1 use ast::{self, Block, Ident, LitKind, NodeId, PatKind, Path};
2 use ast::{MacStmtStyle, StmtKind, ItemKind};
3 use attr::{self, HasAttrs};
4 use source_map::{ExpnInfo, MacroBang, MacroAttribute, dummy_spanned, respan};
5 use config::StripUnconfigured;
6 use errors::{Applicability, FatalError};
8 use ext::derive::{add_derived_markers, collect_derives};
9 use ext::hygiene::{self, Mark, SyntaxContext};
10 use ext::placeholders::{placeholder, PlaceholderExpander};
11 use feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
14 use parse::{DirectoryOwnership, PResult, ParseSess};
15 use parse::token::{self, Token};
16 use parse::parser::Parser;
18 use smallvec::SmallVec;
21 use syntax_pos::{Span, DUMMY_SP, FileName};
22 use syntax_pos::hygiene::ExpnFormat;
23 use tokenstream::{TokenStream, TokenTree};
24 use visit::{self, Visitor};
26 use rustc_data_structures::fx::FxHashMap;
28 use std::io::ErrorKind;
31 use std::path::PathBuf;
33 macro_rules! ast_fragments {
35 $($Kind:ident($AstTy:ty) {
37 // FIXME: HACK: this should be `$(one ...)?` and `$(many ...)?` but `?` macro
38 // repetition was removed from 2015 edition in #51587 because of ambiguities.
39 $(one fn $fold_ast:ident; fn $visit_ast:ident;)*
40 $(many fn $fold_ast_elt:ident; fn $visit_ast_elt:ident;)*
44 /// A fragment of AST that can be produced by a single macro expansion.
45 /// Can also serve as an input and intermediate result for macro expansion operations.
46 pub enum AstFragment {
47 OptExpr(Option<P<ast::Expr>>),
51 /// "Discriminant" of an AST fragment.
52 #[derive(Copy, Clone, PartialEq, Eq)]
53 pub enum AstFragmentKind {
58 impl AstFragmentKind {
59 pub fn name(self) -> &'static str {
61 AstFragmentKind::OptExpr => "expression",
62 $(AstFragmentKind::$Kind => $kind_name,)*
66 fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
68 AstFragmentKind::OptExpr =>
69 result.make_expr().map(Some).map(AstFragment::OptExpr),
70 $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
76 pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
78 AstFragment::OptExpr(expr) => expr,
79 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
83 $(pub fn $make_ast(self) -> $AstTy {
85 AstFragment::$Kind(ast) => ast,
86 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
90 pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
92 AstFragment::OptExpr(expr) =>
93 AstFragment::OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
94 $($(AstFragment::$Kind(ast) =>
95 AstFragment::$Kind(folder.$fold_ast(ast)),)*)*
96 $($(AstFragment::$Kind(ast) =>
97 AstFragment::$Kind(ast.into_iter()
98 .flat_map(|ast| folder.$fold_ast_elt(ast))
103 pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
105 AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
106 AstFragment::OptExpr(None) => {}
107 $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)*)*
108 $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
109 visitor.$visit_ast_elt(ast_elt);
115 impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
116 fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
117 self.expand_fragment(AstFragment::OptExpr(Some(expr))).make_opt_expr()
119 $($(fn $fold_ast(&mut self, ast: $AstTy) -> $AstTy {
120 self.expand_fragment(AstFragment::$Kind(ast)).$make_ast()
122 $($(fn $fold_ast_elt(&mut self, ast_elt: <$AstTy as IntoIterator>::Item) -> $AstTy {
123 self.expand_fragment(AstFragment::$Kind(smallvec![ast_elt])).$make_ast()
127 impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
128 $(fn $make_ast(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>)
130 Some(self.make(AstFragmentKind::$Kind).$make_ast())
137 Expr(P<ast::Expr>) { "expression"; one fn fold_expr; fn visit_expr; fn make_expr; }
138 Pat(P<ast::Pat>) { "pattern"; one fn fold_pat; fn visit_pat; fn make_pat; }
139 Ty(P<ast::Ty>) { "type"; one fn fold_ty; fn visit_ty; fn make_ty; }
140 Stmts(SmallVec<[ast::Stmt; 1]>) {
141 "statement"; many fn fold_stmt; fn visit_stmt; fn make_stmts;
143 Items(SmallVec<[P<ast::Item>; 1]>) {
144 "item"; many fn fold_item; fn visit_item; fn make_items;
146 TraitItems(SmallVec<[ast::TraitItem; 1]>) {
147 "trait item"; many fn fold_trait_item; fn visit_trait_item; fn make_trait_items;
149 ImplItems(SmallVec<[ast::ImplItem; 1]>) {
150 "impl item"; many fn fold_impl_item; fn visit_impl_item; fn make_impl_items;
152 ForeignItems(SmallVec<[ast::ForeignItem; 1]>) {
153 "foreign item"; many fn fold_foreign_item; fn visit_foreign_item; fn make_foreign_items;
157 impl AstFragmentKind {
158 fn dummy(self, span: Span) -> Option<AstFragment> {
159 self.make_from(DummyResult::any(span))
162 fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
164 let mut items = items.into_iter();
166 AstFragmentKind::Items =>
167 AstFragment::Items(items.map(Annotatable::expect_item).collect()),
168 AstFragmentKind::ImplItems =>
169 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
170 AstFragmentKind::TraitItems =>
171 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
172 AstFragmentKind::ForeignItems =>
173 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect()),
174 AstFragmentKind::Stmts =>
175 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect()),
176 AstFragmentKind::Expr => AstFragment::Expr(
177 items.next().expect("expected exactly one expression").expect_expr()
179 AstFragmentKind::OptExpr =>
180 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr)),
181 AstFragmentKind::Pat | AstFragmentKind::Ty =>
182 panic!("patterns and types aren't annotatable"),
187 fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
188 // We don't want to format a path using pretty-printing,
189 // `format!("{}", path)`, because that tries to insert
190 // line-breaks and is slow.
