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::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};
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: ForeignItem) -> SmallVec<[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: TraitItem) -> SmallVec<[TraitItem; 1]> {
107 noop_flat_map_trait_item(i, self)
110 fn flat_map_impl_item(&mut self, i: ImplItem) -> SmallVec<[ImplItem; 1]> {
111 noop_flat_map_impl_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 IsAsync) {
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 Mac) {
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) where F: FnOnce(T) -> T {
309 // Safe because `t` is used in a read-only fashion by `read()` before
310 // being overwritten by `write()`.
311 let old_t = ptr::read(t);
312 let new_t = panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t)))
313 .unwrap_or_else(|_| process::abort());
314 ptr::write(t, new_t);
318 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
320 pub fn visit_vec<T, F>(elems: &mut Vec<T>, mut visit_elem: F) where F: FnMut(&mut T) {
326 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
328 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F) where F: FnMut(&mut T) {
329 if let Some(elem) = opt {
334 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
335 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
336 visit_vec(attrs, |attr| vis.visit_attribute(attr));
339 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
340 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut ThinVec<Attribute>, vis: &mut T) {
341 for attr in attrs.iter_mut() {
342 vis.visit_attribute(attr);
346 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
347 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
348 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
351 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
352 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
353 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
356 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
357 pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
358 vis.visit_fn_header(header);
359 vis.visit_fn_decl(decl);
362 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
365 ) -> SmallVec<[FieldPat; 1]> {
376 vis.visit_ident(ident);
378 vis.visit_span(span);
379 visit_thin_attrs(attrs, vis);
383 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
384 let UseTree { prefix, kind, span } = use_tree;
385 vis.visit_path(prefix);
387 UseTreeKind::Simple(rename, id1, id2) => {
388 visit_opt(rename, |rename| vis.visit_ident(rename));
392 UseTreeKind::Nested(items) => {
393 for (tree, id) in items {
394 vis.visit_use_tree(tree);
398 UseTreeKind::Glob => {}
400 vis.visit_span(span);
403 pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[Arm; 1]> {
404 let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = &mut arm;
405 visit_attrs(attrs, vis);
408 visit_opt(guard, |guard| vis.visit_expr(guard));
409 vis.visit_expr(body);
410 vis.visit_span(span);
414 pub fn noop_visit_ty_constraint<T: MutVisitor>(
415 AssocTyConstraint { id, ident, kind, span }: &mut AssocTyConstraint,
419 vis.visit_ident(ident);
421 AssocTyConstraintKind::Equality { ref mut ty } => {
424 AssocTyConstraintKind::Bound { ref mut bounds } => {
425 visit_bounds(bounds, vis);
428 vis.visit_span(span);
431 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
432 let Ty { id, kind, span } = ty.deref_mut();
435 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err |
436 TyKind::Never | TyKind::CVarArgs => {}
437 TyKind::Slice(ty) => vis.visit_ty(ty),
438 TyKind::Ptr(mt) => vis.visit_mt(mt),
439 TyKind::Rptr(lt, mt) => {
440 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
443 TyKind::BareFn(bft) => {
444 let BareFnTy { unsafety: _, ext: _, generic_params, decl } = bft.deref_mut();
445 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
446 vis.visit_fn_decl(decl);
448 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
449 TyKind::Paren(ty) => vis.visit_ty(ty),
450 TyKind::Path(qself, path) => {
451 vis.visit_qself(qself);
452 vis.visit_path(path);
454 TyKind::Array(ty, length) => {
456 vis.visit_anon_const(length);
458 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
459 TyKind::TraitObject(bounds, _syntax) =>
460 visit_vec(bounds, |bound| vis.visit_param_bound(bound)),
461 TyKind::ImplTrait(id, bounds) => {
463 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
465 TyKind::Mac(mac) => vis.visit_mac(mac),
467 vis.visit_span(span);
470 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
471 let ForeignMod { abi: _, items} = foreign_mod;
472 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
475 pub fn noop_flat_map_variant<T: MutVisitor>(mut variant: Variant, vis: &mut T)
476 -> SmallVec<[Variant; 1]>
478 let Variant { ident, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
479 vis.visit_ident(ident);
480 visit_attrs(attrs, vis);
482 vis.visit_variant_data(data);
483 visit_opt(disr_expr, |disr_expr| vis.visit_anon_const(disr_expr));
484 vis.visit_span(span);
488 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
489 vis.visit_span(span);
492 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
493 vis.visit_span(span);
