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_arg(&mut self, arg: Arg) -> SmallVec<[Arg; 1]> {
229 noop_flat_map_arg(arg, 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]> {
378 vis.visit_ident(ident);
380 vis.visit_span(span);
381 visit_thin_attrs(attrs, vis);
385 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
386 let UseTree { prefix, kind, span } = use_tree;
387 vis.visit_path(prefix);
389 UseTreeKind::Simple(rename, id1, id2) => {
390 visit_opt(rename, |rename| vis.visit_ident(rename));
394 UseTreeKind::Nested(items) => {
395 for (tree, id) in items {
396 vis.visit_use_tree(tree);
400 UseTreeKind::Glob => {}
402 vis.visit_span(span);
405 pub fn noop_flat_map_arm<T: MutVisitor>(
408 ) -> SmallVec<[Arm; 1]> {
409 let Arm { attrs, pats, guard, body, span, id } = &mut arm;
410 visit_attrs(attrs, vis);
412 visit_vec(pats, |pat| vis.visit_pat(pat));
413 visit_opt(guard, |guard| vis.visit_expr(guard));
414 vis.visit_expr(body);
415 vis.visit_span(span);
419 pub fn noop_visit_ty_constraint<T: MutVisitor>(
420 AssocTyConstraint { id, ident, kind, span }: &mut AssocTyConstraint,
424 vis.visit_ident(ident);
426 AssocTyConstraintKind::Equality { ref mut ty } => {
429 AssocTyConstraintKind::Bound { ref mut bounds } => {
430 visit_bounds(bounds, vis);
433 vis.visit_span(span);
436 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
437 let Ty { id, node, span } = ty.deref_mut();
440 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err |
441 TyKind::Never | TyKind::CVarArgs => {}
442 TyKind::Slice(ty) => vis.visit_ty(ty),
443 TyKind::Ptr(mt) => vis.visit_mt(mt),
444 TyKind::Rptr(lt, mt) => {
445 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
448 TyKind::BareFn(bft) => {
449 let BareFnTy { unsafety: _, abi: _, generic_params, decl } = bft.deref_mut();
450 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
451 vis.visit_fn_decl(decl);
453 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
454 TyKind::Paren(ty) => vis.visit_ty(ty),
455 TyKind::Path(qself, path) => {
456 vis.visit_qself(qself);
457 vis.visit_path(path);
459 TyKind::Array(ty, length) => {
461 vis.visit_anon_const(length);
463 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
464 TyKind::TraitObject(bounds, _syntax) =>
465 visit_vec(bounds, |bound| vis.visit_param_bound(bound)),
466 TyKind::ImplTrait(id, bounds) => {
468 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
470 TyKind::Mac(mac) => vis.visit_mac(mac),
472 vis.visit_span(span);
475 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
476 let ForeignMod { abi: _, items} = foreign_mod;
477 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
480 pub fn noop_flat_map_variant<T: MutVisitor>(mut variant: Variant, vis: &mut T)
481 -> SmallVec<[Variant; 1]>
483 let Variant { ident, attrs, id, data, disr_expr, span } = &mut variant;
484 vis.visit_ident(ident);
485 visit_attrs(attrs, vis);
487 vis.visit_variant_data(data);
488 visit_opt(disr_expr, |disr_expr| vis.visit_anon_const(disr_expr));
489 vis.visit_span(span);
493 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
494 vis.visit_span(span);
497 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
498 vis.visit_span(span);
499 for PathSegment { ident, id, args } in segments {
500 vis.visit_ident(ident);
502 visit_opt(args, |args| vis.visit_generic_args(args));
506 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
507 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
509 vis.visit_span(path_span);
513 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
515 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
516 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
520 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
522 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
523 GenericArg::Type(ty) => vis.visit_ty(ty),
524 GenericArg::Const(ct) => vis.visit_anon_const(ct),
528 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(data: &mut AngleBracketedArgs,
530 let AngleBracketedArgs { args, constraints, span } = data;
531 visit_vec(args, |arg| vis.visit_generic_arg(arg));
532 visit_vec(constraints, |constraint| vis.visit_ty_constraint(constraint));
533 vis.visit_span(span);
536 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(args: &mut ParenthesizedArgs,
538 let ParenthesizedArgs { inputs, output, span } = args;
539 visit_vec(inputs, |input| vis.visit_ty(input));
540 visit_opt(output, |output| vis.visit_ty(output));
541 vis.visit_span(span);
544 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
545 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
548 visit_opt(ty, |ty| vis.visit_ty(ty));
549 visit_opt(init, |init| vis.visit_expr(init));
550 vis.visit_span(span);
551 visit_thin_attrs(attrs, vis);