191 let mut path_str = String::with_capacity(64);
192 for (i, segment) in path.segments.iter().enumerate() {
194 path_str.push_str("::");
196 if segment.ident.name != keywords::PathRoot.name() {
197 path_str.push_str(&segment.ident.as_str())
201 MacroBang(Symbol::intern(&path_str))
204 pub struct Invocation {
205 pub kind: InvocationKind,
206 fragment_kind: AstFragmentKind,
207 pub expansion_data: ExpansionData,
210 pub enum InvocationKind {
213 ident: Option<Ident>,
217 attr: Option<ast::Attribute>,
220 // We temporarily report errors for attribute macros placed after derives
230 pub fn span(&self) -> Span {
232 InvocationKind::Bang { span, .. } => span,
233 InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
234 InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
235 InvocationKind::Derive { ref path, .. } => path.span,
240 pub struct MacroExpander<'a, 'b:'a> {
241 pub cx: &'a mut ExtCtxt<'b>,
242 monotonic: bool, // cf. `cx.monotonic_expander()`
245 impl<'a, 'b> MacroExpander<'a, 'b> {
246 pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
247 MacroExpander { cx: cx, monotonic: monotonic }
250 pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
251 let mut module = ModuleData {
252 mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
253 directory: match self.cx.source_map().span_to_unmapped_path(krate.span) {
254 FileName::Real(path) => path,
255 other => PathBuf::from(other.to_string()),
258 module.directory.pop();
259 self.cx.root_path = module.directory.clone();
260 self.cx.current_expansion.module = Rc::new(module);
261 self.cx.current_expansion.crate_span = Some(krate.span);
263 let orig_mod_span = krate.module.inner;
265 let krate_item = AstFragment::Items(smallvec![P(ast::Item {
268 node: ast::ItemKind::Mod(krate.module),
269 ident: keywords::Invalid.ident(),
270 id: ast::DUMMY_NODE_ID,
271 vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
275 match self.expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
276 Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
278 krate.module = module;
281 // Resolution failed so we return an empty expansion
282 krate.attrs = vec![];
283 krate.module = ast::Mod {
284 inner: orig_mod_span,
291 self.cx.trace_macros_diag();
295 // Fully expand all macro invocations in this AST fragment.
296 fn expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
297 let orig_expansion_data = self.cx.current_expansion.clone();
298 self.cx.current_expansion.depth = 0;
300 // Collect all macro invocations and replace them with placeholders.
301 let (fragment_with_placeholders, mut invocations)
302 = self.collect_invocations(input_fragment, &[]);
304 // Optimization: if we resolve all imports now,
305 // we'll be able to immediately resolve most of imported macros.
306 self.resolve_imports();
308 // Resolve paths in all invocations and produce output expanded fragments for them, but
309 // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
310 // The output fragments also go through expansion recursively until no invocations are left.
311 // Unresolved macros produce dummy outputs as a recovery measure.
312 invocations.reverse();
313 let mut expanded_fragments = Vec::new();
314 let mut derives: FxHashMap<Mark, Vec<_>> = FxHashMap::default();
315 let mut undetermined_invocations = Vec::new();
316 let (mut progress, mut force) = (false, !self.monotonic);
318 let invoc = if let Some(invoc) = invocations.pop() {
321 self.resolve_imports();
322 if undetermined_invocations.is_empty() { break }
323 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
324 force = !mem::replace(&mut progress, false);
329 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
330 let ext = match self.cx.resolver.resolve_macro_invocation(&invoc, scope, force) {
331 Ok(ext) => Some(ext),
332 Err(Determinacy::Determined) => None,
333 Err(Determinacy::Undetermined) => {
334 undetermined_invocations.push(invoc);
340 let ExpansionData { depth, mark, .. } = invoc.expansion_data;
341 self.cx.current_expansion = invoc.expansion_data.clone();
343 self.cx.current_expansion.mark = scope;
344 // FIXME(jseyfried): Refactor out the following logic
345 let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
346 if let Some(ext) = ext {
347 let dummy = invoc.fragment_kind.dummy(invoc.span()).unwrap();
348 let fragment = self.expand_invoc(invoc, &*ext).unwrap_or(dummy);
349 self.collect_invocations(fragment, &[])
350 } else if let InvocationKind::Attr { attr: None, traits, item, .. } = invoc.kind {
351 if !item.derive_allowed() {
352 let attr = attr::find_by_name(item.attrs(), "derive")
353 .expect("`derive` attribute should exist");
354 let span = attr.span;
355 let mut err = self.cx.mut_span_err(span,
356 "`derive` may only be applied to \
357 structs, enums and unions");
358 if let ast::AttrStyle::Inner = attr.style {
359 let trait_list = traits.iter()
360 .map(|t| t.to_string()).collect::<Vec<_>>();
361 let suggestion = format!("#[derive({})]", trait_list.join(", "));
362 err.span_suggestion_with_applicability(
363 span, "try an outer attribute", suggestion,
364 // We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
365 Applicability::MaybeIncorrect
371 let item = self.fully_configure(item)
372 .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
373 let item_with_markers =
374 add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
375 let derives = derives.entry(invoc.expansion_data.mark).or_default();
377 derives.reserve(traits.len());
378 invocations.reserve(traits.len());
379 for path in &traits {
380 let mark = Mark::fresh(self.cx.current_expansion.mark);
382 let item = match self.cx.resolver.resolve_macro_path(
383 path, MacroKind::Derive, Mark::root(), Vec::new(), false) {
384 Ok(ext) => match *ext {
385 BuiltinDerive(..) => item_with_markers.clone(),
390 invocations.push(Invocation {
391 kind: InvocationKind::Derive { path: path.clone(), item: item },
392 fragment_kind: invoc.fragment_kind,
393 expansion_data: ExpansionData {
395 ..invoc.expansion_data.clone()
399 let fragment = invoc.fragment_kind
400 .expect_from_annotatables(::std::iter::once(item_with_markers));
401 self.collect_invocations(fragment, derives)
406 self.collect_invocations(invoc.fragment_kind.dummy(invoc.span()).unwrap(), &[])
409 if expanded_fragments.len() < depth {
410 expanded_fragments.push(Vec::new());
412 expanded_fragments[depth - 1].push((mark, expanded_fragment));
413 if !self.cx.ecfg.single_step {
414 invocations.extend(new_invocations.into_iter().rev());
418 self.cx.current_expansion = orig_expansion_data;
420 // Finally incorporate all the expanded macros into the input AST fragment.
