1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use ast::{self, Block, Ident, NodeId, PatKind, Path};
12 use ast::{MacStmtStyle, StmtKind, ItemKind};
13 use attr::{self, HasAttrs};
14 use codemap::{ExpnInfo, MacroBang, MacroAttribute, dummy_spanned, respan};
15 use config::{is_test_or_bench, StripUnconfigured};
16 use errors::{Applicability, FatalError};
18 use ext::build::AstBuilder;
19 use ext::derive::{add_derived_markers, collect_derives};
20 use ext::hygiene::{self, Mark, SyntaxContext};
21 use ext::placeholders::{placeholder, PlaceholderExpander};
22 use feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
25 use parse::{DirectoryOwnership, PResult, ParseSess};
26 use parse::token::{self, Token};
27 use parse::parser::Parser;
31 use syntax_pos::{Span, DUMMY_SP, FileName};
32 use syntax_pos::hygiene::ExpnFormat;
33 use tokenstream::{TokenStream, TokenTree};
34 use util::small_vector::SmallVector;
35 use visit::{self, Visitor};
37 use std::collections::HashMap;
42 use std::path::PathBuf;
44 macro_rules! ast_fragments {
46 $($Kind:ident($AstTy:ty) {
48 // FIXME: HACK: this should be `$(one ...)?` and `$(many ...)?` but `?` macro
49 // repetition was removed from 2015 edition in #51587 because of ambiguities.
50 $(one fn $fold_ast:ident; fn $visit_ast:ident;)*
51 $(many fn $fold_ast_elt:ident; fn $visit_ast_elt:ident;)*
55 /// A fragment of AST that can be produced by a single macro expansion.
56 /// Can also serve as an input and intermediate result for macro expansion operations.
57 pub enum AstFragment {
58 OptExpr(Option<P<ast::Expr>>),
62 /// "Discriminant" of an AST fragment.
63 #[derive(Copy, Clone, PartialEq, Eq)]
64 pub enum AstFragmentKind {
69 impl AstFragmentKind {
70 pub fn name(self) -> &'static str {
72 AstFragmentKind::OptExpr => "expression",
73 $(AstFragmentKind::$Kind => $kind_name,)*
77 fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
79 AstFragmentKind::OptExpr =>
80 result.make_expr().map(Some).map(AstFragment::OptExpr),
81 $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
87 pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
89 AstFragment::OptExpr(expr) => expr,
90 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
94 $(pub fn $make_ast(self) -> $AstTy {
96 AstFragment::$Kind(ast) => ast,
97 _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
101 pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
103 AstFragment::OptExpr(expr) =>
104 AstFragment::OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
105 $($(AstFragment::$Kind(ast) =>
106 AstFragment::$Kind(folder.$fold_ast(ast)),)*)*
107 $($(AstFragment::$Kind(ast) =>
108 AstFragment::$Kind(ast.into_iter()
109 .flat_map(|ast| folder.$fold_ast_elt(ast))
114 pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
116 AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
117 AstFragment::OptExpr(None) => {}
118 $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)*)*
119 $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
120 visitor.$visit_ast_elt(ast_elt);
126 impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
127 fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
128 self.expand_fragment(AstFragment::OptExpr(Some(expr))).make_opt_expr()
130 $($(fn $fold_ast(&mut self, ast: $AstTy) -> $AstTy {
131 self.expand_fragment(AstFragment::$Kind(ast)).$make_ast()
133 $($(fn $fold_ast_elt(&mut self, ast_elt: <$AstTy as IntoIterator>::Item) -> $AstTy {
134 self.expand_fragment(AstFragment::$Kind(SmallVector::one(ast_elt))).$make_ast()
138 impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
139 $(fn $make_ast(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>)
141 Some(self.make(AstFragmentKind::$Kind).$make_ast())
148 Expr(P<ast::Expr>) { "expression"; one fn fold_expr; fn visit_expr; fn make_expr; }
149 Pat(P<ast::Pat>) { "pattern"; one fn fold_pat; fn visit_pat; fn make_pat; }
150 Ty(P<ast::Ty>) { "type"; one fn fold_ty; fn visit_ty; fn make_ty; }
151 Stmts(SmallVector<ast::Stmt>) { "statement"; many fn fold_stmt; fn visit_stmt; fn make_stmts; }
152 Items(SmallVector<P<ast::Item>>) { "item"; many fn fold_item; fn visit_item; fn make_items; }
153 TraitItems(SmallVector<ast::TraitItem>) {
154 "trait item"; many fn fold_trait_item; fn visit_trait_item; fn make_trait_items;
156 ImplItems(SmallVector<ast::ImplItem>) {
157 "impl item"; many fn fold_impl_item; fn visit_impl_item; fn make_impl_items;
159 ForeignItems(SmallVector<ast::ForeignItem>) {
160 "foreign item"; many fn fold_foreign_item; fn visit_foreign_item; fn make_foreign_items;
164 impl AstFragmentKind {
165 fn dummy(self, span: Span) -> Option<AstFragment> {
166 self.make_from(DummyResult::any(span))
169 fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
171 let mut items = items.into_iter();
173 AstFragmentKind::Items =>
174 AstFragment::Items(items.map(Annotatable::expect_item).collect()),
175 AstFragmentKind::ImplItems =>
176 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
177 AstFragmentKind::TraitItems =>
178 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
179 AstFragmentKind::ForeignItems =>
180 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect()),
181 AstFragmentKind::Stmts =>
182 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect()),
183 AstFragmentKind::Expr => AstFragment::Expr(
184 items.next().expect("expected exactly one expression").expect_expr()
186 AstFragmentKind::OptExpr =>
187 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr)),
188 AstFragmentKind::Pat | AstFragmentKind::Ty =>
189 panic!("patterns and types aren't annotatable"),
194 fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
195 // We don't want to format a path using pretty-printing,
196 // `format!("{}", path)`, because that tries to insert
197 // line-breaks and is slow.
