1 //! A `MutVisitor` represents an AST modification; it accepts an AST piece and
2 //! and mutates it in place. So, for instance, macro expansion is a `MutVisitor`
3 //! that walks over an AST and modifies it.
5 //! Note: using a `MutVisitor` (other than the `MacroExpander` `MutVisitor`) on
6 //! an AST before macro expansion is probably a bad idea. For instance,
7 //! a `MutVisitor` renaming item names in a module will miss all of those
8 //! that are created by the expansion of a macro.
11 use crate::source_map::{Spanned, respan};
12 use crate::parse::token::{self, Token};
15 use crate::tokenstream::*;
16 use crate::util::map_in_place::MapInPlace;
18 use smallvec::{smallvec, Array, SmallVec};
21 use rustc_data_structures::sync::Lrc;
22 use std::ops::DerefMut;
23 use std::{panic, process, ptr};
28 pub trait ExpectOne<A: Array> {
29 fn expect_one(self, err: &'static str) -> A::Item;
32 impl<A: Array> ExpectOne<A> for SmallVec<A> {
33 fn expect_one(self, err: &'static str) -> A::Item {
34 assert!(self.len() == 1, err);
35 self.into_iter().next().unwrap()
39 pub trait MutVisitor: Sized {
40 // Methods in this trait have one of three forms:
42 // fn visit_t(&mut self, t: &mut T); // common
43 // fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
44 // fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
46 // Any additions to this trait should happen in form of a call to a public
47 // `noop_*` function that only calls out to the visitor again, not other
48 // `noop_*` functions. This is a necessary API workaround to the problem of
49 // not being able to call out to the super default method in an overridden
52 // When writing these methods, it is better to use destructuring like this:
54 // fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
59 // than to use field access like this:
61 // fn visit_abc(&mut self, abc: &mut ABC) {
62 // visit_a(&mut abc.a);
63 // visit_b(&mut abc.b);
67 // As well as being more concise, the former is explicit about which fields
68 // are skipped. Furthermore, if a new field is added, the destructuring
69 // version will cause a compile error, which is good. In comparison, the
70 // field access version will continue working and it would be easy to
71 // forget to add handling for it.
73 fn visit_crate(&mut self, c: &mut Crate) {
74 noop_visit_crate(c, self)
77 fn visit_meta_list_item(&mut self, list_item: &mut NestedMetaItem) {
78 noop_visit_meta_list_item(list_item, self);
81 fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
82 noop_visit_meta_item(meta_item, self);
85 fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
86 noop_visit_use_tree(use_tree, self);
89 fn flat_map_foreign_item(&mut self, ni: ForeignItem) -> SmallVec<[ForeignItem; 1]> {
90 noop_flat_map_foreign_item(ni, self)
93 fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
94 noop_flat_map_item(i, self)
97 fn visit_fn_header(&mut self, header: &mut FnHeader) {
98 noop_visit_fn_header(header, self);
101 fn flat_map_struct_field(&mut self, sf: StructField) -> SmallVec<[StructField; 1]> {
102 noop_flat_map_struct_field(sf, self)
105 fn visit_item_kind(&mut self, i: &mut ItemKind) {
106 noop_visit_item_kind(i, self);
109 fn flat_map_trait_item(&mut self, i: TraitItem) -> SmallVec<[TraitItem; 1]> {
110 noop_flat_map_trait_item(i, self)
113 fn flat_map_impl_item(&mut self, i: ImplItem) -> SmallVec<[ImplItem; 1]> {
114 noop_flat_map_impl_item(i, self)
117 fn visit_fn_decl(&mut self, d: &mut P<FnDecl>) {
118 noop_visit_fn_decl(d, self);
121 fn visit_asyncness(&mut self, a: &mut IsAsync) {
122 noop_visit_asyncness(a, self);
125 fn visit_block(&mut self, b: &mut P<Block>) {
126 noop_visit_block(b, self);
129 fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
130 noop_flat_map_stmt(s, self)
133 fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
134 noop_flat_map_arm(arm, self)
137 fn visit_pat(&mut self, p: &mut P<Pat>) {
138 noop_visit_pat(p, self);
141 fn visit_anon_const(&mut self, c: &mut AnonConst) {
142 noop_visit_anon_const(c, self);
145 fn visit_expr(&mut self, e: &mut P<Expr>) {
146 noop_visit_expr(e, self);
