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[rust.git] / compiler / rustc_hir_pretty / src / lib.rs
1 #![recursion_limit = "256"]
2
3 use rustc_ast as ast;
4 use rustc_ast::util::parser::{self, AssocOp, Fixity};
5 use rustc_ast_pretty::pp::Breaks::{Consistent, Inconsistent};
6 use rustc_ast_pretty::pp::{self, Breaks};
7 use rustc_ast_pretty::pprust::{Comments, PrintState};
8 use rustc_hir as hir;
9 use rustc_hir::{GenericArg, GenericParam, GenericParamKind, Node};
10 use rustc_hir::{GenericBound, PatKind, RangeEnd, TraitBoundModifier};
11 use rustc_span::source_map::{SourceMap, Spanned};
12 use rustc_span::symbol::{kw, Ident, IdentPrinter, Symbol};
13 use rustc_span::{self, BytePos, FileName};
14 use rustc_target::spec::abi::Abi;
15
16 use std::borrow::Cow;
17 use std::cell::Cell;
18 use std::collections::BTreeMap;
19 use std::vec;
20
21 pub fn id_to_string(map: &dyn rustc_hir::intravisit::Map<'_>, hir_id: hir::HirId) -> String {
22     to_string(&map, |s| s.print_node(map.find(hir_id).unwrap()))
23 }
24
25 pub enum AnnNode<'a> {
26     Name(&'a Symbol),
27     Block(&'a hir::Block<'a>),
28     Item(&'a hir::Item<'a>),
29     SubItem(hir::HirId),
30     Expr(&'a hir::Expr<'a>),
31     Pat(&'a hir::Pat<'a>),
32     Arm(&'a hir::Arm<'a>),
33 }
34
35 pub enum Nested {
36     Item(hir::ItemId),
37     TraitItem(hir::TraitItemId),
38     ImplItem(hir::ImplItemId),
39     ForeignItem(hir::ForeignItemId),
40     Body(hir::BodyId),
41     BodyParamPat(hir::BodyId, usize),
42 }
43
44 pub trait PpAnn {
45     fn nested(&self, _state: &mut State<'_>, _nested: Nested) {}
46     fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
47     fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) {}
48 }
49
50 pub struct NoAnn;
51 impl PpAnn for NoAnn {}
52 pub const NO_ANN: &dyn PpAnn = &NoAnn;
53
54 impl PpAnn for hir::Crate<'_> {
55     fn nested(&self, state: &mut State<'_>, nested: Nested) {
56         match nested {
57             Nested::Item(id) => state.print_item(self.item(id)),
58             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
59             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
60             Nested::ForeignItem(id) => state.print_foreign_item(self.foreign_item(id)),
61             Nested::Body(id) => state.print_expr(&self.body(id).value),
62             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
63         }
64     }
65 }
66
67 /// Identical to the `PpAnn` implementation for `hir::Crate`,
68 /// except it avoids creating a dependency on the whole crate.
69 impl PpAnn for &dyn rustc_hir::intravisit::Map<'_> {
70     fn nested(&self, state: &mut State<'_>, nested: Nested) {
71         match nested {
72             Nested::Item(id) => state.print_item(self.item(id)),
73             Nested::TraitItem(id) => state.print_trait_item(self.trait_item(id)),
74             Nested::ImplItem(id) => state.print_impl_item(self.impl_item(id)),
75             Nested::ForeignItem(id) => state.print_foreign_item(self.foreign_item(id)),
76             Nested::Body(id) => state.print_expr(&self.body(id).value),
77             Nested::BodyParamPat(id, i) => state.print_pat(&self.body(id).params[i].pat),
78         }
79     }
80 }
81
82 pub struct State<'a> {
83     pub s: pp::Printer,
84     comments: Option<Comments<'a>>,
85     attrs: &'a BTreeMap<hir::HirId, &'a [ast::Attribute]>,
86     ann: &'a (dyn PpAnn + 'a),
87 }
88
89 impl<'a> State<'a> {
90     pub fn print_node(&mut self, node: Node<'_>) {
91         match node {
92             Node::Param(a) => self.print_param(&a),
93             Node::Item(a) => self.print_item(&a),
94             Node::ForeignItem(a) => self.print_foreign_item(&a),
95             Node::TraitItem(a) => self.print_trait_item(a),
96             Node::ImplItem(a) => self.print_impl_item(a),
97             Node::Variant(a) => self.print_variant(&a),
98             Node::AnonConst(a) => self.print_anon_const(&a),
99             Node::Expr(a) => self.print_expr(&a),
100             Node::Stmt(a) => self.print_stmt(&a),
101             Node::PathSegment(a) => self.print_path_segment(&a),
102             Node::Ty(a) => self.print_type(&a),
103             Node::TraitRef(a) => self.print_trait_ref(&a),
104             Node::Binding(a) | Node::Pat(a) => self.print_pat(&a),
105             Node::Arm(a) => self.print_arm(&a),
106             Node::Block(a) => {
107                 // Containing cbox, will be closed by print-block at `}`.
108                 self.cbox(INDENT_UNIT);
109                 // Head-ibox, will be closed by print-block after `{`.
110                 self.ibox(0);
111                 self.print_block(&a)
112             }
113             Node::Lifetime(a) => self.print_lifetime(&a),
114             Node::Visibility(a) => self.print_visibility(&a),
115             Node::GenericParam(_) => panic!("cannot print Node::GenericParam"),
116             Node::Field(_) => panic!("cannot print Node::Field"),
117             // These cases do not carry enough information in the
118             // `hir_map` to reconstruct their full structure for pretty
119             // printing.
120             Node::Ctor(..) => panic!("cannot print isolated Ctor"),
121             Node::Local(a) => self.print_local_decl(&a),
122             Node::MacroDef(_) => panic!("cannot print MacroDef"),
123             Node::Crate(..) => panic!("cannot print Crate"),
124         }
125     }
126 }
127
128 impl std::ops::Deref for State<'_> {
129     type Target = pp::Printer;
130     fn deref(&self) -> &Self::Target {
131         &self.s
132     }
133 }
134
135 impl std::ops::DerefMut for State<'_> {
136     fn deref_mut(&mut self) -> &mut Self::Target {
137         &mut self.s
138     }
139 }
140
141 impl<'a> PrintState<'a> for State<'a> {
142     fn comments(&mut self) -> &mut Option<Comments<'a>> {
143         &mut self.comments
144     }
145
146     fn print_ident(&mut self, ident: Ident) {
147         self.s.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
148         self.ann.post(self, AnnNode::Name(&ident.name))
149     }
150
151     fn print_generic_args(&mut self, _: &ast::GenericArgs, _colons_before_params: bool) {
152         panic!("AST generic args printed by HIR pretty-printer");
153     }
154 }
155
156 pub const INDENT_UNIT: usize = 4;
157
158 /// Requires you to pass an input filename and reader so that
159 /// it can scan the input text for comments to copy forward.
160 pub fn print_crate<'a>(
161     sm: &'a SourceMap,
162     krate: &hir::Crate<'_>,
163     filename: FileName,
164     input: String,
165     ann: &'a dyn PpAnn,
166 ) -> String {
167     let mut s = State::new_from_input(sm, filename, input, &krate.attrs, ann);
168
169     // When printing the AST, we sometimes need to inject `#[no_std]` here.
170     // Since you can't compile the HIR, it's not necessary.
171
172     s.print_mod(&krate.item, s.attrs(hir::CRATE_HIR_ID));
173     s.print_remaining_comments();
174     s.s.eof()
175 }
176
177 impl<'a> State<'a> {
178     pub fn new_from_input(
179         sm: &'a SourceMap,
180         filename: FileName,
181         input: String,
182         attrs: &'a BTreeMap<hir::HirId, &[ast::Attribute]>,
183         ann: &'a dyn PpAnn,
184     ) -> State<'a> {
185         State {
186             s: pp::mk_printer(),
187             comments: Some(Comments::new(sm, filename, input)),
188             attrs,
189             ann,
190         }
191     }
192
193     fn attrs(&self, id: hir::HirId) -> &'a [ast::Attribute] {
194         self.attrs.get(&id).map_or(&[], |la| *la)
195     }
196 }
197
198 pub fn to_string<F>(ann: &dyn PpAnn, f: F) -> String
199 where
200     F: FnOnce(&mut State<'_>),
201 {
202     let mut printer =
203         State { s: pp::mk_printer(), comments: None, attrs: &BTreeMap::default(), ann };
204     f(&mut printer);
205     printer.s.eof()
206 }
207
208 pub fn visibility_qualified<S: Into<Cow<'static, str>>>(vis: &hir::Visibility<'_>, w: S) -> String {
209     to_string(NO_ANN, |s| {
210         s.print_visibility(vis);
211         s.s.word(w)
212     })
213 }
214
215 pub fn generic_params_to_string(generic_params: &[GenericParam<'_>]) -> String {
216     to_string(NO_ANN, |s| s.print_generic_params(generic_params))
217 }
218
219 pub fn bounds_to_string<'b>(bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>) -> String {
220     to_string(NO_ANN, |s| s.print_bounds("", bounds))
221 }
222
223 pub fn ty_to_string(ty: &hir::Ty<'_>) -> String {
224     to_string(NO_ANN, |s| s.print_type(ty))
225 }
226
227 pub fn path_segment_to_string(segment: &hir::PathSegment<'_>) -> String {
228     to_string(NO_ANN, |s| s.print_path_segment(segment))
229 }
230
231 pub fn path_to_string(segment: &hir::Path<'_>) -> String {
232     to_string(NO_ANN, |s| s.print_path(segment, false))
233 }
234
235 pub fn fn_to_string(
236     decl: &hir::FnDecl<'_>,
237     header: hir::FnHeader,
238     name: Option<Symbol>,
239     generics: &hir::Generics<'_>,
240     vis: &hir::Visibility<'_>,
241     arg_names: &[Ident],
242     body_id: Option<hir::BodyId>,
243 ) -> String {
244     to_string(NO_ANN, |s| s.print_fn(decl, header, name, generics, vis, arg_names, body_id))
245 }
246
247 pub fn enum_def_to_string(
248     enum_definition: &hir::EnumDef<'_>,
249     generics: &hir::Generics<'_>,
250     name: Symbol,
251     span: rustc_span::Span,
252     visibility: &hir::Visibility<'_>,
253 ) -> String {
254     to_string(NO_ANN, |s| s.print_enum_def(enum_definition, generics, name, span, visibility))
255 }
256
257 impl<'a> State<'a> {
258     pub fn cbox(&mut self, u: usize) {
259         self.s.cbox(u);
260     }
261
262     pub fn nbsp(&mut self) {
263         self.s.word(" ")
264     }
265
266     pub fn word_nbsp<S: Into<Cow<'static, str>>>(&mut self, w: S) {
267         self.s.word(w);
268         self.nbsp()
269     }
270
271     pub fn head<S: Into<Cow<'static, str>>>(&mut self, w: S) {
272         let w = w.into();
273         // outer-box is consistent
274         self.cbox(INDENT_UNIT);
275         // head-box is inconsistent
276         self.ibox(w.len() + 1);
277         // keyword that starts the head
278         if !w.is_empty() {
279             self.word_nbsp(w);
280         }
281     }
282
283     pub fn bopen(&mut self) {
284         self.s.word("{");
285         self.end(); // close the head-box
286     }
287
288     pub fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
289         self.maybe_print_comment(span.hi());
290         self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
291         self.s.word("}");
292         if close_box {
293             self.end(); // close the outer-box
294         }
295     }
296
297     pub fn bclose(&mut self, span: rustc_span::Span) {
298         self.bclose_maybe_open(span, true)
299     }
300
301     pub fn space_if_not_bol(&mut self) {
302         if !self.s.is_beginning_of_line() {
303             self.s.space();
304         }
305     }
306
307     pub fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
308         if !self.s.is_beginning_of_line() {
309             self.s.break_offset(n, off)
310         } else if off != 0 && self.s.last_token().is_hardbreak_tok() {
311             // We do something pretty sketchy here: tuck the nonzero
312             // offset-adjustment we were going to deposit along with the
313             // break into the previous hardbreak.