494 for PathSegment { ident, id, args } in segments {
495 vis.visit_ident(ident);
497 visit_opt(args, |args| vis.visit_generic_args(args));
501 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
502 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
504 vis.visit_span(path_span);
508 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
510 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
511 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
515 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
517 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
518 GenericArg::Type(ty) => vis.visit_ty(ty),
519 GenericArg::Const(ct) => vis.visit_anon_const(ct),
523 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(data: &mut AngleBracketedArgs,
525 let AngleBracketedArgs { args, constraints, span } = data;
526 visit_vec(args, |arg| vis.visit_generic_arg(arg));
527 visit_vec(constraints, |constraint| vis.visit_ty_constraint(constraint));
528 vis.visit_span(span);
531 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(args: &mut ParenthesizedArgs,
533 let ParenthesizedArgs { inputs, output, span } = args;
534 visit_vec(inputs, |input| vis.visit_ty(input));
535 visit_opt(output, |output| vis.visit_ty(output));
536 vis.visit_span(span);
539 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
540 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
543 visit_opt(ty, |ty| vis.visit_ty(ty));
544 visit_opt(init, |init| vis.visit_expr(init));
545 vis.visit_span(span);
546 visit_thin_attrs(attrs, vis);
549 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
550 let Attribute { kind, id: _, style: _, span } = attr;
552 AttrKind::Normal(AttrItem { path, tokens }) => {
553 vis.visit_path(path);
554 vis.visit_tts(tokens);
556 AttrKind::DocComment(_) => {}
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: _, kind, 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_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
591 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
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 let tts = Lrc::make_mut(tts);
615 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
618 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
619 // In practice the ident part is not actually used by specific visitors right now,
620 // but there's a test below checking that it works.
621 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
622 let Token { kind, span } = t;
624 token::Ident(name, _) | token::Lifetime(name) => {
625 let mut ident = Ident::new(*name, *span);
626 vis.visit_ident(&mut ident);
629 return; // Avoid visiting the span for the second time.
631 token::Interpolated(nt) => {
632 let mut nt = Lrc::make_mut(nt);
633 vis.visit_interpolated(&mut nt);
637 vis.visit_span(span);
640 /// Applies the visitor to elements of interpolated nodes.
642 // N.B., this can occur only when applying a visitor to partially expanded
643 // code, where parsed pieces have gotten implanted ito *other* macro
644 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
646 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
647 // etc., allow the visitor to return *multiple* items; this is a problem for the
648 // nodes here, because they insist on having exactly one piece. One solution
649 // would be to mangle the MutVisitor trait to include one-to-many and
650 // one-to-one versions of these entry points, but that would probably confuse a
651 // lot of people and help very few. Instead, I'm just going to put in dynamic
652 // checks. I think the performance impact of this will be pretty much
653 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
654 // partially expanded node, and will be confused by the fact that their
655 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
656 // nodes. Hopefully they'll wind up reading this comment, and doing something
659 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
660 // contain multiple items, but decided against it when I looked at
661 // `parse_item_or_view_item` and tried to figure out what I would do with
662 // multiple items there....
663 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
665 token::NtItem(item) =>
666 visit_clobber(item, |item| {
667 // This is probably okay, because the only visitors likely to
668 // peek inside interpolated nodes will be renamings/markings,
669 // which map single items to single items.
670 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
672 token::NtBlock(block) => vis.visit_block(block),
673 token::NtStmt(stmt) =>
674 visit_clobber(stmt, |stmt| {
675 // See reasoning above.
676 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
678 token::NtPat(pat) => vis.visit_pat(pat),
679 token::NtExpr(expr) => vis.visit_expr(expr),
680 token::NtTy(ty) => vis.visit_ty(ty),
681 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
682 token::NtLifetime(ident) => vis.visit_ident(ident),
683 token::NtLiteral(expr) => vis.visit_expr(expr),
684 token::NtMeta(AttrItem { path, tokens }) => {
685 vis.visit_path(path);
686 vis.visit_tts(tokens);
688 token::NtPath(path) => vis.visit_path(path),
689 token::NtTT(tt) => vis.visit_tt(tt),
690 token::NtImplItem(item) =>
691 visit_clobber(item, |item| {
692 // See reasoning above.