149 fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
150 noop_filter_map_expr(e, self)
153 fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
154 noop_visit_generic_arg(arg, self);
157 fn visit_ty(&mut self, t: &mut P<Ty>) {
158 noop_visit_ty(t, self);
161 fn visit_lifetime(&mut self, l: &mut Lifetime) {
162 noop_visit_lifetime(l, self);
165 fn visit_ty_constraint(&mut self, t: &mut AssocTyConstraint) {
166 noop_visit_ty_constraint(t, self);
169 fn visit_mod(&mut self, m: &mut Mod) {
170 noop_visit_mod(m, self);
173 fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
174 noop_visit_foreign_mod(nm, self);
177 fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
178 noop_flat_map_variant(v, self)
181 fn visit_ident(&mut self, i: &mut Ident) {
182 noop_visit_ident(i, self);
185 fn visit_path(&mut self, p: &mut Path) {
186 noop_visit_path(p, self);
189 fn visit_qself(&mut self, qs: &mut Option<QSelf>) {
190 noop_visit_qself(qs, self);
193 fn visit_generic_args(&mut self, p: &mut GenericArgs) {
194 noop_visit_generic_args(p, self);
197 fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
198 noop_visit_angle_bracketed_parameter_data(p, self);
201 fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
202 noop_visit_parenthesized_parameter_data(p, self);
205 fn visit_local(&mut self, l: &mut P<Local>) {
206 noop_visit_local(l, self);
209 fn visit_mac(&mut self, _mac: &mut Mac) {
210 panic!("visit_mac disabled by default");
211 // N.B., see note about macros above. If you really want a visitor that
212 // works on macros, use this definition in your trait impl:
213 // mut_visit::noop_visit_mac(_mac, self);
216 fn visit_macro_def(&mut self, def: &mut MacroDef) {
217 noop_visit_macro_def(def, self);
220 fn visit_label(&mut self, label: &mut Label) {
221 noop_visit_label(label, self);
224 fn visit_attribute(&mut self, at: &mut Attribute) {
225 noop_visit_attribute(at, self);
228 fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
229 noop_flat_map_param(param, self)
232 fn visit_generics(&mut self, generics: &mut Generics) {
233 noop_visit_generics(generics, self);
236 fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
237 noop_visit_trait_ref(tr, self);
240 fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
241 noop_visit_poly_trait_ref(p, self);
244 fn visit_variant_data(&mut self, vdata: &mut VariantData) {
245 noop_visit_variant_data(vdata, self);
248 fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
249 noop_flat_map_generic_param(param, self)
252 fn visit_tt(&mut self, tt: &mut TokenTree) {
253 noop_visit_tt(tt, self);
256 fn visit_tts(&mut self, tts: &mut TokenStream) {
257 noop_visit_tts(tts, self);
260 fn visit_token(&mut self, t: &mut Token) {
261 noop_visit_token(t, self);
264 fn visit_interpolated(&mut self, nt: &mut token::Nonterminal) {
265 noop_visit_interpolated(nt, self);
268 fn visit_param_bound(&mut self, tpb: &mut GenericBound) {
269 noop_visit_param_bound(tpb, self);
272 fn visit_mt(&mut self, mt: &mut MutTy) {
273 noop_visit_mt(mt, self);
276 fn flat_map_field(&mut self, f: Field) -> SmallVec<[Field; 1]> {
277 noop_flat_map_field(f, self)
280 fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
281 noop_visit_where_clause(where_clause, self);
284 fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
285 noop_visit_where_predicate(where_predicate, self);
288 fn visit_vis(&mut self, vis: &mut Visibility) {
289 noop_visit_vis(vis, self);
292 fn visit_id(&mut self, _id: &mut NodeId) {
296 fn visit_span(&mut self, _sp: &mut Span) {
300 fn flat_map_field_pattern(&mut self, fp: FieldPat) -> SmallVec<[FieldPat; 1]> {
301 noop_flat_map_field_pattern(fp, self)
305 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
306 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
307 /// method. Abort the program if the closure panics.
309 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
310 pub fn visit_clobber<T, F>(t: &mut T, f: F) where F: FnOnce(T) -> T {
312 // Safe because `t` is used in a read-only fashion by `read()` before
313 // being overwritten by `write()`.