314             self.s.replace_last_token(pp::Printer::hardbreak_tok_offset(off));
315         }
316     }
317
318     // Synthesizes a comment that was not textually present in the original source
319     // file.
320     pub fn synth_comment(&mut self, text: String) {
321         self.s.word("/*");
322         self.s.space();
323         self.s.word(text);
324         self.s.space();
325         self.s.word("*/")
326     }
327
328     pub fn commasep_cmnt<T, F, G>(&mut self, b: Breaks, elts: &[T], mut op: F, mut get_span: G)
329     where
330         F: FnMut(&mut State<'_>, &T),
331         G: FnMut(&T) -> rustc_span::Span,
332     {
333         self.rbox(0, b);
334         let len = elts.len();
335         let mut i = 0;
336         for elt in elts {
337             self.maybe_print_comment(get_span(elt).hi());
338             op(self, elt);
339             i += 1;
340             if i < len {
341                 self.s.word(",");
342                 self.maybe_print_trailing_comment(get_span(elt), Some(get_span(&elts[i]).hi()));
343                 self.space_if_not_bol();
344             }
345         }
346         self.end();
347     }
348
349     pub fn commasep_exprs(&mut self, b: Breaks, exprs: &[hir::Expr<'_>]) {
350         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(&e), |e| e.span)
351     }
352
353     pub fn print_mod(&mut self, _mod: &hir::Mod<'_>, attrs: &[ast::Attribute]) {
354         self.print_inner_attributes(attrs);
355         for &item_id in _mod.item_ids {
356             self.ann.nested(self, Nested::Item(item_id));
357         }
358     }
359
360     pub fn print_opt_lifetime(&mut self, lifetime: &hir::Lifetime) {
361         if !lifetime.is_elided() {
362             self.print_lifetime(lifetime);
363             self.nbsp();
364         }
365     }
366
367     pub fn print_type(&mut self, ty: &hir::Ty<'_>) {
368         self.maybe_print_comment(ty.span.lo());
369         self.ibox(0);
370         match ty.kind {
371             hir::TyKind::Slice(ref ty) => {
372                 self.s.word("[");
373                 self.print_type(&ty);
374                 self.s.word("]");
375             }
376             hir::TyKind::Ptr(ref mt) => {
377                 self.s.word("*");
378                 self.print_mt(mt, true);
379             }
380             hir::TyKind::Rptr(ref lifetime, ref mt) => {
381                 self.s.word("&");
382                 self.print_opt_lifetime(lifetime);
383                 self.print_mt(mt, false);
384             }
385             hir::TyKind::Never => {
386                 self.s.word("!");
387             }
388             hir::TyKind::Tup(ref elts) => {
389                 self.popen();
390                 self.commasep(Inconsistent, &elts[..], |s, ty| s.print_type(&ty));
391                 if elts.len() == 1 {
392                     self.s.word(",");
393                 }
394                 self.pclose();
395             }
396             hir::TyKind::BareFn(ref f) => {
397                 self.print_ty_fn(
398                     f.abi,
399                     f.unsafety,
400                     &f.decl,
401                     None,
402                     &f.generic_params,
403                     f.param_names,
404                 );
405             }
406             hir::TyKind::OpaqueDef(..) => self.s.word("/*impl Trait*/"),
407             hir::TyKind::Path(ref qpath) => self.print_qpath(qpath, false),
408             hir::TyKind::TraitObject(bounds, ref lifetime, syntax) => {
409                 if syntax == ast::TraitObjectSyntax::Dyn {
410                     self.word_space("dyn");
411                 }
412                 let mut first = true;
413                 for bound in bounds {
414                     if first {
415                         first = false;
416                     } else {
417                         self.nbsp();
418                         self.word_space("+");
419                     }
420                     self.print_poly_trait_ref(bound);
421                 }
422                 if !lifetime.is_elided() {
423                     self.nbsp();
424                     self.word_space("+");
425                     self.print_lifetime(lifetime);
426                 }
427             }
428             hir::TyKind::Array(ref ty, ref length) => {
429                 self.s.word("[");
430                 self.print_type(&ty);
431                 self.s.word("; ");
432                 self.print_anon_const(length);
433                 self.s.word("]");
434             }
435             hir::TyKind::Typeof(ref e) => {
436                 self.s.word("typeof(");
437                 self.print_anon_const(e);
438                 self.s.word(")");
439             }
440             hir::TyKind::Infer => {
441                 self.s.word("_");
442             }
443             hir::TyKind::Err => {
444                 self.popen();
445                 self.s.word("/*ERROR*/");
446                 self.pclose();
447             }
448         }
449         self.end()
450     }
451
452     pub fn print_foreign_item(&mut self, item: &hir::ForeignItem<'_>) {
453         self.hardbreak_if_not_bol();
454         self.maybe_print_comment(item.span.lo());
455         self.print_outer_attributes(self.attrs(item.hir_id()));
456         match item.kind {
457             hir::ForeignItemKind::Fn(ref decl, ref arg_names, ref generics) => {
458                 self.head("");
459                 self.print_fn(
460                     decl,
461                     hir::FnHeader {
462                         unsafety: hir::Unsafety::Normal,
463                         constness: hir::Constness::NotConst,
464                         abi: Abi::Rust,
465                         asyncness: hir::IsAsync::NotAsync,
466                     },
467                     Some(item.ident.name),
468                     generics,
469                     &item.vis,
470                     arg_names,
471                     None,
472                 );
473                 self.end(); // end head-ibox
474                 self.s.word(";");
475                 self.end() // end the outer fn box
476             }
477             hir::ForeignItemKind::Static(ref t, m) => {
478                 self.head(visibility_qualified(&item.vis, "static"));
479                 if m == hir::Mutability::Mut {
480                     self.word_space("mut");
481                 }
482                 self.print_ident(item.ident);
483                 self.word_space(":");
484                 self.print_type(&t);
485                 self.s.word(";");
486                 self.end(); // end the head-ibox
487                 self.end() // end the outer cbox
488             }
489             hir::ForeignItemKind::Type => {
490                 self.head(visibility_qualified(&item.vis, "type"));
491                 self.print_ident(item.ident);
492                 self.s.word(";");
493                 self.end(); // end the head-ibox
494                 self.end() // end the outer cbox
495             }
496         }
497     }
498
499     fn print_associated_const(
500         &mut self,
501         ident: Ident,
502         ty: &hir::Ty<'_>,
503         default: Option<hir::BodyId>,
504         vis: &hir::Visibility<'_>,
505     ) {
506         self.s.word(visibility_qualified(vis, ""));
507         self.word_space("const");
508         self.print_ident(ident);
509         self.word_space(":");
510         self.print_type(ty);
511         if let Some(expr) = default {
512             self.s.space();
513             self.word_space("=");
514             self.ann.nested(self, Nested::Body(expr));
515         }
516         self.s.word(";")
517     }
518
519     fn print_associated_type(
520         &mut self,
521         ident: Ident,
522         generics: &hir::Generics<'_>,
523         bounds: Option<hir::GenericBounds<'_>>,
524         ty: Option<&hir::Ty<'_>>,
525     ) {
526         self.word_space("type");
527         self.print_ident(ident);
528         self.print_generic_params(&generics.params);
529         if let Some(bounds) = bounds {
530             self.print_bounds(":", bounds);
531         }
532         self.print_where_clause(&generics.where_clause);
533         if let Some(ty) = ty {
534             self.s.space();
535             self.word_space("=");
536             self.print_type(ty);
537         }
538         self.s.word(";")
539     }
540
541     fn print_item_type(
542         &mut self,
543         item: &hir::Item<'_>,
544         generics: &hir::Generics<'_>,
545         inner: impl Fn(&mut Self),
546     ) {
547         self.head(visibility_qualified(&item.vis, "type"));
548         self.print_ident(item.ident);
549         self.print_generic_params(&generics.params);
550         self.end(); // end the inner ibox
551
552         self.print_where_clause(&generics.where_clause);
553         self.s.space();
554         inner(self);
555         self.s.word(";");
556         self.end(); // end the outer ibox
557     }
558
559     /// Pretty-print an item
560     pub fn print_item(&mut self, item: &hir::Item<'_>) {
561         self.hardbreak_if_not_bol();
562         self.maybe_print_comment(item.span.lo());
563         let attrs = self.attrs(item.hir_id());
564         self.print_outer_attributes(attrs);
565         self.ann.pre(self, AnnNode::Item(item));
566         match item.kind {
567             hir::ItemKind::ExternCrate(orig_name) => {
568                 self.head(visibility_qualified(&item.vis, "extern crate"));
569                 if let Some(orig_name) = orig_name {
570                     self.print_name(orig_name);
571                     self.s.space();
572                     self.s.word("as");
573                     self.s.space();
574                 }
575                 self.print_ident(item.ident);
576                 self.s.word(";");
577                 self.end(); // end inner head-block
578                 self.end(); // end outer head-block
579             }
580             hir::ItemKind::Use(ref path, kind) => {
581                 self.head(visibility_qualified(&item.vis, "use"));
582                 self.print_path(path, false);
583
584                 match kind {
585                     hir::UseKind::Single => {
586                         if path.segments.last().unwrap().ident != item.ident {
587                             self.s.space();
588                             self.word_space("as");
589                             self.print_ident(item.ident);
590                         }
591                         self.s.word(";");
592                     }
593                     hir::UseKind::Glob => self.s.word("::*;"),
594                     hir::UseKind::ListStem => self.s.word("::{};"),
595                 }
596                 self.end(); // end inner head-block
597                 self.end(); // end outer head-block
598             }
599             hir::ItemKind::Static(ref ty, m, expr) => {
600                 self.head(visibility_qualified(&item.vis, "static"));
601                 if m == hir::Mutability::Mut {
602                     self.word_space("mut");
603                 }
604                 self.print_ident(item.ident);
605                 self.word_space(":");