198 let mut path_str = String::with_capacity(64);
199 for (i, segment) in path.segments.iter().enumerate() {
201 path_str.push_str("::");
204 if segment.ident.name != keywords::CrateRoot.name() &&
205 segment.ident.name != keywords::DollarCrate.name()
207 path_str.push_str(&segment.ident.as_str())
211 MacroBang(Symbol::intern(&path_str))
214 pub struct Invocation {
215 pub kind: InvocationKind,
216 fragment_kind: AstFragmentKind,
217 pub expansion_data: ExpansionData,
220 pub enum InvocationKind {
223 ident: Option<Ident>,
227 attr: Option<ast::Attribute>,
238 pub fn span(&self) -> Span {
240 InvocationKind::Bang { span, .. } => span,
241 InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
242 InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
243 InvocationKind::Derive { ref path, .. } => path.span,
247 pub fn path_span(&self) -> Span {
249 InvocationKind::Bang { ref mac, .. } => mac.node.path.span,
250 InvocationKind::Attr { attr: Some(ref attr), .. } => attr.path.span,
251 InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
252 InvocationKind::Derive { ref path, .. } => path.span,
256 pub fn attr_id(&self) -> Option<ast::AttrId> {
258 InvocationKind::Attr { attr: Some(ref attr), .. } => Some(attr.id),
264 pub struct MacroExpander<'a, 'b:'a> {
265 pub cx: &'a mut ExtCtxt<'b>,
266 monotonic: bool, // c.f. `cx.monotonic_expander()`
269 impl<'a, 'b> MacroExpander<'a, 'b> {
270 pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
271 MacroExpander { cx: cx, monotonic: monotonic }
274 pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
275 let mut module = ModuleData {
276 mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
277 directory: match self.cx.codemap().span_to_unmapped_path(krate.span) {
278 FileName::Real(path) => path,
279 other => PathBuf::from(other.to_string()),
282 module.directory.pop();
283 self.cx.root_path = module.directory.clone();
284 self.cx.current_expansion.module = Rc::new(module);
285 self.cx.current_expansion.crate_span = Some(krate.span);
287 let orig_mod_span = krate.module.inner;
289 let krate_item = AstFragment::Items(SmallVector::one(P(ast::Item {
292 node: ast::ItemKind::Mod(krate.module),
293 ident: keywords::Invalid.ident(),
294 id: ast::DUMMY_NODE_ID,
295 vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
299 match self.expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
300 Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
302 krate.module = module;
305 // Resolution failed so we return an empty expansion
306 krate.attrs = vec![];
307 krate.module = ast::Mod {
308 inner: orig_mod_span,
314 self.cx.trace_macros_diag();
318 // Fully expand all macro invocations in this AST fragment.
319 fn expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
320 let orig_expansion_data = self.cx.current_expansion.clone();
321 self.cx.current_expansion.depth = 0;
323 // Collect all macro invocations and replace them with placeholders.
324 let (fragment_with_placeholders, mut invocations)
325 = self.collect_invocations(input_fragment, &[]);
327 // Optimization: if we resolve all imports now,
328 // we'll be able to immediately resolve most of imported macros.
329 self.resolve_imports();
331 // Resolve paths in all invocations and produce ouput expanded fragments for them, but
332 // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
333 // The output fragments also go through expansion recursively until no invocations are left.
334 // Unresolved macros produce dummy outputs as a recovery measure.
335 invocations.reverse();
336 let mut expanded_fragments = Vec::new();
337 let mut derives = HashMap::new();
338 let mut undetermined_invocations = Vec::new();
339 let (mut progress, mut force) = (false, !self.monotonic);
341 let mut invoc = if let Some(invoc) = invocations.pop() {
344 self.resolve_imports();
345 if undetermined_invocations.is_empty() { break }
346 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
347 force = !mem::replace(&mut progress, false);
352 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
353 let attr_id_before = invoc.attr_id();
354 let ext = match self.cx.resolver.resolve_invoc(&mut invoc, scope, force) {
355 Ok(ext) => Some(ext),
356 Err(Determinacy::Determined) => None,
357 Err(Determinacy::Undetermined) => {
358 // Sometimes attributes which we thought were invocations
359 // end up being custom attributes for custom derives. If
360 // that's the case our `invoc` will have changed out from
361 // under us. If this is the case we're making progress so we
362 // want to flag it as such, and we test this by looking if
363 // the `attr_id()` method has been changing over time.
364 if invoc.attr_id() != attr_id_before {
367 undetermined_invocations.push(invoc);
373 let ExpansionData { depth, mark, .. } = invoc.expansion_data;
374 self.cx.current_expansion = invoc.expansion_data.clone();
376 self.cx.current_expansion.mark = scope;
377 // FIXME(jseyfried): Refactor out the following logic
378 let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
379 if let Some(ext) = ext {
380 let dummy = invoc.fragment_kind.dummy(invoc.span()).unwrap();
381 let fragment = self.expand_invoc(invoc, &*ext).unwrap_or(dummy);
382 self.collect_invocations(fragment, &[])
383 } else if let InvocationKind::Attr { attr: None, traits, item } = invoc.kind {
384 if !item.derive_allowed() {
385 let attr = attr::find_by_name(item.attrs(), "derive")
386 .expect("`derive` attribute should exist");
387 let span = attr.span;
388 let mut err = self.cx.mut_span_err(span,
389 "`derive` may only be applied to \
390 structs, enums and unions");
391 if let ast::AttrStyle::Inner = attr.style {
392 let trait_list = traits.iter()
393 .map(|t| t.to_string()).collect::<Vec<_>>();
394 let suggestion = format!("#[derive({})]", trait_list.join(", "));
395 err.span_suggestion_with_applicability(
396 span, "try an outer attribute", suggestion,
397 // We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
398 Applicability::MaybeIncorrect
404 let item = self.fully_configure(item)
405 .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
406 let item_with_markers =
407 add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
408 let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
410 for path in &traits {
411 let mark = Mark::fresh(self.cx.current_expansion.mark);
413 let item = match self.cx.resolver.resolve_macro(
414 Mark::root(), path, MacroKind::Derive, false) {
415 Ok(ext) => match *ext {
416 BuiltinDerive(..) => item_with_markers.clone(),
421 invocations.push(Invocation {
422 kind: InvocationKind::Derive { path: path.clone(), item: item },
423 fragment_kind: invoc.fragment_kind,
424 expansion_data: ExpansionData {
426 ..invoc.expansion_data.clone()
430 let fragment = invoc.fragment_kind
431 .expect_from_annotatables(::std::iter::once(item_with_markers));
432 self.collect_invocations(fragment, derives)
437 self.collect_invocations(invoc.fragment_kind.dummy(invoc.span()).unwrap(), &[])
440 if expanded_fragments.len() < depth {
441 expanded_fragments.push(Vec::new());
443 expanded_fragments[depth - 1].push((mark, expanded_fragment));
444 if !self.cx.ecfg.single_step {
445 invocations.extend(new_invocations.into_iter().rev());
449 self.cx.current_expansion = orig_expansion_data;
451 // Finally incorporate all the expanded macros into the input AST fragment.