314 let old_t = ptr::read(t);
315 let new_t = panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t)))
316 .unwrap_or_else(|_| process::abort());
317 ptr::write(t, new_t);
321 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
323 pub fn visit_vec<T, F>(elems: &mut Vec<T>, mut visit_elem: F) where F: FnMut(&mut T) {
329 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
331 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F) where F: FnMut(&mut T) {
332 if let Some(elem) = opt {
337 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
338 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
339 visit_vec(attrs, |attr| vis.visit_attribute(attr));
342 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
343 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut ThinVec<Attribute>, vis: &mut T) {
344 for attr in attrs.iter_mut() {
345 vis.visit_attribute(attr);
349 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
350 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
351 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
354 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
355 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
356 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
359 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
360 pub fn visit_method_sig<T: MutVisitor>(MethodSig { header, decl }: &mut MethodSig, vis: &mut T) {
361 vis.visit_fn_header(header);
362 vis.visit_fn_decl(decl);
365 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
368 ) -> SmallVec<[FieldPat; 1]> {
379 vis.visit_ident(ident);
381 vis.visit_span(span);
382 visit_thin_attrs(attrs, vis);
386 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
387 let UseTree { prefix, kind, span } = use_tree;
388 vis.visit_path(prefix);
390 UseTreeKind::Simple(rename, id1, id2) => {
391 visit_opt(rename, |rename| vis.visit_ident(rename));
395 UseTreeKind::Nested(items) => {
396 for (tree, id) in items {
397 vis.visit_use_tree(tree);
401 UseTreeKind::Glob => {}
403 vis.visit_span(span);
406 pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[Arm; 1]> {
407 let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = &mut arm;
408 visit_attrs(attrs, vis);
411 visit_opt(guard, |guard| vis.visit_expr(guard));
412 vis.visit_expr(body);
413 vis.visit_span(span);
417 pub fn noop_visit_ty_constraint<T: MutVisitor>(
418 AssocTyConstraint { id, ident, kind, span }: &mut AssocTyConstraint,
422 vis.visit_ident(ident);
424 AssocTyConstraintKind::Equality { ref mut ty } => {
427 AssocTyConstraintKind::Bound { ref mut bounds } => {
428 visit_bounds(bounds, vis);
431 vis.visit_span(span);
434 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
435 let Ty { id, kind, span } = ty.deref_mut();
438 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err |
439 TyKind::Never | TyKind::CVarArgs => {}
440 TyKind::Slice(ty) => vis.visit_ty(ty),
441 TyKind::Ptr(mt) => vis.visit_mt(mt),
442 TyKind::Rptr(lt, mt) => {
443 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
446 TyKind::BareFn(bft) => {
447 let BareFnTy { unsafety: _, abi: _, generic_params, decl } = bft.deref_mut();
448 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
449 vis.visit_fn_decl(decl);
451 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
452 TyKind::Paren(ty) => vis.visit_ty(ty),
453 TyKind::Path(qself, path) => {
454 vis.visit_qself(qself);
455 vis.visit_path(path);
457 TyKind::Array(ty, length) => {
459 vis.visit_anon_const(length);
461 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
462 TyKind::TraitObject(bounds, _syntax) =>
463 visit_vec(bounds, |bound| vis.visit_param_bound(bound)),
464 TyKind::ImplTrait(id, bounds) => {
466 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
468 TyKind::Mac(mac) => vis.visit_mac(mac),
470 vis.visit_span(span);
473 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
474 let ForeignMod { abi: _, items} = foreign_mod;
475 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
478 pub fn noop_flat_map_variant<T: MutVisitor>(mut variant: Variant, vis: &mut T)
479 -> SmallVec<[Variant; 1]>
481 let Variant { ident, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
482 vis.visit_ident(ident);
483 visit_attrs(attrs, vis);
485 vis.visit_variant_data(data);
486 visit_opt(disr_expr, |disr_expr| vis.visit_anon_const(disr_expr));
487 vis.visit_span(span);
491 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
492 vis.visit_span(span);
495 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
496 vis.visit_span(span);
497 for PathSegment { ident, id, args } in segments {
498 vis.visit_ident(ident);
500 visit_opt(args, |args| vis.visit_generic_args(args));
504 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
505 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
507 vis.visit_span(path_span);
511 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
513 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
514 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
518 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
520 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
521 GenericArg::Type(ty) => vis.visit_ty(ty),
522 GenericArg::Const(ct) => vis.visit_anon_const(ct),
526 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(data: &mut AngleBracketedArgs,
528 let AngleBracketedArgs { args, constraints, span } = data;
529 visit_vec(args, |arg| vis.visit_generic_arg(arg));