421 let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
422 while let Some(expanded_fragments) = expanded_fragments.pop() {
423 for (mark, expanded_fragment) in expanded_fragments.into_iter().rev() {
424 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
425 placeholder_expander.add(NodeId::placeholder_from_mark(mark),
426 expanded_fragment, derives);
429 fragment_with_placeholders.fold_with(&mut placeholder_expander)
432 fn resolve_imports(&mut self) {
434 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
435 self.cx.resolver.resolve_imports();
436 self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
440 /// Collect all macro invocations reachable at this time in this AST fragment, and replace
441 /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
442 /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
443 /// prepares data for resolving paths of macro invocations.
444 fn collect_invocations(&mut self, fragment: AstFragment, derives: &[Mark])
445 -> (AstFragment, Vec<Invocation>) {
446 let (fragment_with_placeholders, invocations) = {
447 let mut collector = InvocationCollector {
448 cfg: StripUnconfigured {
449 sess: self.cx.parse_sess,
450 features: self.cx.ecfg.features,
453 invocations: Vec::new(),
454 monotonic: self.monotonic,
456 (fragment.fold_with(&mut collector), collector.invocations)
460 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
461 let mark = self.cx.current_expansion.mark;
462 self.cx.resolver.visit_ast_fragment_with_placeholders(mark, &fragment_with_placeholders,
464 self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
467 (fragment_with_placeholders, invocations)
470 fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
471 let mut cfg = StripUnconfigured {
472 sess: self.cx.parse_sess,
473 features: self.cx.ecfg.features,
475 // Since the item itself has already been configured by the InvocationCollector,
476 // we know that fold result vector will contain exactly one element
478 Annotatable::Item(item) => {
479 Annotatable::Item(cfg.fold_item(item).pop().unwrap())
481 Annotatable::TraitItem(item) => {
482 Annotatable::TraitItem(item.map(|item| cfg.fold_trait_item(item).pop().unwrap()))
484 Annotatable::ImplItem(item) => {
485 Annotatable::ImplItem(item.map(|item| cfg.fold_impl_item(item).pop().unwrap()))
487 Annotatable::ForeignItem(item) => {
488 Annotatable::ForeignItem(
489 item.map(|item| cfg.fold_foreign_item(item).pop().unwrap())
492 Annotatable::Stmt(stmt) => {
493 Annotatable::Stmt(stmt.map(|stmt| cfg.fold_stmt(stmt).pop().unwrap()))
495 Annotatable::Expr(expr) => {
496 Annotatable::Expr(cfg.fold_expr(expr))
501 fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
502 if invoc.fragment_kind == AstFragmentKind::ForeignItems &&
503 !self.cx.ecfg.macros_in_extern_enabled() {
504 if let SyntaxExtension::NonMacroAttr { .. } = *ext {} else {
505 emit_feature_err(&self.cx.parse_sess, "macros_in_extern",
506 invoc.span(), GateIssue::Language,
507 "macro invocations in `extern {}` blocks are experimental");
511 let result = match invoc.kind {
512 InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext)?,
513 InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext)?,
514 InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext)?,
517 if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
518 let info = self.cx.current_expansion.mark.expn_info().unwrap();
519 let suggested_limit = self.cx.ecfg.recursion_limit * 2;
520 let mut err = self.cx.struct_span_err(info.call_site,
521 &format!("recursion limit reached while expanding the macro `{}`",
522 info.format.name()));
524 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
527 self.cx.trace_macros_diag();
534 fn expand_attr_invoc(&mut self,
536 ext: &SyntaxExtension)
537 -> Option<AstFragment> {
538 let (attr, item) = match invoc.kind {
539 InvocationKind::Attr { attr, item, .. } => (attr?, item),
543 if let NonMacroAttr { mark_used: false } = *ext {} else {
544 // Macro attrs are always used when expanded,
545 // non-macro attrs are considered used when the field says so.
