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.
12 use crate::token::{self, Token};
13 use crate::tokenstream::*;
15 use rustc_data_structures::map_in_place::MapInPlace;
16 use rustc_data_structures::sync::Lrc;
17 use rustc_span::source_map::{respan, Spanned};
18 use rustc_span::symbol::Ident;
21 use smallvec::{smallvec, Array, SmallVec};
22 use std::ops::DerefMut;
23 use std::{panic, process, ptr};
25 pub trait ExpectOne<A: Array> {
26 fn expect_one(self, err: &'static str) -> A::Item;
29 impl<A: Array> ExpectOne<A> for SmallVec<A> {
30 fn expect_one(self, err: &'static str) -> A::Item {
31 assert!(self.len() == 1, err);
32 self.into_iter().next().unwrap()
36 pub trait MutVisitor: Sized {
37 // Methods in this trait have one of three forms:
39 // fn visit_t(&mut self, t: &mut T); // common
40 // fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
41 // fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
43 // Any additions to this trait should happen in form of a call to a public
44 // `noop_*` function that only calls out to the visitor again, not other
45 // `noop_*` functions. This is a necessary API workaround to the problem of
46 // not being able to call out to the super default method in an overridden
49 // When writing these methods, it is better to use destructuring like this:
51 // fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
56 // than to use field access like this:
58 // fn visit_abc(&mut self, abc: &mut ABC) {
59 // visit_a(&mut abc.a);
60 // visit_b(&mut abc.b);
64 // As well as being more concise, the former is explicit about which fields
65 // are skipped. Furthermore, if a new field is added, the destructuring
66 // version will cause a compile error, which is good. In comparison, the
67 // field access version will continue working and it would be easy to
68 // forget to add handling for it.
70 fn visit_crate(&mut self, c: &mut Crate) {
71 noop_visit_crate(c, self)
74 fn visit_meta_list_item(&mut self, list_item: &mut NestedMetaItem) {
75 noop_visit_meta_list_item(list_item, self);
78 fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
79 noop_visit_meta_item(meta_item, self);
82 fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
83 noop_visit_use_tree(use_tree, self);
86 fn flat_map_foreign_item(&mut self, ni: P<ForeignItem>) -> SmallVec<[P<ForeignItem>; 1]> {
87 noop_flat_map_foreign_item(ni, self)
90 fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
91 noop_flat_map_item(i, self)
94 fn visit_fn_header(&mut self, header: &mut FnHeader) {
95 noop_visit_fn_header(header, self);
98 fn flat_map_struct_field(&mut self, sf: StructField) -> SmallVec<[StructField; 1]> {
99 noop_flat_map_struct_field(sf, self)
102 fn visit_item_kind(&mut self, i: &mut ItemKind) {
103 noop_visit_item_kind(i, self);
106 fn flat_map_trait_item(&mut self, i: P<AssocItem>) -> SmallVec<[P<AssocItem>; 1]> {
107 noop_flat_map_assoc_item(i, self)
110 fn flat_map_impl_item(&mut self, i: P<AssocItem>) -> SmallVec<[P<AssocItem>; 1]> {
111 noop_flat_map_assoc_item(i, self)
114 fn visit_fn_decl(&mut self, d: &mut P<FnDecl>) {
115 noop_visit_fn_decl(d, self);
118 fn visit_asyncness(&mut self, a: &mut Async) {
119 noop_visit_asyncness(a, self);
122 fn visit_block(&mut self, b: &mut P<Block>) {
123 noop_visit_block(b, self);
126 fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
127 noop_flat_map_stmt(s, self)
130 fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
131 noop_flat_map_arm(arm, self)
134 fn visit_pat(&mut self, p: &mut P<Pat>) {
135 noop_visit_pat(p, self);
138 fn visit_anon_const(&mut self, c: &mut AnonConst) {
139 noop_visit_anon_const(c, self);
142 fn visit_expr(&mut self, e: &mut P<Expr>) {
143 noop_visit_expr(e, self);
146 fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