452 let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
453 while let Some(expanded_fragments) = expanded_fragments.pop() {
454 for (mark, expanded_fragment) in expanded_fragments.into_iter().rev() {
455 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
456 placeholder_expander.add(NodeId::placeholder_from_mark(mark),
457 expanded_fragment, derives);
460 fragment_with_placeholders.fold_with(&mut placeholder_expander)
463 fn resolve_imports(&mut self) {
465 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
466 self.cx.resolver.resolve_imports();
467 self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
471 /// Collect all macro invocations reachable at this time in this AST fragment, and replace
472 /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
473 /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
474 /// prepares data for resolving paths of macro invocations.
475 fn collect_invocations(&mut self, fragment: AstFragment, derives: &[Mark])
476 -> (AstFragment, Vec<Invocation>) {
477 let (fragment_with_placeholders, invocations) = {
478 let mut collector = InvocationCollector {
479 cfg: StripUnconfigured {
480 should_test: self.cx.ecfg.should_test,
481 sess: self.cx.parse_sess,
482 features: self.cx.ecfg.features,
485 invocations: Vec::new(),
486 monotonic: self.monotonic,
487 tests_nameable: true,
489 (fragment.fold_with(&mut collector), collector.invocations)
493 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
494 let mark = self.cx.current_expansion.mark;
495 self.cx.resolver.visit_ast_fragment_with_placeholders(mark, &fragment_with_placeholders,
497 self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
500 (fragment_with_placeholders, invocations)
503 fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
504 let mut cfg = StripUnconfigured {
505 should_test: self.cx.ecfg.should_test,
506 sess: self.cx.parse_sess,
507 features: self.cx.ecfg.features,
509 // Since the item itself has already been configured by the InvocationCollector,
510 // we know that fold result vector will contain exactly one element
512 Annotatable::Item(item) => {
513 Annotatable::Item(cfg.fold_item(item).pop().unwrap())
515 Annotatable::TraitItem(item) => {
516 Annotatable::TraitItem(item.map(|item| cfg.fold_trait_item(item).pop().unwrap()))
518 Annotatable::ImplItem(item) => {
519 Annotatable::ImplItem(item.map(|item| cfg.fold_impl_item(item).pop().unwrap()))
521 Annotatable::ForeignItem(item) => {
522 Annotatable::ForeignItem(
523 item.map(|item| cfg.fold_foreign_item(item).pop().unwrap())
526 Annotatable::Stmt(stmt) => {
527 Annotatable::Stmt(stmt.map(|stmt| cfg.fold_stmt(stmt).pop().unwrap()))
529 Annotatable::Expr(expr) => {
530 Annotatable::Expr(cfg.fold_expr(expr))
535 fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
536 let result = match invoc.kind {
537 InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext)?,
538 InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext)?,
539 InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext)?,
542 if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
543 let info = self.cx.current_expansion.mark.expn_info().unwrap();
544 let suggested_limit = self.cx.ecfg.recursion_limit * 2;
545 let mut err = self.cx.struct_span_err(info.call_site,
546 &format!("recursion limit reached while expanding the macro `{}`",
547 info.format.name()));
549 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
552 self.cx.trace_macros_diag();
559 fn expand_attr_invoc(&mut self,
561 ext: &SyntaxExtension)
562 -> Option<AstFragment> {
563 let (attr, item) = match invoc.kind {
564 InvocationKind::Attr { attr, item, .. } => (attr?, item),
568 attr::mark_used(&attr);
569 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
570 call_site: attr.span,
572 format: MacroAttribute(Symbol::intern(&attr.path.to_string())),
573 allow_internal_unstable: false,
574 allow_internal_unsafe: false,
575 local_inner_macros: false,
576 edition: ext.edition(),
581 attr::mark_known(&attr);
582 let item = item.map_attrs(|mut attrs| { attrs.push(attr); attrs });
583 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
585 MultiModifier(ref mac) => {
586 let meta = attr.parse_meta(self.cx.parse_sess)
587 .map_err(|mut e| { e.emit(); }).ok()?;
588 let item = mac.expand(self.cx, attr.span, &meta, item);
589 Some(invoc.fragment_kind.expect_from_annotatables(item))
591 MultiDecorator(ref mac) => {
592 let mut items = Vec::new();
593 let meta = attr.parse_meta(self.cx.parse_sess)
594 .expect("derive meta should already have been parsed");
595 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
597 Some(invoc.fragment_kind.expect_from_annotatables(items))
599 AttrProcMacro(ref mac, ..) => {
600 self.gate_proc_macro_attr_item(attr.span, &item);
601 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
602 Annotatable::Item(item) => token::NtItem(item),
603 Annotatable::TraitItem(item) => token::NtTraitItem(item.into_inner()),
604 Annotatable::ImplItem(item) => token::NtImplItem(item.into_inner()),
605 Annotatable::ForeignItem(item) => token::NtForeignItem(item.into_inner()),
606 Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
607 Annotatable::Expr(expr) => token::NtExpr(expr),
609 let input = self.extract_proc_macro_attr_input(attr.tokens, attr.span);
610 let tok_result = mac.expand(self.cx, attr.span, input, item_tok);
611 let res = self.parse_ast_fragment(tok_result, invoc.fragment_kind,
612 &attr.path, attr.span);
613 self.gate_proc_macro_expansion(attr.span, &res);
616 ProcMacroDerive(..) | BuiltinDerive(..) => {
617 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
618 self.cx.trace_macros_diag();
619 invoc.fragment_kind.dummy(attr.span)
622 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
623 self.cx.span_err(attr.span, msg);
624 self.cx.trace_macros_diag();