606                 self.print_type(&ty);
607                 self.s.space();
608                 self.end(); // end the head-ibox
609
610                 self.word_space("=");
611                 self.ann.nested(self, Nested::Body(expr));
612                 self.s.word(";");
613                 self.end(); // end the outer cbox
614             }
615             hir::ItemKind::Const(ref ty, expr) => {
616                 self.head(visibility_qualified(&item.vis, "const"));
617                 self.print_ident(item.ident);
618                 self.word_space(":");
619                 self.print_type(&ty);
620                 self.s.space();
621                 self.end(); // end the head-ibox
622
623                 self.word_space("=");
624                 self.ann.nested(self, Nested::Body(expr));
625                 self.s.word(";");
626                 self.end(); // end the outer cbox
627             }
628             hir::ItemKind::Fn(ref sig, ref param_names, body) => {
629                 self.head("");
630                 self.print_fn(
631                     &sig.decl,
632                     sig.header,
633                     Some(item.ident.name),
634                     param_names,
635                     &item.vis,
636                     &[],
637                     Some(body),
638                 );
639                 self.s.word(" ");
640                 self.end(); // need to close a box
641                 self.end(); // need to close a box
642                 self.ann.nested(self, Nested::Body(body));
643             }
644             hir::ItemKind::Mod(ref _mod) => {
645                 self.head(visibility_qualified(&item.vis, "mod"));
646                 self.print_ident(item.ident);
647                 self.nbsp();
648                 self.bopen();
649                 self.print_mod(_mod, attrs);
650                 self.bclose(item.span);
651             }
652             hir::ItemKind::ForeignMod { abi, items } => {
653                 self.head("extern");
654                 self.word_nbsp(abi.to_string());
655                 self.bopen();
656                 self.print_inner_attributes(self.attrs(item.hir_id()));
657                 for item in items {
658                     self.ann.nested(self, Nested::ForeignItem(item.id));
659                 }
660                 self.bclose(item.span);
661             }
662             hir::ItemKind::GlobalAsm(ref asm) => {
663                 self.head(visibility_qualified(&item.vis, "global_asm!"));
664                 self.print_inline_asm(asm);
665                 self.end()
666             }
667             hir::ItemKind::TyAlias(ref ty, ref generics) => {
668                 self.print_item_type(item, &generics, |state| {
669                     state.word_space("=");
670                     state.print_type(&ty);
671                 });
672             }
673             hir::ItemKind::OpaqueTy(ref opaque_ty) => {
674                 self.print_item_type(item, &opaque_ty.generics, |state| {
675                     let mut real_bounds = Vec::with_capacity(opaque_ty.bounds.len());
676                     for b in opaque_ty.bounds.iter() {
677                         if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
678                             state.s.space();
679                             state.word_space("for ?");
680                             state.print_trait_ref(&ptr.trait_ref);
681                         } else {
682                             real_bounds.push(b);
683                         }
684                     }
685                     state.print_bounds("= impl", real_bounds);
686                 });
687             }
688             hir::ItemKind::Enum(ref enum_definition, ref params) => {
689                 self.print_enum_def(enum_definition, params, item.ident.name, item.span, &item.vis);
690             }
691             hir::ItemKind::Struct(ref struct_def, ref generics) => {
692                 self.head(visibility_qualified(&item.vis, "struct"));
693                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
694             }
695             hir::ItemKind::Union(ref struct_def, ref generics) => {
696                 self.head(visibility_qualified(&item.vis, "union"));
697                 self.print_struct(struct_def, generics, item.ident.name, item.span, true);
698             }
699             hir::ItemKind::Impl(hir::Impl {
700                 unsafety,
701                 polarity,
702                 defaultness,
703                 constness,
704                 defaultness_span: _,
705                 ref generics,
706                 ref of_trait,
707                 ref self_ty,
708                 items,
709             }) => {
710                 self.head("");
711                 self.print_visibility(&item.vis);
712                 self.print_defaultness(defaultness);
713                 self.print_unsafety(unsafety);
714                 self.word_nbsp("impl");
715
716                 if !generics.params.is_empty() {
717                     self.print_generic_params(&generics.params);
718                     self.s.space();
719                 }
720
721                 if constness == hir::Constness::Const {
722                     self.word_nbsp("const");
723                 }
724
725                 if let hir::ImplPolarity::Negative(_) = polarity {
726                     self.s.word("!");
727                 }
728
729                 if let Some(ref t) = of_trait {
730                     self.print_trait_ref(t);
731                     self.s.space();
732                     self.word_space("for");
733                 }
734
735                 self.print_type(&self_ty);
736                 self.print_where_clause(&generics.where_clause);
737
738                 self.s.space();
739                 self.bopen();
740                 self.print_inner_attributes(attrs);
741                 for impl_item in items {
742                     self.ann.nested(self, Nested::ImplItem(impl_item.id));
743                 }
744                 self.bclose(item.span);
745             }
746             hir::ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, trait_items) => {
747                 self.head("");
748                 self.print_visibility(&item.vis);
749                 self.print_is_auto(is_auto);
750                 self.print_unsafety(unsafety);
751                 self.word_nbsp("trait");
752                 self.print_ident(item.ident);
753                 self.print_generic_params(&generics.params);
754                 let mut real_bounds = Vec::with_capacity(bounds.len());
755                 for b in bounds.iter() {
756                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
757                         self.s.space();
758                         self.word_space("for ?");
759                         self.print_trait_ref(&ptr.trait_ref);
760                     } else {
761                         real_bounds.push(b);
762                     }
763                 }
764                 self.print_bounds(":", real_bounds);
765                 self.print_where_clause(&generics.where_clause);
766                 self.s.word(" ");
767                 self.bopen();
768                 for trait_item in trait_items {
769                     self.ann.nested(self, Nested::TraitItem(trait_item.id));
770                 }
771                 self.bclose(item.span);
772             }
773             hir::ItemKind::TraitAlias(ref generics, ref bounds) => {
774                 self.head("");
775                 self.print_visibility(&item.vis);
776                 self.word_nbsp("trait");
777                 self.print_ident(item.ident);
778                 self.print_generic_params(&generics.params);
779                 let mut real_bounds = Vec::with_capacity(bounds.len());
780                 // FIXME(durka) this seems to be some quite outdated syntax
781                 for b in bounds.iter() {
782                     if let GenericBound::Trait(ref ptr, hir::TraitBoundModifier::Maybe) = *b {
783                         self.s.space();
784                         self.word_space("for ?");
785                         self.print_trait_ref(&ptr.trait_ref);
786                     } else {
787                         real_bounds.push(b);
788                     }
789                 }
790                 self.nbsp();
791                 self.print_bounds("=", real_bounds);
792                 self.print_where_clause(&generics.where_clause);
793                 self.s.word(";");
794             }
795         }
796         self.ann.post(self, AnnNode::Item(item))
797     }
798
799     pub fn print_trait_ref(&mut self, t: &hir::TraitRef<'_>) {
800         self.print_path(&t.path, false)
801     }
802
803     fn print_formal_generic_params(&mut self, generic_params: &[hir::GenericParam<'_>]) {
804         if !generic_params.is_empty() {
805             self.s.word("for");
806             self.print_generic_params(generic_params);
807             self.nbsp();
808         }
809     }
810
811     fn print_poly_trait_ref(&mut self, t: &hir::PolyTraitRef<'_>) {
812         self.print_formal_generic_params(&t.bound_generic_params);
813         self.print_trait_ref(&t.trait_ref)
814     }
815
816     pub fn print_enum_def(
817         &mut self,
818         enum_definition: &hir::EnumDef<'_>,
819         generics: &hir::Generics<'_>,
820         name: Symbol,
821         span: rustc_span::Span,
822         visibility: &hir::Visibility<'_>,
823     ) {
824         self.head(visibility_qualified(visibility, "enum"));
825         self.print_name(name);
826         self.print_generic_params(&generics.params);
827         self.print_where_clause(&generics.where_clause);
828         self.s.space();
829         self.print_variants(&enum_definition.variants, span)
830     }
831
832     pub fn print_variants(&mut self, variants: &[hir::Variant<'_>], span: rustc_span::Span) {
833         self.bopen();
834         for v in variants {
835             self.space_if_not_bol();
836             self.maybe_print_comment(v.span.lo());
837             self.print_outer_attributes(self.attrs(v.id));
838             self.ibox(INDENT_UNIT);
839             self.print_variant(v);
840             self.s.word(",");
841             self.end();
842             self.maybe_print_trailing_comment(v.span, None);
843         }
844         self.bclose(span)
845     }
846
847     pub fn print_visibility(&mut self, vis: &hir::Visibility<'_>) {
848         match vis.node {
849             hir::VisibilityKind::Public => self.word_nbsp("pub"),
850             hir::VisibilityKind::Crate(ast::CrateSugar::JustCrate) => self.word_nbsp("crate"),
851             hir::VisibilityKind::Crate(ast::CrateSugar::PubCrate) => self.word_nbsp("pub(crate)"),
852             hir::VisibilityKind::Restricted { ref path, .. } => {
853                 self.s.word("pub(");
854                 if path.segments.len() == 1 && path.segments[0].ident.name == kw::Super {
855                     // Special case: `super` can print like `pub(super)`.
856                     self.s.word("super");
857                 } else {
858                     // Everything else requires `in` at present.