147 noop_filter_map_expr(e, self)
150 fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
151 noop_visit_generic_arg(arg, self);
154 fn visit_ty(&mut self, t: &mut P<Ty>) {
155 noop_visit_ty(t, self);
158 fn visit_lifetime(&mut self, l: &mut Lifetime) {
159 noop_visit_lifetime(l, self);
162 fn visit_ty_constraint(&mut self, t: &mut AssocTyConstraint) {
163 noop_visit_ty_constraint(t, self);
166 fn visit_mod(&mut self, m: &mut Mod) {
167 noop_visit_mod(m, self);
170 fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
171 noop_visit_foreign_mod(nm, self);
174 fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
175 noop_flat_map_variant(v, self)
178 fn visit_ident(&mut self, i: &mut Ident) {
179 noop_visit_ident(i, self);
182 fn visit_path(&mut self, p: &mut Path) {
183 noop_visit_path(p, self);
186 fn visit_qself(&mut self, qs: &mut Option<QSelf>) {
187 noop_visit_qself(qs, self);
190 fn visit_generic_args(&mut self, p: &mut GenericArgs) {
191 noop_visit_generic_args(p, self);
194 fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
195 noop_visit_angle_bracketed_parameter_data(p, self);
198 fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
199 noop_visit_parenthesized_parameter_data(p, self);
202 fn visit_local(&mut self, l: &mut P<Local>) {
203 noop_visit_local(l, self);
206 fn visit_mac(&mut self, _mac: &mut MacCall) {
207 panic!("visit_mac disabled by default");
208 // N.B., see note about macros above. If you really want a visitor that
209 // works on macros, use this definition in your trait impl:
210 // mut_visit::noop_visit_mac(_mac, self);
213 fn visit_macro_def(&mut self, def: &mut MacroDef) {
214 noop_visit_macro_def(def, self);
217 fn visit_label(&mut self, label: &mut Label) {
218 noop_visit_label(label, self);
221 fn visit_attribute(&mut self, at: &mut Attribute) {
222 noop_visit_attribute(at, self);
225 fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
226 noop_flat_map_param(param, self)
229 fn visit_generics(&mut self, generics: &mut Generics) {
230 noop_visit_generics(generics, self);
233 fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
234 noop_visit_trait_ref(tr, self);
237 fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
238 noop_visit_poly_trait_ref(p, self);
241 fn visit_variant_data(&mut self, vdata: &mut VariantData) {
242 noop_visit_variant_data(vdata, self);
245 fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
246 noop_flat_map_generic_param(param, self)
249 fn visit_tt(&mut self, tt: &mut TokenTree) {
250 noop_visit_tt(tt, self);
253 fn visit_tts(&mut self, tts: &mut TokenStream) {
254 noop_visit_tts(tts, self);
257 fn visit_token(&mut self, t: &mut Token) {
258 noop_visit_token(t, self);
261 fn visit_interpolated(&mut self, nt: &mut token::Nonterminal) {
262 noop_visit_interpolated(nt, self);
265 fn visit_param_bound(&mut self, tpb: &mut GenericBound) {
266 noop_visit_param_bound(tpb, self);
269 fn visit_mt(&mut self, mt: &mut MutTy) {
270 noop_visit_mt(mt, self);
273 fn flat_map_field(&mut self, f: Field) -> SmallVec<[Field; 1]> {
274 noop_flat_map_field(f, self)
277 fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
278 noop_visit_where_clause(where_clause, self);
281 fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
282 noop_visit_where_predicate(where_predicate, self);
285 fn visit_vis(&mut self, vis: &mut Visibility) {
286 noop_visit_vis(vis, self);
289 fn visit_id(&mut self, _id: &mut NodeId) {
293 fn visit_span(&mut self, _sp: &mut Span) {
297 fn flat_map_field_pattern(&mut self, fp: FieldPat) -> SmallVec<[FieldPat; 1]> {
298 noop_flat_map_field_pattern(fp, self)
302 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
303 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
304 /// method. Abort the program if the closure panics.