546 attr::mark_used(&attr);
548 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
549 call_site: attr.span,
551 format: MacroAttribute(Symbol::intern(&attr.path.to_string())),
552 allow_internal_unstable: false,
553 allow_internal_unsafe: false,
554 local_inner_macros: false,
555 edition: ext.edition(),
559 NonMacroAttr { .. } => {
560 attr::mark_known(&attr);
561 let item = item.map_attrs(|mut attrs| { attrs.push(attr); attrs });
562 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
564 MultiModifier(ref mac) => {
565 let meta = attr.parse_meta(self.cx.parse_sess)
566 .map_err(|mut e| { e.emit(); }).ok()?;
567 let item = mac.expand(self.cx, attr.span, &meta, item);
568 Some(invoc.fragment_kind.expect_from_annotatables(item))
570 MultiDecorator(ref mac) => {
571 let mut items = Vec::new();
572 let meta = attr.parse_meta(self.cx.parse_sess)
573 .expect("derive meta should already have been parsed");
574 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
576 Some(invoc.fragment_kind.expect_from_annotatables(items))
578 AttrProcMacro(ref mac, ..) => {
579 self.gate_proc_macro_attr_item(attr.span, &item);
580 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
581 Annotatable::Item(item) => token::NtItem(item),
582 Annotatable::TraitItem(item) => token::NtTraitItem(item.into_inner()),
583 Annotatable::ImplItem(item) => token::NtImplItem(item.into_inner()),
584 Annotatable::ForeignItem(item) => token::NtForeignItem(item.into_inner()),
585 Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
586 Annotatable::Expr(expr) => token::NtExpr(expr),
588 let input = self.extract_proc_macro_attr_input(attr.tokens, attr.span);
589 let tok_result = mac.expand(self.cx, attr.span, input, item_tok);
590 let res = self.parse_ast_fragment(tok_result, invoc.fragment_kind,
591 &attr.path, attr.span);
592 self.gate_proc_macro_expansion(attr.span, &res);
595 ProcMacroDerive(..) | BuiltinDerive(..) => {
596 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
597 self.cx.trace_macros_diag();
598 invoc.fragment_kind.dummy(attr.span)
601 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
602 self.cx.span_err(attr.span, msg);
603 self.cx.trace_macros_diag();
604 invoc.fragment_kind.dummy(attr.span)
609 fn extract_proc_macro_attr_input(&self, tokens: TokenStream, span: Span) -> TokenStream {
610 let mut trees = tokens.trees();
612 Some(TokenTree::Delimited(_, _, tts)) => {
613 if trees.next().is_none() {
617 Some(TokenTree::Token(..)) => {}
618 None => return TokenStream::empty(),
620 self.cx.span_err(span, "custom attribute invocations must be \
621 of the form #[foo] or #[foo(..)], the macro name must only be \
622 followed by a delimiter token");
626 fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
627 let (kind, gate) = match *item {
628 Annotatable::Item(ref item) => {
630 ItemKind::Mod(_) if self.cx.ecfg.proc_macro_hygiene() => return,
631 ItemKind::Mod(_) => ("modules", "proc_macro_hygiene"),
635 Annotatable::TraitItem(_) => return,
636 Annotatable::ImplItem(_) => return,
637 Annotatable::ForeignItem(_) => return,
638 Annotatable::Stmt(_) |
639 Annotatable::Expr(_) if self.cx.ecfg.proc_macro_hygiene() => return,
640 Annotatable::Stmt(_) => ("statements", "proc_macro_hygiene"),
641 Annotatable::Expr(_) => ("expressions", "proc_macro_hygiene"),
648 &format!("custom attributes cannot be applied to {}", kind),
652 fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>) {
653 if self.cx.ecfg.proc_macro_hygiene() {
656 let fragment = match fragment {
657 Some(fragment) => fragment,
661 fragment.visit_with(&mut DisallowMacros {
663 parse_sess: self.cx.parse_sess,
666 struct DisallowMacros<'a> {
668 parse_sess: &'a ParseSess,
671 impl<'ast, 'a> Visitor<'ast> for DisallowMacros<'a> {
672 fn visit_item(&mut self, i: &'ast ast::Item) {
673 if let ast::ItemKind::MacroDef(_) = i.node {
676 "proc_macro_hygiene",
679 "procedural macros cannot expand to macro definitions",
682 visit::walk_item(self, i);
685 fn visit_mac(&mut self, _mac: &'ast ast::Mac) {
691 /// Expand a macro invocation. Returns the resulting expanded AST fragment.
692 fn expand_bang_invoc(&mut self,
694 ext: &SyntaxExtension)
695 -> Option<AstFragment> {
696 let (mark, kind) = (invoc.expansion_data.mark, invoc.fragment_kind);
697 let (mac, ident, span) = match invoc.kind {
698 InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
701 let path = &mac.node.path;
703 let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
704 let validate_and_set_expn_info = |this: &mut Self, // arg instead of capture
705 def_site_span: Option<Span>,
706 allow_internal_unstable,
707 allow_internal_unsafe,
709 // can't infer this type
710 unstable_feature: Option<(Symbol, u32)>,
713 // feature-gate the macro invocation
714 if let Some((feature, issue)) = unstable_feature {
715 let crate_span = this.cx.current_expansion.crate_span.unwrap();
716 // don't stability-check macros in the same crate
717 // (the only time this is null is for syntax extensions registered as macros)
718 if def_site_span.map_or(false, |def_span| !crate_span.contains(def_span))
719 && !span.allows_unstable() && this.cx.ecfg.features.map_or(true, |feats| {
720 // macro features will count as lib features
721 !feats.declared_lib_features.iter().any(|&(feat, _)| feat == feature)
723 let explain = format!("macro {}! is unstable", path);
724 emit_feature_err(this.cx.parse_sess, &*feature.as_str(), span,
725 GateIssue::Library(Some(issue)), &explain);
726 this.cx.trace_macros_diag();
727 return Err(kind.dummy(span));
731 if ident.name != keywords::Invalid.name() {
732 let msg = format!("macro {}! expects no ident argument, given '{}'", path, ident);
733 this.cx.span_err(path.span, &msg);
734 this.cx.trace_macros_diag();
735 return Err(kind.dummy(span));
737 mark.set_expn_info(ExpnInfo {
739 def_site: def_site_span,
740 format: macro_bang_format(path),
741 allow_internal_unstable,
742 allow_internal_unsafe,
749 let opt_expanded = match *ext {
750 DeclMacro { ref expander, def_info, edition, .. } => {
751 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
752 false, false, false, None,
756 kind.make_from(expander.expand(self.cx, span, mac.node.stream(), None))
763 allow_internal_unstable,
764 allow_internal_unsafe,
769 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
770 allow_internal_unstable,
771 allow_internal_unsafe,
777 kind.make_from(expander.expand(
781 def_info.map(|(_, s)| s),
786 IdentTT(ref expander, tt_span, allow_internal_unstable) => {
787 if ident.name == keywords::Invalid.name() {
788 self.cx.span_err(path.span,
789 &format!("macro {}! expects an ident argument", path));
790 self.cx.trace_macros_diag();
793 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
796 format: macro_bang_format(path),
797 allow_internal_unstable,
798 allow_internal_unsafe: false,
799 local_inner_macros: false,
800 edition: hygiene::default_edition(),
803 let input: Vec<_> = mac.node.stream().into_trees().collect();
804 kind.make_from(expander.expand(self.cx, span, ident, input))
808 MultiDecorator(..) | MultiModifier(..) |
809 AttrProcMacro(..) | SyntaxExtension::NonMacroAttr { .. } => {
810 self.cx.span_err(path.span,
811 &format!("`{}` can only be used in attributes", path));
812 self.cx.trace_macros_diag();
816 ProcMacroDerive(..) | BuiltinDerive(..) => {
817 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
818 self.cx.trace_macros_diag();
822 SyntaxExtension::ProcMacro { ref expander, allow_internal_unstable, edition } => {
823 if ident.name != keywords::Invalid.name() {
825 format!("macro {}! expects no ident argument, given '{}'", path, ident);
826 self.cx.span_err(path.span, &msg);
827 self.cx.trace_macros_diag();
830 self.gate_proc_macro_expansion_kind(span, kind);
831 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
833 // FIXME procedural macros do not have proper span info
834 // yet, when they do, we should use it here.