625 invoc.fragment_kind.dummy(attr.span)
630 fn extract_proc_macro_attr_input(&self, tokens: TokenStream, span: Span) -> TokenStream {
631 let mut trees = tokens.trees();
633 Some(TokenTree::Delimited(_, delim)) => {
634 if trees.next().is_none() {
635 return delim.tts.into()
638 Some(TokenTree::Token(..)) => {}
639 None => return TokenStream::empty(),
641 self.cx.span_err(span, "custom attribute invocations must be \
642 of the form #[foo] or #[foo(..)], the macro name must only be \
643 followed by a delimiter token");
647 fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
648 let (kind, gate) = match *item {
649 Annotatable::Item(ref item) => {
651 ItemKind::Mod(_) if self.cx.ecfg.proc_macro_mod() => return,
652 ItemKind::Mod(_) => ("modules", "proc_macro_mod"),
656 Annotatable::TraitItem(_) => return,
657 Annotatable::ImplItem(_) => return,
658 Annotatable::ForeignItem(_) => return,
659 Annotatable::Stmt(_) |
660 Annotatable::Expr(_) if self.cx.ecfg.proc_macro_expr() => return,
661 Annotatable::Stmt(_) => ("statements", "proc_macro_expr"),
662 Annotatable::Expr(_) => ("expressions", "proc_macro_expr"),
669 &format!("custom attributes cannot be applied to {}", kind),
673 fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>) {
674 if self.cx.ecfg.proc_macro_gen() {
677 let fragment = match fragment {
678 Some(fragment) => fragment,
682 fragment.visit_with(&mut DisallowModules {
684 parse_sess: self.cx.parse_sess,
687 struct DisallowModules<'a> {
689 parse_sess: &'a ParseSess,
692 impl<'ast, 'a> Visitor<'ast> for DisallowModules<'a> {
693 fn visit_item(&mut self, i: &'ast ast::Item) {
694 let name = match i.node {
695 ast::ItemKind::Mod(_) => Some("modules"),
696 ast::ItemKind::MacroDef(_) => Some("macro definitions"),
699 if let Some(name) = name {
705 &format!("procedural macros cannot expand to {}", name),
708 visit::walk_item(self, i);
711 fn visit_mac(&mut self, _mac: &'ast ast::Mac) {
717 /// Expand a macro invocation. Returns the resulting expanded AST fragment.
718 fn expand_bang_invoc(&mut self,
720 ext: &SyntaxExtension)
721 -> Option<AstFragment> {
722 let (mark, kind) = (invoc.expansion_data.mark, invoc.fragment_kind);
723 let (mac, ident, span) = match invoc.kind {
724 InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
727 let path = &mac.node.path;
729 let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
730 let validate_and_set_expn_info = |this: &mut Self, // arg instead of capture
731 def_site_span: Option<Span>,
732 allow_internal_unstable,
733 allow_internal_unsafe,
735 // can't infer this type
736 unstable_feature: Option<(Symbol, u32)>,
739 // feature-gate the macro invocation
740 if let Some((feature, issue)) = unstable_feature {
741 let crate_span = this.cx.current_expansion.crate_span.unwrap();
742 // don't stability-check macros in the same crate
743 // (the only time this is null is for syntax extensions registered as macros)
744 if def_site_span.map_or(false, |def_span| !crate_span.contains(def_span))
745 && !span.allows_unstable() && this.cx.ecfg.features.map_or(true, |feats| {
746 // macro features will count as lib features
747 !feats.declared_lib_features.iter().any(|&(feat, _)| feat == feature)
749 let explain = format!("macro {}! is unstable", path);
750 emit_feature_err(this.cx.parse_sess, &*feature.as_str(), span,
751 GateIssue::Library(Some(issue)), &explain);
752 this.cx.trace_macros_diag();
753 return Err(kind.dummy(span));
757 if ident.name != keywords::Invalid.name() {
758 let msg = format!("macro {}! expects no ident argument, given '{}'", path, ident);
759 this.cx.span_err(path.span, &msg);
760 this.cx.trace_macros_diag();
761 return Err(kind.dummy(span));
763 mark.set_expn_info(ExpnInfo {
765 def_site: def_site_span,
766 format: macro_bang_format(path),
767 allow_internal_unstable,
768 allow_internal_unsafe,
775 let opt_expanded = match *ext {
776 DeclMacro { ref expander, def_info, edition, .. } => {
777 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
778 false, false, false, None,
782 kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
789 allow_internal_unstable,
790 allow_internal_unsafe,
795 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
796 allow_internal_unstable,
797 allow_internal_unsafe,
803 kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
807 IdentTT(ref expander, tt_span, allow_internal_unstable) => {
808 if ident.name == keywords::Invalid.name() {
809 self.cx.span_err(path.span,
810 &format!("macro {}! expects an ident argument", path));
811 self.cx.trace_macros_diag();
814 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
817 format: macro_bang_format(path),
818 allow_internal_unstable,
819 allow_internal_unsafe: false,
820 local_inner_macros: false,
821 edition: hygiene::default_edition(),
824 let input: Vec<_> = mac.node.stream().into_trees().collect();
825 kind.make_from(expander.expand(self.cx, span, ident, input))
829 MultiDecorator(..) | MultiModifier(..) |
830 AttrProcMacro(..) | SyntaxExtension::NonMacroAttr => {
831 self.cx.span_err(path.span,
832 &format!("`{}` can only be used in attributes", path));
833 self.cx.trace_macros_diag();
837 ProcMacroDerive(..) | BuiltinDerive(..) => {
838 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
839 self.cx.trace_macros_diag();
843 SyntaxExtension::ProcMacro { ref expander, allow_internal_unstable, edition } => {
844 if ident.name != keywords::Invalid.name() {
846 format!("macro {}! expects no ident argument, given '{}'", path, ident);
847 self.cx.span_err(path.span, &msg);
848 self.cx.trace_macros_diag();
851 self.gate_proc_macro_expansion_kind(span, kind);
852 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
854 // FIXME procedural macros do not have proper span info
855 // yet, when they do, we should use it here.