306 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
307 pub fn visit_clobber<T, F>(t: &mut T, f: F)
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)
332 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
334 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F)
338 if let Some(elem) = opt {
343 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
344 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
345 visit_vec(attrs, |attr| vis.visit_attribute(attr));
348 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
349 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut AttrVec, vis: &mut T) {
350 for attr in attrs.iter_mut() {
351 vis.visit_attribute(attr);
355 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
356 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
357 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
360 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
361 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
362 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
365 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
366 pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
367 vis.visit_fn_header(header);
368 vis.visit_fn_decl(decl);
371 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
372 pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
375 MacArgs::Delimited(dspan, _delim, tokens) => {
376 visit_delim_span(dspan, vis);
377 vis.visit_tts(tokens);
379 MacArgs::Eq(eq_span, tokens) => {
380 vis.visit_span(eq_span);
381 vis.visit_tts(tokens);
386 pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
387 vis.visit_span(&mut dspan.open);
388 vis.visit_span(&mut dspan.close);
391 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
394 ) -> SmallVec<[FieldPat; 1]> {
395 let FieldPat { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = &mut fp;
397 vis.visit_ident(ident);
399 vis.visit_span(span);
400 visit_thin_attrs(attrs, vis);
404 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
405 let UseTree { prefix, kind, span } = use_tree;
406 vis.visit_path(prefix);
408 UseTreeKind::Simple(rename, id1, id2) => {
409 visit_opt(rename, |rename| vis.visit_ident(rename));
413 UseTreeKind::Nested(items) => {
414 for (tree, id) in items {
415 vis.visit_use_tree(tree);
419 UseTreeKind::Glob => {}
421 vis.visit_span(span);
424 pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[Arm; 1]> {
425 let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = &mut arm;
426 visit_attrs(attrs, vis);
429 visit_opt(guard, |guard| vis.visit_expr(guard));
430 vis.visit_expr(body);
431 vis.visit_span(span);
435 pub fn noop_visit_ty_constraint<T: MutVisitor>(
436 AssocTyConstraint { id, ident, kind, span }: &mut AssocTyConstraint,
440 vis.visit_ident(ident);
442 AssocTyConstraintKind::Equality { ref mut ty } => {
445 AssocTyConstraintKind::Bound { ref mut bounds } => {
446 visit_bounds(bounds, vis);
449 vis.visit_span(span);
452 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
453 let Ty { id, kind, span } = ty.deref_mut();
456 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err | TyKind::Never | TyKind::CVarArgs => {}
457 TyKind::Slice(ty) => vis.visit_ty(ty),
458 TyKind::Ptr(mt) => vis.visit_mt(mt),
459 TyKind::Rptr(lt, mt) => {
460 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
463 TyKind::BareFn(bft) => {
464 let BareFnTy { unsafety: _, ext: _, generic_params, decl } = bft.deref_mut();
465 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
466 vis.visit_fn_decl(decl);
468 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
469 TyKind::Paren(ty) => vis.visit_ty(ty),
470 TyKind::Path(qself, path) => {
471 vis.visit_qself(qself);
472 vis.visit_path(path);
474 TyKind::Array(ty, length) => {
476 vis.visit_anon_const(length);
478 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
479 TyKind::TraitObject(bounds, _syntax) => {
480 visit_vec(bounds, |bound| vis.visit_param_bound(bound))
482 TyKind::ImplTrait(id, bounds) => {
484 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
486 TyKind::MacCall(mac) => vis.visit_mac(mac),
488 vis.visit_span(span);
491 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
492 let ForeignMod { abi: _, items } = foreign_mod;
493 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
496 pub fn noop_flat_map_variant<T: MutVisitor>(
497 mut variant: Variant,
499 ) -> SmallVec<[Variant; 1]> {
