2 use crate::config::StripUnconfigured;
3 use crate::hygiene::SyntaxContext;
4 use crate::mbe::macro_rules::annotate_err_with_kind;
5 use crate::module::{mod_dir_path, parse_external_mod, DirOwnership, ParsedExternalMod};
6 use crate::placeholders::{placeholder, PlaceholderExpander};
9 use rustc_ast::mut_visit::*;
10 use rustc_ast::ptr::P;
12 use rustc_ast::tokenstream::TokenStream;
13 use rustc_ast::visit::{self, AssocCtxt, Visitor};
14 use rustc_ast::{AssocItemKind, AstLike, AstLikeWrapper, AttrStyle, ExprKind, ForeignItemKind};
15 use rustc_ast::{Inline, ItemKind, MacArgs, MacStmtStyle, MetaItemKind, ModKind};
16 use rustc_ast::{NestedMetaItem, NodeId, PatKind, StmtKind, TyKind};
17 use rustc_ast_pretty::pprust;
18 use rustc_data_structures::map_in_place::MapInPlace;
19 use rustc_data_structures::sync::Lrc;
20 use rustc_errors::{Applicability, PResult};
21 use rustc_feature::Features;
22 use rustc_parse::parser::{
23 AttemptLocalParseRecovery, CommaRecoveryMode, ForceCollect, Parser, RecoverColon, RecoverComma,
25 use rustc_parse::validate_attr;
26 use rustc_session::lint::builtin::{UNUSED_ATTRIBUTES, UNUSED_DOC_COMMENTS};
27 use rustc_session::lint::BuiltinLintDiagnostics;
28 use rustc_session::parse::{feature_err, ParseSess};
29 use rustc_session::Limit;
30 use rustc_span::symbol::{sym, Ident};
31 use rustc_span::{FileName, LocalExpnId, Span};
33 use smallvec::SmallVec;
35 use std::path::PathBuf;
39 macro_rules! ast_fragments {
41 $($Kind:ident($AstTy:ty) {
43 $(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)?
44 $(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident($($args:tt)*);)?
48 /// A fragment of AST that can be produced by a single macro expansion.
49 /// Can also serve as an input and intermediate result for macro expansion operations.
50 pub enum AstFragment {
51 OptExpr(Option<P<ast::Expr>>),
55 /// "Discriminant" of an AST fragment.
56 #[derive(Copy, Clone, PartialEq, Eq)]
57 pub enum AstFragmentKind {
62 impl AstFragmentKind {
63 pub fn name(self) -> &'static str {
65 AstFragmentKind::OptExpr => "expression",
66 $(AstFragmentKind::$Kind => $kind_name,)*
70 fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
72 AstFragmentKind::OptExpr =>
73 result.make_expr().map(Some).map(AstFragment::OptExpr),
74 $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
80 pub fn add_placeholders(&mut self, placeholders: &[NodeId]) {
81 if placeholders.is_empty() {
85 $($(AstFragment::$Kind(ast) => ast.extend(placeholders.iter().flat_map(|id| {
86 // We are repeating through arguments with `many`, to do that we have to
87 // mention some macro variable from those arguments even if it's not used.
88 macro _repeating($flat_map_ast_elt) {}
89 placeholder(AstFragmentKind::$Kind, *id, None).$make_ast()
91 _ => panic!("unexpected AST fragment kind")
95 pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
97 AstFragment::OptExpr(expr) => expr,
98 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
102 $(pub fn $make_ast(self) -> $AstTy {
104 AstFragment::$Kind(ast) => ast,
105 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
109 fn make_ast<T: InvocationCollectorNode>(self) -> T::OutputTy {
110 T::fragment_to_output(self)
113 pub fn mut_visit_with<F: MutVisitor>(&mut self, vis: &mut F) {
115 AstFragment::OptExpr(opt_expr) => {
116 visit_clobber(opt_expr, |opt_expr| {
117 if let Some(expr) = opt_expr {
118 vis.filter_map_expr(expr)
124 $($(AstFragment::$Kind(ast) => vis.$mut_visit_ast(ast),)?)*
125 $($(AstFragment::$Kind(ast) =>
126 ast.flat_map_in_place(|ast| vis.$flat_map_ast_elt(ast)),)?)*
130 pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
132 AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
133 AstFragment::OptExpr(None) => {}
134 $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)?)*
135 $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
136 visitor.$visit_ast_elt(ast_elt, $($args)*);
142 impl<'a> MacResult for crate::mbe::macro_rules::ParserAnyMacro<'a> {
143 $(fn $make_ast(self: Box<crate::mbe::macro_rules::ParserAnyMacro<'a>>)
145 Some(self.make(AstFragmentKind::$Kind).$make_ast())
152 Expr(P<ast::Expr>) { "expression"; one fn visit_expr; fn visit_expr; fn make_expr; }
153 Pat(P<ast::Pat>) { "pattern"; one fn visit_pat; fn visit_pat; fn make_pat; }
154 Ty(P<ast::Ty>) { "type"; one fn visit_ty; fn visit_ty; fn make_ty; }
155 Stmts(SmallVec<[ast::Stmt; 1]>) {
156 "statement"; many fn flat_map_stmt; fn visit_stmt(); fn make_stmts;
158 Items(SmallVec<[P<ast::Item>; 1]>) {
159 "item"; many fn flat_map_item; fn visit_item(); fn make_items;
161 TraitItems(SmallVec<[P<ast::AssocItem>; 1]>) {
163 many fn flat_map_trait_item;
164 fn visit_assoc_item(AssocCtxt::Trait);
167 ImplItems(SmallVec<[P<ast::AssocItem>; 1]>) {
169 many fn flat_map_impl_item;
170 fn visit_assoc_item(AssocCtxt::Impl);
173 ForeignItems(SmallVec<[P<ast::ForeignItem>; 1]>) {
175 many fn flat_map_foreign_item;
176 fn visit_foreign_item();
177 fn make_foreign_items;
179 Arms(SmallVec<[ast::Arm; 1]>) {
180 "match arm"; many fn flat_map_arm; fn visit_arm(); fn make_arms;
182 ExprFields(SmallVec<[ast::ExprField; 1]>) {
183 "field expression"; many fn flat_map_expr_field; fn visit_expr_field(); fn make_expr_fields;
185 PatFields(SmallVec<[ast::PatField; 1]>) {
187 many fn flat_map_pat_field;
188 fn visit_pat_field();
191 GenericParams(SmallVec<[ast::GenericParam; 1]>) {
193 many fn flat_map_generic_param;
194 fn visit_generic_param();
195 fn make_generic_params;
197 Params(SmallVec<[ast::Param; 1]>) {
198 "function parameter"; many fn flat_map_param; fn visit_param(); fn make_params;
200 FieldDefs(SmallVec<[ast::FieldDef; 1]>) {
202 many fn flat_map_field_def;
203 fn visit_field_def();
206 Variants(SmallVec<[ast::Variant; 1]>) {
207 "variant"; many fn flat_map_variant; fn visit_variant(); fn make_variants;
209 Crate(ast::Crate) { "crate"; one fn visit_crate; fn visit_crate; fn make_crate; }
212 pub enum SupportsMacroExpansion {
214 Yes { supports_inner_attrs: bool },
217 impl AstFragmentKind {
218 crate fn dummy(self, span: Span) -> AstFragment {
219 self.make_from(DummyResult::any(span)).expect("couldn't create a dummy AST fragment")
222 pub fn supports_macro_expansion(self) -> SupportsMacroExpansion {
224 AstFragmentKind::OptExpr
225 | AstFragmentKind::Expr
226 | AstFragmentKind::Stmts
227 | AstFragmentKind::Ty
228 | AstFragmentKind::Pat => SupportsMacroExpansion::Yes { supports_inner_attrs: false },
229 AstFragmentKind::Items
230 | AstFragmentKind::TraitItems
231 | AstFragmentKind::ImplItems
232 | AstFragmentKind::ForeignItems
233 | AstFragmentKind::Crate => SupportsMacroExpansion::Yes { supports_inner_attrs: true },
234 AstFragmentKind::Arms
235 | AstFragmentKind::ExprFields
236 | AstFragmentKind::PatFields
237 | AstFragmentKind::GenericParams
238 | AstFragmentKind::Params
239 | AstFragmentKind::FieldDefs
240 | AstFragmentKind::Variants => SupportsMacroExpansion::No,
244 fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(
248 let mut items = items.into_iter();
250 AstFragmentKind::Arms => {
251 AstFragment::Arms(items.map(Annotatable::expect_arm).collect())
253 AstFragmentKind::ExprFields => {