554 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
555 let Attribute { id: _, style: _, path, tokens, is_sugared_doc: _, span } = attr;
556 vis.visit_path(path);
557 vis.visit_tts(tokens);
558 vis.visit_span(span);
561 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut Mac, vis: &mut T) {
562 let Mac { path, delim: _, tts, span, prior_type_ascription: _ } = mac;
563 vis.visit_path(path);
565 vis.visit_span(span);
568 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
569 let MacroDef { tokens, legacy: _ } = macro_def;
570 vis.visit_tts(tokens);
573 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
575 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
576 NestedMetaItem::Literal(_lit) => {}
580 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
581 let MetaItem { path: _, node, span } = mi;
583 MetaItemKind::Word => {}
584 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
585 MetaItemKind::NameValue(_s) => {}
587 vis.visit_span(span);
590 pub fn noop_flat_map_arg<T: MutVisitor>(mut arg: Arg, vis: &mut T) -> SmallVec<[Arg; 1]> {
591 let Arg { attrs, id, pat, span, ty } = &mut arg;
593 visit_thin_attrs(attrs, vis);
595 vis.visit_span(span);
600 pub fn noop_visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
602 TokenTree::Token(token) => {
603 vis.visit_token(token);
605 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
606 vis.visit_span(open);
607 vis.visit_span(close);
613 pub fn noop_visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
614 visit_opt(tts, |tts| {
615 let tts = Lrc::make_mut(tts);
616 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
620 // Apply ident visitor if it's an ident, apply other visits to interpolated nodes.
621 // In practice the ident part is not actually used by specific visitors right now,
622 // but there's a test below checking that it works.
623 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
624 let Token { kind, span } = t;
626 token::Ident(name, _) | token::Lifetime(name) => {
627 let mut ident = Ident::new(*name, *span);
628 vis.visit_ident(&mut ident);
631 return; // avoid visiting the span for the second time
633 token::Interpolated(nt) => {
634 let mut nt = Lrc::make_mut(nt);
635 vis.visit_interpolated(&mut nt);
639 vis.visit_span(span);
642 /// Apply visitor to elements of interpolated nodes.
644 // N.B., this can occur only when applying a visitor to partially expanded
645 // code, where parsed pieces have gotten implanted ito *other* macro
646 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
648 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
649 // etc. allow the visitor to return *multiple* items; this is a problem for the
650 // nodes here, because they insist on having exactly one piece. One solution
651 // would be to mangle the MutVisitor trait to include one-to-many and
652 // one-to-one versions of these entry points, but that would probably confuse a
653 // lot of people and help very few. Instead, I'm just going to put in dynamic
654 // checks. I think the performance impact of this will be pretty much
655 // nonexistent. The danger is that someone will apply a MutVisitor to a
656 // partially expanded node, and will be confused by the fact that their
657 // "flat_map_item" or "flat_map_stmt" isn't getting called on NtItem or NtStmt
658 // nodes. Hopefully they'll wind up reading this comment, and doing something
661 // BTW, design choice: I considered just changing the type of, e.g., NtItem to
662 // contain multiple items, but decided against it when I looked at
663 // parse_item_or_view_item and tried to figure out what I would do with
664 // multiple items there....
665 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
667 token::NtItem(item) =>
668 visit_clobber(item, |item| {
669 // This is probably okay, because the only visitors likely to
670 // peek inside interpolated nodes will be renamings/markings,
671 // which map single items to single items.
672 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
674 token::NtBlock(block) => vis.visit_block(block),
675 token::NtStmt(stmt) =>
676 visit_clobber(stmt, |stmt| {
677 // See reasoning above.
678 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
680 token::NtPat(pat) => vis.visit_pat(pat),
681 token::NtExpr(expr) => vis.visit_expr(expr),
682 token::NtTy(ty) => vis.visit_ty(ty),
683 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
684 token::NtLifetime(ident) => vis.visit_ident(ident),
685 token::NtLiteral(expr) => vis.visit_expr(expr),
686 token::NtMeta(meta) => vis.visit_meta_item(meta),
687 token::NtPath(path) => vis.visit_path(path),
688 token::NtTT(tt) => vis.visit_tt(tt),
689 token::NtImplItem(item) =>
690 visit_clobber(item, |item| {
691 // See reasoning above.