500 let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
501 visitor.visit_ident(ident);
502 visitor.visit_vis(vis);
503 visit_attrs(attrs, visitor);
504 visitor.visit_id(id);
505 visitor.visit_variant_data(data);
506 visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
507 visitor.visit_span(span);
511 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
512 vis.visit_span(span);
515 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
516 vis.visit_span(span);
517 for PathSegment { ident, id, args } in segments {
518 vis.visit_ident(ident);
520 visit_opt(args, |args| vis.visit_generic_args(args));
524 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
525 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
527 vis.visit_span(path_span);
531 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
533 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
534 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
538 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
540 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
541 GenericArg::Type(ty) => vis.visit_ty(ty),
542 GenericArg::Const(ct) => vis.visit_anon_const(ct),
546 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(
547 data: &mut AngleBracketedArgs,
550 let AngleBracketedArgs { args, span } = data;
551 visit_vec(args, |arg| match arg {
552 AngleBracketedArg::Arg(arg) => vis.visit_generic_arg(arg),
553 AngleBracketedArg::Constraint(constraint) => vis.visit_ty_constraint(constraint),
555 vis.visit_span(span);
558 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(
559 args: &mut ParenthesizedArgs,
562 let ParenthesizedArgs { inputs, output, span } = args;
563 visit_vec(inputs, |input| vis.visit_ty(input));
564 noop_visit_fn_ret_ty(output, vis);
565 vis.visit_span(span);
568 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
569 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
572 visit_opt(ty, |ty| vis.visit_ty(ty));
573 visit_opt(init, |init| vis.visit_expr(init));
574 vis.visit_span(span);
575 visit_thin_attrs(attrs, vis);
578 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
579 let Attribute { kind, id: _, style: _, span } = attr;
581 AttrKind::Normal(AttrItem { path, args }) => {
582 vis.visit_path(path);
583 visit_mac_args(args, vis);
585 AttrKind::DocComment(..) => {}
587 vis.visit_span(span);
590 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut MacCall, vis: &mut T) {
591 let MacCall { path, args, prior_type_ascription: _ } = mac;
592 vis.visit_path(path);
593 visit_mac_args(args, vis);
596 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
597 let MacroDef { body, macro_rules: _ } = macro_def;
598 visit_mac_args(body, vis);
601 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
603 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
604 NestedMetaItem::Literal(_lit) => {}
608 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
609 let MetaItem { path: _, kind, span } = mi;
611 MetaItemKind::Word => {}
612 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
613 MetaItemKind::NameValue(_s) => {}
615 vis.visit_span(span);
618 pub fn noop_flat_map_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
619 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
621 visit_thin_attrs(attrs, vis);
623 vis.visit_span(span);
628 pub fn noop_visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
630 TokenTree::Token(token) => {
631 vis.visit_token(token);
633 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
634 vis.visit_span(open);
635 vis.visit_span(close);
641 pub fn noop_visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
642 let tts = Lrc::make_mut(tts);
643 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
646 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
647 // In practice the ident part is not actually used by specific visitors right now,
648 // but there's a test below checking that it works.
649 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
650 let Token { kind, span } = t;
652 token::Ident(name, _) | token::Lifetime(name) => {
653 let mut ident = Ident::new(*name, *span);
654 vis.visit_ident(&mut ident);
657 return; // Avoid visiting the span for the second time.
659 token::Interpolated(nt) => {
660 let mut nt = Lrc::make_mut(nt);
661 vis.visit_interpolated(&mut nt);
665 vis.visit_span(span);
668 /// Applies the visitor to elements of interpolated nodes.