859                     self.word_nbsp("in");
860                     self.print_path(path, false);
861                 }
862                 self.word_nbsp(")");
863             }
864             hir::VisibilityKind::Inherited => (),
865         }
866     }
867
868     pub fn print_defaultness(&mut self, defaultness: hir::Defaultness) {
869         match defaultness {
870             hir::Defaultness::Default { .. } => self.word_nbsp("default"),
871             hir::Defaultness::Final => (),
872         }
873     }
874
875     pub fn print_struct(
876         &mut self,
877         struct_def: &hir::VariantData<'_>,
878         generics: &hir::Generics<'_>,
879         name: Symbol,
880         span: rustc_span::Span,
881         print_finalizer: bool,
882     ) {
883         self.print_name(name);
884         self.print_generic_params(&generics.params);
885         match struct_def {
886             hir::VariantData::Tuple(..) | hir::VariantData::Unit(..) => {
887                 if let hir::VariantData::Tuple(..) = struct_def {
888                     self.popen();
889                     self.commasep(Inconsistent, struct_def.fields(), |s, field| {
890                         s.maybe_print_comment(field.span.lo());
891                         s.print_outer_attributes(s.attrs(field.hir_id));
892                         s.print_visibility(&field.vis);
893                         s.print_type(&field.ty)
894                     });
895                     self.pclose();
896                 }
897                 self.print_where_clause(&generics.where_clause);
898                 if print_finalizer {
899                     self.s.word(";");
900                 }
901                 self.end();
902                 self.end() // close the outer-box
903             }
904             hir::VariantData::Struct(..) => {
905                 self.print_where_clause(&generics.where_clause);
906                 self.nbsp();
907                 self.bopen();
908                 self.hardbreak_if_not_bol();
909
910                 for field in struct_def.fields() {
911                     self.hardbreak_if_not_bol();
912                     self.maybe_print_comment(field.span.lo());
913                     self.print_outer_attributes(self.attrs(field.hir_id));
914                     self.print_visibility(&field.vis);
915                     self.print_ident(field.ident);
916                     self.word_nbsp(":");
917                     self.print_type(&field.ty);
918                     self.s.word(",");
919                 }
920
921                 self.bclose(span)
922             }
923         }
924     }
925
926     pub fn print_variant(&mut self, v: &hir::Variant<'_>) {
927         self.head("");
928         let generics = hir::Generics::empty();
929         self.print_struct(&v.data, &generics, v.ident.name, v.span, false);
930         if let Some(ref d) = v.disr_expr {
931             self.s.space();
932             self.word_space("=");
933             self.print_anon_const(d);
934         }
935     }
936     pub fn print_method_sig(
937         &mut self,
938         ident: Ident,
939         m: &hir::FnSig<'_>,
940         generics: &hir::Generics<'_>,
941         vis: &hir::Visibility<'_>,
942         arg_names: &[Ident],
943         body_id: Option<hir::BodyId>,
944     ) {
945         self.print_fn(&m.decl, m.header, Some(ident.name), generics, vis, arg_names, body_id)
946     }
947
948     pub fn print_trait_item(&mut self, ti: &hir::TraitItem<'_>) {
949         self.ann.pre(self, AnnNode::SubItem(ti.hir_id()));
950         self.hardbreak_if_not_bol();
951         self.maybe_print_comment(ti.span.lo());
952         self.print_outer_attributes(self.attrs(ti.hir_id()));
953         match ti.kind {
954             hir::TraitItemKind::Const(ref ty, default) => {
955                 let vis =
956                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
957                 self.print_associated_const(ti.ident, &ty, default, &vis);
958             }
959             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Required(ref arg_names)) => {
960                 let vis =
961                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
962                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, arg_names, None);
963                 self.s.word(";");
964             }
965             hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
966                 let vis =
967                     Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited };
968                 self.head("");
969                 self.print_method_sig(ti.ident, sig, &ti.generics, &vis, &[], Some(body));
970                 self.nbsp();
971                 self.end(); // need to close a box
972                 self.end(); // need to close a box
973                 self.ann.nested(self, Nested::Body(body));
974             }
975             hir::TraitItemKind::Type(ref bounds, ref default) => {
976                 self.print_associated_type(
977                     ti.ident,
978                     &ti.generics,
979                     Some(bounds),
980                     default.as_ref().map(|ty| &**ty),
981                 );
982             }
983         }
984         self.ann.post(self, AnnNode::SubItem(ti.hir_id()))
985     }
986
987     pub fn print_impl_item(&mut self, ii: &hir::ImplItem<'_>) {
988         self.ann.pre(self, AnnNode::SubItem(ii.hir_id()));
989         self.hardbreak_if_not_bol();
990         self.maybe_print_comment(ii.span.lo());
991         self.print_outer_attributes(self.attrs(ii.hir_id()));
992         self.print_defaultness(ii.defaultness);
993
994         match ii.kind {
995             hir::ImplItemKind::Const(ref ty, expr) => {
996                 self.print_associated_const(ii.ident, &ty, Some(expr), &ii.vis);
997             }
998             hir::ImplItemKind::Fn(ref sig, body) => {
999                 self.head("");
1000                 self.print_method_sig(ii.ident, sig, &ii.generics, &ii.vis, &[], Some(body));
1001                 self.nbsp();
1002                 self.end(); // need to close a box
1003                 self.end(); // need to close a box
1004                 self.ann.nested(self, Nested::Body(body));
1005             }
1006             hir::ImplItemKind::TyAlias(ref ty) => {
1007                 self.print_associated_type(ii.ident, &ii.generics, None, Some(ty));
1008             }
1009         }
1010         self.ann.post(self, AnnNode::SubItem(ii.hir_id()))
1011     }
1012
1013     pub fn print_local(&mut self, init: Option<&hir::Expr<'_>>, decl: impl Fn(&mut Self)) {
1014         self.space_if_not_bol();
1015         self.ibox(INDENT_UNIT);
1016         self.word_nbsp("let");
1017
1018         self.ibox(INDENT_UNIT);
1019         decl(self);
1020         self.end();
1021
1022         if let Some(ref init) = init {
1023             self.nbsp();
1024             self.word_space("=");
1025             self.print_expr(&init);
1026         }
1027         self.end()
1028     }
1029
1030     pub fn print_stmt(&mut self, st: &hir::Stmt<'_>) {
1031         self.maybe_print_comment(st.span.lo());
1032         match st.kind {
1033             hir::StmtKind::Local(ref loc) => {
1034                 self.print_local(loc.init.as_deref(), |this| this.print_local_decl(&loc));
1035             }
1036             hir::StmtKind::Item(item) => self.ann.nested(self, Nested::Item(item)),
1037             hir::StmtKind::Expr(ref expr) => {
1038                 self.space_if_not_bol();
1039                 self.print_expr(&expr);
1040             }
1041             hir::StmtKind::Semi(ref expr) => {
1042                 self.space_if_not_bol();
1043                 self.print_expr(&expr);
1044                 self.s.word(";");
1045             }
1046         }
1047         if stmt_ends_with_semi(&st.kind) {
1048             self.s.word(";");
1049         }
1050         self.maybe_print_trailing_comment(st.span, None)
1051     }
1052
1053     pub fn print_block(&mut self, blk: &hir::Block<'_>) {
1054         self.print_block_with_attrs(blk, &[])
1055     }
1056
1057     pub fn print_block_unclosed(&mut self, blk: &hir::Block<'_>) {
1058         self.print_block_maybe_unclosed(blk, &[], false)
1059     }
1060
1061     pub fn print_block_with_attrs(&mut self, blk: &hir::Block<'_>, attrs: &[ast::Attribute]) {
1062         self.print_block_maybe_unclosed(blk, attrs, true)
1063     }
1064
1065     pub fn print_block_maybe_unclosed(
1066         &mut self,
1067         blk: &hir::Block<'_>,
1068         attrs: &[ast::Attribute],
1069         close_box: bool,
1070     ) {
1071         match blk.rules {
1072             hir::BlockCheckMode::UnsafeBlock(..) => self.word_space("unsafe"),
1073             hir::BlockCheckMode::DefaultBlock => (),
1074         }
1075         self.maybe_print_comment(blk.span.lo());
1076         self.ann.pre(self, AnnNode::Block(blk));
1077         self.bopen();
1078
1079         self.print_inner_attributes(attrs);
1080
1081         for st in blk.stmts {
1082             self.print_stmt(st);
1083         }
1084         if let Some(ref expr) = blk.expr {
1085             self.space_if_not_bol();
1086             self.print_expr(&expr);
1087             self.maybe_print_trailing_comment(expr.span, Some(blk.span.hi()));
1088         }
1089         self.bclose_maybe_open(blk.span, close_box);
1090         self.ann.post(self, AnnNode::Block(blk))
1091     }
1092
1093     fn print_else(&mut self, els: Option<&hir::Expr<'_>>) {
1094         match els {
1095             Some(else_) => {
1096                 match else_.kind {
1097                     // "another else-if"
1098                     hir::ExprKind::If(ref i, ref then, ref e) => {
1099                         self.cbox(INDENT_UNIT - 1);
1100                         self.ibox(0);
1101                         self.s.word(" else if ");
1102                         self.print_expr_as_cond(&i);
1103                         self.s.space();
1104                         self.print_expr(&then);
1105                         self.print_else(e.as_ref().map(|e| &**e))
1106                     }
1107                     // "final else"
1108                     hir::ExprKind::Block(ref b, _) => {
1109                         self.cbox(INDENT_UNIT - 1);
1110                         self.ibox(0);
1111                         self.s.word(" else ");
1112                         self.print_block(&b)
1113                     }
1114                     hir::ExprKind::Match(ref expr, arms, _) => {
1115                         // else if let desugared to match
1116                         assert!(arms.len() == 2, "if let desugars to match with two arms");
1117
1118                         self.s.word(" else ");
1119                         self.s.word("{");
1120
1121                         self.cbox(INDENT_UNIT);
1122                         self.ibox(INDENT_UNIT);
1123                         self.word_nbsp("match");
1124                         self.print_expr_as_cond(&expr);
1125                         self.s.space();
1126                         self.bopen();
1127                         for arm in arms {
1128                             self.print_arm(arm);
1129                         }
1130                         self.bclose(expr.span);
1131
1132                         self.s.word("}");
1133                     }
1134                     // BLEAH, constraints would be great here
1135                     _ => {
1136                         panic!("print_if saw if with weird alternative");
1137                     }
1138                 }
1139             }
1140             _ => {}
1141         }
1142     }
1143
1144     pub fn print_if(
1145         &mut self,
1146         test: &hir::Expr<'_>,
1147         blk: &hir::Expr<'_>,
1148         elseopt: Option<&hir::Expr<'_>>,
1149     ) {
1150         self.head("if");
1151         self.print_expr_as_cond(test);
1152         self.s.space();
1153         self.print_expr(blk);
1154         self.print_else(elseopt)
1155     }
1156
1157     pub fn print_anon_const(&mut self, constant: &hir::AnonConst) {
1158         self.ann.nested(self, Nested::Body(constant.body))
1159     }
1160
1161     fn print_call_post(&mut self, args: &[hir::Expr<'_>]) {
1162         self.popen();
1163         self.commasep_exprs(Inconsistent, args);
1164         self.pclose()
1165     }
1166
1167     pub fn print_expr_maybe_paren(&mut self, expr: &hir::Expr<'_>, prec: i8) {
1168         let needs_par = expr.precedence().order() < prec;
1169         if needs_par {
1170             self.popen();
1171         }
1172         self.print_expr(expr);
1173         if needs_par {
1174             self.pclose();
1175         }
1176     }
1177
1178     /// Print an expr using syntax that's acceptable in a condition position, such as the `cond` in
1179     /// `if cond { ... }`.