692 vis.flat_map_impl_item(item)
693 .expect_one("expected visitor to produce exactly one item")
695 token::NtTraitItem(item) =>
696 visit_clobber(item, |item| {
697 // See reasoning above.
698 vis.flat_map_trait_item(item)
699 .expect_one("expected visitor to produce exactly one item")
701 token::NtVis(visib) => vis.visit_vis(visib),
702 token::NtForeignItem(item) =>
703 visit_clobber(item, |item| {
704 // See reasoning above.
705 vis.flat_map_foreign_item(item)
706 .expect_one("expected visitor to produce exactly one item")
711 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut IsAsync, vis: &mut T) {
713 IsAsync::Async { closure_id, return_impl_trait_id } => {
714 vis.visit_id(closure_id);
715 vis.visit_id(return_impl_trait_id);
717 IsAsync::NotAsync => {}
721 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
722 let FnDecl { inputs, output, c_variadic: _ } = decl.deref_mut();
723 inputs.flat_map_in_place(|arg| vis.flat_map_arg(arg));
725 FunctionRetTy::Default(span) => vis.visit_span(span),
726 FunctionRetTy::Ty(ty) => vis.visit_ty(ty),
730 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
732 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
733 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
737 pub fn noop_flat_map_generic_param<T: MutVisitor>(
738 mut param: GenericParam,
740 ) -> SmallVec<[GenericParam; 1]>
742 let GenericParam { id, ident, attrs, bounds, kind } = &mut param;
744 vis.visit_ident(ident);
745 visit_thin_attrs(attrs, vis);
746 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
748 GenericParamKind::Lifetime => {}
749 GenericParamKind::Type { default } => {
750 visit_opt(default, |default| vis.visit_ty(default));
752 GenericParamKind::Const { ty } => {
759 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
760 vis.visit_ident(ident);
763 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
765 vis.visit_ident(ident);
768 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
769 let Generics { params, where_clause, span } = generics;
770 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
771 vis.visit_where_clause(where_clause);
772 vis.visit_span(span);
775 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
776 let WhereClause { predicates, span } = wc;
777 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
778 vis.visit_span(span);
781 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
783 WherePredicate::BoundPredicate(bp) => {
784 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
785 vis.visit_span(span);
786 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
787 vis.visit_ty(bounded_ty);
788 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
790 WherePredicate::RegionPredicate(rp) => {
791 let WhereRegionPredicate { span, lifetime, bounds } = rp;
792 vis.visit_span(span);
793 noop_visit_lifetime(lifetime, vis);
794 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
796 WherePredicate::EqPredicate(ep) => {
797 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
799 vis.visit_span(span);
800 vis.visit_ty(lhs_ty);
801 vis.visit_ty(rhs_ty);
806 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
808 VariantData::Struct(fields, ..) => {
809 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
811 VariantData::Tuple(fields, id) => {
812 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
815 VariantData::Unit(id) => vis.visit_id(id),
819 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
820 vis.visit_path(path);
821 vis.visit_id(ref_id);
824 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
825 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
826 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
827 vis.visit_trait_ref(trait_ref);
828 vis.visit_span(span);
831 pub fn noop_flat_map_struct_field<T: MutVisitor>(mut sf: StructField, visitor: &mut T)
832 -> SmallVec<[StructField; 1]>
834 let StructField { span, ident, vis, id, ty, attrs } = &mut sf;
835 visitor.visit_span(span);
836 visit_opt(ident, |ident| visitor.visit_ident(ident));
837 visitor.visit_vis(vis);
838 visitor.visit_id(id);
839 visitor.visit_ty(ty);
840 visit_attrs(attrs, visitor);
844 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
845 let Field { ident, expr, span, is_shorthand: _, attrs, id } = &mut f;
846 vis.visit_ident(ident);
847 vis.visit_expr(expr);
849 vis.visit_span(span);
850 visit_thin_attrs(attrs, vis);
854 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
858 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