670 // N.B., this can occur only when applying a visitor to partially expanded
671 // code, where parsed pieces have gotten implanted ito *other* macro
672 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
674 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
675 // etc., allow the visitor to return *multiple* items; this is a problem for the
676 // nodes here, because they insist on having exactly one piece. One solution
677 // would be to mangle the MutVisitor trait to include one-to-many and
678 // one-to-one versions of these entry points, but that would probably confuse a
679 // lot of people and help very few. Instead, I'm just going to put in dynamic
680 // checks. I think the performance impact of this will be pretty much
681 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
682 // partially expanded node, and will be confused by the fact that their
683 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
684 // nodes. Hopefully they'll wind up reading this comment, and doing something
687 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
688 // contain multiple items, but decided against it when I looked at
689 // `parse_item_or_view_item` and tried to figure out what I would do with
690 // multiple items there....
691 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
693 token::NtItem(item) => visit_clobber(item, |item| {
694 // This is probably okay, because the only visitors likely to
695 // peek inside interpolated nodes will be renamings/markings,
696 // which map single items to single items.
697 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
699 token::NtBlock(block) => vis.visit_block(block),
700 token::NtStmt(stmt) => visit_clobber(stmt, |stmt| {
701 // See reasoning above.
702 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
704 token::NtPat(pat) => vis.visit_pat(pat),
705 token::NtExpr(expr) => vis.visit_expr(expr),
706 token::NtTy(ty) => vis.visit_ty(ty),
707 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
708 token::NtLifetime(ident) => vis.visit_ident(ident),
709 token::NtLiteral(expr) => vis.visit_expr(expr),
710 token::NtMeta(item) => {
711 let AttrItem { path, args } = item.deref_mut();
712 vis.visit_path(path);
713 visit_mac_args(args, vis);
715 token::NtPath(path) => vis.visit_path(path),
716 token::NtTT(tt) => vis.visit_tt(tt),
717 token::NtVis(visib) => vis.visit_vis(visib),
721 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut Async, vis: &mut T) {
723 Async::Yes { span: _, closure_id, return_impl_trait_id } => {
724 vis.visit_id(closure_id);
725 vis.visit_id(return_impl_trait_id);
731 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
732 let FnDecl { inputs, output } = decl.deref_mut();
733 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
734 noop_visit_fn_ret_ty(output, vis);
737 pub fn noop_visit_fn_ret_ty<T: MutVisitor>(fn_ret_ty: &mut FnRetTy, vis: &mut T) {
739 FnRetTy::Default(span) => vis.visit_span(span),
740 FnRetTy::Ty(ty) => vis.visit_ty(ty),
744 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
746 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
747 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
751 pub fn noop_flat_map_generic_param<T: MutVisitor>(
752 mut param: GenericParam,
754 ) -> SmallVec<[GenericParam; 1]> {
755 let GenericParam { id, ident, attrs, bounds, kind, is_placeholder: _ } = &mut param;
757 vis.visit_ident(ident);
758 visit_thin_attrs(attrs, vis);
759 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
761 GenericParamKind::Lifetime => {}
762 GenericParamKind::Type { default } => {
763 visit_opt(default, |default| vis.visit_ty(default));
765 GenericParamKind::Const { ty, kw_span: _ } => {
772 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
773 vis.visit_ident(ident);
776 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
778 vis.visit_ident(ident);
781 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
782 let Generics { params, where_clause, span } = generics;
783 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
784 vis.visit_where_clause(where_clause);
785 vis.visit_span(span);
788 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
789 let WhereClause { has_where_token: _, predicates, span } = wc;
790 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
791 vis.visit_span(span);
794 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
796 WherePredicate::BoundPredicate(bp) => {
797 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
798 vis.visit_span(span);
799 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
800 vis.visit_ty(bounded_ty);
801 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
803 WherePredicate::RegionPredicate(rp) => {
804 let WhereRegionPredicate { span, lifetime, bounds } = rp;
805 vis.visit_span(span);
806 noop_visit_lifetime(lifetime, vis);
807 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
809 WherePredicate::EqPredicate(ep) => {
810 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
812 vis.visit_span(span);
813 vis.visit_ty(lhs_ty);
814 vis.visit_ty(rhs_ty);