530 visit_vec(constraints, |constraint| vis.visit_ty_constraint(constraint));
531 vis.visit_span(span);
534 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(args: &mut ParenthesizedArgs,
536 let ParenthesizedArgs { inputs, output, span } = args;
537 visit_vec(inputs, |input| vis.visit_ty(input));
538 visit_opt(output, |output| vis.visit_ty(output));
539 vis.visit_span(span);
542 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
543 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
546 visit_opt(ty, |ty| vis.visit_ty(ty));
547 visit_opt(init, |init| vis.visit_expr(init));
548 vis.visit_span(span);
549 visit_thin_attrs(attrs, vis);
552 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
553 let Attribute { item: AttrItem { path, tokens }, id: _, style: _, is_sugared_doc: _, span }
555 vis.visit_path(path);
556 vis.visit_tts(tokens);
557 vis.visit_span(span);
560 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut Mac, vis: &mut T) {
561 let Mac { path, delim: _, tts, span, prior_type_ascription: _ } = mac;
562 vis.visit_path(path);
564 vis.visit_span(span);
567 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
568 let MacroDef { tokens, legacy: _ } = macro_def;
569 vis.visit_tts(tokens);
572 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
574 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
575 NestedMetaItem::Literal(_lit) => {}
579 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
580 let MetaItem { path: _, kind, span } = mi;
582 MetaItemKind::Word => {}
583 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
584 MetaItemKind::NameValue(_s) => {}
586 vis.visit_span(span);
589 pub fn noop_flat_map_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
590 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
592 visit_thin_attrs(attrs, vis);
594 vis.visit_span(span);
599 pub fn noop_visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
601 TokenTree::Token(token) => {
602 vis.visit_token(token);
604 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
605 vis.visit_span(open);
606 vis.visit_span(close);
612 pub fn noop_visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
613 visit_opt(tts, |tts| {
614 let tts = Lrc::make_mut(tts);
615 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
619 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
620 // In practice the ident part is not actually used by specific visitors right now,
621 // but there's a test below checking that it works.
622 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
623 let Token { kind, span } = t;
625 token::Ident(name, _) | token::Lifetime(name) => {
626 let mut ident = Ident::new(*name, *span);
627 vis.visit_ident(&mut ident);
630 return; // Avoid visiting the span for the second time.
632 token::Interpolated(nt) => {
633 let mut nt = Lrc::make_mut(nt);
634 vis.visit_interpolated(&mut nt);
638 vis.visit_span(span);
641 /// Applies the visitor to elements of interpolated nodes.
643 // N.B., this can occur only when applying a visitor to partially expanded
644 // code, where parsed pieces have gotten implanted ito *other* macro
645 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
647 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
648 // etc., allow the visitor to return *multiple* items; this is a problem for the
649 // nodes here, because they insist on having exactly one piece. One solution
650 // would be to mangle the MutVisitor trait to include one-to-many and
651 // one-to-one versions of these entry points, but that would probably confuse a
652 // lot of people and help very few. Instead, I'm just going to put in dynamic
653 // checks. I think the performance impact of this will be pretty much
654 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
655 // partially expanded node, and will be confused by the fact that their
656 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
657 // nodes. Hopefully they'll wind up reading this comment, and doing something
660 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
661 // contain multiple items, but decided against it when I looked at
662 // `parse_item_or_view_item` and tried to figure out what I would do with
663 // multiple items there....
664 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
666 token::NtItem(item) =>
667 visit_clobber(item, |item| {
668 // This is probably okay, because the only visitors likely to
669 // peek inside interpolated nodes will be renamings/markings,
670 // which map single items to single items.
671 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
673 token::NtBlock(block) => vis.visit_block(block),
674 token::NtStmt(stmt) =>
675 visit_clobber(stmt, |stmt| {
676 // See reasoning above.
677 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
679 token::NtPat(pat) => vis.visit_pat(pat),
680 token::NtExpr(expr) => vis.visit_expr(expr),
681 token::NtTy(ty) => vis.visit_ty(ty),
682 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
683 token::NtLifetime(ident) => vis.visit_ident(ident),
684 token::NtLiteral(expr) => vis.visit_expr(expr),
685 token::NtMeta(AttrItem { path, tokens }) => {
686 vis.visit_path(path);
687 vis.visit_tts(tokens);
689 token::NtPath(path) => vis.visit_path(path),
690 token::NtTT(tt) => vis.visit_tt(tt),
691 token::NtImplItem(item) =>
692 visit_clobber(item, |item| {
693 // See reasoning above.