693 vis.flat_map_impl_item(item)
694 .expect_one("expected visitor to produce exactly one item")
696 token::NtTraitItem(item) =>
697 visit_clobber(item, |item| {
698 // See reasoning above.
699 vis.flat_map_trait_item(item)
700 .expect_one("expected visitor to produce exactly one item")
702 token::NtVis(visib) => vis.visit_vis(visib),
703 token::NtForeignItem(item) =>
704 visit_clobber(item, |item| {
705 // See reasoning above.
706 vis.flat_map_foreign_item(item)
707 .expect_one("expected visitor to produce exactly one item")
712 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut IsAsync, vis: &mut T) {
714 IsAsync::Async { closure_id, return_impl_trait_id } => {
715 vis.visit_id(closure_id);
716 vis.visit_id(return_impl_trait_id);
718 IsAsync::NotAsync => {}
722 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
723 let FnDecl { inputs, output } = decl.deref_mut();
724 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
726 FunctionRetTy::Default(span) => vis.visit_span(span),
727 FunctionRetTy::Ty(ty) => vis.visit_ty(ty),
731 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
733 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
734 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
738 pub fn noop_flat_map_generic_param<T: MutVisitor>(
739 mut param: GenericParam,
741 ) -> SmallVec<[GenericParam; 1]>
743 let GenericParam { id, ident, attrs, bounds, kind, is_placeholder: _ } = &mut param;
745 vis.visit_ident(ident);
746 visit_thin_attrs(attrs, vis);
747 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
749 GenericParamKind::Lifetime => {}
750 GenericParamKind::Type { default } => {
751 visit_opt(default, |default| vis.visit_ty(default));
753 GenericParamKind::Const { ty } => {
760 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
761 vis.visit_ident(ident);
764 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
766 vis.visit_ident(ident);
769 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
770 let Generics { params, where_clause, span } = generics;
771 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
772 vis.visit_where_clause(where_clause);
773 vis.visit_span(span);
776 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
777 let WhereClause { predicates, span } = wc;
778 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
779 vis.visit_span(span);
782 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
784 WherePredicate::BoundPredicate(bp) => {
785 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
786 vis.visit_span(span);
787 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
788 vis.visit_ty(bounded_ty);
789 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
791 WherePredicate::RegionPredicate(rp) => {
792 let WhereRegionPredicate { span, lifetime, bounds } = rp;
793 vis.visit_span(span);
794 noop_visit_lifetime(lifetime, vis);
795 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
797 WherePredicate::EqPredicate(ep) => {
798 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
800 vis.visit_span(span);
801 vis.visit_ty(lhs_ty);
802 vis.visit_ty(rhs_ty);
807 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
809 VariantData::Struct(fields, ..) => {
810 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
812 VariantData::Tuple(fields, id) => {
813 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
816 VariantData::Unit(id) => vis.visit_id(id),
820 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
821 vis.visit_path(path);
822 vis.visit_id(ref_id);
825 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
826 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
827 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
828 vis.visit_trait_ref(trait_ref);
829 vis.visit_span(span);
832 pub fn noop_flat_map_struct_field<T: MutVisitor>(mut sf: StructField, visitor: &mut T)
833 -> SmallVec<[StructField; 1]>
835 let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
836 visitor.visit_span(span);
837 visit_opt(ident, |ident| visitor.visit_ident(ident));
838 visitor.visit_vis(vis);
839 visitor.visit_id(id);
840 visitor.visit_ty(ty);
841 visit_attrs(attrs, visitor);
845 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
846 let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
847 vis.visit_ident(ident);
848 vis.visit_expr(expr);
850 vis.visit_span(span);
851 visit_thin_attrs(attrs, vis);
855 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
859 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