254 AstFragment::ExprFields(items.map(Annotatable::expect_expr_field).collect())
256 AstFragmentKind::PatFields => {
257 AstFragment::PatFields(items.map(Annotatable::expect_pat_field).collect())
259 AstFragmentKind::GenericParams => {
260 AstFragment::GenericParams(items.map(Annotatable::expect_generic_param).collect())
262 AstFragmentKind::Params => {
263 AstFragment::Params(items.map(Annotatable::expect_param).collect())
265 AstFragmentKind::FieldDefs => {
266 AstFragment::FieldDefs(items.map(Annotatable::expect_field_def).collect())
268 AstFragmentKind::Variants => {
269 AstFragment::Variants(items.map(Annotatable::expect_variant).collect())
271 AstFragmentKind::Items => {
272 AstFragment::Items(items.map(Annotatable::expect_item).collect())
274 AstFragmentKind::ImplItems => {
275 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect())
277 AstFragmentKind::TraitItems => {
278 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect())
280 AstFragmentKind::ForeignItems => {
281 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect())
283 AstFragmentKind::Stmts => {
284 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect())
286 AstFragmentKind::Expr => AstFragment::Expr(
287 items.next().expect("expected exactly one expression").expect_expr(),
289 AstFragmentKind::OptExpr => {
290 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr))
292 AstFragmentKind::Crate => {
293 AstFragment::Crate(items.next().expect("expected exactly one crate").expect_crate())
295 AstFragmentKind::Pat | AstFragmentKind::Ty => {
296 panic!("patterns and types aren't annotatable")
302 pub struct Invocation {
303 pub kind: InvocationKind,
304 pub fragment_kind: AstFragmentKind,
305 pub expansion_data: ExpansionData,
308 pub enum InvocationKind {
314 attr: ast::Attribute,
315 // Re-insertion position for inert attributes.
318 // Required for resolving derive helper attributes.
319 derives: Vec<ast::Path>,
327 impl InvocationKind {
328 fn placeholder_visibility(&self) -> Option<ast::Visibility> {
329 // HACK: For unnamed fields placeholders should have the same visibility as the actual
330 // fields because for tuple structs/variants resolve determines visibilities of their
331 // constructor using these field visibilities before attributes on them are are expanded.
332 // The assumption is that the attribute expansion cannot change field visibilities,
333 // and it holds because only inert attributes are supported in this position.
335 InvocationKind::Attr { item: Annotatable::FieldDef(field), .. }
336 | InvocationKind::Derive { item: Annotatable::FieldDef(field), .. }
337 if field.ident.is_none() =>
339 Some(field.vis.clone())
347 pub fn span(&self) -> Span {
349 InvocationKind::Bang { span, .. } => *span,
350 InvocationKind::Attr { attr, .. } => attr.span,
351 InvocationKind::Derive { path, .. } => path.span,
356 pub struct MacroExpander<'a, 'b> {
357 pub cx: &'a mut ExtCtxt<'b>,
358 monotonic: bool, // cf. `cx.monotonic_expander()`
361 impl<'a, 'b> MacroExpander<'a, 'b> {
362 pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
363 MacroExpander { cx, monotonic }
366 pub fn expand_crate(&mut self, krate: ast::Crate) -> ast::Crate {
367 let file_path = match self.cx.source_map().span_to_filename(krate.spans.inner_span) {
368 FileName::Real(name) => name
370 .expect("attempting to resolve a file path in an external file"),
371 other => PathBuf::from(other.prefer_local().to_string()),
373 let dir_path = file_path.parent().unwrap_or(&file_path).to_owned();
374 self.cx.root_path = dir_path.clone();
375 self.cx.current_expansion.module = Rc::new(ModuleData {
376 mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
377 file_path_stack: vec![file_path],
380 let krate = self.fully_expand_fragment(AstFragment::Crate(krate)).make_crate();
381 assert_eq!(krate.id, ast::CRATE_NODE_ID);
382 self.cx.trace_macros_diag();
386 // Recursively expand all macro invocations in this AST fragment.
387 pub fn fully_expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
388 let orig_expansion_data = self.cx.current_expansion.clone();
389 let orig_force_mode = self.cx.force_mode;
391 // Collect all macro invocations and replace them with placeholders.
392 let (mut fragment_with_placeholders, mut invocations) =
393 self.collect_invocations(input_fragment, &[]);
395 // Optimization: if we resolve all imports now,
396 // we'll be able to immediately resolve most of imported macros.
397 self.resolve_imports();
399 // Resolve paths in all invocations and produce output expanded fragments for them, but
400 // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
401 // The output fragments also go through expansion recursively until no invocations are left.
402 // Unresolved macros produce dummy outputs as a recovery measure.
403 invocations.reverse();
404 let mut expanded_fragments = Vec::new();
405 let mut undetermined_invocations = Vec::new();
406 let (mut progress, mut force) = (false, !self.monotonic);
408 let Some((invoc, ext)) = invocations.pop() else {
409 self.resolve_imports();
410 if undetermined_invocations.is_empty() {
413 invocations = mem::take(&mut undetermined_invocations);
414 force = !mem::replace(&mut progress, false);
415 if force && self.monotonic {
416 self.cx.sess.delay_span_bug(
417 invocations.last().unwrap().0.span(),
418 "expansion entered force mode without producing any errors",
424 let ext = match ext {
427 let eager_expansion_root = if self.monotonic {
428 invoc.expansion_data.id
430 orig_expansion_data.id
432 match self.cx.resolver.resolve_macro_invocation(
434 eager_expansion_root,
438 Err(Indeterminate) => {
439 // Cannot resolve, will retry this invocation later.
440 undetermined_invocations.push((invoc, None));
447 let ExpansionData { depth, id: expn_id, .. } = invoc.expansion_data;
448 let depth = depth - orig_expansion_data.depth;
449 self.cx.current_expansion = invoc.expansion_data.clone();
450 self.cx.force_mode = force;
452 let fragment_kind = invoc.fragment_kind;
453 let (expanded_fragment, new_invocations) = match self.expand_invoc(invoc, &ext.kind) {
454 ExpandResult::Ready(fragment) => {
455 let mut derive_invocations = Vec::new();
456 let derive_placeholders = self
459 .take_derive_resolutions(expn_id)
461 derive_invocations.reserve(derives.len());
464 .map(|(path, item, _exts)| {
465 // FIXME: Consider using the derive resolutions (`_exts`)
466 // instead of enqueuing the derives to be resolved again later.
467 let expn_id = LocalExpnId::fresh_empty();
468 derive_invocations.push((
470 kind: InvocationKind::Derive { path, item },
472 expansion_data: ExpansionData {
474 ..self.cx.current_expansion.clone()
479 NodeId::placeholder_from_expn_id(expn_id)
483 .unwrap_or_default();
485 let (fragment, collected_invocations) =
486 self.collect_invocations(fragment, &derive_placeholders);
487 // We choose to expand any derive invocations associated with this macro invocation
488 // *before* any macro invocations collected from the output fragment
489 derive_invocations.extend(collected_invocations);
490 (fragment, derive_invocations)
492 ExpandResult::Retry(invoc) => {
496 "expansion entered force mode but is still stuck",
499 // Cannot expand, will retry this invocation later.