859 let Block { id, stmts, rules: _, span } = block.deref_mut();
861 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
862 vis.visit_span(span);
865 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
867 ItemKind::ExternCrate(_orig_name) => {}
868 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
869 ItemKind::Static(ty, _mut, expr) => {
871 vis.visit_expr(expr);
873 ItemKind::Const(ty, expr) => {
875 vis.visit_expr(expr);
877 ItemKind::Fn(decl, header, generics, body) => {
878 vis.visit_fn_decl(decl);
879 vis.visit_fn_header(header);
880 vis.visit_generics(generics);
881 vis.visit_block(body);
883 ItemKind::Mod(m) => vis.visit_mod(m),
884 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
885 ItemKind::GlobalAsm(_ga) => {}
886 ItemKind::TyAlias(ty, generics) => {
888 vis.visit_generics(generics);
890 ItemKind::OpaqueTy(bounds, generics) => {
891 visit_bounds(bounds, vis);
892 vis.visit_generics(generics);
894 ItemKind::Enum(EnumDef { variants }, generics) => {
895 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
896 vis.visit_generics(generics);
898 ItemKind::Struct(variant_data, generics) |
899 ItemKind::Union(variant_data, generics) => {
900 vis.visit_variant_data(variant_data);
901 vis.visit_generics(generics);
903 ItemKind::Impl(_unsafety, _polarity, _defaultness, generics, trait_ref, ty, items) => {
904 vis.visit_generics(generics);
905 visit_opt(trait_ref, |trait_ref| vis.visit_trait_ref(trait_ref));
907 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
909 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
910 vis.visit_generics(generics);
911 visit_bounds(bounds, vis);
912 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
914 ItemKind::TraitAlias(generics, bounds) => {
915 vis.visit_generics(generics);
916 visit_bounds(bounds, vis);
918 ItemKind::Mac(m) => vis.visit_mac(m),
919 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
923 pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, vis: &mut T)
924 -> SmallVec<[TraitItem; 1]>
926 let TraitItem { id, ident, attrs, generics, node, span, tokens: _ } = &mut item;
928 vis.visit_ident(ident);
929 visit_attrs(attrs, vis);
930 vis.visit_generics(generics);
932 TraitItemKind::Const(ty, default) => {
934 visit_opt(default, |default| vis.visit_expr(default));
936 TraitItemKind::Method(sig, body) => {
937 visit_method_sig(sig, vis);
938 visit_opt(body, |body| vis.visit_block(body));
940 TraitItemKind::Type(bounds, default) => {
941 visit_bounds(bounds, vis);
942 visit_opt(default, |default| vis.visit_ty(default));
944 TraitItemKind::Macro(mac) => {
948 vis.visit_span(span);
953 pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut T)
954 -> SmallVec<[ImplItem; 1]>
956 let ImplItem { id, ident, vis, defaultness: _, attrs, generics, node, span, tokens: _ } =
958 visitor.visit_id(id);
959 visitor.visit_ident(ident);
960 visitor.visit_vis(vis);
961 visit_attrs(attrs, visitor);
962 visitor.visit_generics(generics);
964 ImplItemKind::Const(ty, expr) => {
965 visitor.visit_ty(ty);
966 visitor.visit_expr(expr);
968 ImplItemKind::Method(sig, body) => {
969 visit_method_sig(sig, visitor);
970 visitor.visit_block(body);
972 ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
973 ImplItemKind::OpaqueTy(bounds) => visit_bounds(bounds, visitor),
974 ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
976 visitor.visit_span(span);
981 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
982 let FnHeader { unsafety: _, asyncness, constness: _, abi: _ } = header;
983 vis.visit_asyncness(&mut asyncness.node);
986 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
987 vis.visit_span(inner);
988 items.flat_map_in_place(|item| vis.flat_map_item(item));
991 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
992 visit_clobber(krate, |Crate { module, attrs, span }| {
994 ident: Ident::invalid(),
997 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
999 node: ItemKind::Mod(module),
1002 let items = vis.flat_map_item(item);
1004 let len = items.len();
1006 let module = Mod { inner: span, items: vec![], inline: true };
1007 Crate { module, attrs: vec![], span }
1008 } else if len == 1 {
1009 let Item { attrs, span, node, .. } = items.into_iter().next().unwrap().into_inner();
1011 ItemKind::Mod(module) => Crate { module, attrs, span },
1012 _ => panic!("visitor converted a module to not a module"),
1015 panic!("a crate cannot expand to more than one item");
1020 // Mutate one item into possibly many items.