857 format: macro_bang_format(path),
858 // FIXME probably want to follow macro_rules macros here.
859 allow_internal_unstable,
860 allow_internal_unsafe: false,
861 local_inner_macros: false,
865 let tok_result = expander.expand(self.cx, span, mac.node.stream());
866 let result = self.parse_ast_fragment(tok_result, kind, path, span);
867 self.gate_proc_macro_expansion(span, &result);
873 if opt_expanded.is_some() {
876 let msg = format!("non-{kind} macro in {kind} position: {name}",
877 name = path.segments[0].ident.name, kind = kind.name());
878 self.cx.span_err(path.span, &msg);
879 self.cx.trace_macros_diag();
884 fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
885 let kind = match kind {
886 AstFragmentKind::Expr => "expressions",
887 AstFragmentKind::OptExpr => "expressions",
888 AstFragmentKind::Pat => "patterns",
889 AstFragmentKind::Ty => "types",
890 AstFragmentKind::Stmts => "statements",
891 AstFragmentKind::Items => return,
892 AstFragmentKind::TraitItems => return,
893 AstFragmentKind::ImplItems => return,
894 AstFragmentKind::ForeignItems => return,
896 if self.cx.ecfg.proc_macro_non_items() {
901 "proc_macro_non_items",
904 &format!("procedural macros cannot be expanded to {}", kind),
908 /// Expand a derive invocation. Returns the resulting expanded AST fragment.
909 fn expand_derive_invoc(&mut self,
911 ext: &SyntaxExtension)
912 -> Option<AstFragment> {
913 let (path, item) = match invoc.kind {
914 InvocationKind::Derive { path, item } => (path, item),
917 if !item.derive_allowed() {
921 let pretty_name = Symbol::intern(&format!("derive({})", path));
922 let span = path.span;
923 let attr = ast::Attribute {
925 tokens: TokenStream::empty(),
927 id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
930 let mut expn_info = ExpnInfo {
933 format: MacroAttribute(pretty_name),
934 allow_internal_unstable: false,
935 allow_internal_unsafe: false,
936 local_inner_macros: false,
937 edition: ext.edition(),
941 ProcMacroDerive(ref ext, ..) => {
942 invoc.expansion_data.mark.set_expn_info(expn_info);
943 let span = span.with_ctxt(self.cx.backtrace());
944 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
945 ident: Path::from_ident(keywords::Invalid.ident()),
947 node: ast::MetaItemKind::Word,
949 let items = ext.expand(self.cx, span, &dummy, item);
950 Some(invoc.fragment_kind.expect_from_annotatables(items))
952 BuiltinDerive(func) => {
953 expn_info.allow_internal_unstable = true;
954 invoc.expansion_data.mark.set_expn_info(expn_info);
955 let span = span.with_ctxt(self.cx.backtrace());
956 let mut items = Vec::new();
957 func(self.cx, span, &attr.meta()?, &item, &mut |a| items.push(a));
958 Some(invoc.fragment_kind.expect_from_annotatables(items))
961 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
962 self.cx.span_err(span, msg);
963 self.cx.trace_macros_diag();
964 invoc.fragment_kind.dummy(span)
969 fn parse_ast_fragment(&mut self,
971 kind: AstFragmentKind,
974 -> Option<AstFragment> {
975 let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
976 match parser.parse_ast_fragment(kind, false) {
978 parser.ensure_complete_parse(path, kind.name(), span);
984 self.cx.trace_macros_diag();
991 impl<'a> Parser<'a> {
992 pub fn parse_ast_fragment(&mut self, kind: AstFragmentKind, macro_legacy_warnings: bool)
993 -> PResult<'a, AstFragment> {
995 AstFragmentKind::Items => {
996 let mut items = SmallVector::new();
997 while let Some(item) = self.parse_item()? {
1000 AstFragment::Items(items)
1002 AstFragmentKind::TraitItems => {
1003 let mut items = SmallVector::new();
1004 while self.token != token::Eof {
1005 items.push(self.parse_trait_item(&mut false)?);
1007 AstFragment::TraitItems(items)
1009 AstFragmentKind::ImplItems => {
1010 let mut items = SmallVector::new();
1011 while self.token != token::Eof {
1012 items.push(self.parse_impl_item(&mut false)?);
1014 AstFragment::ImplItems(items)
1016 AstFragmentKind::ForeignItems => {
1017 let mut items = SmallVector::new();
1018 while self.token != token::Eof {
1019 if let Some(item) = self.parse_foreign_item()? {
1023 AstFragment::ForeignItems(items)
1025 AstFragmentKind::Stmts => {
1026 let mut stmts = SmallVector::new();
1027 while self.token != token::Eof &&
1028 // won't make progress on a `}`
1029 self.token != token::CloseDelim(token::Brace) {
1030 if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
1034 AstFragment::Stmts(stmts)
1036 AstFragmentKind::Expr => AstFragment::Expr(self.parse_expr()?),
1037 AstFragmentKind::OptExpr => {
1038 if self.token != token::Eof {
1039 AstFragment::OptExpr(Some(self.parse_expr()?))
1041 AstFragment::OptExpr(None)
1044 AstFragmentKind::Ty => AstFragment::Ty(self.parse_ty()?),
1045 AstFragmentKind::Pat => AstFragment::Pat(self.parse_pat()?),
1049 pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
1050 if self.token != token::Eof {
1051 let msg = format!("macro expansion ignores token `{}` and any following",
1052 self.this_token_to_string());
1053 // Avoid emitting backtrace info twice.