500 undetermined_invocations.push((invoc, Some(ext)));
507 if expanded_fragments.len() < depth {
508 expanded_fragments.push(Vec::new());
510 expanded_fragments[depth - 1].push((expn_id, expanded_fragment));
511 invocations.extend(new_invocations.into_iter().rev());
514 self.cx.current_expansion = orig_expansion_data;
515 self.cx.force_mode = orig_force_mode;
517 // Finally incorporate all the expanded macros into the input AST fragment.
518 let mut placeholder_expander = PlaceholderExpander::default();
519 while let Some(expanded_fragments) = expanded_fragments.pop() {
520 for (expn_id, expanded_fragment) in expanded_fragments.into_iter().rev() {
522 .add(NodeId::placeholder_from_expn_id(expn_id), expanded_fragment);
525 fragment_with_placeholders.mut_visit_with(&mut placeholder_expander);
526 fragment_with_placeholders
529 fn resolve_imports(&mut self) {
531 self.cx.resolver.resolve_imports();
535 /// Collects all macro invocations reachable at this time in this AST fragment, and replace
536 /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
537 /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
538 /// prepares data for resolving paths of macro invocations.
539 fn collect_invocations(
541 mut fragment: AstFragment,
542 extra_placeholders: &[NodeId],
543 ) -> (AstFragment, Vec<(Invocation, Option<Lrc<SyntaxExtension>>)>) {
544 // Resolve `$crate`s in the fragment for pretty-printing.
545 self.cx.resolver.resolve_dollar_crates();
547 let mut invocations = {
548 let mut collector = InvocationCollector {
549 // Non-derive macro invocations cannot see the results of cfg expansion - they
550 // will either be removed along with the item, or invoked before the cfg/cfg_attr
551 // attribute is expanded. Therefore, we don't need to configure the tokens
552 // Derive macros *can* see the results of cfg-expansion - they are handled
553 // specially in `fully_expand_fragment`
555 invocations: Vec::new(),
556 monotonic: self.monotonic,
558 fragment.mut_visit_with(&mut collector);
559 fragment.add_placeholders(extra_placeholders);
560 collector.invocations
566 .visit_ast_fragment_with_placeholders(self.cx.current_expansion.id, &fragment);
568 if self.cx.sess.opts.debugging_opts.incremental_relative_spans {
569 for (invoc, _) in invocations.iter_mut() {
570 let expn_id = invoc.expansion_data.id;
571 let parent_def = self.cx.resolver.invocation_parent(expn_id);
572 let span = match &mut invoc.kind {
573 InvocationKind::Bang { ref mut span, .. } => span,
574 InvocationKind::Attr { attr, .. } => &mut attr.span,
575 InvocationKind::Derive { path, .. } => &mut path.span,
577 *span = span.with_parent(Some(parent_def));
582 (fragment, invocations)
585 fn error_recursion_limit_reached(&mut self) {
586 let expn_data = self.cx.current_expansion.id.expn_data();
587 let suggested_limit = match self.cx.ecfg.recursion_limit {
588 Limit(0) => Limit(2),
594 &format!("recursion limit reached while expanding `{}`", expn_data.kind.descr()),
597 "consider increasing the recursion limit by adding a \
598 `#![recursion_limit = \"{}\"]` attribute to your crate (`{}`)",
599 suggested_limit, self.cx.ecfg.crate_name,
602 self.cx.trace_macros_diag();
605 /// A macro's expansion does not fit in this fragment kind.
606 /// For example, a non-type macro in a type position.
607 fn error_wrong_fragment_kind(&mut self, kind: AstFragmentKind, mac: &ast::MacCall, span: Span) {
609 "non-{kind} macro in {kind} position: {path}",
611 path = pprust::path_to_string(&mac.path),
613 self.cx.span_err(span, &msg);
614 self.cx.trace_macros_diag();
620 ext: &SyntaxExtensionKind,
621 ) -> ExpandResult<AstFragment, Invocation> {
622 let recursion_limit =
623 self.cx.reduced_recursion_limit.unwrap_or(self.cx.ecfg.recursion_limit);
624 if !recursion_limit.value_within_limit(self.cx.current_expansion.depth) {
625 if self.cx.reduced_recursion_limit.is_none() {
626 self.error_recursion_limit_reached();
629 // Reduce the recursion limit by half each time it triggers.
630 self.cx.reduced_recursion_limit = Some(recursion_limit / 2);
632 return ExpandResult::Ready(invoc.fragment_kind.dummy(invoc.span()));
635 let (fragment_kind, span) = (invoc.fragment_kind, invoc.span());
636 ExpandResult::Ready(match invoc.kind {
637 InvocationKind::Bang { mac, .. } => match ext {
638 SyntaxExtensionKind::Bang(expander) => {
639 let Ok(tok_result) = expander.expand(self.cx, span, mac.args.inner_tokens()) else {
640 return ExpandResult::Ready(fragment_kind.dummy(span));
642 self.parse_ast_fragment(tok_result, fragment_kind, &mac.path, span)
644 SyntaxExtensionKind::LegacyBang(expander) => {
645 let prev = self.cx.current_expansion.prior_type_ascription;
646 self.cx.current_expansion.prior_type_ascription = mac.prior_type_ascription;
647 let tok_result = expander.expand(self.cx, span, mac.args.inner_tokens());
648 let result = if let Some(result) = fragment_kind.make_from(tok_result) {
651 self.error_wrong_fragment_kind(fragment_kind, &mac, span);
652 fragment_kind.dummy(span)
654 self.cx.current_expansion.prior_type_ascription = prev;
659 InvocationKind::Attr { attr, pos, mut item, derives } => match ext {
660 SyntaxExtensionKind::Attr(expander) => {
661 self.gate_proc_macro_input(&item);
662 self.gate_proc_macro_attr_item(span, &item);
663 let tokens = match &item {
664 // FIXME: Collect tokens and use them instead of generating
665 // fake ones. These are unstable, so it needs to be
666 // fixed prior to stabilization
667 // Fake tokens when we are invoking an inner attribute, and
668 // we are invoking it on an out-of-line module or crate.
669 Annotatable::Crate(krate) => rustc_parse::fake_token_stream_for_crate(
670 &self.cx.sess.parse_sess,
673 Annotatable::Item(item_inner)
674 if matches!(attr.style, AttrStyle::Inner)
679 ModKind::Unloaded | ModKind::Loaded(_, Inline::No, _),
683 rustc_parse::fake_token_stream(
684 &self.cx.sess.parse_sess,
685 &item.into_nonterminal(),
688 _ => item.into_tokens(&self.cx.sess.parse_sess),
690 let attr_item = attr.unwrap_normal_item();
691 if let MacArgs::Eq(..) = attr_item.args {
692 self.cx.span_err(span, "key-value macro attributes are not supported");
694 let inner_tokens = attr_item.args.inner_tokens();
695 let Ok(tok_result) = expander.expand(self.cx, span, inner_tokens, tokens) else {
696 return ExpandResult::Ready(fragment_kind.dummy(span));
698 self.parse_ast_fragment(tok_result, fragment_kind, &attr_item.path, span)
700 SyntaxExtensionKind::LegacyAttr(expander) => {
701 match validate_attr::parse_meta(&self.cx.sess.parse_sess, &attr) {
703 let items = match expander.expand(self.cx, span, &meta, item) {
704 ExpandResult::Ready(items) => items,
705 ExpandResult::Retry(item) => {
706 // Reassemble the original invocation for retrying.