1180     pub fn print_expr_as_cond(&mut self, expr: &hir::Expr<'_>) {
1181         let needs_par = match expr.kind {
1182             // These cases need parens due to the parse error observed in #26461: `if return {}`
1183             // parses as the erroneous construct `if (return {})`, not `if (return) {}`.
1184             hir::ExprKind::Closure(..) | hir::ExprKind::Ret(..) | hir::ExprKind::Break(..) => true,
1185
1186             _ => contains_exterior_struct_lit(expr),
1187         };
1188
1189         if needs_par {
1190             self.popen();
1191         }
1192         self.print_expr(expr);
1193         if needs_par {
1194             self.pclose();
1195         }
1196     }
1197
1198     fn print_expr_vec(&mut self, exprs: &[hir::Expr<'_>]) {
1199         self.ibox(INDENT_UNIT);
1200         self.s.word("[");
1201         self.commasep_exprs(Inconsistent, exprs);
1202         self.s.word("]");
1203         self.end()
1204     }
1205
1206     fn print_expr_anon_const(&mut self, anon_const: &hir::AnonConst) {
1207         self.ibox(INDENT_UNIT);
1208         self.s.word_space("const");
1209         self.print_anon_const(anon_const);
1210         self.end()
1211     }
1212
1213     fn print_expr_repeat(&mut self, element: &hir::Expr<'_>, count: &hir::AnonConst) {
1214         self.ibox(INDENT_UNIT);
1215         self.s.word("[");
1216         self.print_expr(element);
1217         self.word_space(";");
1218         self.print_anon_const(count);
1219         self.s.word("]");
1220         self.end()
1221     }
1222
1223     fn print_expr_struct(
1224         &mut self,
1225         qpath: &hir::QPath<'_>,
1226         fields: &[hir::ExprField<'_>],
1227         wth: &Option<&hir::Expr<'_>>,
1228     ) {
1229         self.print_qpath(qpath, true);
1230         self.s.word("{");
1231         self.commasep_cmnt(
1232             Consistent,
1233             fields,
1234             |s, field| {
1235                 s.ibox(INDENT_UNIT);
1236                 if !field.is_shorthand {
1237                     s.print_ident(field.ident);
1238                     s.word_space(":");
1239                 }
1240                 s.print_expr(&field.expr);
1241                 s.end()
1242             },
1243             |f| f.span,
1244         );
1245         match *wth {
1246             Some(ref expr) => {
1247                 self.ibox(INDENT_UNIT);
1248                 if !fields.is_empty() {
1249                     self.s.word(",");
1250                     self.s.space();
1251                 }
1252                 self.s.word("..");
1253                 self.print_expr(&expr);
1254                 self.end();
1255             }
1256             _ => {
1257                 if !fields.is_empty() {
1258                     self.s.word(",")
1259                 }
1260             }
1261         }
1262         self.s.word("}");
1263     }
1264
1265     fn print_expr_tup(&mut self, exprs: &[hir::Expr<'_>]) {
1266         self.popen();
1267         self.commasep_exprs(Inconsistent, exprs);
1268         if exprs.len() == 1 {
1269             self.s.word(",");
1270         }
1271         self.pclose()
1272     }
1273
1274     fn print_expr_call(&mut self, func: &hir::Expr<'_>, args: &[hir::Expr<'_>]) {
1275         let prec = match func.kind {
1276             hir::ExprKind::Field(..) => parser::PREC_FORCE_PAREN,
1277             _ => parser::PREC_POSTFIX,
1278         };
1279
1280         self.print_expr_maybe_paren(func, prec);
1281         self.print_call_post(args)
1282     }
1283
1284     fn print_expr_method_call(&mut self, segment: &hir::PathSegment<'_>, args: &[hir::Expr<'_>]) {
1285         let base_args = &args[1..];
1286         self.print_expr_maybe_paren(&args[0], parser::PREC_POSTFIX);
1287         self.s.word(".");
1288         self.print_ident(segment.ident);
1289
1290         let generic_args = segment.args();
1291         if !generic_args.args.is_empty() || !generic_args.bindings.is_empty() {
1292             self.print_generic_args(generic_args, segment.infer_args, true);
1293         }
1294
1295         self.print_call_post(base_args)
1296     }
1297
1298     fn print_expr_binary(&mut self, op: hir::BinOp, lhs: &hir::Expr<'_>, rhs: &hir::Expr<'_>) {
1299         let assoc_op = bin_op_to_assoc_op(op.node);
1300         let prec = assoc_op.precedence() as i8;
1301         let fixity = assoc_op.fixity();
1302
1303         let (left_prec, right_prec) = match fixity {
1304             Fixity::Left => (prec, prec + 1),
1305             Fixity::Right => (prec + 1, prec),
1306             Fixity::None => (prec + 1, prec + 1),
1307         };
1308
1309         let left_prec = match (&lhs.kind, op.node) {
1310             // These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
1311             // the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
1312             // of `(x as i32) < ...`. We need to convince it _not_ to do that.
1313             (&hir::ExprKind::Cast { .. }, hir::BinOpKind::Lt | hir::BinOpKind::Shl) => {
1314                 parser::PREC_FORCE_PAREN
1315             }
1316             _ => left_prec,
1317         };
1318
1319         self.print_expr_maybe_paren(lhs, left_prec);
1320         self.s.space();
1321         self.word_space(op.node.as_str());
1322         self.print_expr_maybe_paren(rhs, right_prec)
1323     }
1324
1325     fn print_expr_unary(&mut self, op: hir::UnOp, expr: &hir::Expr<'_>) {
1326         self.s.word(op.as_str());
1327         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1328     }
1329
1330     fn print_expr_addr_of(
1331         &mut self,
1332         kind: hir::BorrowKind,
1333         mutability: hir::Mutability,
1334         expr: &hir::Expr<'_>,
1335     ) {
1336         self.s.word("&");
1337         match kind {
1338             hir::BorrowKind::Ref => self.print_mutability(mutability, false),
1339             hir::BorrowKind::Raw => {
1340                 self.word_nbsp("raw");
1341                 self.print_mutability(mutability, true);
1342             }
1343         }
1344         self.print_expr_maybe_paren(expr, parser::PREC_PREFIX)
1345     }
1346
1347     fn print_literal(&mut self, lit: &hir::Lit) {
1348         self.maybe_print_comment(lit.span.lo());
1349         self.word(lit.node.to_lit_token().to_string())
1350     }
1351
1352     fn print_inline_asm(&mut self, asm: &hir::InlineAsm<'_>) {
1353         enum AsmArg<'a> {
1354             Template(String),
1355             Operand(&'a hir::InlineAsmOperand<'a>),
1356             Options(ast::InlineAsmOptions),
1357         }
1358
1359         let mut args = vec![];
1360         args.push(AsmArg::Template(ast::InlineAsmTemplatePiece::to_string(&asm.template)));
1361         args.extend(asm.operands.iter().map(|(o, _)| AsmArg::Operand(o)));
1362         if !asm.options.is_empty() {
1363             args.push(AsmArg::Options(asm.options));
1364         }
1365
1366         self.popen();
1367         self.commasep(Consistent, &args, |s, arg| match arg {
1368             AsmArg::Template(template) => s.print_string(&template, ast::StrStyle::Cooked),
1369             AsmArg::Operand(op) => match op {
1370                 hir::InlineAsmOperand::In { reg, expr } => {
1371                     s.word("in");
1372                     s.popen();
1373                     s.word(format!("{}", reg));
1374                     s.pclose();
1375                     s.space();
1376                     s.print_expr(expr);
1377                 }
1378                 hir::InlineAsmOperand::Out { reg, late, expr } => {
1379                     s.word(if *late { "lateout" } else { "out" });
1380                     s.popen();
1381                     s.word(format!("{}", reg));
1382                     s.pclose();
1383                     s.space();
1384                     match expr {
1385                         Some(expr) => s.print_expr(expr),
1386                         None => s.word("_"),
1387                     }
1388                 }
1389                 hir::InlineAsmOperand::InOut { reg, late, expr } => {
1390                     s.word(if *late { "inlateout" } else { "inout" });
1391                     s.popen();
1392                     s.word(format!("{}", reg));
1393                     s.pclose();
1394                     s.space();
1395                     s.print_expr(expr);
1396                 }
1397                 hir::InlineAsmOperand::SplitInOut { reg, late, in_expr, out_expr } => {
1398                     s.word(if *late { "inlateout" } else { "inout" });
1399                     s.popen();
1400                     s.word(format!("{}", reg));
1401                     s.pclose();
1402                     s.space();
1403                     s.print_expr(in_expr);
1404                     s.space();
1405                     s.word_space("=>");
1406                     match out_expr {
1407                         Some(out_expr) => s.print_expr(out_expr),
1408                         None => s.word("_"),
1409                     }
1410                 }
1411                 hir::InlineAsmOperand::Const { anon_const } => {
1412                     s.word("const");
1413                     s.space();
1414                     s.print_anon_const(anon_const);
1415                 }
1416                 hir::InlineAsmOperand::Sym { expr } => {
1417                     s.word("sym");
1418                     s.space();
1419                     s.print_expr(expr);
1420                 }
1421             },
1422             AsmArg::Options(opts) => {
1423                 s.word("options");
1424                 s.popen();
1425                 let mut options = vec![];
1426                 if opts.contains(ast::InlineAsmOptions::PURE) {
1427                     options.push("pure");
1428                 }
1429                 if opts.contains(ast::InlineAsmOptions::NOMEM) {
1430                     options.push("nomem");
1431                 }
1432                 if opts.contains(ast::InlineAsmOptions::READONLY) {
1433                     options.push("readonly");
1434                 }
1435                 if opts.contains(ast::InlineAsmOptions::PRESERVES_FLAGS) {
1436                     options.push("preserves_flags");
1437                 }
1438                 if opts.contains(ast::InlineAsmOptions::NORETURN) {
1439                     options.push("noreturn");
1440                 }
1441                 if opts.contains(ast::InlineAsmOptions::NOSTACK) {
1442                     options.push("nostack");
1443                 }
1444                 if opts.contains(ast::InlineAsmOptions::ATT_SYNTAX) {
1445                     options.push("att_syntax");
1446                 }
1447                 s.commasep(Inconsistent, &options, |s, &opt| {
1448                     s.word(opt);
1449                 });
1450                 s.pclose();
1451             }
1452         });
1453         self.pclose();
1454     }
1455
1456     pub fn print_expr(&mut self, expr: &hir::Expr<'_>) {
1457         self.maybe_print_comment(expr.span.lo());
1458         self.print_outer_attributes(self.attrs(expr.hir_id));
1459         self.ibox(INDENT_UNIT);
1460         self.ann.pre(self, AnnNode::Expr(expr));
1461         match expr.kind {
1462             hir::ExprKind::Box(ref expr) => {
1463                 self.word_space("box");
1464                 self.print_expr_maybe_paren(expr, parser::PREC_PREFIX);
1465             }
1466             hir::ExprKind::Array(ref exprs) => {
1467                 self.print_expr_vec(exprs);
1468             }
1469             hir::ExprKind::ConstBlock(ref anon_const) => {
1470                 self.print_expr_anon_const(anon_const);
1471             }
1472             hir::ExprKind::Repeat(ref element, ref count) => {
1473                 self.print_expr_repeat(&element, count);
1474             }
1475             hir::ExprKind::Struct(ref qpath, fields, ref wth) => {
1476                 self.print_expr_struct(qpath, fields, wth);
1477             }
1478             hir::ExprKind::Tup(ref exprs) => {