860 let Block { id, stmts, rules: _, span } = block.deref_mut();
862 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
863 vis.visit_span(span);
866 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
868 ItemKind::ExternCrate(_orig_name) => {}
869 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
870 ItemKind::Static(ty, _mut, expr) => {
872 vis.visit_expr(expr);
874 ItemKind::Const(ty, expr) => {
876 vis.visit_expr(expr);
878 ItemKind::Fn(sig, generics, body) => {
879 visit_fn_sig(sig, vis);
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::Enum(EnumDef { variants }, generics) => {
891 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
892 vis.visit_generics(generics);
894 ItemKind::Struct(variant_data, generics) |
895 ItemKind::Union(variant_data, generics) => {
896 vis.visit_variant_data(variant_data);
897 vis.visit_generics(generics);
899 ItemKind::Impl(_unsafety, _polarity, _defaultness, generics, trait_ref, ty, items) => {
900 vis.visit_generics(generics);
901 visit_opt(trait_ref, |trait_ref| vis.visit_trait_ref(trait_ref));
903 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
905 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
906 vis.visit_generics(generics);
907 visit_bounds(bounds, vis);
908 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
910 ItemKind::TraitAlias(generics, bounds) => {
911 vis.visit_generics(generics);
912 visit_bounds(bounds, vis);
914 ItemKind::Mac(m) => vis.visit_mac(m),
915 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
919 pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, vis: &mut T)
920 -> SmallVec<[TraitItem; 1]>
922 let TraitItem { id, ident, attrs, generics, kind, span, tokens: _ } = &mut item;
924 vis.visit_ident(ident);
925 visit_attrs(attrs, vis);
926 vis.visit_generics(generics);
928 TraitItemKind::Const(ty, default) => {
930 visit_opt(default, |default| vis.visit_expr(default));
932 TraitItemKind::Method(sig, body) => {
933 visit_fn_sig(sig, vis);
934 visit_opt(body, |body| vis.visit_block(body));
936 TraitItemKind::Type(bounds, default) => {
937 visit_bounds(bounds, vis);
938 visit_opt(default, |default| vis.visit_ty(default));
940 TraitItemKind::Macro(mac) => {
944 vis.visit_span(span);
949 pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut T)
950 -> SmallVec<[ImplItem; 1]>
952 let ImplItem { id, ident, vis, defaultness: _, attrs, generics, kind, span, tokens: _ } =
954 visitor.visit_id(id);
955 visitor.visit_ident(ident);
956 visitor.visit_vis(vis);
957 visit_attrs(attrs, visitor);
958 visitor.visit_generics(generics);
960 ImplItemKind::Const(ty, expr) => {
961 visitor.visit_ty(ty);
962 visitor.visit_expr(expr);
964 ImplItemKind::Method(sig, body) => {
965 visit_fn_sig(sig, visitor);
966 visitor.visit_block(body);
968 ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
969 ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
971 visitor.visit_span(span);
976 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
977 let FnHeader { unsafety: _, asyncness, constness: _, ext: _ } = header;
978 vis.visit_asyncness(&mut asyncness.node);
981 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
982 vis.visit_span(inner);
983 items.flat_map_in_place(|item| vis.flat_map_item(item));
986 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
987 visit_clobber(krate, |Crate { module, attrs, span }| {
989 ident: Ident::invalid(),
992 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
994 kind: ItemKind::Mod(module),
997 let items = vis.flat_map_item(item);
999 let len = items.len();
1001 let module = Mod { inner: span, items: vec![], inline: true };
1002 Crate { module, attrs: vec![], span }
1003 } else if len == 1 {
1004 let Item { attrs, span, kind, .. } = items.into_iter().next().unwrap().into_inner();
1006 ItemKind::Mod(module) => Crate { module, attrs, span },
1007 _ => panic!("visitor converted a module to not a module"),
1010 panic!("a crate cannot expand to more than one item");
1015 // Mutates one item into possibly many items.
1016 pub fn noop_flat_map_item<T: MutVisitor>(mut item: P<Item>, visitor: &mut T)
1017 -> SmallVec<[P<Item>; 1]> {
1018 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1019 visitor.visit_ident(ident);
1020 visit_attrs(attrs, visitor);
1021 visitor.visit_id(id);
1022 visitor.visit_item_kind(kind);
1023 visitor.visit_vis(vis);
1024 visitor.visit_span(span);
1026 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1027 // an ICE during resolve... odd!