819 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
821 VariantData::Struct(fields, ..) => {
822 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
824 VariantData::Tuple(fields, id) => {
825 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
828 VariantData::Unit(id) => vis.visit_id(id),
832 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
833 vis.visit_path(path);
834 vis.visit_id(ref_id);
837 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
838 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
839 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
840 vis.visit_trait_ref(trait_ref);
841 vis.visit_span(span);
844 pub fn noop_flat_map_struct_field<T: MutVisitor>(
847 ) -> SmallVec<[StructField; 1]> {
848 let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
849 visitor.visit_span(span);
850 visit_opt(ident, |ident| visitor.visit_ident(ident));
851 visitor.visit_vis(vis);
852 visitor.visit_id(id);
853 visitor.visit_ty(ty);
854 visit_attrs(attrs, visitor);
858 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
859 let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
860 vis.visit_ident(ident);
861 vis.visit_expr(expr);
863 vis.visit_span(span);
864 visit_thin_attrs(attrs, vis);
868 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
872 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
873 let Block { id, stmts, rules: _, span } = block.deref_mut();
875 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
876 vis.visit_span(span);
879 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
881 ItemKind::ExternCrate(_orig_name) => {}
882 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
883 ItemKind::Static(ty, _, expr) | ItemKind::Const(_, ty, expr) => {
885 visit_opt(expr, |expr| vis.visit_expr(expr));
887 ItemKind::Fn(_, sig, generics, body) => {
888 visit_fn_sig(sig, vis);
889 vis.visit_generics(generics);
890 visit_opt(body, |body| vis.visit_block(body));
892 ItemKind::Mod(m) => vis.visit_mod(m),
893 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
894 ItemKind::GlobalAsm(_ga) => {}
895 ItemKind::TyAlias(_, generics, bounds, ty) => {
896 vis.visit_generics(generics);
897 visit_bounds(bounds, vis);
898 visit_opt(ty, |ty| vis.visit_ty(ty));
900 ItemKind::Enum(EnumDef { variants }, generics) => {
901 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
902 vis.visit_generics(generics);
904 ItemKind::Struct(variant_data, generics) | ItemKind::Union(variant_data, generics) => {
905 vis.visit_variant_data(variant_data);
906 vis.visit_generics(generics);
918 vis.visit_generics(generics);
919 visit_opt(of_trait, |trait_ref| vis.visit_trait_ref(trait_ref));
920 vis.visit_ty(self_ty);
921 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
923 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
924 vis.visit_generics(generics);
925 visit_bounds(bounds, vis);
926 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
928 ItemKind::TraitAlias(generics, bounds) => {
929 vis.visit_generics(generics);
930 visit_bounds(bounds, vis);
932 ItemKind::MacCall(m) => vis.visit_mac(m),
933 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
937 pub fn noop_flat_map_assoc_item<T: MutVisitor>(
938 mut item: P<AssocItem>,
940 ) -> SmallVec<[P<AssocItem>; 1]> {
941 let Item { id, ident, vis, attrs, kind, span, tokens: _ } = item.deref_mut();
942 visitor.visit_id(id);
943 visitor.visit_ident(ident);
944 visitor.visit_vis(vis);
945 visit_attrs(attrs, visitor);
947 AssocItemKind::Const(_, ty, expr) => {
948 visitor.visit_ty(ty);
949 visit_opt(expr, |expr| visitor.visit_expr(expr));
951 AssocItemKind::Fn(_, sig, generics, body) => {
952 visitor.visit_generics(generics);
953 visit_fn_sig(sig, visitor);
954 visit_opt(body, |body| visitor.visit_block(body));
956 AssocItemKind::TyAlias(_, generics, bounds, ty) => {
957 visitor.visit_generics(generics);
958 visit_bounds(bounds, visitor);
959 visit_opt(ty, |ty| visitor.visit_ty(ty));
961 AssocItemKind::MacCall(mac) => visitor.visit_mac(mac),
963 visitor.visit_span(span);
967 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
968 let FnHeader { unsafety: _, asyncness, constness: _, ext: _ } = header;
969 vis.visit_asyncness(asyncness);
972 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
973 vis.visit_span(inner);
974 items.flat_map_in_place(|item| vis.flat_map_item(item));
977 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
978 visit_clobber(krate, |Crate { module, attrs, span, proc_macros }| {
980 ident: Ident::invalid(),
983 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
985 kind: ItemKind::Mod(module),
988 let items = vis.flat_map_item(item);
990 let len = items.len();
992 let module = Mod { inner: span, items: vec![], inline: true };
993 Crate { module, attrs: vec![], span, proc_macros }
995 let Item { attrs, span, kind, .. } = items.into_iter().next().unwrap().into_inner();
997 ItemKind::Mod(module) => Crate { module, attrs, span, proc_macros },
998 _ => panic!("visitor converted a module to not a module"),
1001 panic!("a crate cannot expand to more than one item");
1006 // Mutates one item into possibly many items.