836 format: macro_bang_format(path),
837 // FIXME probably want to follow macro_rules macros here.
838 allow_internal_unstable,
839 allow_internal_unsafe: false,
840 local_inner_macros: false,
844 let tok_result = expander.expand(self.cx, span, mac.node.stream());
845 let result = self.parse_ast_fragment(tok_result, kind, path, span);
846 self.gate_proc_macro_expansion(span, &result);
852 if opt_expanded.is_some() {
855 let msg = format!("non-{kind} macro in {kind} position: {name}",
856 name = path.segments[0].ident.name, kind = kind.name());
857 self.cx.span_err(path.span, &msg);
858 self.cx.trace_macros_diag();
863 fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
864 let kind = match kind {
865 AstFragmentKind::Expr => "expressions",
866 AstFragmentKind::OptExpr => "expressions",
867 AstFragmentKind::Pat => "patterns",
868 AstFragmentKind::Ty => "types",
869 AstFragmentKind::Stmts => "statements",
870 AstFragmentKind::Items => return,
871 AstFragmentKind::TraitItems => return,
872 AstFragmentKind::ImplItems => return,
873 AstFragmentKind::ForeignItems => return,
875 if self.cx.ecfg.proc_macro_hygiene() {
880 "proc_macro_hygiene",
883 &format!("procedural macros cannot be expanded to {}", kind),
887 /// Expand a derive invocation. Returns the resulting expanded AST fragment.
888 fn expand_derive_invoc(&mut self,
890 ext: &SyntaxExtension)
891 -> Option<AstFragment> {
892 let (path, item) = match invoc.kind {
893 InvocationKind::Derive { path, item } => (path, item),
896 if !item.derive_allowed() {
900 let pretty_name = Symbol::intern(&format!("derive({})", path));
901 let span = path.span;
902 let attr = ast::Attribute {
904 tokens: TokenStream::empty(),
906 id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
909 let mut expn_info = ExpnInfo {
912 format: MacroAttribute(pretty_name),
913 allow_internal_unstable: false,
914 allow_internal_unsafe: false,
915 local_inner_macros: false,
916 edition: ext.edition(),
920 ProcMacroDerive(ref ext, ..) => {
921 invoc.expansion_data.mark.set_expn_info(expn_info);
922 let span = span.with_ctxt(self.cx.backtrace());
923 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
924 ident: Path::from_ident(keywords::Invalid.ident()),
926 node: ast::MetaItemKind::Word,
928 let items = ext.expand(self.cx, span, &dummy, item);
929 Some(invoc.fragment_kind.expect_from_annotatables(items))
931 BuiltinDerive(func) => {
932 expn_info.allow_internal_unstable = true;
933 invoc.expansion_data.mark.set_expn_info(expn_info);
934 let span = span.with_ctxt(self.cx.backtrace());
935 let mut items = Vec::new();
936 func(self.cx, span, &attr.meta()?, &item, &mut |a| items.push(a));
937 Some(invoc.fragment_kind.expect_from_annotatables(items))
940 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
941 self.cx.span_err(span, msg);
942 self.cx.trace_macros_diag();
943 invoc.fragment_kind.dummy(span)
948 fn parse_ast_fragment(&mut self,
950 kind: AstFragmentKind,
953 -> Option<AstFragment> {
954 let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
955 match parser.parse_ast_fragment(kind, false) {
957 parser.ensure_complete_parse(path, kind.name(), span);
963 self.cx.trace_macros_diag();
970 impl<'a> Parser<'a> {
971 pub fn parse_ast_fragment(&mut self, kind: AstFragmentKind, macro_legacy_warnings: bool)
972 -> PResult<'a, AstFragment> {
974 AstFragmentKind::Items => {
975 let mut items = SmallVec::new();
976 while let Some(item) = self.parse_item()? {
979 AstFragment::Items(items)
981 AstFragmentKind::TraitItems => {
982 let mut items = SmallVec::new();
983 while self.token != token::Eof {
984 items.push(self.parse_trait_item(&mut false)?);
986 AstFragment::TraitItems(items)
988 AstFragmentKind::ImplItems => {
989 let mut items = SmallVec::new();
990 while self.token != token::Eof {
991 items.push(self.parse_impl_item(&mut false)?);
993 AstFragment::ImplItems(items)
995 AstFragmentKind::ForeignItems => {
996 let mut items = SmallVec::new();
997 while self.token != token::Eof {
998 items.push(self.parse_foreign_item()?);
1000 AstFragment::ForeignItems(items)
1002 AstFragmentKind::Stmts => {
1003 let mut stmts = SmallVec::new();
1004 while self.token != token::Eof &&
1005 // won't make progress on a `}`
1006 self.token != token::CloseDelim(token::Brace) {
1007 if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
1011 AstFragment::Stmts(stmts)
1013 AstFragmentKind::Expr => AstFragment::Expr(self.parse_expr()?),
1014 AstFragmentKind::OptExpr => {
1015 if self.token != token::Eof {
1016 AstFragment::OptExpr(Some(self.parse_expr()?))
1018 AstFragment::OptExpr(None)
1021 AstFragmentKind::Ty => AstFragment::Ty(self.parse_ty()?),
1022 AstFragmentKind::Pat => AstFragment::Pat(self.parse_pat(None)?),
1026 pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
1027 if self.token != token::Eof {
1028 let msg = format!("macro expansion ignores token `{}` and any following",
1029 self.this_token_to_string());
1030 // Avoid emitting backtrace info twice.