1032 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
1033 -> SmallVec<[ForeignItem; 1]>
1035 let ForeignItem { ident, attrs, kind, id, span, vis } = &mut item;
1036 visitor.visit_ident(ident);
1037 visit_attrs(attrs, visitor);
1039 ForeignItemKind::Fn(fdec, generics) => {
1040 visitor.visit_fn_decl(fdec);
1041 visitor.visit_generics(generics);
1043 ForeignItemKind::Static(t, _m) => visitor.visit_ty(t),
1044 ForeignItemKind::Ty => {}
1045 ForeignItemKind::Macro(mac) => visitor.visit_mac(mac),
1047 visitor.visit_id(id);
1048 visitor.visit_span(span);
1049 visitor.visit_vis(vis);
1054 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1055 let Pat { id, kind, span } = pat.deref_mut();
1058 PatKind::Wild | PatKind::Rest => {}
1059 PatKind::Ident(_binding_mode, ident, sub) => {
1060 vis.visit_ident(ident);
1061 visit_opt(sub, |sub| vis.visit_pat(sub));
1063 PatKind::Lit(e) => vis.visit_expr(e),
1064 PatKind::TupleStruct(path, elems) => {
1065 vis.visit_path(path);
1066 visit_vec(elems, |elem| vis.visit_pat(elem));
1068 PatKind::Path(qself, path) => {
1069 vis.visit_qself(qself);
1070 vis.visit_path(path);
1072 PatKind::Struct(path, fields, _etc) => {
1073 vis.visit_path(path);
1074 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1076 PatKind::Box(inner) => vis.visit_pat(inner),
1077 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1078 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1081 vis.visit_span(span);
1083 PatKind::Tuple(elems)
1084 | PatKind::Slice(elems)
1085 | PatKind::Or(elems) => visit_vec(elems, |elem| vis.visit_pat(elem)),
1086 PatKind::Paren(inner) => vis.visit_pat(inner),
1087 PatKind::Mac(mac) => vis.visit_mac(mac),
1089 vis.visit_span(span);
1092 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1094 vis.visit_expr(value);
1097 pub fn noop_visit_expr<T: MutVisitor>(Expr { kind, id, span, attrs }: &mut Expr, vis: &mut T) {
1099 ExprKind::Box(expr) => vis.visit_expr(expr),
1100 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1101 ExprKind::Repeat(expr, count) => {
1102 vis.visit_expr(expr);
1103 vis.visit_anon_const(count);
1105 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1106 ExprKind::Call(f, args) => {
1108 visit_exprs(args, vis);
1110 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
1111 vis.visit_ident(ident);
1113 visit_opt(args, |args| vis.visit_generic_args(args));
1114 visit_exprs(exprs, vis);
1116 ExprKind::Binary(_binop, lhs, rhs) => {
1117 vis.visit_expr(lhs);
1118 vis.visit_expr(rhs);
1120 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1121 ExprKind::Cast(expr, ty) => {
1122 vis.visit_expr(expr);
1125 ExprKind::Type(expr, ty) => {
1126 vis.visit_expr(expr);
1129 ExprKind::AddrOf(_m, ohs) => vis.visit_expr(ohs),
1130 ExprKind::Let(pat, scrutinee) => {
1132 vis.visit_expr(scrutinee);
1134 ExprKind::If(cond, tr, fl) => {
1135 vis.visit_expr(cond);
1136 vis.visit_block(tr);
1137 visit_opt(fl, |fl| vis.visit_expr(fl));
1139 ExprKind::While(cond, body, label) => {
1140 vis.visit_expr(cond);
1141 vis.visit_block(body);
1142 visit_opt(label, |label| vis.visit_label(label));
1144 ExprKind::ForLoop(pat, iter, body, label) => {
1146 vis.visit_expr(iter);
1147 vis.visit_block(body);
1148 visit_opt(label, |label| vis.visit_label(label));
1150 ExprKind::Loop(body, label) => {
1151 vis.visit_block(body);
1152 visit_opt(label, |label| vis.visit_label(label));
1154 ExprKind::Match(expr, arms) => {
1155 vis.visit_expr(expr);
1156 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1158 ExprKind::Closure(_capture_by, asyncness, _movability, decl, body, span) => {