707 return ExpandResult::Retry(Invocation {
708 kind: InvocationKind::Attr { attr, pos, item, derives },
713 if fragment_kind == AstFragmentKind::Expr && items.is_empty() {
715 "removing an expression is not supported in this position";
716 self.cx.span_err(span, msg);
717 fragment_kind.dummy(span)
719 fragment_kind.expect_from_annotatables(items)
724 fragment_kind.dummy(span)
728 SyntaxExtensionKind::NonMacroAttr => {
729 self.cx.expanded_inert_attrs.mark(&attr);
730 item.visit_attrs(|attrs| attrs.insert(pos, attr));
731 fragment_kind.expect_from_annotatables(iter::once(item))
735 InvocationKind::Derive { path, item } => match ext {
736 SyntaxExtensionKind::Derive(expander)
737 | SyntaxExtensionKind::LegacyDerive(expander) => {
738 if let SyntaxExtensionKind::Derive(..) = ext {
739 self.gate_proc_macro_input(&item);
741 let meta = ast::MetaItem { kind: MetaItemKind::Word, span, path };
742 let items = match expander.expand(self.cx, span, &meta, item) {
743 ExpandResult::Ready(items) => items,
744 ExpandResult::Retry(item) => {
745 // Reassemble the original invocation for retrying.
746 return ExpandResult::Retry(Invocation {
747 kind: InvocationKind::Derive { path: meta.path, item },
752 fragment_kind.expect_from_annotatables(items)
759 fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
760 let kind = match item {
762 | Annotatable::TraitItem(_)
763 | Annotatable::ImplItem(_)
764 | Annotatable::ForeignItem(_)
765 | Annotatable::Crate(..) => return,
766 Annotatable::Stmt(stmt) => {
767 // Attributes are stable on item statements,
768 // but unstable on all other kinds of statements
774 Annotatable::Expr(_) => "expressions",
776 | Annotatable::ExprField(..)
777 | Annotatable::PatField(..)
778 | Annotatable::GenericParam(..)
779 | Annotatable::Param(..)
780 | Annotatable::FieldDef(..)
781 | Annotatable::Variant(..) => panic!("unexpected annotatable"),
783 if self.cx.ecfg.proc_macro_hygiene() {
787 &self.cx.sess.parse_sess,
788 sym::proc_macro_hygiene,
790 &format!("custom attributes cannot be applied to {}", kind),
795 fn gate_proc_macro_input(&self, annotatable: &Annotatable) {
796 struct GateProcMacroInput<'a> {
797 parse_sess: &'a ParseSess,
800 impl<'ast, 'a> Visitor<'ast> for GateProcMacroInput<'a> {
801 fn visit_item(&mut self, item: &'ast ast::Item) {
803 ItemKind::Mod(_, mod_kind)
804 if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _)) =>
808 sym::proc_macro_hygiene,
810 "non-inline modules in proc macro input are unstable",
817 visit::walk_item(self, item);
821 if !self.cx.ecfg.proc_macro_hygiene() {
823 .visit_with(&mut GateProcMacroInput { parse_sess: &self.cx.sess.parse_sess });
827 fn parse_ast_fragment(
830 kind: AstFragmentKind,
834 let mut parser = self.cx.new_parser_from_tts(toks);
835 match parse_ast_fragment(&mut parser, kind) {
837 ensure_complete_parse(&mut parser, path, kind.name(), span);
841 if err.span.is_dummy() {
844 annotate_err_with_kind(&mut err, kind, span);
846 self.cx.trace_macros_diag();
853 pub fn parse_ast_fragment<'a>(
854 this: &mut Parser<'a>,
855 kind: AstFragmentKind,
856 ) -> PResult<'a, AstFragment> {
858 AstFragmentKind::Items => {
859 let mut items = SmallVec::new();
860 while let Some(item) = this.parse_item(ForceCollect::No)? {
863 AstFragment::Items(items)
865 AstFragmentKind::TraitItems => {
866 let mut items = SmallVec::new();
867 while let Some(item) = this.parse_trait_item(ForceCollect::No)? {
870 AstFragment::TraitItems(items)
872 AstFragmentKind::ImplItems => {
873 let mut items = SmallVec::new();
874 while let Some(item) = this.parse_impl_item(ForceCollect::No)? {
877 AstFragment::ImplItems(items)
879 AstFragmentKind::ForeignItems => {
880 let mut items = SmallVec::new();
881 while let Some(item) = this.parse_foreign_item(ForceCollect::No)? {
884 AstFragment::ForeignItems(items)
886 AstFragmentKind::Stmts => {
887 let mut stmts = SmallVec::new();
888 // Won't make progress on a `}`.
889 while this.token != token::Eof && this.token != token::CloseDelim(token::Brace) {
890 if let Some(stmt) = this.parse_full_stmt(AttemptLocalParseRecovery::Yes)? {
894 AstFragment::Stmts(stmts)
896 AstFragmentKind::Expr => AstFragment::Expr(this.parse_expr()?),
897 AstFragmentKind::OptExpr => {
898 if this.token != token::Eof {
899 AstFragment::OptExpr(Some(this.parse_expr()?))
901 AstFragment::OptExpr(None)
904 AstFragmentKind::Ty => AstFragment::Ty(this.parse_ty()?),
905 AstFragmentKind::Pat => AstFragment::Pat(this.parse_pat_allow_top_alt(
909 CommaRecoveryMode::LikelyTuple,
911 AstFragmentKind::Crate => AstFragment::Crate(this.parse_crate_mod()?),
912 AstFragmentKind::Arms
913 | AstFragmentKind::ExprFields
914 | AstFragmentKind::PatFields
915 | AstFragmentKind::GenericParams
916 | AstFragmentKind::Params
917 | AstFragmentKind::FieldDefs
918 | AstFragmentKind::Variants => panic!("unexpected AST fragment kind"),
922 pub fn ensure_complete_parse<'a>(
923 this: &mut Parser<'a>,
924 macro_path: &ast::Path,
928 if this.token != token::Eof {
929 let token = pprust::token_to_string(&this.token);
930 let msg = format!("macro expansion ignores token `{}` and any following", token);
931 // Avoid emitting backtrace info twice.
932 let def_site_span = this.token.span.with_ctxt(SyntaxContext::root());
933 let mut err = this.struct_span_err(def_site_span, &msg);
934 err.span_label(span, "caused by the macro expansion here");
936 "the usage of `{}!` is likely invalid in {} context",
937 pprust::path_to_string(macro_path),
941 let semi_span = this.sess.source_map().next_point(span);
943 let semi_full_span = semi_span.to(this.sess.source_map().next_point(semi_span));
944 match this.sess.source_map().span_to_snippet(semi_full_span) {
945 Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
948 "you might be missing a semicolon here",
950 Applicability::MaybeIncorrect,
959 /// Wraps a call to `noop_visit_*` / `noop_flat_map_*`
960 /// for an AST node that supports attributes
961 /// (see the `Annotatable` enum)
962 /// This method assigns a `NodeId`, and sets that `NodeId`
963 /// as our current 'lint node id'. If a macro call is found
964 /// inside this AST node, we will use this AST node's `NodeId`
965 /// to emit lints associated with that macro (allowing
966 /// `#[allow]` / `#[deny]` to be applied close to
967 /// the macro invocation).
969 /// Do *not* call this for a macro AST node
970 /// (e.g. `ExprKind::MacCall`) - we cannot emit lints
971 /// at these AST nodes, since they are removed and
972 /// replaced with the result of macro expansion.
974 /// All other `NodeId`s are assigned by `visit_id`.