1054 let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
1055 let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
1056 let msg = format!("caused by the macro expansion here; the usage \
1057 of `{}!` is likely invalid in {} context",
1058 macro_path, kind_name);
1059 err.span_note(span, &msg).emit();
1064 struct InvocationCollector<'a, 'b: 'a> {
1065 cx: &'a mut ExtCtxt<'b>,
1066 cfg: StripUnconfigured<'a>,
1067 invocations: Vec<Invocation>,
1070 /// Test functions need to be nameable. Tests inside functions or in other
1071 /// unnameable locations need to be ignored. `tests_nameable` tracks whether
1072 /// any test functions found in the current context would be nameable.
1073 tests_nameable: bool,
1076 impl<'a, 'b> InvocationCollector<'a, 'b> {
1077 fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
1078 let mark = Mark::fresh(self.cx.current_expansion.mark);
1079 self.invocations.push(Invocation {
1082 expansion_data: ExpansionData {
1084 depth: self.cx.current_expansion.depth + 1,
1085 ..self.cx.current_expansion.clone()
1088 placeholder(fragment_kind, NodeId::placeholder_from_mark(mark))
1091 /// Folds the item allowing tests to be expanded because they are still nameable.
1092 /// This should probably only be called with module items
1093 fn fold_nameable(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
1094 fold::noop_fold_item(item, self)
1097 /// Folds the item but doesn't allow tests to occur within it
1098 fn fold_unnameable(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
1099 let was_nameable = mem::replace(&mut self.tests_nameable, false);
1100 let items = fold::noop_fold_item(item, self);
1101 self.tests_nameable = was_nameable;
1105 fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
1106 self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
1109 fn collect_attr(&mut self,
1110 attr: Option<ast::Attribute>,
1113 kind: AstFragmentKind)
1115 self.collect(kind, InvocationKind::Attr { attr, traits, item })
1118 /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
1119 fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
1122 let (mut attr, mut traits) = (None, Vec::new());
1124 item = item.map_attrs(|mut attrs| {
1125 if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
1127 attr = Some(legacy_attr_invoc);
1131 if self.cx.ecfg.use_extern_macros_enabled() {
1132 attr = find_attr_invoc(&mut attrs);
1134 traits = collect_derives(&mut self.cx, &mut attrs);
1138 (attr, traits, item)
1141 /// Alternative of `classify_item()` that ignores `#[derive]` so invocations fallthrough
1142 /// to the unused-attributes lint (making it an error on statements and expressions
1143 /// is a breaking change)
1144 fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T) -> (Option<ast::Attribute>, T) {
1145 let mut attr = None;
1147 item = item.map_attrs(|mut attrs| {
1148 if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
1150 attr = Some(legacy_attr_invoc);
1154 if self.cx.ecfg.use_extern_macros_enabled() {
1155 attr = find_attr_invoc(&mut attrs);
1163 fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
1164 self.cfg.configure(node)
1167 // Detect use of feature-gated or invalid attributes on macro invocations
1168 // since they will not be detected after macro expansion.
1169 fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
1170 let features = self.cx.ecfg.features.unwrap();
1171 for attr in attrs.iter() {
1172 self.check_attribute_inner(attr, features);
1174 // macros are expanded before any lint passes so this warning has to be hardcoded
1175 if attr.path == "derive" {
1176 self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
1177 .note("this may become a hard error in a future release")
1183 fn check_attribute(&mut self, at: &ast::Attribute) {
1184 let features = self.cx.ecfg.features.unwrap();
1185 self.check_attribute_inner(at, features);
1188 fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
1189 feature_gate::check_attribute(at, self.cx.parse_sess, features);
1193 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
1195 .position(|a| !attr::is_known(a) && !is_builtin_attr(a))
1196 .map(|i| attrs.remove(i))
1199 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
1200 fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
1201 let mut expr = self.cfg.configure_expr(expr).into_inner();
1202 expr.node = self.cfg.configure_expr_kind(expr.node);
1204 // ignore derives so they remain unused
1205 let (attr, expr) = self.classify_nonitem(expr);
1208 // collect the invoc regardless of whether or not attributes are permitted here
1209 // expansion will eat the attribute so it won't error later
1210 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1212 // AstFragmentKind::Expr requires the macro to emit an expression
1213 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1214 AstFragmentKind::Expr).make_expr();
1217 if let ast::ExprKind::Mac(mac) = expr.node {
1218 self.check_attributes(&expr.attrs);
1219 self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr()
1221 P(noop_fold_expr(expr, self))
1225 fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
1226 let mut expr = configure!(self, expr).into_inner();
1227 expr.node = self.cfg.configure_expr_kind(expr.node);
1229 // ignore derives so they remain unused
1230 let (attr, expr) = self.classify_nonitem(expr);
1233 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1235 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1236 AstFragmentKind::OptExpr)
1240 if let ast::ExprKind::Mac(mac) = expr.node {
1241 self.check_attributes(&expr.attrs);
1242 self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr).make_opt_expr()
1244 Some(P(noop_fold_expr(expr, self)))
1248 fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
1249 let pat = self.cfg.configure_pat(pat);
1251 PatKind::Mac(_) => {}
1252 _ => return noop_fold_pat(pat, self),
1255 pat.and_then(|pat| match pat.node {
1256 PatKind::Mac(mac) => self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
1257 _ => unreachable!(),
1261 fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
1262 let mut stmt = match self.cfg.configure_stmt(stmt) {
1264 None => return SmallVector::new(),
1267 // we'll expand attributes on expressions separately
1268 if !stmt.is_expr() {
1269 let (attr, derives, stmt_) = if stmt.is_item() {
1270 self.classify_item(stmt)
1272 // ignore derives on non-item statements so it falls through
1273 // to the unused-attributes lint
1274 let (attr, stmt) = self.classify_nonitem(stmt);
1275 (attr, vec![], stmt)
1278 if attr.is_some() || !derives.is_empty() {
1279 return self.collect_attr(attr, derives,
1280 Annotatable::Stmt(P(stmt_)), AstFragmentKind::Stmts)
1287 if let StmtKind::Mac(mac) = stmt.node {
1288 let (mac, style, attrs) = mac.into_inner();
1289 self.check_attributes(&attrs);
1290 let mut placeholder = self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts)
1293 // If this is a macro invocation with a semicolon, then apply that
1294 // semicolon to the final statement produced by expansion.