1159 vis.visit_asyncness(asyncness);
1160 vis.visit_fn_decl(decl);
1161 vis.visit_expr(body);
1162 vis.visit_span(span);
1164 ExprKind::Block(blk, label) => {
1165 vis.visit_block(blk);
1166 visit_opt(label, |label| vis.visit_label(label));
1168 ExprKind::Async(_capture_by, node_id, body) => {
1169 vis.visit_id(node_id);
1170 vis.visit_block(body);
1172 ExprKind::Await(expr) => vis.visit_expr(expr),
1173 ExprKind::Assign(el, er) => {
1177 ExprKind::AssignOp(_op, el, er) => {
1181 ExprKind::Field(el, ident) => {
1183 vis.visit_ident(ident);
1185 ExprKind::Index(el, er) => {
1189 ExprKind::Range(e1, e2, _lim) => {
1190 visit_opt(e1, |e1| vis.visit_expr(e1));
1191 visit_opt(e2, |e2| vis.visit_expr(e2));
1193 ExprKind::Path(qself, path) => {
1194 vis.visit_qself(qself);
1195 vis.visit_path(path);
1197 ExprKind::Break(label, expr) => {
1198 visit_opt(label, |label| vis.visit_label(label));
1199 visit_opt(expr, |expr| vis.visit_expr(expr));
1201 ExprKind::Continue(label) => {
1202 visit_opt(label, |label| vis.visit_label(label));
1204 ExprKind::Ret(expr) => {
1205 visit_opt(expr, |expr| vis.visit_expr(expr));
1207 ExprKind::InlineAsm(asm) => {
1208 let InlineAsm { asm: _, asm_str_style: _, outputs, inputs, clobbers: _, volatile: _,
1209 alignstack: _, dialect: _ } = asm.deref_mut();
1210 for out in outputs {
1211 let InlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1212 vis.visit_expr(expr);
1214 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1216 ExprKind::Mac(mac) => vis.visit_mac(mac),
1217 ExprKind::Struct(path, fields, expr) => {
1218 vis.visit_path(path);
1219 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1220 visit_opt(expr, |expr| vis.visit_expr(expr));
1222 ExprKind::Paren(expr) => {
1223 vis.visit_expr(expr);
1225 // Nodes that are equal modulo `Paren` sugar no-ops should have the same IDs.
1227 vis.visit_span(span);
1228 visit_thin_attrs(attrs, vis);
1231 ExprKind::Yield(expr) => {
1232 visit_opt(expr, |expr| vis.visit_expr(expr));
1234 ExprKind::Try(expr) => vis.visit_expr(expr),
1235 ExprKind::TryBlock(body) => vis.visit_block(body),
1236 ExprKind::Lit(_) | ExprKind::Err => {}
1239 vis.visit_span(span);
1240 visit_thin_attrs(attrs, vis);
1243 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1244 Some({ vis.visit_expr(&mut e); e })
1247 pub fn noop_flat_map_stmt<T: MutVisitor>(Stmt { kind, mut span, mut id }: Stmt, vis: &mut T)
1248 -> SmallVec<[Stmt; 1]>
1250 vis.visit_id(&mut id);
1251 vis.visit_span(&mut span);
1252 noop_flat_map_stmt_kind(kind, vis).into_iter().map(|kind| {
1253 Stmt { id, kind, span }
1257 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(kind: StmtKind, vis: &mut T)
1258 -> SmallVec<[StmtKind; 1]> {
1260 StmtKind::Local(mut local) =>
1261 smallvec![StmtKind::Local({ vis.visit_local(&mut local); local })],
1262 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1263 StmtKind::Expr(expr) => {
1264 vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect()
1266 StmtKind::Semi(expr) => {
1267 vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect()
1269 StmtKind::Mac(mut mac) => {
1270 let (mac_, _semi, attrs) = mac.deref_mut();
1271 vis.visit_mac(mac_);
1272 visit_thin_attrs(attrs, vis);
1273 smallvec![StmtKind::Mac(mac)]
1278 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1280 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1281 VisibilityKind::Restricted { path, id } => {
1282 vis.visit_path(path);
1286 vis.visit_span(span);