694 vis.flat_map_impl_item(item)
695 .expect_one("expected visitor to produce exactly one item")
697 token::NtTraitItem(item) =>
698 visit_clobber(item, |item| {
699 // See reasoning above.
700 vis.flat_map_trait_item(item)
701 .expect_one("expected visitor to produce exactly one item")
703 token::NtVis(visib) => vis.visit_vis(visib),
704 token::NtForeignItem(item) =>
705 visit_clobber(item, |item| {
706 // See reasoning above.
707 vis.flat_map_foreign_item(item)
708 .expect_one("expected visitor to produce exactly one item")
713 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut IsAsync, vis: &mut T) {
715 IsAsync::Async { closure_id, return_impl_trait_id } => {
716 vis.visit_id(closure_id);
717 vis.visit_id(return_impl_trait_id);
719 IsAsync::NotAsync => {}
723 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
724 let FnDecl { inputs, output } = decl.deref_mut();
725 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
727 FunctionRetTy::Default(span) => vis.visit_span(span),
728 FunctionRetTy::Ty(ty) => vis.visit_ty(ty),
732 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
734 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
735 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
739 pub fn noop_flat_map_generic_param<T: MutVisitor>(
740 mut param: GenericParam,
742 ) -> SmallVec<[GenericParam; 1]>
744 let GenericParam { id, ident, attrs, bounds, kind, is_placeholder: _ } = &mut param;
746 vis.visit_ident(ident);
747 visit_thin_attrs(attrs, vis);
748 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
750 GenericParamKind::Lifetime => {}
751 GenericParamKind::Type { default } => {
752 visit_opt(default, |default| vis.visit_ty(default));
754 GenericParamKind::Const { ty } => {
761 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
762 vis.visit_ident(ident);
765 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
767 vis.visit_ident(ident);
770 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
771 let Generics { params, where_clause, span } = generics;
772 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
773 vis.visit_where_clause(where_clause);
774 vis.visit_span(span);
777 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
778 let WhereClause { predicates, span } = wc;
779 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
780 vis.visit_span(span);
783 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
785 WherePredicate::BoundPredicate(bp) => {
786 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
787 vis.visit_span(span);
788 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
789 vis.visit_ty(bounded_ty);
790 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
792 WherePredicate::RegionPredicate(rp) => {
793 let WhereRegionPredicate { span, lifetime, bounds } = rp;
794 vis.visit_span(span);
795 noop_visit_lifetime(lifetime, vis);
796 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
798 WherePredicate::EqPredicate(ep) => {
799 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
801 vis.visit_span(span);
802 vis.visit_ty(lhs_ty);
803 vis.visit_ty(rhs_ty);
808 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
810 VariantData::Struct(fields, ..) => {
811 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
813 VariantData::Tuple(fields, id) => {
814 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
817 VariantData::Unit(id) => vis.visit_id(id),
821 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
822 vis.visit_path(path);
823 vis.visit_id(ref_id);
826 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
827 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
828 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
829 vis.visit_trait_ref(trait_ref);
830 vis.visit_span(span);
833 pub fn noop_flat_map_struct_field<T: MutVisitor>(mut sf: StructField, visitor: &mut T)
834 -> SmallVec<[StructField; 1]>
836 let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
837 visitor.visit_span(span);
838 visit_opt(ident, |ident| visitor.visit_ident(ident));
839 visitor.visit_vis(vis);
840 visitor.visit_id(id);
841 visitor.visit_ty(ty);
842 visit_attrs(attrs, visitor);
846 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
847 let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
848 vis.visit_ident(ident);
849 vis.visit_expr(expr);
851 vis.visit_span(span);
852 visit_thin_attrs(attrs, vis);
856 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
860 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