975 /// * `self` is the 'self' parameter for the current method,
976 /// * `id` is a mutable reference to the `NodeId` field
977 /// of the current AST node.
978 /// * `closure` is a closure that executes the
979 /// `noop_visit_*` / `noop_flat_map_*` method
980 /// for the current AST node.
981 macro_rules! assign_id {
982 ($self:ident, $id:expr, $closure:expr) => {{
983 let old_id = $self.cx.current_expansion.lint_node_id;
985 debug_assert_eq!(*$id, ast::DUMMY_NODE_ID);
986 let new_id = $self.cx.resolver.next_node_id();
988 $self.cx.current_expansion.lint_node_id = new_id;
990 let ret = ($closure)();
991 $self.cx.current_expansion.lint_node_id = old_id;
1001 /// A trait implemented for all `AstFragment` nodes and providing all pieces
1002 /// of functionality used by `InvocationCollector`.
1003 trait InvocationCollectorNode: AstLike {
1004 type OutputTy = SmallVec<[Self; 1]>;
1005 type AttrsTy: Deref<Target = [ast::Attribute]> = Vec<ast::Attribute>;
1006 const KIND: AstFragmentKind;
1007 fn to_annotatable(self) -> Annotatable;
1008 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy;
1009 fn id(&mut self) -> &mut NodeId;
1010 fn descr() -> &'static str {
1013 fn noop_flat_map<V: MutVisitor>(self, _visitor: &mut V) -> Self::OutputTy {
1016 fn noop_visit<V: MutVisitor>(&mut self, _visitor: &mut V) {
1019 fn is_mac_call(&self) -> bool {
1022 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1025 fn pre_flat_map_node_collect_attr(_cfg: &StripUnconfigured<'_>, _attr: &ast::Attribute) {}
1026 fn post_flat_map_node_collect_bang(_output: &mut Self::OutputTy, _add_semicolon: AddSemicolon) {
1028 fn wrap_flat_map_node_noop_flat_map(
1030 collector: &mut InvocationCollector<'_, '_>,
1031 noop_flat_map: impl FnOnce(Self, &mut InvocationCollector<'_, '_>) -> Self::OutputTy,
1032 ) -> Result<Self::OutputTy, Self> {
1033 Ok(noop_flat_map(node, collector))
1037 impl InvocationCollectorNode for P<ast::Item> {
1038 const KIND: AstFragmentKind = AstFragmentKind::Items;
1039 fn to_annotatable(self) -> Annotatable {
1040 Annotatable::Item(self)
1042 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1043 fragment.make_items()
1045 fn id(&mut self) -> &mut NodeId {
1048 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1049 noop_flat_map_item(self, visitor)
1051 fn is_mac_call(&self) -> bool {
1052 matches!(self.kind, ItemKind::MacCall(..))
1054 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1055 let node = self.into_inner();
1057 ItemKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
1058 _ => unreachable!(),
1061 fn wrap_flat_map_node_noop_flat_map(
1063 collector: &mut InvocationCollector<'_, '_>,
1064 noop_flat_map: impl FnOnce(Self, &mut InvocationCollector<'_, '_>) -> Self::OutputTy,
1065 ) -> Result<Self::OutputTy, Self> {
1066 if !matches!(node.kind, ItemKind::Mod(..)) {
1067 return Ok(noop_flat_map(node, collector));
1070 // Work around borrow checker not seeing through `P`'s deref.
1071 let (ident, span, mut attrs) = (node.ident, node.span, mem::take(&mut node.attrs));
1072 let ItemKind::Mod(_, mod_kind) = &mut node.kind else {
1076 let ecx = &mut collector.cx;
1077 let (file_path, dir_path, dir_ownership) = match mod_kind {
1078 ModKind::Loaded(_, inline, _) => {
1079 // Inline `mod foo { ... }`, but we still need to push directories.
1080 let (dir_path, dir_ownership) = mod_dir_path(
1084 &ecx.current_expansion.module,
1085 ecx.current_expansion.dir_ownership,
1089 (None, dir_path, dir_ownership)
1091 ModKind::Unloaded => {
1092 // We have an outline `mod foo;` so we need to parse the file.
1093 let old_attrs_len = attrs.len();
1094 let ParsedExternalMod { items, spans, file_path, dir_path, dir_ownership } =
1099 &ecx.current_expansion.module,
1100 ecx.current_expansion.dir_ownership,
1104 if let Some(lint_store) = ecx.lint_store {
1105 lint_store.pre_expansion_lint(
1107 ecx.resolver.registered_tools(),
1108 ecx.current_expansion.lint_node_id,
1111 ident.name.as_str(),
1115 *mod_kind = ModKind::Loaded(items, Inline::No, spans);
1117 if node.attrs.len() > old_attrs_len {
1118 // If we loaded an out-of-line module and added some inner attributes,
1119 // then we need to re-configure it and re-collect attributes for
1120 // resolution and expansion.
1123 (Some(file_path), dir_path, dir_ownership)
1127 // Set the module info before we flat map.
1128 let mut module = ecx.current_expansion.module.with_dir_path(dir_path);
1129 module.mod_path.push(ident);
1130 if let Some(file_path) = file_path {
1131 module.file_path_stack.push(file_path);
1134 let orig_module = mem::replace(&mut ecx.current_expansion.module, Rc::new(module));
1135 let orig_dir_ownership =
1136 mem::replace(&mut ecx.current_expansion.dir_ownership, dir_ownership);
1138 let res = Ok(noop_flat_map(node, collector));
1140 collector.cx.current_expansion.dir_ownership = orig_dir_ownership;
1141 collector.cx.current_expansion.module = orig_module;
1146 struct TraitItemTag;
1147 impl InvocationCollectorNode for AstLikeWrapper<P<ast::AssocItem>, TraitItemTag> {
1148 type OutputTy = SmallVec<[P<ast::AssocItem>; 1]>;
1149 const KIND: AstFragmentKind = AstFragmentKind::TraitItems;
1150 fn to_annotatable(self) -> Annotatable {
1151 Annotatable::TraitItem(self.wrapped)
1153 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1154 fragment.make_trait_items()
1156 fn id(&mut self) -> &mut NodeId {
1157 &mut self.wrapped.id
1159 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1160 noop_flat_map_assoc_item(self.wrapped, visitor)
1162 fn is_mac_call(&self) -> bool {
1163 matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
1165 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1166 let item = self.wrapped.into_inner();
1168 AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
1169 _ => unreachable!(),
1175 impl InvocationCollectorNode for AstLikeWrapper<P<ast::AssocItem>, ImplItemTag> {
1176 type OutputTy = SmallVec<[P<ast::AssocItem>; 1]>;
1177 const KIND: AstFragmentKind = AstFragmentKind::ImplItems;
1178 fn to_annotatable(self) -> Annotatable {
1179 Annotatable::ImplItem(self.wrapped)
1181 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1182 fragment.make_impl_items()
1184 fn id(&mut self) -> &mut NodeId {
1185 &mut self.wrapped.id
1187 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1188 noop_flat_map_assoc_item(self.wrapped, visitor)
1190 fn is_mac_call(&self) -> bool {
1191 matches!(self.wrapped.kind, AssocItemKind::MacCall(..))
1193 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1194 let item = self.wrapped.into_inner();
1196 AssocItemKind::MacCall(mac) => (mac, item.attrs, AddSemicolon::No),
1197 _ => unreachable!(),
1202 impl InvocationCollectorNode for P<ast::ForeignItem> {
1203 const KIND: AstFragmentKind = AstFragmentKind::ForeignItems;
1204 fn to_annotatable(self) -> Annotatable {
1205 Annotatable::ForeignItem(self)
1207 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1208 fragment.make_foreign_items()
1210 fn id(&mut self) -> &mut NodeId {
1213 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1214 noop_flat_map_foreign_item(self, visitor)
1216 fn is_mac_call(&self) -> bool {
1217 matches!(self.kind, ForeignItemKind::MacCall(..))