1021 pub fn noop_flat_map_item<T: MutVisitor>(mut item: P<Item>, visitor: &mut T)
1022 -> SmallVec<[P<Item>; 1]> {
1023 let Item { ident, attrs, id, node, vis, span, tokens: _ } = item.deref_mut();
1024 visitor.visit_ident(ident);
1025 visit_attrs(attrs, visitor);
1026 visitor.visit_id(id);
1027 visitor.visit_item_kind(node);
1028 visitor.visit_vis(vis);
1029 visitor.visit_span(span);
1031 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1032 // an ICE during resolve... odd!
1037 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
1038 -> SmallVec<[ForeignItem; 1]>
1040 let ForeignItem { ident, attrs, node, id, span, vis } = &mut item;
1041 visitor.visit_ident(ident);
1042 visit_attrs(attrs, visitor);
1044 ForeignItemKind::Fn(fdec, generics) => {
1045 visitor.visit_fn_decl(fdec);
1046 visitor.visit_generics(generics);
1048 ForeignItemKind::Static(t, _m) => visitor.visit_ty(t),
1049 ForeignItemKind::Ty => {}
1050 ForeignItemKind::Macro(mac) => visitor.visit_mac(mac),
1052 visitor.visit_id(id);
1053 visitor.visit_span(span);
1054 visitor.visit_vis(vis);
1059 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1060 let Pat { id, node, span } = pat.deref_mut();
1063 PatKind::Wild | PatKind::Rest => {}
1064 PatKind::Ident(_binding_mode, ident, sub) => {
1065 vis.visit_ident(ident);
1066 visit_opt(sub, |sub| vis.visit_pat(sub));
1068 PatKind::Lit(e) => vis.visit_expr(e),
1069 PatKind::TupleStruct(path, elems) => {
1070 vis.visit_path(path);
1071 visit_vec(elems, |elem| vis.visit_pat(elem));
1073 PatKind::Path(qself, path) => {
1074 vis.visit_qself(qself);
1075 vis.visit_path(path);
1077 PatKind::Struct(path, fields, _etc) => {
1078 vis.visit_path(path);
1079 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1081 PatKind::Box(inner) => vis.visit_pat(inner),
1082 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1083 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1086 vis.visit_span(span);
1088 PatKind::Tuple(elems)
1089 | PatKind::Slice(elems)
1090 | PatKind::Or(elems) => visit_vec(elems, |elem| vis.visit_pat(elem)),
1091 PatKind::Paren(inner) => vis.visit_pat(inner),
1092 PatKind::Mac(mac) => vis.visit_mac(mac),
1094 vis.visit_span(span);
1097 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1099 vis.visit_expr(value);
1102 pub fn noop_visit_expr<T: MutVisitor>(Expr { node, id, span, attrs }: &mut Expr, vis: &mut T) {
1104 ExprKind::Box(expr) => vis.visit_expr(expr),
1105 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1106 ExprKind::Repeat(expr, count) => {
1107 vis.visit_expr(expr);
1108 vis.visit_anon_const(count);
1110 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1111 ExprKind::Call(f, args) => {
1113 visit_exprs(args, vis);
1115 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
1116 vis.visit_ident(ident);
1118 visit_opt(args, |args| vis.visit_generic_args(args));
1119 visit_exprs(exprs, vis);
1121 ExprKind::Binary(_binop, lhs, rhs) => {
1122 vis.visit_expr(lhs);
1123 vis.visit_expr(rhs);
1125 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1126 ExprKind::Cast(expr, ty) => {
1127 vis.visit_expr(expr);
1130 ExprKind::Type(expr, ty) => {
1131 vis.visit_expr(expr);
1134 ExprKind::AddrOf(_m, ohs) => vis.visit_expr(ohs),
1135 ExprKind::Let(pats, scrutinee) => {
1136 visit_vec(pats, |pat| vis.visit_pat(pat));
1137 vis.visit_expr(scrutinee);
1139 ExprKind::If(cond, tr, fl) => {
1140 vis.visit_expr(cond);
1141 vis.visit_block(tr);
1142 visit_opt(fl, |fl| vis.visit_expr(fl));
1144 ExprKind::While(cond, body, label) => {
1145 vis.visit_expr(cond);
1146 vis.visit_block(body);
1147 visit_opt(label, |label| vis.visit_label(label));
1149 ExprKind::ForLoop(pat, iter, body, label) => {
1151 vis.visit_expr(iter);
1152 vis.visit_block(body);
1153 visit_opt(label, |label| vis.visit_label(label));