861 let Block { id, stmts, rules: _, span } = block.deref_mut();
863 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
864 vis.visit_span(span);
867 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
869 ItemKind::ExternCrate(_orig_name) => {}
870 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
871 ItemKind::Static(ty, _mut, expr) => {
873 vis.visit_expr(expr);
875 ItemKind::Const(ty, expr) => {
877 vis.visit_expr(expr);
879 ItemKind::Fn(decl, header, generics, body) => {
880 vis.visit_fn_decl(decl);
881 vis.visit_fn_header(header);
882 vis.visit_generics(generics);
883 vis.visit_block(body);
885 ItemKind::Mod(m) => vis.visit_mod(m),
886 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
887 ItemKind::GlobalAsm(_ga) => {}
888 ItemKind::TyAlias(ty, generics) => {
890 vis.visit_generics(generics);
892 ItemKind::OpaqueTy(bounds, generics) => {
893 visit_bounds(bounds, vis);
894 vis.visit_generics(generics);
896 ItemKind::Enum(EnumDef { variants }, generics) => {
897 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
898 vis.visit_generics(generics);
900 ItemKind::Struct(variant_data, generics) |
901 ItemKind::Union(variant_data, generics) => {
902 vis.visit_variant_data(variant_data);
903 vis.visit_generics(generics);
905 ItemKind::Impl(_unsafety, _polarity, _defaultness, generics, trait_ref, ty, items) => {
906 vis.visit_generics(generics);
907 visit_opt(trait_ref, |trait_ref| vis.visit_trait_ref(trait_ref));
909 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
911 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
912 vis.visit_generics(generics);
913 visit_bounds(bounds, vis);
914 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
916 ItemKind::TraitAlias(generics, bounds) => {
917 vis.visit_generics(generics);
918 visit_bounds(bounds, vis);
920 ItemKind::Mac(m) => vis.visit_mac(m),
921 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
925 pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, vis: &mut T)
926 -> SmallVec<[TraitItem; 1]>
928 let TraitItem { id, ident, attrs, generics, kind, span, tokens: _ } = &mut item;
930 vis.visit_ident(ident);
931 visit_attrs(attrs, vis);
932 vis.visit_generics(generics);
934 TraitItemKind::Const(ty, default) => {
936 visit_opt(default, |default| vis.visit_expr(default));
938 TraitItemKind::Method(sig, body) => {
939 visit_method_sig(sig, vis);
940 visit_opt(body, |body| vis.visit_block(body));
942 TraitItemKind::Type(bounds, default) => {
943 visit_bounds(bounds, vis);
944 visit_opt(default, |default| vis.visit_ty(default));
946 TraitItemKind::Macro(mac) => {
950 vis.visit_span(span);
955 pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut T)
956 -> SmallVec<[ImplItem; 1]>
958 let ImplItem { id, ident, vis, defaultness: _, attrs, generics, kind, span, tokens: _ } =
960 visitor.visit_id(id);
961 visitor.visit_ident(ident);
962 visitor.visit_vis(vis);
963 visit_attrs(attrs, visitor);
964 visitor.visit_generics(generics);
966 ImplItemKind::Const(ty, expr) => {
967 visitor.visit_ty(ty);
968 visitor.visit_expr(expr);
970 ImplItemKind::Method(sig, body) => {
971 visit_method_sig(sig, visitor);
972 visitor.visit_block(body);
974 ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
975 ImplItemKind::OpaqueTy(bounds) => visit_bounds(bounds, visitor),
976 ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
978 visitor.visit_span(span);
983 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
984 let FnHeader { unsafety: _, asyncness, constness: _, abi: _ } = header;
985 vis.visit_asyncness(&mut asyncness.node);
988 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
989 vis.visit_span(inner);
990 items.flat_map_in_place(|item| vis.flat_map_item(item));
993 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
994 visit_clobber(krate, |Crate { module, attrs, span }| {
996 ident: Ident::invalid(),
999 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
1001 kind: ItemKind::Mod(module),
1004 let items = vis.flat_map_item(item);
1006 let len = items.len();
1008 let module = Mod { inner: span, items: vec![], inline: true };
1009 Crate { module, attrs: vec![], span }
1010 } else if len == 1 {
1011 let Item { attrs, span, kind, .. } = items.into_iter().next().unwrap().into_inner();
1013 ItemKind::Mod(module) => Crate { module, attrs, span },
1014 _ => panic!("visitor converted a module to not a module"),
1017 panic!("a crate cannot expand to more than one item");
1022 // Mutates one item into possibly many items.