1479                 self.print_expr_tup(exprs);
1480             }
1481             hir::ExprKind::Call(ref func, ref args) => {
1482                 self.print_expr_call(&func, args);
1483             }
1484             hir::ExprKind::MethodCall(ref segment, _, ref args, _) => {
1485                 self.print_expr_method_call(segment, args);
1486             }
1487             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
1488                 self.print_expr_binary(op, &lhs, &rhs);
1489             }
1490             hir::ExprKind::Unary(op, ref expr) => {
1491                 self.print_expr_unary(op, &expr);
1492             }
1493             hir::ExprKind::AddrOf(k, m, ref expr) => {
1494                 self.print_expr_addr_of(k, m, &expr);
1495             }
1496             hir::ExprKind::Lit(ref lit) => {
1497                 self.print_literal(&lit);
1498             }
1499             hir::ExprKind::Cast(ref expr, ref ty) => {
1500                 let prec = AssocOp::As.precedence() as i8;
1501                 self.print_expr_maybe_paren(&expr, prec);
1502                 self.s.space();
1503                 self.word_space("as");
1504                 self.print_type(&ty);
1505             }
1506             hir::ExprKind::Type(ref expr, ref ty) => {
1507                 let prec = AssocOp::Colon.precedence() as i8;
1508                 self.print_expr_maybe_paren(&expr, prec);
1509                 self.word_space(":");
1510                 self.print_type(&ty);
1511             }
1512             hir::ExprKind::DropTemps(ref init) => {
1513                 // Print `{`:
1514                 self.cbox(INDENT_UNIT);
1515                 self.ibox(0);
1516                 self.bopen();
1517
1518                 // Print `let _t = $init;`:
1519                 let temp = Ident::from_str("_t");
1520                 self.print_local(Some(init), |this| this.print_ident(temp));
1521                 self.s.word(";");
1522
1523                 // Print `_t`:
1524                 self.space_if_not_bol();
1525                 self.print_ident(temp);
1526
1527                 // Print `}`:
1528                 self.bclose_maybe_open(expr.span, true);
1529             }
1530             hir::ExprKind::If(ref test, ref blk, ref elseopt) => {
1531                 self.print_if(&test, &blk, elseopt.as_ref().map(|e| &**e));
1532             }
1533             hir::ExprKind::Loop(ref blk, opt_label, _, _) => {
1534                 if let Some(label) = opt_label {
1535                     self.print_ident(label.ident);
1536                     self.word_space(":");
1537                 }
1538                 self.head("loop");
1539                 self.s.space();
1540                 self.print_block(&blk);
1541             }
1542             hir::ExprKind::Match(ref expr, arms, _) => {
1543                 self.cbox(INDENT_UNIT);
1544                 self.ibox(INDENT_UNIT);
1545                 self.word_nbsp("match");
1546                 self.print_expr_as_cond(&expr);
1547                 self.s.space();
1548                 self.bopen();
1549                 for arm in arms {
1550                     self.print_arm(arm);
1551                 }
1552                 self.bclose(expr.span);
1553             }
1554             hir::ExprKind::Closure(capture_clause, ref decl, body, _fn_decl_span, _gen) => {
1555                 self.print_capture_clause(capture_clause);
1556
1557                 self.print_closure_params(&decl, body);
1558                 self.s.space();
1559
1560                 // This is a bare expression.
1561                 self.ann.nested(self, Nested::Body(body));
1562                 self.end(); // need to close a box
1563
1564                 // A box will be closed by `print_expr`, but we didn't want an overall
1565                 // wrapper so we closed the corresponding opening. so create an
1566                 // empty box to satisfy the close.
1567                 self.ibox(0);
1568             }
1569             hir::ExprKind::Block(ref blk, opt_label) => {
1570                 if let Some(label) = opt_label {
1571                     self.print_ident(label.ident);
1572                     self.word_space(":");
1573                 }
1574                 // containing cbox, will be closed by print-block at `}`
1575                 self.cbox(INDENT_UNIT);
1576                 // head-box, will be closed by print-block after `{`
1577                 self.ibox(0);
1578                 self.print_block(&blk);
1579             }
1580             hir::ExprKind::Assign(ref lhs, ref rhs, _) => {
1581                 let prec = AssocOp::Assign.precedence() as i8;
1582                 self.print_expr_maybe_paren(&lhs, prec + 1);
1583                 self.s.space();
1584                 self.word_space("=");
1585                 self.print_expr_maybe_paren(&rhs, prec);
1586             }
1587             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
1588                 let prec = AssocOp::Assign.precedence() as i8;
1589                 self.print_expr_maybe_paren(&lhs, prec + 1);
1590                 self.s.space();
1591                 self.s.word(op.node.as_str());
1592                 self.word_space("=");
1593                 self.print_expr_maybe_paren(&rhs, prec);
1594             }
1595             hir::ExprKind::Field(ref expr, ident) => {
1596                 self.print_expr_maybe_paren(expr, parser::PREC_POSTFIX);
1597                 self.s.word(".");
1598                 self.print_ident(ident);
1599             }
1600             hir::ExprKind::Index(ref expr, ref index) => {
1601                 self.print_expr_maybe_paren(&expr, parser::PREC_POSTFIX);
1602                 self.s.word("[");
1603                 self.print_expr(&index);
1604                 self.s.word("]");
1605             }
1606             hir::ExprKind::Path(ref qpath) => self.print_qpath(qpath, true),
1607             hir::ExprKind::Break(destination, ref opt_expr) => {
1608                 self.s.word("break");
1609                 self.s.space();
1610                 if let Some(label) = destination.label {
1611                     self.print_ident(label.ident);
1612                     self.s.space();
1613                 }
1614                 if let Some(ref expr) = *opt_expr {
1615                     self.print_expr_maybe_paren(expr, parser::PREC_JUMP);
1616                     self.s.space();
1617                 }
1618             }
1619             hir::ExprKind::Continue(destination) => {
1620                 self.s.word("continue");
1621                 self.s.space();
1622                 if let Some(label) = destination.label {
1623                     self.print_ident(label.ident);
1624                     self.s.space()
1625                 }
1626             }
1627             hir::ExprKind::Ret(ref result) => {
1628                 self.s.word("return");
1629                 if let Some(ref expr) = *result {
1630                     self.s.word(" ");
1631                     self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1632                 }
1633             }
1634             hir::ExprKind::InlineAsm(ref asm) => {
1635                 self.word("asm!");
1636                 self.print_inline_asm(asm);
1637             }
1638             hir::ExprKind::LlvmInlineAsm(ref a) => {
1639                 let i = &a.inner;
1640                 self.s.word("llvm_asm!");
1641                 self.popen();
1642                 self.print_symbol(i.asm, i.asm_str_style);
1643                 self.word_space(":");
1644
1645                 let mut out_idx = 0;
1646                 self.commasep(Inconsistent, &i.outputs, |s, out| {
1647                     let constraint = out.constraint.as_str();
1648                     let mut ch = constraint.chars();
1649                     match ch.next() {
1650                         Some('=') if out.is_rw => {
1651                             s.print_string(&format!("+{}", ch.as_str()), ast::StrStyle::Cooked)
1652                         }
1653                         _ => s.print_string(&constraint, ast::StrStyle::Cooked),
1654                     }
1655                     s.popen();
1656                     s.print_expr(&a.outputs_exprs[out_idx]);
1657                     s.pclose();
1658                     out_idx += 1;
1659                 });
1660                 self.s.space();
1661                 self.word_space(":");
1662
1663                 let mut in_idx = 0;
1664                 self.commasep(Inconsistent, &i.inputs, |s, &co| {
1665                     s.print_symbol(co, ast::StrStyle::Cooked);
1666                     s.popen();
1667                     s.print_expr(&a.inputs_exprs[in_idx]);
1668                     s.pclose();
1669                     in_idx += 1;
1670                 });
1671                 self.s.space();
1672                 self.word_space(":");
1673
1674                 self.commasep(Inconsistent, &i.clobbers, |s, &co| {
1675                     s.print_symbol(co, ast::StrStyle::Cooked);
1676                 });
1677
1678                 let mut options = vec![];
1679                 if i.volatile {
1680                     options.push("volatile");
1681                 }
1682                 if i.alignstack {
1683                     options.push("alignstack");
1684                 }
1685                 if i.dialect == ast::LlvmAsmDialect::Intel {
1686                     options.push("intel");
1687                 }
1688
1689                 if !options.is_empty() {
1690                     self.s.space();
1691                     self.word_space(":");
1692                     self.commasep(Inconsistent, &options, |s, &co| {
1693                         s.print_string(co, ast::StrStyle::Cooked);
1694                     });
1695                 }
1696
1697                 self.pclose();
1698             }
1699             hir::ExprKind::Yield(ref expr, _) => {
1700                 self.word_space("yield");
1701                 self.print_expr_maybe_paren(&expr, parser::PREC_JUMP);
1702             }
1703             hir::ExprKind::Err => {
1704                 self.popen();
1705                 self.s.word("/*ERROR*/");
1706                 self.pclose();
1707             }
1708         }
1709         self.ann.post(self, AnnNode::Expr(expr));
1710         self.end()
1711     }
1712
1713     pub fn print_local_decl(&mut self, loc: &hir::Local<'_>) {
1714         self.print_pat(&loc.pat);
1715         if let Some(ref ty) = loc.ty {
1716             self.word_space(":");
1717             self.print_type(&ty);
1718         }
1719     }
1720
1721     pub fn print_name(&mut self, name: Symbol) {
1722         self.print_ident(Ident::with_dummy_span(name))
1723     }
1724
1725     pub fn print_path(&mut self, path: &hir::Path<'_>, colons_before_params: bool) {
1726         self.maybe_print_comment(path.span.lo());
1727
1728         for (i, segment) in path.segments.iter().enumerate() {
1729             if i > 0 {
1730                 self.s.word("::")
1731             }
1732             if segment.ident.name != kw::PathRoot {
1733                 self.print_ident(segment.ident);
1734                 self.print_generic_args(segment.args(), segment.infer_args, colons_before_params);
1735             }
1736         }
1737     }
1738
1739     pub fn print_path_segment(&mut self, segment: &hir::PathSegment<'_>) {
1740         if segment.ident.name != kw::PathRoot {
1741             self.print_ident(segment.ident);
1742             self.print_generic_args(segment.args(), segment.infer_args, false);
1743         }
1744     }
1745
1746     pub fn print_qpath(&mut self, qpath: &hir::QPath<'_>, colons_before_params: bool) {
1747         match *qpath {
1748             hir::QPath::Resolved(None, ref path) => self.print_path(path, colons_before_params),
1749             hir::QPath::Resolved(Some(ref qself), ref path) => {
1750                 self.s.word("<");
1751                 self.print_type(qself);
1752                 self.s.space();
1753                 self.word_space("as");
1754