1155 ExprKind::Loop(body, label) => {
1156 vis.visit_block(body);
1157 visit_opt(label, |label| vis.visit_label(label));
1159 ExprKind::Match(expr, arms) => {
1160 vis.visit_expr(expr);
1161 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1163 ExprKind::Closure(_capture_by, asyncness, _movability, decl, body, span) => {
1164 vis.visit_asyncness(asyncness);
1165 vis.visit_fn_decl(decl);
1166 vis.visit_expr(body);
1167 vis.visit_span(span);
1169 ExprKind::Block(blk, label) => {
1170 vis.visit_block(blk);
1171 visit_opt(label, |label| vis.visit_label(label));
1173 ExprKind::Async(_capture_by, node_id, body) => {
1174 vis.visit_id(node_id);
1175 vis.visit_block(body);
1177 ExprKind::Await(expr) => vis.visit_expr(expr),
1178 ExprKind::Assign(el, er) => {
1182 ExprKind::AssignOp(_op, el, er) => {
1186 ExprKind::Field(el, ident) => {
1188 vis.visit_ident(ident);
1190 ExprKind::Index(el, er) => {
1194 ExprKind::Range(e1, e2, _lim) => {
1195 visit_opt(e1, |e1| vis.visit_expr(e1));
1196 visit_opt(e2, |e2| vis.visit_expr(e2));
1198 ExprKind::Path(qself, path) => {
1199 vis.visit_qself(qself);
1200 vis.visit_path(path);
1202 ExprKind::Break(label, expr) => {
1203 visit_opt(label, |label| vis.visit_label(label));
1204 visit_opt(expr, |expr| vis.visit_expr(expr));
1206 ExprKind::Continue(label) => {
1207 visit_opt(label, |label| vis.visit_label(label));
1209 ExprKind::Ret(expr) => {
1210 visit_opt(expr, |expr| vis.visit_expr(expr));
1212 ExprKind::InlineAsm(asm) => {
1213 let InlineAsm { asm: _, asm_str_style: _, outputs, inputs, clobbers: _, volatile: _,
1214 alignstack: _, dialect: _ } = asm.deref_mut();
1215 for out in outputs {
1216 let InlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1217 vis.visit_expr(expr);
1219 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1221 ExprKind::Mac(mac) => vis.visit_mac(mac),
1222 ExprKind::Struct(path, fields, expr) => {
1223 vis.visit_path(path);
1224 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1225 visit_opt(expr, |expr| vis.visit_expr(expr));
1227 ExprKind::Paren(expr) => {
1228 vis.visit_expr(expr);
1230 // Nodes that are equal modulo `Paren` sugar no-ops should have the same ids.
1232 vis.visit_span(span);
1233 visit_thin_attrs(attrs, vis);
1236 ExprKind::Yield(expr) => {
1237 visit_opt(expr, |expr| vis.visit_expr(expr));
1239 ExprKind::Try(expr) => vis.visit_expr(expr),
1240 ExprKind::TryBlock(body) => vis.visit_block(body),
1241 ExprKind::Lit(_) | ExprKind::Err => {}
1244 vis.visit_span(span);
1245 visit_thin_attrs(attrs, vis);
1248 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1249 Some({ vis.visit_expr(&mut e); e })
1252 pub fn noop_flat_map_stmt<T: MutVisitor>(Stmt { node, mut span, mut id }: Stmt, vis: &mut T)
1253 -> SmallVec<[Stmt; 1]>
1255 vis.visit_id(&mut id);
1256 vis.visit_span(&mut span);
1257 noop_flat_map_stmt_kind(node, vis).into_iter().map(|node| {
1258 Stmt { id, node, span }
1262 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(node: StmtKind, vis: &mut T)
1263 -> SmallVec<[StmtKind; 1]> {
1265 StmtKind::Local(mut local) =>
1266 smallvec![StmtKind::Local({ vis.visit_local(&mut local); local })],
1267 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1268 StmtKind::Expr(expr) => {
1269 vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect()
1271 StmtKind::Semi(expr) => {
1272 vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect()
1274 StmtKind::Mac(mut mac) => {
1275 let (mac_, _semi, attrs) = mac.deref_mut();
1276 vis.visit_mac(mac_);
1277 visit_thin_attrs(attrs, vis);
1278 smallvec![StmtKind::Mac(mac)]
1283 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1285 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1286 VisibilityKind::Restricted { path, id } => {
1287 vis.visit_path(path);
1291 vis.visit_span(span);