1023 pub fn noop_flat_map_item<T: MutVisitor>(mut item: P<Item>, visitor: &mut T)
1024 -> SmallVec<[P<Item>; 1]> {
1025 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1026 visitor.visit_ident(ident);
1027 visit_attrs(attrs, visitor);
1028 visitor.visit_id(id);
1029 visitor.visit_item_kind(kind);
1030 visitor.visit_vis(vis);
1031 visitor.visit_span(span);
1033 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1034 // an ICE during resolve... odd!
1039 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
1040 -> SmallVec<[ForeignItem; 1]>
1042 let ForeignItem { ident, attrs, kind, id, span, vis } = &mut item;
1043 visitor.visit_ident(ident);
1044 visit_attrs(attrs, visitor);
1046 ForeignItemKind::Fn(fdec, generics) => {
1047 visitor.visit_fn_decl(fdec);
1048 visitor.visit_generics(generics);
1050 ForeignItemKind::Static(t, _m) => visitor.visit_ty(t),
1051 ForeignItemKind::Ty => {}
1052 ForeignItemKind::Macro(mac) => visitor.visit_mac(mac),
1054 visitor.visit_id(id);
1055 visitor.visit_span(span);
1056 visitor.visit_vis(vis);
1061 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1062 let Pat { id, kind, span } = pat.deref_mut();
1065 PatKind::Wild | PatKind::Rest => {}
1066 PatKind::Ident(_binding_mode, ident, sub) => {
1067 vis.visit_ident(ident);
1068 visit_opt(sub, |sub| vis.visit_pat(sub));
1070 PatKind::Lit(e) => vis.visit_expr(e),
1071 PatKind::TupleStruct(path, elems) => {
1072 vis.visit_path(path);
1073 visit_vec(elems, |elem| vis.visit_pat(elem));
1075 PatKind::Path(qself, path) => {
1076 vis.visit_qself(qself);
1077 vis.visit_path(path);
1079 PatKind::Struct(path, fields, _etc) => {
1080 vis.visit_path(path);
1081 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1083 PatKind::Box(inner) => vis.visit_pat(inner),
1084 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1085 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1088 vis.visit_span(span);
1090 PatKind::Tuple(elems)
1091 | PatKind::Slice(elems)
1092 | PatKind::Or(elems) => visit_vec(elems, |elem| vis.visit_pat(elem)),
1093 PatKind::Paren(inner) => vis.visit_pat(inner),
1094 PatKind::Mac(mac) => vis.visit_mac(mac),
1096 vis.visit_span(span);
1099 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1101 vis.visit_expr(value);
1104 pub fn noop_visit_expr<T: MutVisitor>(Expr { kind, id, span, attrs }: &mut Expr, vis: &mut T) {
1106 ExprKind::Box(expr) => vis.visit_expr(expr),
1107 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1108 ExprKind::Repeat(expr, count) => {
1109 vis.visit_expr(expr);
1110 vis.visit_anon_const(count);
1112 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1113 ExprKind::Call(f, args) => {
1115 visit_exprs(args, vis);
1117 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
1118 vis.visit_ident(ident);
1120 visit_opt(args, |args| vis.visit_generic_args(args));
1121 visit_exprs(exprs, vis);
1123 ExprKind::Binary(_binop, lhs, rhs) => {
1124 vis.visit_expr(lhs);
1125 vis.visit_expr(rhs);
1127 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1128 ExprKind::Cast(expr, ty) => {
1129 vis.visit_expr(expr);
1132 ExprKind::Type(expr, ty) => {
1133 vis.visit_expr(expr);
1136 ExprKind::AddrOf(_m, ohs) => vis.visit_expr(ohs),
1137 ExprKind::Let(pat, scrutinee) => {
1139 vis.visit_expr(scrutinee);
1141 ExprKind::If(cond, tr, fl) => {
1142 vis.visit_expr(cond);
1143 vis.visit_block(tr);
1144 visit_opt(fl, |fl| vis.visit_expr(fl));
1146 ExprKind::While(cond, body, label) => {
1147 vis.visit_expr(cond);
1148 vis.visit_block(body);
1149 visit_opt(label, |label| vis.visit_label(label));
1151 ExprKind::ForLoop(pat, iter, body, label) => {
1153 vis.visit_expr(iter);
1154 vis.visit_block(body);
1155 visit_opt(label, |label| vis.visit_label(label));
1157 ExprKind::Loop(body, label) => {