1007 pub fn noop_flat_map_item<T: MutVisitor>(
1010 ) -> SmallVec<[P<Item>; 1]> {
1011 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1012 visitor.visit_ident(ident);
1013 visit_attrs(attrs, visitor);
1014 visitor.visit_id(id);
1015 visitor.visit_item_kind(kind);
1016 visitor.visit_vis(vis);
1017 visitor.visit_span(span);
1019 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1020 // an ICE during resolve... odd!
1025 pub fn noop_flat_map_foreign_item<T: MutVisitor>(
1026 mut item: P<ForeignItem>,
1028 ) -> SmallVec<[P<ForeignItem>; 1]> {
1029 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1030 visitor.visit_id(id);
1031 visitor.visit_ident(ident);
1032 visitor.visit_vis(vis);
1033 visit_attrs(attrs, visitor);
1035 ForeignItemKind::Static(ty, _, expr) => {
1036 visitor.visit_ty(ty);
1037 visit_opt(expr, |expr| visitor.visit_expr(expr));
1039 ForeignItemKind::Fn(_, sig, generics, body) => {
1040 visitor.visit_generics(generics);
1041 visit_fn_sig(sig, visitor);
1042 visit_opt(body, |body| visitor.visit_block(body));
1044 ForeignItemKind::TyAlias(_, generics, bounds, ty) => {
1045 visitor.visit_generics(generics);
1046 visit_bounds(bounds, visitor);
1047 visit_opt(ty, |ty| visitor.visit_ty(ty));
1049 ForeignItemKind::MacCall(mac) => visitor.visit_mac(mac),
1051 visitor.visit_span(span);
1055 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1056 let Pat { id, kind, span, tokens: _ } = pat.deref_mut();
1059 PatKind::Wild | PatKind::Rest => {}
1060 PatKind::Ident(_binding_mode, ident, sub) => {
1061 vis.visit_ident(ident);
1062 visit_opt(sub, |sub| vis.visit_pat(sub));
1064 PatKind::Lit(e) => vis.visit_expr(e),
1065 PatKind::TupleStruct(path, elems) => {
1066 vis.visit_path(path);
1067 visit_vec(elems, |elem| vis.visit_pat(elem));
1069 PatKind::Path(qself, path) => {
1070 vis.visit_qself(qself);
1071 vis.visit_path(path);
1073 PatKind::Struct(path, fields, _etc) => {
1074 vis.visit_path(path);
1075 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1077 PatKind::Box(inner) => vis.visit_pat(inner),
1078 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1079 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1080 visit_opt(e1, |e| vis.visit_expr(e));
1081 visit_opt(e2, |e| vis.visit_expr(e));
1082 vis.visit_span(span);
1084 PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => {
1085 visit_vec(elems, |elem| vis.visit_pat(elem))
1087 PatKind::Paren(inner) => vis.visit_pat(inner),
1088 PatKind::MacCall(mac) => vis.visit_mac(mac),
1090 vis.visit_span(span);
1093 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1095 vis.visit_expr(value);
1098 pub fn noop_visit_expr<T: MutVisitor>(
1099 Expr { kind, id, span, attrs, tokens: _ }: &mut Expr,
1103 ExprKind::Box(expr) => vis.visit_expr(expr),
1104 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1105 ExprKind::Repeat(expr, count) => {
1106 vis.visit_expr(expr);
1107 vis.visit_anon_const(count);
1109 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1110 ExprKind::Call(f, args) => {
1112 visit_exprs(args, vis);