1219 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1220 let node = self.into_inner();
1222 ForeignItemKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
1223 _ => unreachable!(),
1228 impl InvocationCollectorNode for ast::Variant {
1229 const KIND: AstFragmentKind = AstFragmentKind::Variants;
1230 fn to_annotatable(self) -> Annotatable {
1231 Annotatable::Variant(self)
1233 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1234 fragment.make_variants()
1236 fn id(&mut self) -> &mut NodeId {
1239 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1240 noop_flat_map_variant(self, visitor)
1244 impl InvocationCollectorNode for ast::FieldDef {
1245 const KIND: AstFragmentKind = AstFragmentKind::FieldDefs;
1246 fn to_annotatable(self) -> Annotatable {
1247 Annotatable::FieldDef(self)
1249 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1250 fragment.make_field_defs()
1252 fn id(&mut self) -> &mut NodeId {
1255 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1256 noop_flat_map_field_def(self, visitor)
1260 impl InvocationCollectorNode for ast::PatField {
1261 const KIND: AstFragmentKind = AstFragmentKind::PatFields;
1262 fn to_annotatable(self) -> Annotatable {
1263 Annotatable::PatField(self)
1265 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1266 fragment.make_pat_fields()
1268 fn id(&mut self) -> &mut NodeId {
1271 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1272 noop_flat_map_pat_field(self, visitor)
1276 impl InvocationCollectorNode for ast::ExprField {
1277 const KIND: AstFragmentKind = AstFragmentKind::ExprFields;
1278 fn to_annotatable(self) -> Annotatable {
1279 Annotatable::ExprField(self)
1281 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1282 fragment.make_expr_fields()
1284 fn id(&mut self) -> &mut NodeId {
1287 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1288 noop_flat_map_expr_field(self, visitor)
1292 impl InvocationCollectorNode for ast::Param {
1293 const KIND: AstFragmentKind = AstFragmentKind::Params;
1294 fn to_annotatable(self) -> Annotatable {
1295 Annotatable::Param(self)
1297 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1298 fragment.make_params()
1300 fn id(&mut self) -> &mut NodeId {
1303 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1304 noop_flat_map_param(self, visitor)
1308 impl InvocationCollectorNode for ast::GenericParam {
1309 const KIND: AstFragmentKind = AstFragmentKind::GenericParams;
1310 fn to_annotatable(self) -> Annotatable {
1311 Annotatable::GenericParam(self)
1313 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1314 fragment.make_generic_params()
1316 fn id(&mut self) -> &mut NodeId {
1319 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1320 noop_flat_map_generic_param(self, visitor)
1324 impl InvocationCollectorNode for ast::Arm {
1325 const KIND: AstFragmentKind = AstFragmentKind::Arms;
1326 fn to_annotatable(self) -> Annotatable {
1327 Annotatable::Arm(self)
1329 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1330 fragment.make_arms()
1332 fn id(&mut self) -> &mut NodeId {
1335 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1336 noop_flat_map_arm(self, visitor)
1340 impl InvocationCollectorNode for ast::Stmt {
1341 type AttrsTy = ast::AttrVec;
1342 const KIND: AstFragmentKind = AstFragmentKind::Stmts;
1343 fn to_annotatable(self) -> Annotatable {
1344 Annotatable::Stmt(P(self))
1346 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1347 fragment.make_stmts()
1349 fn id(&mut self) -> &mut NodeId {
1352 fn noop_flat_map<V: MutVisitor>(self, visitor: &mut V) -> Self::OutputTy {
1353 noop_flat_map_stmt(self, visitor)
1355 fn is_mac_call(&self) -> bool {
1357 StmtKind::MacCall(..) => true,
1358 StmtKind::Item(item) => matches!(item.kind, ItemKind::MacCall(..)),
1359 StmtKind::Semi(expr) => matches!(expr.kind, ExprKind::MacCall(..)),
1360 StmtKind::Expr(..) => unreachable!(),
1361 StmtKind::Local(..) | StmtKind::Empty => false,
1364 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1365 // We pull macro invocations (both attributes and fn-like macro calls) out of their
1366 // `StmtKind`s and treat them as statement macro invocations, not as items or expressions.
1367 let (add_semicolon, mac, attrs) = match self.kind {
1368 StmtKind::MacCall(mac) => {
1369 let ast::MacCallStmt { mac, style, attrs, .. } = mac.into_inner();
1370 (style == MacStmtStyle::Semicolon, mac, attrs)
1372 StmtKind::Item(item) => match item.into_inner() {
1373 ast::Item { kind: ItemKind::MacCall(mac), attrs, .. } => {
1374 (mac.args.need_semicolon(), mac, attrs.into())
1376 _ => unreachable!(),
1378 StmtKind::Semi(expr) => match expr.into_inner() {
1379 ast::Expr { kind: ExprKind::MacCall(mac), attrs, .. } => {
1380 (mac.args.need_semicolon(), mac, attrs)
1382 _ => unreachable!(),
1384 _ => unreachable!(),
1386 (mac, attrs, if add_semicolon { AddSemicolon::Yes } else { AddSemicolon::No })
1388 fn post_flat_map_node_collect_bang(stmts: &mut Self::OutputTy, add_semicolon: AddSemicolon) {
1389 // If this is a macro invocation with a semicolon, then apply that
1390 // semicolon to the final statement produced by expansion.
1391 if matches!(add_semicolon, AddSemicolon::Yes) {
1392 if let Some(stmt) = stmts.pop() {
1393 stmts.push(stmt.add_trailing_semicolon());
1399 impl InvocationCollectorNode for ast::Crate {
1400 type OutputTy = ast::Crate;
1401 const KIND: AstFragmentKind = AstFragmentKind::Crate;
1402 fn to_annotatable(self) -> Annotatable {
1403 Annotatable::Crate(self)
1405 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1406 fragment.make_crate()
1408 fn id(&mut self) -> &mut NodeId {
1411 fn noop_visit<V: MutVisitor>(&mut self, visitor: &mut V) {
1412 noop_visit_crate(self, visitor)
1416 impl InvocationCollectorNode for P<ast::Ty> {
1417 type OutputTy = P<ast::Ty>;
1418 const KIND: AstFragmentKind = AstFragmentKind::Ty;
1419 fn to_annotatable(self) -> Annotatable {
1422 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1425 fn id(&mut self) -> &mut NodeId {
1428 fn noop_visit<V: MutVisitor>(&mut self, visitor: &mut V) {
1429 noop_visit_ty(self, visitor)
1431 fn is_mac_call(&self) -> bool {
1432 matches!(self.kind, ast::TyKind::MacCall(..))
1434 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1435 let node = self.into_inner();
1437 TyKind::MacCall(mac) => (mac, Vec::new(), AddSemicolon::No),
1438 _ => unreachable!(),
1443 impl InvocationCollectorNode for P<ast::Pat> {
1444 type OutputTy = P<ast::Pat>;
1445 const KIND: AstFragmentKind = AstFragmentKind::Pat;
1446 fn to_annotatable(self) -> Annotatable {
1449 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1452 fn id(&mut self) -> &mut NodeId {
1455 fn noop_visit<V: MutVisitor>(&mut self, visitor: &mut V) {
1456 noop_visit_pat(self, visitor)
1458 fn is_mac_call(&self) -> bool {
1459 matches!(self.kind, PatKind::MacCall(..))