1031 let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
1032 let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
1033 err.span_label(span, "caused by the macro expansion here");
1035 "the usage of `{}!` is likely invalid in {} context",
1040 let semi_span = self.sess.source_map().next_point(span);
1042 let semi_full_span = semi_span.to(self.sess.source_map().next_point(semi_span));
1043 match self.sess.source_map().span_to_snippet(semi_full_span) {
1044 Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
1045 err.span_suggestion_with_applicability(
1047 "you might be missing a semicolon here",
1049 Applicability::MaybeIncorrect,
1059 struct InvocationCollector<'a, 'b: 'a> {
1060 cx: &'a mut ExtCtxt<'b>,
1061 cfg: StripUnconfigured<'a>,
1062 invocations: Vec<Invocation>,
1066 impl<'a, 'b> InvocationCollector<'a, 'b> {
1067 fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
1068 let mark = Mark::fresh(self.cx.current_expansion.mark);
1069 self.invocations.push(Invocation {
1072 expansion_data: ExpansionData {
1074 depth: self.cx.current_expansion.depth + 1,
1075 ..self.cx.current_expansion.clone()
1078 placeholder(fragment_kind, NodeId::placeholder_from_mark(mark))
1081 fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
1082 self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
1085 fn collect_attr(&mut self,
1086 attr: Option<ast::Attribute>,
1089 kind: AstFragmentKind,
1092 self.collect(kind, InvocationKind::Attr { attr, traits, item, after_derive })
1095 fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, after_derive: &mut bool)
1096 -> Option<ast::Attribute> {
1097 let attr = attrs.iter()
1099 if a.path == "derive" {
1100 *after_derive = true;
1102 !attr::is_known(a) && !is_builtin_attr(a)
1104 .map(|i| attrs.remove(i));
1105 if let Some(attr) = &attr {
1106 if !self.cx.ecfg.enable_custom_inner_attributes() &&
1107 attr.style == ast::AttrStyle::Inner && attr.path != "test" {
1108 emit_feature_err(&self.cx.parse_sess, "custom_inner_attributes",
1109 attr.span, GateIssue::Language,
1110 "non-builtin inner attributes are unstable");
1116 /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
1117 fn classify_item<T>(&mut self, mut item: T)
1118 -> (Option<ast::Attribute>, Vec<Path>, T, /* after_derive */ bool)
1121 let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
1123 item = item.map_attrs(|mut attrs| {
1124 attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1125 traits = collect_derives(&mut self.cx, &mut attrs);
1129 (attr, traits, item, after_derive)
1132 /// Alternative of `classify_item()` that ignores `#[derive]` so invocations fallthrough
1133 /// to the unused-attributes lint (making it an error on statements and expressions
1134 /// is a breaking change)
1135 fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T)
1136 -> (Option<ast::Attribute>, T, /* after_derive */ bool) {
1137 let (mut attr, mut after_derive) = (None, false);
1139 item = item.map_attrs(|mut attrs| {
1140 attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1144 (attr, item, after_derive)
1147 fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
1148 self.cfg.configure(node)
1151 // Detect use of feature-gated or invalid attributes on macro invocations
1152 // since they will not be detected after macro expansion.
1153 fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
1154 let features = self.cx.ecfg.features.unwrap();
1155 for attr in attrs.iter() {
1156 self.check_attribute_inner(attr, features);
1158 // macros are expanded before any lint passes so this warning has to be hardcoded
1159 if attr.path == "derive" {
1160 self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
1161 .note("this may become a hard error in a future release")
1167 fn check_attribute(&mut self, at: &ast::Attribute) {
1168 let features = self.cx.ecfg.features.unwrap();
1169 self.check_attribute_inner(at, features);
1172 fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
1173 feature_gate::check_attribute(at, self.cx.parse_sess, features);
1177 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
1178 fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
1179 let expr = self.cfg.configure_expr(expr);
1180 expr.map(|mut expr| {
1181 expr.node = self.cfg.configure_expr_kind(expr.node);
1183 // ignore derives so they remain unused
1184 let (attr, expr, after_derive) = self.classify_nonitem(expr);
1187 // Collect the invoc regardless of whether or not attributes are permitted here
1188 // expansion will eat the attribute so it won't error later.
1189 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1191 // AstFragmentKind::Expr requires the macro to emit an expression.
1192 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1193 AstFragmentKind::Expr, after_derive)
1198 if let ast::ExprKind::Mac(mac) = expr.node {
1199 self.check_attributes(&expr.attrs);
1200 self.collect_bang(mac, expr.span, AstFragmentKind::Expr)
1204 noop_fold_expr(expr, self)
1209 fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
1210 let expr = configure!(self, expr);
1211 expr.filter_map(|mut expr| {
1212 expr.node = self.cfg.configure_expr_kind(expr.node);
1214 // Ignore derives so they remain unused.