1114 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs, span) => {
1115 vis.visit_ident(ident);
1117 visit_opt(args, |args| vis.visit_generic_args(args));
1118 visit_exprs(exprs, vis);
1119 vis.visit_span(span);
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(_, _, ohs) => vis.visit_expr(ohs),
1135 ExprKind::Let(pat, scrutinee) => {
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 for (op, _) in &mut asm.operands {
1215 InlineAsmOperand::In { expr, .. }
1216 | InlineAsmOperand::InOut { expr, .. }
1217 | InlineAsmOperand::Const { expr, .. }
1218 | InlineAsmOperand::Sym { expr, .. } => vis.visit_expr(expr),
1219 InlineAsmOperand::Out { expr, .. } => {
1220 if let Some(expr) = expr {
1221 vis.visit_expr(expr);
1224 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1225 vis.visit_expr(in_expr);
1226 if let Some(out_expr) = out_expr {
1227 vis.visit_expr(out_expr);
1233 ExprKind::LlvmInlineAsm(asm) => {
1243 } = asm.deref_mut();
1244 for out in outputs {
1245 let LlvmInlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1246 vis.visit_expr(expr);
1248 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1250 ExprKind::MacCall(mac) => vis.visit_mac(mac),
1251 ExprKind::Struct(path, fields, expr) => {
1252 vis.visit_path(path);
1253 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1254 visit_opt(expr, |expr| vis.visit_expr(expr));
1256 ExprKind::Paren(expr) => {
1257 vis.visit_expr(expr);
1259 // Nodes that are equal modulo `Paren` sugar no-ops should have the same IDs.
1261 vis.visit_span(span);
1262 visit_thin_attrs(attrs, vis);
1265 ExprKind::Yield(expr) => {
1266 visit_opt(expr, |expr| vis.visit_expr(expr));
1268 ExprKind::Try(expr) => vis.visit_expr(expr),
1269 ExprKind::TryBlock(body) => vis.visit_block(body),
1270 ExprKind::Lit(_) | ExprKind::Err => {}
1273 vis.visit_span(span);
1274 visit_thin_attrs(attrs, vis);
1277 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1279 vis.visit_expr(&mut e);
1284 pub fn noop_flat_map_stmt<T: MutVisitor>(
1285 Stmt { kind, mut span, mut id }: Stmt,
1287 ) -> SmallVec<[Stmt; 1]> {
1288 vis.visit_id(&mut id);
1289 vis.visit_span(&mut span);
1290 noop_flat_map_stmt_kind(kind, vis).into_iter().map(|kind| Stmt { id, kind, span }).collect()
1293 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(
1296 ) -> SmallVec<[StmtKind; 1]> {
1298 StmtKind::Local(mut local) => smallvec![StmtKind::Local({
1299 vis.visit_local(&mut local);
1302 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1303 StmtKind::Expr(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect(),
1304 StmtKind::Semi(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect(),
1305 StmtKind::Empty => smallvec![StmtKind::Empty],
1306 StmtKind::MacCall(mut mac) => {
1307 let (mac_, _semi, attrs) = mac.deref_mut();
1308 vis.visit_mac(mac_);
1309 visit_thin_attrs(attrs, vis);
1310 smallvec![StmtKind::MacCall(mac)]
1315 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1317 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1318 VisibilityKind::Restricted { path, id } => {
1319 vis.visit_path(path);
1323 vis.visit_span(span);