!("name `{}` is reserved in attribute namespace", ident)
878 /// Compile the macro into a `SyntaxExtension` and possibly replace
879 /// its expander to a pre-defined one for built-in macros.
880 crate fn compile_macro(&mut self, item: &ast::Item, edition: Edition) -> SyntaxExtension {
881 let mut result = compile_declarative_macro(
882 &self.session.parse_sess, self.session.features_untracked(), item, edition
885 if result.is_builtin {
886 // The macro was marked with `#[rustc_builtin_macro]`.
887 if let Some(ext) = self.builtin_macros.remove(&item.ident.name) {
888 // The macro is a built-in, replace its expander function
889 // while still taking everything else from the source code.
890 result.kind = ext.kind;
892 let msg = format!("cannot find a built-in macro with name `{}`", item.ident);
893 self.session.span_err(item.span, &msg);