1215 let (attr, expr, after_derive) = self.classify_nonitem(expr);
1218 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1220 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1221 AstFragmentKind::OptExpr, after_derive)
1223 .map(|expr| expr.into_inner())
1226 if let ast::ExprKind::Mac(mac) = expr.node {
1227 self.check_attributes(&expr.attrs);
1228 self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
1230 .map(|expr| expr.into_inner())
1232 Some(noop_fold_expr(expr, self))
1237 fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
1238 let pat = self.cfg.configure_pat(pat);
1240 PatKind::Mac(_) => {}
1241 _ => return noop_fold_pat(pat, self),
1244 pat.and_then(|pat| match pat.node {
1245 PatKind::Mac(mac) => self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
1246 _ => unreachable!(),
1250 fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
1251 let mut stmt = match self.cfg.configure_stmt(stmt) {
1253 None => return SmallVec::new(),
1256 // we'll expand attributes on expressions separately
1257 if !stmt.is_expr() {
1258 let (attr, derives, stmt_, after_derive) = if stmt.is_item() {
1259 self.classify_item(stmt)
1261 // ignore derives on non-item statements so it falls through
1262 // to the unused-attributes lint
1263 let (attr, stmt, after_derive) = self.classify_nonitem(stmt);
1264 (attr, vec![], stmt, after_derive)
1267 if attr.is_some() || !derives.is_empty() {
1268 return self.collect_attr(attr, derives, Annotatable::Stmt(P(stmt_)),
1269 AstFragmentKind::Stmts, after_derive).make_stmts();
1275 if let StmtKind::Mac(mac) = stmt.node {
1276 let (mac, style, attrs) = mac.into_inner();
1277 self.check_attributes(&attrs);
1278 let mut placeholder = self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts)
1281 // If this is a macro invocation with a semicolon, then apply that
1282 // semicolon to the final statement produced by expansion.
1283 if style == MacStmtStyle::Semicolon {
1284 if let Some(stmt) = placeholder.pop() {
1285 placeholder.push(stmt.add_trailing_semicolon());
1292 // The placeholder expander gives ids to statements, so we avoid folding the id here.
1293 let ast::Stmt { id, node, span } = stmt;
1294 noop_fold_stmt_kind(node, self).into_iter().map(|node| {
1295 ast::Stmt { id, node, span }
1300 fn fold_block(&mut self, block: P<Block>) -> P<Block> {
1301 let old_directory_ownership = self.cx.current_expansion.directory_ownership;
1302 self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
1303 let result = noop_fold_block(block, self);
1304 self.cx.current_expansion.directory_ownership = old_directory_ownership;
1308 fn fold_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
1309 let item = configure!(self, item);
1311 let (attr, traits, item, after_derive) = self.classify_item(item);
1312 if attr.is_some() || !traits.is_empty() {
1313 return self.collect_attr(attr, traits, Annotatable::Item(item),
1314 AstFragmentKind::Items, after_derive).make_items();
1318 ast::ItemKind::Mac(..) => {
1319 self.check_attributes(&item.attrs);
1320 item.and_then(|item| match item.node {
1321 ItemKind::Mac(mac) => {
1322 self.collect(AstFragmentKind::Items, InvocationKind::Bang {
1324 ident: Some(item.ident),
1328 _ => unreachable!(),
1331 ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
1332 if item.ident == keywords::Invalid.ident() {
1333 return noop_fold_item(item, self);
1336 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
1337 let mut module = (*self.cx.current_expansion.module).clone();
1338 module.mod_path.push(item.ident);
1340 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
1341 // In the non-inline case, `inner` is never the dummy span (cf. `parse_item_mod`).
1342 // Thus, if `inner` is the dummy span, we know the module is inline.
1343 let inline_module = item.span.contains(inner) || inner.is_dummy();
1346 if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
1347 self.cx.current_expansion.directory_ownership =
1348 DirectoryOwnership::Owned { relative: None };
1349 module.directory.push(&*path.as_str());
1351 module.directory.push(&*item.ident.as_str());
1354 let path = self.cx.parse_sess.source_map().span_to_unmapped_path(inner);
1355 let mut path = match path {
1356 FileName::Real(path) => path,
1357 other => PathBuf::from(other.to_string()),
1359 let directory_ownership = match path.file_name().unwrap().to_str() {
1360 Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
1361 Some(_) => DirectoryOwnership::Owned {
1362 relative: Some(item.ident),
1364 None => DirectoryOwnership::UnownedViaMod(false),
1367 module.directory = path;
1368 self.cx.current_expansion.directory_ownership = directory_ownership;
1372 mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
1373 let result = noop_fold_item(item, self);
1374 self.cx.current_expansion.module = orig_module;
1375 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
1379 _ => noop_fold_item(item, self),
1383 fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
1384 let item = configure!(self, item);
1386 let (attr, traits, item, after_derive) = self.classify_item(item);
1387 if attr.is_some() || !traits.is_empty() {
1388 return self.collect_attr(attr, traits, Annotatable::TraitItem(P(item)),
1389 AstFragmentKind::TraitItems, after_derive).make_trait_items()
1393 ast::TraitItemKind::Macro(mac) => {
1394 let ast::TraitItem { attrs, span, .. } = item;
1395 self.check_attributes(&attrs);
1396 self.collect_bang(mac, span, AstFragmentKind::TraitItems).make_trait_items()
1398 _ => fold::noop_fold_trait_item(item, self),
1402 fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
1403 let item = configure!(self, item);
1405 let (attr, traits, item, after_derive) = self.classify_item(item);
1406 if attr.is_some() || !traits.is_empty() {
1407 return self.collect_attr(attr, traits, Annotatable::ImplItem(P(item)),
1408 AstFragmentKind::ImplItems, after_derive).make_impl_items();
1412 ast::ImplItemKind::Macro(mac) => {
1413 let ast::ImplItem { attrs, span, .. } = item;
1414 self.check_attributes(&attrs);
1415 self.collect_bang(mac, span, AstFragmentKind::ImplItems).make_impl_items()
1417 _ => fold::noop_fold_impl_item(item, self),