1295 if style == MacStmtStyle::Semicolon {
1296 if let Some(stmt) = placeholder.pop() {
1297 placeholder.push(stmt.add_trailing_semicolon());
1304 // The placeholder expander gives ids to statements, so we avoid folding the id here.
1305 let ast::Stmt { id, node, span } = stmt;
1306 noop_fold_stmt_kind(node, self).into_iter().map(|node| {
1307 ast::Stmt { id, node, span }
1312 fn fold_block(&mut self, block: P<Block>) -> P<Block> {
1313 let old_directory_ownership = self.cx.current_expansion.directory_ownership;
1314 self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
1315 let result = noop_fold_block(block, self);
1316 self.cx.current_expansion.directory_ownership = old_directory_ownership;
1320 fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
1321 let item = configure!(self, item);
1323 let (attr, traits, mut item) = self.classify_item(item);
1324 if attr.is_some() || !traits.is_empty() {
1325 let item = Annotatable::Item(item);
1326 return self.collect_attr(attr, traits, item, AstFragmentKind::Items).make_items();
1330 ast::ItemKind::Mac(..) => {
1331 self.check_attributes(&item.attrs);
1332 item.and_then(|item| match item.node {
1333 ItemKind::Mac(mac) => {
1334 self.collect(AstFragmentKind::Items, InvocationKind::Bang {
1336 ident: Some(item.ident),
1340 _ => unreachable!(),
1343 ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
1344 if item.ident == keywords::Invalid.ident() {
1345 return self.fold_nameable(item);
1348 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
1349 let mut module = (*self.cx.current_expansion.module).clone();
1350 module.mod_path.push(item.ident);
1352 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
1353 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
1354 // Thus, if `inner` is the dummy span, we know the module is inline.
1355 let inline_module = item.span.contains(inner) || inner.is_dummy();
1358 if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
1359 self.cx.current_expansion.directory_ownership =
1360 DirectoryOwnership::Owned { relative: None };
1361 module.directory.push(&*path.as_str());
1363 module.directory.push(&*item.ident.as_str());
1366 let path = self.cx.parse_sess.codemap().span_to_unmapped_path(inner);
1367 let mut path = match path {
1368 FileName::Real(path) => path,
1369 other => PathBuf::from(other.to_string()),
1371 let directory_ownership = match path.file_name().unwrap().to_str() {
1372 Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
1373 Some(_) => DirectoryOwnership::Owned {
1374 relative: Some(item.ident),
1376 None => DirectoryOwnership::UnownedViaMod(false),
1379 module.directory = path;
1380 self.cx.current_expansion.directory_ownership = directory_ownership;
1384 mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
1385 let result = self.fold_nameable(item);
1386 self.cx.current_expansion.module = orig_module;
1387 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
1390 // Ensure that test functions are accessible from the test harness.
1391 // #[test] fn foo() {}
1393 // #[test] pub fn foo_gensym(){}
1395 // use foo_gensym as foo;
1396 ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
1397 if self.tests_nameable && item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
1398 let orig_ident = item.ident;
1399 let orig_vis = item.vis.clone();
1401 // Publicize the item under gensymed name to avoid pollution
1402 item = item.map(|mut item| {
1403 item.vis = respan(item.vis.span, ast::VisibilityKind::Public);
1404 item.ident = item.ident.gensym();
1408 // Use the gensymed name under the item's original visibility
1409 let mut use_item = self.cx.item_use_simple_(
1413 self.cx.path(item.ident.span,
1414 vec![keywords::SelfValue.ident(), item.ident]));
1416 // #[allow(unused)] because the test function probably isn't being referenced
1417 use_item = use_item.map(|mut ui| {
1419 self.cx.attribute(DUMMY_SP, attr::mk_list_item(DUMMY_SP,
1420 Ident::from_str("allow"), vec![
1421 attr::mk_nested_word_item(Ident::from_str("unused"))
1430 self.fold_unnameable(item).into_iter()
1431 .chain(self.fold_unnameable(use_item)))
1433 self.fold_unnameable(item)
1436 _ => self.fold_unnameable(item),
1440 fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
1441 let item = configure!(self, item);
1443 let (attr, traits, item) = self.classify_item(item);
1444 if attr.is_some() || !traits.is_empty() {
1445 let item = Annotatable::TraitItem(P(item));
1446 return self.collect_attr(attr, traits, item, AstFragmentKind::TraitItems)
1451 ast::TraitItemKind::Macro(mac) => {
1452 let ast::TraitItem { attrs, span, .. } = item;
1453 self.check_attributes(&attrs);
1454 self.collect_bang(mac, span, AstFragmentKind::TraitItems).make_trait_items()
1456 _ => fold::noop_fold_trait_item(item, self),
1460 fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
1461 let item = configure!(self, item);
1463 let (attr, traits, item) = self.classify_item(item);
1464 if attr.is_some() || !traits.is_empty() {
1465 let item = Annotatable::ImplItem(P(item));
1466 return self.collect_attr(attr, traits, item, AstFragmentKind::ImplItems)
1471 ast::ImplItemKind::Macro(mac) => {
1472 let ast::ImplItem { attrs, span, .. } = item;
1473 self.check_attributes(&attrs);
1474 self.collect_bang(mac, span, AstFragmentKind::ImplItems).make_impl_items()
1476 _ => fold::noop_fold_impl_item(item, self),
1480 fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1481 let ty = match ty.node {
1482 ast::TyKind::Mac(_) => ty.into_inner(),
1483 _ => return fold::noop_fold_ty(ty, self),
1487 ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
1488 _ => unreachable!(),