1461 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1462 let node = self.into_inner();
1464 PatKind::MacCall(mac) => (mac, Vec::new(), AddSemicolon::No),
1465 _ => unreachable!(),
1470 impl InvocationCollectorNode for P<ast::Expr> {
1471 type OutputTy = P<ast::Expr>;
1472 type AttrsTy = ast::AttrVec;
1473 const KIND: AstFragmentKind = AstFragmentKind::Expr;
1474 fn to_annotatable(self) -> Annotatable {
1475 Annotatable::Expr(self)
1477 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1478 fragment.make_expr()
1480 fn id(&mut self) -> &mut NodeId {
1483 fn descr() -> &'static str {
1486 fn noop_visit<V: MutVisitor>(&mut self, visitor: &mut V) {
1487 noop_visit_expr(self, visitor)
1489 fn is_mac_call(&self) -> bool {
1490 matches!(self.kind, ExprKind::MacCall(..))
1492 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1493 let node = self.into_inner();
1495 ExprKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
1496 _ => unreachable!(),
1502 impl InvocationCollectorNode for AstLikeWrapper<P<ast::Expr>, OptExprTag> {
1503 type OutputTy = Option<P<ast::Expr>>;
1504 type AttrsTy = ast::AttrVec;
1505 const KIND: AstFragmentKind = AstFragmentKind::OptExpr;
1506 fn to_annotatable(self) -> Annotatable {
1507 Annotatable::Expr(self.wrapped)
1509 fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
1510 fragment.make_opt_expr()
1512 fn id(&mut self) -> &mut NodeId {
1513 &mut self.wrapped.id
1515 fn noop_flat_map<V: MutVisitor>(mut self, visitor: &mut V) -> Self::OutputTy {
1516 noop_visit_expr(&mut self.wrapped, visitor);
1519 fn is_mac_call(&self) -> bool {
1520 matches!(self.wrapped.kind, ast::ExprKind::MacCall(..))
1522 fn take_mac_call(self) -> (ast::MacCall, Self::AttrsTy, AddSemicolon) {
1523 let node = self.wrapped.into_inner();
1525 ExprKind::MacCall(mac) => (mac, node.attrs, AddSemicolon::No),
1526 _ => unreachable!(),
1529 fn pre_flat_map_node_collect_attr(cfg: &StripUnconfigured<'_>, attr: &ast::Attribute) {
1530 cfg.maybe_emit_expr_attr_err(&attr);
1534 struct InvocationCollector<'a, 'b> {
1535 cx: &'a mut ExtCtxt<'b>,
1536 invocations: Vec<(Invocation, Option<Lrc<SyntaxExtension>>)>,
1540 impl<'a, 'b> InvocationCollector<'a, 'b> {
1541 fn cfg(&self) -> StripUnconfigured<'_> {
1543 sess: &self.cx.sess,
1544 features: self.cx.ecfg.features,
1545 config_tokens: false,
1546 lint_node_id: self.cx.current_expansion.lint_node_id,
1550 fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
1551 let expn_id = LocalExpnId::fresh_empty();
1552 let vis = kind.placeholder_visibility();
1553 self.invocations.push((
1557 expansion_data: ExpansionData {
1559 depth: self.cx.current_expansion.depth + 1,
1560 ..self.cx.current_expansion.clone()
1565 placeholder(fragment_kind, NodeId::placeholder_from_expn_id(expn_id), vis)
1568 fn collect_bang(&mut self, mac: ast::MacCall, kind: AstFragmentKind) -> AstFragment {
1569 // cache the macro call span so that it can be
1570 // easily adjusted for incremental compilation
1571 let span = mac.span();
1572 self.collect(kind, InvocationKind::Bang { mac, span })
1577 (attr, pos, derives): (ast::Attribute, usize, Vec<ast::Path>),
1579 kind: AstFragmentKind,
1581 self.collect(kind, InvocationKind::Attr { attr, pos, item, derives })
1584 /// If `item` is an attribute invocation, remove the attribute and return it together with
1585 /// its position and derives following it. We have to collect the derives in order to resolve
1586 /// legacy derive helpers (helpers written before derives that introduce them).
1589 item: &mut impl AstLike,
1590 ) -> Option<(ast::Attribute, usize, Vec<ast::Path>)> {
1591 let mut attr = None;
1593 let mut cfg_pos = None;
1594 let mut attr_pos = None;
1595 for (pos, attr) in item.attrs().iter().enumerate() {
1596 if !attr.is_doc_comment() && !self.cx.expanded_inert_attrs.is_marked(attr) {
1597 let name = attr.ident().map(|ident| ident.name);
1598 if name == Some(sym::cfg) || name == Some(sym::cfg_attr) {
1599 cfg_pos = Some(pos); // a cfg attr found, no need to search anymore
1601 } else if attr_pos.is_none()
1602 && !name.map_or(false, rustc_feature::is_builtin_attr_name)
1604 attr_pos = Some(pos); // a non-cfg attr found, still may find a cfg attr
1609 item.visit_attrs(|attrs| {
1610 attr = Some(match (cfg_pos, attr_pos) {
1611 (Some(pos), _) => (attrs.remove(pos), pos, Vec::new()),
1613 let attr = attrs.remove(pos);
1614 let following_derives = attrs[pos..]
1616 .filter(|a| a.has_name(sym::derive))
1617 .flat_map(|a| a.meta_item_list().unwrap_or_default())
1618 .filter_map(|nested_meta| match nested_meta {
1619 NestedMetaItem::MetaItem(ast::MetaItem {
1620 kind: MetaItemKind::Word,
1628 (attr, pos, following_derives)
1637 // Detect use of feature-gated or invalid attributes on macro invocations
1638 // since they will not be detected after macro expansion.
1639 fn check_attributes(&self, attrs: &[ast::Attribute], call: &ast::MacCall) {
1640 let features = self.cx.ecfg.features.unwrap();
1641 let mut attrs = attrs.iter().peekable();
1642 let mut span: Option<Span> = None;
1643 while let Some(attr) = attrs.next() {
1644 rustc_ast_passes::feature_gate::check_attribute(attr, self.cx.sess, features);
1645 validate_attr::check_meta(&self.cx.sess.parse_sess, attr);
1647 let current_span = if let Some(sp) = span { sp.to(attr.span) } else { attr.span };
1648 span = Some(current_span);
1650 if attrs.peek().map_or(false, |next_attr| next_attr.doc_str().is_some()) {
1654 if attr.is_doc_comment() {
1655 self.cx.sess.parse_sess.buffer_lint_with_diagnostic(
1656 &UNUSED_DOC_COMMENTS,
1658 self.cx.current_expansion.lint_node_id,
1659 "unused doc comment",
1660 BuiltinLintDiagnostics::UnusedDocComment(attr.span),
1662 } else if rustc_attr::is_builtin_attr(attr) {
1663 let attr_name = attr.ident().unwrap().name;
1664 // `#[cfg]` and `#[cfg_attr]` are special - they are
1665 // eagerly evaluated.
1666 if attr_name != sym::cfg && attr_name != sym::cfg_attr {
1667 self.cx.sess.parse_sess.buffer_lint_with_diagnostic(
1670 self.cx.current_expansion.lint_node_id,
1671 &format!("unused attribute `{}`", attr_name),
1672 BuiltinLintDiagnostics::UnusedBuiltinAttribute {
1674 macro_name: pprust::path_to_string(&call.path),
1675 invoc_span: call.path.span,
1685 node: &mut impl AstLike,
1686 attr: ast::Attribute,
1689 let res = self.cfg().cfg_true(&attr);
1691 // FIXME: `cfg(TRUE)` attributes do not currently remove themselves during expansion,
1692 // and some tools like rustdoc and clippy rely on that. Find a way to remove them
1693 // while keeping the tools working.