1158 vis.visit_block(body);
1159 visit_opt(label, |label| vis.visit_label(label));
1161 ExprKind::Match(expr, arms) => {
1162 vis.visit_expr(expr);
1163 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1165 ExprKind::Closure(_capture_by, asyncness, _movability, decl, body, span) => {
1166 vis.visit_asyncness(asyncness);
1167 vis.visit_fn_decl(decl);
1168 vis.visit_expr(body);
1169 vis.visit_span(span);
1171 ExprKind::Block(blk, label) => {
1172 vis.visit_block(blk);
1173 visit_opt(label, |label| vis.visit_label(label));
1175 ExprKind::Async(_capture_by, node_id, body) => {
1176 vis.visit_id(node_id);
1177 vis.visit_block(body);
1179 ExprKind::Await(expr) => vis.visit_expr(expr),
1180 ExprKind::Assign(el, er) => {
1184 ExprKind::AssignOp(_op, el, er) => {
1188 ExprKind::Field(el, ident) => {
1190 vis.visit_ident(ident);
1192 ExprKind::Index(el, er) => {
1196 ExprKind::Range(e1, e2, _lim) => {
1197 visit_opt(e1, |e1| vis.visit_expr(e1));
1198 visit_opt(e2, |e2| vis.visit_expr(e2));
1200 ExprKind::Path(qself, path) => {
1201 vis.visit_qself(qself);
1202 vis.visit_path(path);
1204 ExprKind::Break(label, expr) => {
1205 visit_opt(label, |label| vis.visit_label(label));
1206 visit_opt(expr, |expr| vis.visit_expr(expr));
1208 ExprKind::Continue(label) => {
1209 visit_opt(label, |label| vis.visit_label(label));
1211 ExprKind::Ret(expr) => {
1212 visit_opt(expr, |expr| vis.visit_expr(expr));
1214 ExprKind::InlineAsm(asm) => {
1215 let InlineAsm { asm: _, asm_str_style: _, outputs, inputs, clobbers: _, volatile: _,
1216 alignstack: _, dialect: _ } = asm.deref_mut();
1217 for out in outputs {
1218 let InlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1219 vis.visit_expr(expr);
1221 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1223 ExprKind::Mac(mac) => vis.visit_mac(mac),
1224 ExprKind::Struct(path, fields, expr) => {
1225 vis.visit_path(path);
1226 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1227 visit_opt(expr, |expr| vis.visit_expr(expr));
1229 ExprKind::Paren(expr) => {
1230 vis.visit_expr(expr);
1232 // Nodes that are equal modulo `Paren` sugar no-ops should have the same IDs.
1234 vis.visit_span(span);
1235 visit_thin_attrs(attrs, vis);
1238 ExprKind::Yield(expr) => {
1239 visit_opt(expr, |expr| vis.visit_expr(expr));
1241 ExprKind::Try(expr) => vis.visit_expr(expr),
1242 ExprKind::TryBlock(body) => vis.visit_block(body),
1243 ExprKind::Lit(_) | ExprKind::Err => {}
1246 vis.visit_span(span);
1247 visit_thin_attrs(attrs, vis);
1250 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1251 Some({ vis.visit_expr(&mut e); e })
1254 pub fn noop_flat_map_stmt<T: MutVisitor>(Stmt { kind, mut span, mut id }: Stmt, vis: &mut T)
1255 -> SmallVec<[Stmt; 1]>
1257 vis.visit_id(&mut id);
1258 vis.visit_span(&mut span);
1259 noop_flat_map_stmt_kind(kind, vis).into_iter().map(|kind| {
1260 Stmt { id, kind, span }
1264 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(kind: StmtKind, vis: &mut T)
1265 -> SmallVec<[StmtKind; 1]> {
1267 StmtKind::Local(mut local) =>
1268 smallvec![StmtKind::Local({ vis.visit_local(&mut local); local })],
1269 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1270 StmtKind::Expr(expr) => {
1271 vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect()
1273 StmtKind::Semi(expr) => {
1274 vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect()
1276 StmtKind::Mac(mut mac) => {
1277 let (mac_, _semi, attrs) = mac.deref_mut();
1278 vis.visit_mac(mac_);
1279 visit_thin_attrs(attrs, vis);
1280 smallvec![StmtKind::Mac(mac)]
1285 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1287 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1288 VisibilityKind::Restricted { path, id } => {
1289 vis.visit_path(path);
1293 vis.visit_span(span);