1492 fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1493 noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1496 fn fold_foreign_item(&mut self,
1497 foreign_item: ast::ForeignItem) -> SmallVector<ast::ForeignItem> {
1498 let (attr, traits, foreign_item) = self.classify_item(foreign_item);
1500 let explain = if self.cx.ecfg.use_extern_macros_enabled() {
1501 feature_gate::EXPLAIN_PROC_MACROS_IN_EXTERN
1503 feature_gate::EXPLAIN_MACROS_IN_EXTERN
1506 if attr.is_some() || !traits.is_empty() {
1507 if !self.cx.ecfg.macros_in_extern_enabled() {
1508 if let Some(ref attr) = attr {
1509 emit_feature_err(&self.cx.parse_sess, "macros_in_extern", attr.span,
1510 GateIssue::Language, explain);
1514 let item = Annotatable::ForeignItem(P(foreign_item));
1515 return self.collect_attr(attr, traits, item, AstFragmentKind::ForeignItems)
1516 .make_foreign_items();
1519 if let ast::ForeignItemKind::Macro(mac) = foreign_item.node {
1520 self.check_attributes(&foreign_item.attrs);
1522 if !self.cx.ecfg.macros_in_extern_enabled() {
1523 emit_feature_err(&self.cx.parse_sess, "macros_in_extern", foreign_item.span,
1524 GateIssue::Language, explain);
1527 return self.collect_bang(mac, foreign_item.span, AstFragmentKind::ForeignItems)
1528 .make_foreign_items();
1531 noop_fold_foreign_item(foreign_item, self)
1534 fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1536 ast::ItemKind::MacroDef(..) => item,
1537 _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1541 fn fold_generic_param(&mut self, param: ast::GenericParam) -> ast::GenericParam {
1542 self.cfg.disallow_cfg_on_generic_param(¶m);
1543 noop_fold_generic_param(param, self)
1546 fn fold_attribute(&mut self, at: ast::Attribute) -> Option<ast::Attribute> {
1547 // turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
1548 // contents="file contents")]` attributes
1549 if !at.check_name("doc") {
1550 return noop_fold_attribute(at, self);
1553 if let Some(list) = at.meta_item_list() {
1554 if !list.iter().any(|it| it.check_name("include")) {
1555 return noop_fold_attribute(at, self);
1558 let mut items = vec![];
1561 if !it.check_name("include") {
1562 items.push(noop_fold_meta_list_item(it, self));
1566 if let Some(file) = it.value_str() {
1567 let err_count = self.cx.parse_sess.span_diagnostic.err_count();
1568 self.check_attribute(&at);
1569 if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
1570 // avoid loading the file if they haven't enabled the feature
1571 return noop_fold_attribute(at, self);
1574 let mut buf = vec![];
1575 let filename = self.cx.root_path.join(file.to_string());
1577 match File::open(&filename).and_then(|mut f| f.read_to_end(&mut buf)) {
1580 self.cx.span_err(at.span,
1581 &format!("couldn't read {}: {}",
1587 match String::from_utf8(buf) {
1589 let src_interned = Symbol::intern(&src);
1591 // Add this input file to the code map to make it available as
1592 // dependency information
1593 self.cx.codemap().new_filemap(filename.into(), src);
1595 let include_info = vec![
1596 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1597 attr::mk_name_value_item_str(Ident::from_str("file"),
1598 dummy_spanned(file)))),
1599 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1600 attr::mk_name_value_item_str(Ident::from_str("contents"),
1601 dummy_spanned(src_interned)))),
1604 let include_ident = Ident::from_str("include");
1605 let item = attr::mk_list_item(DUMMY_SP, include_ident, include_info);
1606 items.push(dummy_spanned(ast::NestedMetaItemKind::MetaItem(item)));
1609 self.cx.span_err(at.span,
1610 &format!("{} wasn't a utf-8 file",
1611 filename.display()));
1615 items.push(noop_fold_meta_list_item(it, self));
1619 let meta = attr::mk_list_item(DUMMY_SP, Ident::from_str("doc"), items);
1621 ast::AttrStyle::Inner =>
1622 Some(attr::mk_spanned_attr_inner(at.span, at.id, meta)),
1623 ast::AttrStyle::Outer =>
1624 Some(attr::mk_spanned_attr_outer(at.span, at.id, meta)),
1627 noop_fold_attribute(at, self)
1631 fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1633 assert_eq!(id, ast::DUMMY_NODE_ID);
1634 self.cx.resolver.next_node_id()
1641 pub struct ExpansionConfig<'feat> {
1642 pub crate_name: String,
1643 pub features: Option<&'feat Features>,
1644 pub recursion_limit: usize,
1645 pub trace_mac: bool,
1646 pub should_test: bool, // If false, strip `#[test]` nodes
1647 pub single_step: bool,
1648 pub keep_macs: bool,
1651 macro_rules! feature_tests {
1652 ($( fn $getter:ident = $field:ident, )*) => {
1654 pub fn $getter(&self) -> bool {
1655 match self.features {
1656 Some(&Features { $field: true, .. }) => true,
1664 impl<'feat> ExpansionConfig<'feat> {
1665 pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1669 recursion_limit: 1024,
1678 fn enable_quotes = quote,
1679 fn enable_asm = asm,
1680 fn enable_global_asm = global_asm,
1681 fn enable_log_syntax = log_syntax,
1682 fn enable_concat_idents = concat_idents,
1683 fn enable_trace_macros = trace_macros,
1684 fn enable_allow_internal_unstable = allow_internal_unstable,
1685 fn enable_custom_derive = custom_derive,
1686 fn enable_format_args_nl = format_args_nl,
1687 fn macros_in_extern_enabled = macros_in_extern,
1688 fn proc_macro_mod = proc_macro_mod,
1689 fn proc_macro_gen = proc_macro_gen,
1690 fn proc_macro_expr = proc_macro_expr,
1691 fn proc_macro_non_items = proc_macro_non_items,
1694 pub fn use_extern_macros_enabled(&self) -> bool {
1695 self.features.map_or(false, |features| features.use_extern_macros())
1699 // A Marker adds the given mark to the syntax context.
1701 pub struct Marker(pub Mark);
1703 impl Folder for Marker {
1704 fn new_span(&mut self, span: Span) -> Span {
1705 span.apply_mark(self.0)
1708 fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1709 noop_fold_mac(mac, self)