1694 self.cx.expanded_inert_attrs.mark(&attr);
1695 node.visit_attrs(|attrs| attrs.insert(pos, attr));
1700 fn expand_cfg_attr(&self, node: &mut impl AstLike, attr: ast::Attribute, pos: usize) {
1701 node.visit_attrs(|attrs| {
1702 attrs.splice(pos..pos, self.cfg().expand_cfg_attr(attr, false));
1706 fn flat_map_node<Node: InvocationCollectorNode<OutputTy: Default>>(
1709 ) -> Node::OutputTy {
1711 return match self.take_first_attr(&mut node) {
1712 Some((attr, pos, derives)) => match attr.name_or_empty() {
1714 if self.expand_cfg_true(&mut node, attr, pos) {
1720 self.expand_cfg_attr(&mut node, attr, pos);
1724 Node::pre_flat_map_node_collect_attr(&self.cfg(), &attr);
1725 self.collect_attr((attr, pos, derives), node.to_annotatable(), Node::KIND)
1729 None if node.is_mac_call() => {
1730 let (mac, attrs, add_semicolon) = node.take_mac_call();
1731 self.check_attributes(&attrs, &mac);
1732 let mut res = self.collect_bang(mac, Node::KIND).make_ast::<Node>();
1733 Node::post_flat_map_node_collect_bang(&mut res, add_semicolon);
1737 match Node::wrap_flat_map_node_noop_flat_map(node, self, |mut node, this| {
1738 assign_id!(this, node.id(), || node.noop_flat_map(this))
1740 Ok(output) => output,
1741 Err(returned_node) => {
1742 node = returned_node;
1751 fn visit_node<Node: InvocationCollectorNode<OutputTy = Node> + DummyAstNode>(
1756 return match self.take_first_attr(node) {
1757 Some((attr, pos, derives)) => match attr.name_or_empty() {
1759 let span = attr.span;
1760 if self.expand_cfg_true(node, attr, pos) {
1764 format!("removing {} is not supported in this position", Node::descr());
1765 self.cx.span_err(span, &msg);
1769 self.expand_cfg_attr(node, attr, pos);
1772 _ => visit_clobber(node, |node| {
1773 self.collect_attr((attr, pos, derives), node.to_annotatable(), Node::KIND)
1777 None if node.is_mac_call() => {
1778 visit_clobber(node, |node| {
1779 // Do not clobber unless it's actually a macro (uncommon case).
1780 let (mac, attrs, _) = node.take_mac_call();
1781 self.check_attributes(&attrs, &mac);
1782 self.collect_bang(mac, Node::KIND).make_ast::<Node>()
1786 assign_id!(self, node.id(), || node.noop_visit(self))
1793 impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
1794 fn flat_map_item(&mut self, node: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
1795 self.flat_map_node(node)
1798 fn flat_map_trait_item(&mut self, node: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
1799 self.flat_map_node(AstLikeWrapper::new(node, TraitItemTag))
1802 fn flat_map_impl_item(&mut self, node: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
1803 self.flat_map_node(AstLikeWrapper::new(node, ImplItemTag))
1806 fn flat_map_foreign_item(
1808 node: P<ast::ForeignItem>,
1809 ) -> SmallVec<[P<ast::ForeignItem>; 1]> {
1810 self.flat_map_node(node)
1813 fn flat_map_variant(&mut self, node: ast::Variant) -> SmallVec<[ast::Variant; 1]> {
1814 self.flat_map_node(node)
1817 fn flat_map_field_def(&mut self, node: ast::FieldDef) -> SmallVec<[ast::FieldDef; 1]> {
1818 self.flat_map_node(node)
1821 fn flat_map_pat_field(&mut self, node: ast::PatField) -> SmallVec<[ast::PatField; 1]> {
1822 self.flat_map_node(node)
1825 fn flat_map_expr_field(&mut self, node: ast::ExprField) -> SmallVec<[ast::ExprField; 1]> {
1826 self.flat_map_node(node)
1829 fn flat_map_param(&mut self, node: ast::Param) -> SmallVec<[ast::Param; 1]> {
1830 self.flat_map_node(node)
1833 fn flat_map_generic_param(
1835 node: ast::GenericParam,
1836 ) -> SmallVec<[ast::GenericParam; 1]> {
1837 self.flat_map_node(node)
1840 fn flat_map_arm(&mut self, node: ast::Arm) -> SmallVec<[ast::Arm; 1]> {
1841 self.flat_map_node(node)
1844 fn flat_map_stmt(&mut self, node: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
1845 // FIXME: invocations in semicolon-less expressions positions are expanded as expressions,
1846 // changing that requires some compatibility measures.
1848 // The only way that we can end up with a `MacCall` expression statement,
1849 // (as opposed to a `StmtKind::MacCall`) is if we have a macro as the
1850 // trailing expression in a block (e.g. `fn foo() { my_macro!() }`).
1851 // Record this information, so that we can report a more specific
1852 // `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint if needed.
1853 // See #78991 for an investigation of treating macros in this position
1854 // as statements, rather than expressions, during parsing.
1855 return match &node.kind {
1856 StmtKind::Expr(expr)
1857 if matches!(**expr, ast::Expr { kind: ExprKind::MacCall(..), .. }) =>
1859 self.cx.current_expansion.is_trailing_mac = true;
1860 // Don't use `assign_id` for this statement - it may get removed
1861 // entirely due to a `#[cfg]` on the contained expression
1862 let res = noop_flat_map_stmt(node, self);
1863 self.cx.current_expansion.is_trailing_mac = false;
1866 _ => noop_flat_map_stmt(node, self),
1870 self.flat_map_node(node)
1873 fn visit_crate(&mut self, node: &mut ast::Crate) {
1874 self.visit_node(node)
1877 fn visit_ty(&mut self, node: &mut P<ast::Ty>) {
1878 self.visit_node(node)
1881 fn visit_pat(&mut self, node: &mut P<ast::Pat>) {
1882 self.visit_node(node)
1885 fn visit_expr(&mut self, node: &mut P<ast::Expr>) {
1886 // FIXME: Feature gating is performed inconsistently between `Expr` and `OptExpr`.
1887 if let Some(attr) = node.attrs.first() {
1888 self.cfg().maybe_emit_expr_attr_err(attr);
1890 self.visit_node(node)
1893 fn filter_map_expr(&mut self, node: P<ast::Expr>) -> Option<P<ast::Expr>> {
1894 self.flat_map_node(AstLikeWrapper::new(node, OptExprTag))
1897 fn visit_block(&mut self, node: &mut P<ast::Block>) {
1898 let orig_dir_ownership = mem::replace(
1899 &mut self.cx.current_expansion.dir_ownership,
1900 DirOwnership::UnownedViaBlock,
1902 noop_visit_block(node, self);
1903 self.cx.current_expansion.dir_ownership = orig_dir_ownership;
1906 fn visit_id(&mut self, id: &mut NodeId) {
1907 // We may have already assigned a `NodeId`
1908 // by calling `assign_id`
1909 if self.monotonic && *id == ast::DUMMY_NODE_ID {
1910 *id = self.cx.resolver.next_node_id();
1915 pub struct ExpansionConfig<'feat> {
1916 pub crate_name: String,
1917 pub features: Option<&'feat Features>,
1918 pub recursion_limit: Limit,
1919 pub trace_mac: bool,
1920 pub should_test: bool, // If false, strip `#[test]` nodes
1921 pub span_debug: bool, // If true, use verbose debugging for `proc_macro::Span`
1922 pub proc_macro_backtrace: bool, // If true, show backtraces for proc-macro panics
1925 impl<'feat> ExpansionConfig<'feat> {
1926 pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1930 recursion_limit: Limit::new(1024),
1934 proc_macro_backtrace: false,
1938 fn proc_macro_hygiene(&self) -> bool {
1939 self.features.map_or(false, |features| features.proc_macro_hygiene)