1755                 for (i, segment) in path.segments[..path.segments.len() - 1].iter().enumerate() {
1756                     if i > 0 {
1757                         self.s.word("::")
1758                     }
1759                     if segment.ident.name != kw::PathRoot {
1760                         self.print_ident(segment.ident);
1761                         self.print_generic_args(
1762                             segment.args(),
1763                             segment.infer_args,
1764                             colons_before_params,
1765                         );
1766                     }
1767                 }
1768
1769                 self.s.word(">");
1770                 self.s.word("::");
1771                 let item_segment = path.segments.last().unwrap();
1772                 self.print_ident(item_segment.ident);
1773                 self.print_generic_args(
1774                     item_segment.args(),
1775                     item_segment.infer_args,
1776                     colons_before_params,
1777                 )
1778             }
1779             hir::QPath::TypeRelative(ref qself, ref item_segment) => {
1780                 // If we've got a compound-qualified-path, let's push an additional pair of angle
1781                 // brackets, so that we pretty-print `<<A::B>::C>` as `<A::B>::C`, instead of just
1782                 // `A::B::C` (since the latter could be ambiguous to the user)
1783                 if let hir::TyKind::Path(hir::QPath::Resolved(None, _)) = &qself.kind {
1784                     self.print_type(qself);
1785                 } else {
1786                     self.s.word("<");
1787                     self.print_type(qself);
1788                     self.s.word(">");
1789                 }
1790
1791                 self.s.word("::");
1792                 self.print_ident(item_segment.ident);
1793                 self.print_generic_args(
1794                     item_segment.args(),
1795                     item_segment.infer_args,
1796                     colons_before_params,
1797                 )
1798             }
1799             hir::QPath::LangItem(lang_item, span) => {
1800                 self.s.word("#[lang = \"");
1801                 self.print_ident(Ident::new(lang_item.name(), span));
1802                 self.s.word("\"]");
1803             }
1804         }
1805     }
1806
1807     fn print_generic_args(
1808         &mut self,
1809         generic_args: &hir::GenericArgs<'_>,
1810         infer_args: bool,
1811         colons_before_params: bool,
1812     ) {
1813         if generic_args.parenthesized {
1814             self.s.word("(");
1815             self.commasep(Inconsistent, generic_args.inputs(), |s, ty| s.print_type(&ty));
1816             self.s.word(")");
1817
1818             self.space_if_not_bol();
1819             self.word_space("->");
1820             self.print_type(generic_args.bindings[0].ty());
1821         } else {
1822             let start = if colons_before_params { "::<" } else { "<" };
1823             let empty = Cell::new(true);
1824             let start_or_comma = |this: &mut Self| {
1825                 if empty.get() {
1826                     empty.set(false);
1827                     this.s.word(start)
1828                 } else {
1829                     this.word_space(",")
1830                 }
1831             };
1832
1833             let mut nonelided_generic_args: bool = false;
1834             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
1835                 GenericArg::Lifetime(lt) => lt.is_elided(),
1836                 _ => {
1837                     nonelided_generic_args = true;
1838                     true
1839                 }
1840             });
1841
1842             if nonelided_generic_args {
1843                 start_or_comma(self);
1844                 self.commasep(
1845                     Inconsistent,
1846                     &generic_args.args,
1847                     |s, generic_arg| match generic_arg {
1848                         GenericArg::Lifetime(lt) if !elide_lifetimes => s.print_lifetime(lt),
1849                         GenericArg::Lifetime(_) => {}
1850                         GenericArg::Type(ty) => s.print_type(ty),
1851                         GenericArg::Const(ct) => s.print_anon_const(&ct.value),
1852                     },
1853                 );
1854             }
1855
1856             // FIXME(eddyb): this would leak into error messages (e.g.,
1857             // "non-exhaustive patterns: `Some::<..>(_)` not covered").
1858             if infer_args && false {
1859                 start_or_comma(self);
1860                 self.s.word("..");
1861             }
1862
1863             for binding in generic_args.bindings.iter() {
1864                 start_or_comma(self);
1865                 self.print_ident(binding.ident);
1866                 self.print_generic_args(binding.gen_args, false, false);
1867                 self.s.space();
1868                 match generic_args.bindings[0].kind {
1869                     hir::TypeBindingKind::Equality { ref ty } => {
1870                         self.word_space("=");
1871                         self.print_type(ty);
1872                     }
1873                     hir::TypeBindingKind::Constraint { bounds } => {
1874                         self.print_bounds(":", bounds);
1875                     }
1876                 }
1877             }
1878
1879             if !empty.get() {
1880                 self.s.word(">")
1881             }
1882         }
1883     }
1884
1885     pub fn print_pat(&mut self, pat: &hir::Pat<'_>) {
1886         self.maybe_print_comment(pat.span.lo());
1887         self.ann.pre(self, AnnNode::Pat(pat));
1888         // Pat isn't normalized, but the beauty of it
1889         // is that it doesn't matter
1890         match pat.kind {
1891             PatKind::Wild => self.s.word("_"),
1892             PatKind::Binding(binding_mode, _, ident, ref sub) => {
1893                 match binding_mode {
1894                     hir::BindingAnnotation::Ref => {
1895                         self.word_nbsp("ref");
1896                         self.print_mutability(hir::Mutability::Not, false);
1897                     }
1898                     hir::BindingAnnotation::RefMut => {
1899                         self.word_nbsp("ref");
1900                         self.print_mutability(hir::Mutability::Mut, false);
1901                     }
1902                     hir::BindingAnnotation::Unannotated => {}
1903                     hir::BindingAnnotation::Mutable => {
1904                         self.word_nbsp("mut");
1905                     }
1906                 }
1907                 self.print_ident(ident);
1908                 if let Some(ref p) = *sub {
1909                     self.s.word("@");
1910                     self.print_pat(&p);
1911                 }
1912             }
1913             PatKind::TupleStruct(ref qpath, ref elts, ddpos) => {
1914                 self.print_qpath(qpath, true);
1915                 self.popen();
1916                 if let Some(ddpos) = ddpos {
1917                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1918                     if ddpos != 0 {
1919                         self.word_space(",");
1920                     }
1921                     self.s.word("..");
1922                     if ddpos != elts.len() {
1923                         self.s.word(",");
1924                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1925                     }
1926                 } else {
1927                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1928                 }
1929                 self.pclose();
1930             }
1931             PatKind::Path(ref qpath) => {
1932                 self.print_qpath(qpath, true);
1933             }
1934             PatKind::Struct(ref qpath, ref fields, etc) => {
1935                 self.print_qpath(qpath, true);
1936                 self.nbsp();
1937                 self.word_space("{");
1938                 self.commasep_cmnt(
1939                     Consistent,
1940                     &fields[..],
1941                     |s, f| {
1942                         s.cbox(INDENT_UNIT);
1943                         if !f.is_shorthand {
1944                             s.print_ident(f.ident);
1945                             s.word_nbsp(":");
1946                         }
1947                         s.print_pat(&f.pat);
1948                         s.end()
1949                     },
1950                     |f| f.pat.span,
1951                 );
1952                 if etc {
1953                     if !fields.is_empty() {
1954                         self.word_space(",");
1955                     }
1956                     self.s.word("..");
1957                 }
1958                 self.s.space();
1959                 self.s.word("}");
1960             }
1961             PatKind::Or(ref pats) => {
1962                 self.strsep("|", true, Inconsistent, &pats[..], |s, p| s.print_pat(&p));
1963             }
1964             PatKind::Tuple(ref elts, ddpos) => {
1965                 self.popen();
1966                 if let Some(ddpos) = ddpos {
1967                     self.commasep(Inconsistent, &elts[..ddpos], |s, p| s.print_pat(&p));
1968                     if ddpos != 0 {
1969                         self.word_space(",");
1970                     }
1971                     self.s.word("..");
1972                     if ddpos != elts.len() {
1973                         self.s.word(",");
1974                         self.commasep(Inconsistent, &elts[ddpos..], |s, p| s.print_pat(&p));
1975                     }
1976                 } else {
1977                     self.commasep(Inconsistent, &elts[..], |s, p| s.print_pat(&p));
1978                     if elts.len() == 1 {
1979                         self.s.word(",");
1980                     }
1981                 }
1982                 self.pclose();
1983             }
1984             PatKind::Box(ref inner) => {
1985                 let is_range_inner = matches!(inner.kind, PatKind::Range(..));
1986                 self.s.word("box ");
1987                 if is_range_inner {
1988                     self.popen();
1989                 }
1990                 self.print_pat(&inner);
1991                 if is_range_inner {
1992                     self.pclose();
1993                 }
1994             }
1995             PatKind::Ref(ref inner, mutbl) => {
1996                 let is_range_inner = matches!(inner.kind, PatKind::Range(..));
1997                 self.s.word("&");
1998                 self.s.word(mutbl.prefix_str());
1999                 if is_range_inner {
2000                     self.popen();
2001                 }
2002                 self.print_pat(&inner);
2003                 if is_range_inner {
2004                     self.pclose();
2005                 }
2006             }
2007             PatKind::Lit(ref e) => self.print_expr(&e),
2008             PatKind::Range(ref begin, ref end, ref end_kind) => {
2009                 if let Some(expr) = begin {
2010                     self.print_expr(expr);
2011                     self.s.space();
2012                 }
2013                 match *end_kind {
2014                     RangeEnd::Included => self.s.word("..."),
2015                     RangeEnd::Excluded => self.s.word(".."),
2016                 }
2017                 if let Some(expr) = end {
2018                     self.print_expr(expr);
2019                 }
2020             }
2021             PatKind::Slice(ref before, ref slice, ref after) => {
2022                 self.s.word("[");
2023                 self.commasep(Inconsistent, &before[..], |s, p| s.print_pat(&p));
2024                 if let Some(ref p) = *slice {
2025                     if !before.is_empty() {
2026                         self.word_space(",");
2027                     }
2028                     if let PatKind::Wild = p.kind {
2029                         // Print nothing.