1421 fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1422 let ty = match ty.node {
1423 ast::TyKind::Mac(_) => ty.into_inner(),
1424 _ => return fold::noop_fold_ty(ty, self),
1428 ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
1429 _ => unreachable!(),
1433 fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1434 noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1437 fn fold_foreign_item(&mut self, foreign_item: ast::ForeignItem)
1438 -> SmallVec<[ast::ForeignItem; 1]>
1440 let (attr, traits, foreign_item, after_derive) = self.classify_item(foreign_item);
1442 if attr.is_some() || !traits.is_empty() {
1443 return self.collect_attr(attr, traits, Annotatable::ForeignItem(P(foreign_item)),
1444 AstFragmentKind::ForeignItems, after_derive)
1445 .make_foreign_items();
1448 if let ast::ForeignItemKind::Macro(mac) = foreign_item.node {
1449 self.check_attributes(&foreign_item.attrs);
1450 return self.collect_bang(mac, foreign_item.span, AstFragmentKind::ForeignItems)
1451 .make_foreign_items();
1454 noop_fold_foreign_item(foreign_item, self)
1457 fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1459 ast::ItemKind::MacroDef(..) => item,
1460 _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1464 fn fold_generic_param(&mut self, param: ast::GenericParam) -> ast::GenericParam {
1465 self.cfg.disallow_cfg_on_generic_param(¶m);
1466 noop_fold_generic_param(param, self)
1469 fn fold_attribute(&mut self, at: ast::Attribute) -> Option<ast::Attribute> {
1470 // turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
1471 // contents="file contents")]` attributes
1472 if !at.check_name("doc") {
1473 return noop_fold_attribute(at, self);
1476 if let Some(list) = at.meta_item_list() {
1477 if !list.iter().any(|it| it.check_name("include")) {
1478 return noop_fold_attribute(at, self);
1481 let mut items = vec![];
1484 if !it.check_name("include") {
1485 items.push(noop_fold_meta_list_item(it, self));
1489 if let Some(file) = it.value_str() {
1490 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
1491 self.check_attribute(&at);
1492 if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
1493 // avoid loading the file if they haven't enabled the feature
1494 return noop_fold_attribute(at, self);
1497 let filename = self.cx.root_path.join(file.to_string());
1498 match fs::read_to_string(&filename) {
1500 let src_interned = Symbol::intern(&src);
1502 // Add this input file to the code map to make it available as
1503 // dependency information
1504 self.cx.source_map().new_source_file(filename.into(), src);
1506 let include_info = vec![
1507 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1508 attr::mk_name_value_item_str(
1509 Ident::from_str("file"),
1510 dummy_spanned(file),
1513 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1514 attr::mk_name_value_item_str(
1515 Ident::from_str("contents"),
1516 dummy_spanned(src_interned),
1521 let include_ident = Ident::from_str("include");
1522 let item = attr::mk_list_item(DUMMY_SP, include_ident, include_info);
1523 items.push(dummy_spanned(ast::NestedMetaItemKind::MetaItem(item)));
1528 .and_then(|item| item.name_value_literal())
1531 if e.kind() == ErrorKind::InvalidData {
1535 &format!("{} wasn't a utf-8 file", filename.display()),
1537 .span_label(lit.span, "contains invalid utf-8")
1540 let mut err = self.cx.struct_span_err(
1542 &format!("couldn't read {}: {}", filename.display(), e),
1544 err.span_label(lit.span, "couldn't read file");
1546 if e.kind() == ErrorKind::NotFound {
1547 err.help("external doc paths are relative to the crate root");
1555 let mut err = self.cx.struct_span_err(
1557 &format!("expected path to external documentation"),
1560 // Check if the user erroneously used `doc(include(...))` syntax.
1561 let literal = it.meta_item_list().and_then(|list| {
1562 if list.len() == 1 {
1563 list[0].literal().map(|literal| &literal.node)
1569 let (path, applicability) = match &literal {
1570 Some(LitKind::Str(path, ..)) => {
1571 (path.to_string(), Applicability::MachineApplicable)
1573 _ => (String::from("<path>"), Applicability::HasPlaceholders),
1576 err.span_suggestion_with_applicability(
1578 "provide a file path with `=`",
1579 format!("include = \"{}\"", path),
1587 let meta = attr::mk_list_item(DUMMY_SP, Ident::from_str("doc"), items);
1589 ast::AttrStyle::Inner =>
1590 Some(attr::mk_spanned_attr_inner(at.span, at.id, meta)),
1591 ast::AttrStyle::Outer =>
1592 Some(attr::mk_spanned_attr_outer(at.span, at.id, meta)),
1595 noop_fold_attribute(at, self)
1599 fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1601 assert_eq!(id, ast::DUMMY_NODE_ID);
1602 self.cx.resolver.next_node_id()
1609 pub struct ExpansionConfig<'feat> {
1610 pub crate_name: String,
1611 pub features: Option<&'feat Features>,
1612 pub recursion_limit: usize,
1613 pub trace_mac: bool,
1614 pub should_test: bool, // If false, strip `#[test]` nodes
1615 pub single_step: bool,
1616 pub keep_macs: bool,
1619 macro_rules! feature_tests {
1620 ($( fn $getter:ident = $field:ident, )*) => {
1622 pub fn $getter(&self) -> bool {
1623 match self.features {
1624 Some(&Features { $field: true, .. }) => true,
1632 impl<'feat> ExpansionConfig<'feat> {
1633 pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1637 recursion_limit: 1024,
1646 fn enable_asm = asm,
1647 fn enable_custom_test_frameworks = custom_test_frameworks,
1648 fn enable_global_asm = global_asm,
1649 fn enable_log_syntax = log_syntax,
1650 fn enable_concat_idents = concat_idents,
1651 fn enable_trace_macros = trace_macros,
1652 fn enable_allow_internal_unstable = allow_internal_unstable,
1653 fn enable_format_args_nl = format_args_nl,
1654 fn macros_in_extern_enabled = macros_in_extern,
1655 fn proc_macro_hygiene = proc_macro_hygiene,
1658 fn enable_custom_inner_attributes(&self) -> bool {
1659 self.features.map_or(false, |features| {
1660 features.custom_inner_attributes || features.custom_attribute || features.rustc_attrs
1665 // A Marker adds the given mark to the syntax context.
1667 pub struct Marker(pub Mark);
1669 impl Folder for Marker {
1670 fn new_span(&mut self, span: Span) -> Span {
1671 span.apply_mark(self.0)
1674 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1675 noop_fold_mac(mac, self)