2030                     } else {
2031                         self.print_pat(&p);
2032                     }
2033                     self.s.word("..");
2034                     if !after.is_empty() {
2035                         self.word_space(",");
2036                     }
2037                 }
2038                 self.commasep(Inconsistent, &after[..], |s, p| s.print_pat(&p));
2039                 self.s.word("]");
2040             }
2041         }
2042         self.ann.post(self, AnnNode::Pat(pat))
2043     }
2044
2045     pub fn print_param(&mut self, arg: &hir::Param<'_>) {
2046         self.print_outer_attributes(self.attrs(arg.hir_id));
2047         self.print_pat(&arg.pat);
2048     }
2049
2050     pub fn print_arm(&mut self, arm: &hir::Arm<'_>) {
2051         // I have no idea why this check is necessary, but here it
2052         // is :(
2053         if self.attrs(arm.hir_id).is_empty() {
2054             self.s.space();
2055         }
2056         self.cbox(INDENT_UNIT);
2057         self.ann.pre(self, AnnNode::Arm(arm));
2058         self.ibox(0);
2059         self.print_outer_attributes(&self.attrs(arm.hir_id));
2060         self.print_pat(&arm.pat);
2061         self.s.space();
2062         if let Some(ref g) = arm.guard {
2063             match g {
2064                 hir::Guard::If(e) => {
2065                     self.word_space("if");
2066                     self.print_expr(&e);
2067                     self.s.space();
2068                 }
2069                 hir::Guard::IfLet(pat, e) => {
2070                     self.word_nbsp("if");
2071                     self.word_nbsp("let");
2072                     self.print_pat(&pat);
2073                     self.s.space();
2074                     self.word_space("=");
2075                     self.print_expr(&e);
2076                     self.s.space();
2077                 }
2078             }
2079         }
2080         self.word_space("=>");
2081
2082         match arm.body.kind {
2083             hir::ExprKind::Block(ref blk, opt_label) => {
2084                 if let Some(label) = opt_label {
2085                     self.print_ident(label.ident);
2086                     self.word_space(":");
2087                 }
2088                 // the block will close the pattern's ibox
2089                 self.print_block_unclosed(&blk);
2090
2091                 // If it is a user-provided unsafe block, print a comma after it
2092                 if let hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) = blk.rules
2093                 {
2094                     self.s.word(",");
2095                 }
2096             }
2097             _ => {
2098                 self.end(); // close the ibox for the pattern
2099                 self.print_expr(&arm.body);
2100                 self.s.word(",");
2101             }
2102         }
2103         self.ann.post(self, AnnNode::Arm(arm));
2104         self.end() // close enclosing cbox
2105     }
2106
2107     pub fn print_fn(
2108         &mut self,
2109         decl: &hir::FnDecl<'_>,
2110         header: hir::FnHeader,
2111         name: Option<Symbol>,
2112         generics: &hir::Generics<'_>,
2113         vis: &hir::Visibility<'_>,
2114         arg_names: &[Ident],
2115         body_id: Option<hir::BodyId>,
2116     ) {
2117         self.print_fn_header_info(header, vis);
2118
2119         if let Some(name) = name {
2120             self.nbsp();
2121             self.print_name(name);
2122         }
2123         self.print_generic_params(&generics.params);
2124
2125         self.popen();
2126         let mut i = 0;
2127         // Make sure we aren't supplied *both* `arg_names` and `body_id`.
2128         assert!(arg_names.is_empty() || body_id.is_none());
2129         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2130             s.ibox(INDENT_UNIT);
2131             if let Some(arg_name) = arg_names.get(i) {
2132                 s.s.word(arg_name.to_string());
2133                 s.s.word(":");
2134                 s.s.space();
2135             } else if let Some(body_id) = body_id {
2136                 s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2137                 s.s.word(":");
2138                 s.s.space();
2139             }
2140             i += 1;
2141             s.print_type(ty);
2142             s.end()
2143         });
2144         if decl.c_variadic {
2145             self.s.word(", ...");
2146         }
2147         self.pclose();
2148
2149         self.print_fn_output(decl);
2150         self.print_where_clause(&generics.where_clause)
2151     }
2152
2153     fn print_closure_params(&mut self, decl: &hir::FnDecl<'_>, body_id: hir::BodyId) {
2154         self.s.word("|");
2155         let mut i = 0;
2156         self.commasep(Inconsistent, &decl.inputs, |s, ty| {
2157             s.ibox(INDENT_UNIT);
2158
2159             s.ann.nested(s, Nested::BodyParamPat(body_id, i));
2160             i += 1;
2161
2162             if let hir::TyKind::Infer = ty.kind {
2163                 // Print nothing.
2164             } else {
2165                 s.s.word(":");
2166                 s.s.space();
2167                 s.print_type(ty);
2168             }
2169             s.end();
2170         });
2171         self.s.word("|");
2172
2173         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2174             return;
2175         }
2176
2177         self.space_if_not_bol();
2178         self.word_space("->");
2179         match decl.output {
2180             hir::FnRetTy::Return(ref ty) => {
2181                 self.print_type(&ty);
2182                 self.maybe_print_comment(ty.span.lo())
2183             }
2184             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2185         }
2186     }
2187
2188     pub fn print_capture_clause(&mut self, capture_clause: hir::CaptureBy) {
2189         match capture_clause {
2190             hir::CaptureBy::Value => self.word_space("move"),
2191             hir::CaptureBy::Ref => {}
2192         }
2193     }
2194
2195     pub fn print_bounds<'b>(
2196         &mut self,
2197         prefix: &'static str,
2198         bounds: impl IntoIterator<Item = &'b hir::GenericBound<'b>>,
2199     ) {
2200         let mut first = true;
2201         for bound in bounds {
2202             if first {
2203                 self.s.word(prefix);
2204             }
2205             if !(first && prefix.is_empty()) {
2206                 self.nbsp();
2207             }
2208             if first {
2209                 first = false;
2210             } else {
2211                 self.word_space("+");
2212             }
2213
2214             match bound {
2215                 GenericBound::Trait(tref, modifier) => {
2216                     if modifier == &TraitBoundModifier::Maybe {
2217                         self.s.word("?");
2218                     }
2219                     self.print_poly_trait_ref(tref);
2220                 }
2221                 GenericBound::LangItemTrait(lang_item, span, ..) => {
2222                     self.s.word("#[lang = \"");
2223                     self.print_ident(Ident::new(lang_item.name(), *span));
2224                     self.s.word("\"]");
2225                 }
2226                 GenericBound::Outlives(lt) => {
2227                     self.print_lifetime(lt);
2228                 }
2229             }
2230         }
2231     }
2232
2233     pub fn print_generic_params(&mut self, generic_params: &[GenericParam<'_>]) {
2234         if !generic_params.is_empty() {
2235             self.s.word("<");
2236
2237             self.commasep(Inconsistent, generic_params, |s, param| s.print_generic_param(param));
2238
2239             self.s.word(">");
2240         }
2241     }
2242
2243     pub fn print_generic_param(&mut self, param: &GenericParam<'_>) {
2244         if let GenericParamKind::Const { .. } = param.kind {
2245             self.word_space("const");
2246         }
2247
2248         self.print_ident(param.name.ident());
2249
2250         match param.kind {
2251             GenericParamKind::Lifetime { .. } => {
2252                 let mut sep = ":";
2253                 for bound in param.bounds {
2254                     match bound {
2255                         GenericBound::Outlives(ref lt) => {
2256                             self.s.word(sep);
2257                             self.print_lifetime(lt);
2258                             sep = "+";
2259                         }
2260                         _ => panic!(),
2261                     }
2262                 }
2263             }
2264             GenericParamKind::Type { ref default, .. } => {
2265                 self.print_bounds(":", param.bounds);
2266                 if let Some(default) = default {
2267                     self.s.space();
2268                     self.word_space("=");
2269                     self.print_type(&default)
2270                 }
2271             }
2272             GenericParamKind::Const { ref ty, ref default } => {
2273                 self.word_space(":");
2274                 self.print_type(ty);
2275                 if let Some(ref default) = default {
2276                     self.s.space();
2277                     self.word_space("=");
2278                     self.print_anon_const(&default)
2279                 }
2280             }
2281         }
2282     }
2283
2284     pub fn print_lifetime(&mut self, lifetime: &hir::Lifetime) {
2285         self.print_ident(lifetime.name.ident())
2286     }
2287
2288     pub fn print_where_clause(&mut self, where_clause: &hir::WhereClause<'_>) {
2289         if where_clause.predicates.is_empty() {
2290             return;
2291         }
2292
2293         self.s.space();
2294         self.word_space("where");
2295
2296         for (i, predicate) in where_clause.predicates.iter().enumerate() {
2297             if i != 0 {
2298                 self.word_space(",");
2299             }
2300
2301             match predicate {
2302                 hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
2303                     bound_generic_params,
2304                     bounded_ty,
2305                     bounds,
2306                     ..
2307                 }) => {
2308                     self.print_formal_generic_params(bound_generic_params);
2309                     self.print_type(&bounded_ty);
2310                     self.print_bounds(":", *bounds);
2311                 }
2312                 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
2313                     lifetime,
2314                     bounds,
2315                     ..
2316                 }) => {
2317                     self.print_lifetime(lifetime);
2318                     self.s.word(":");
2319
2320                     for (i, bound) in bounds.iter().enumerate() {
2321                         match bound {
2322                             GenericBound::Outlives(lt) => {
2323                                 self.print_lifetime(lt);
2324                             }
2325                             _ => panic!(),
2326                         }
2327
2328                         if i != 0 {
2329                             self.s.word(":");
2330                         }
2331                     }
2332                 }
2333                 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
2334                     lhs_ty, rhs_ty, ..
2335                 }) => {
2336                     self.print_type(lhs_ty);
2337                     self.s.space();
2338                     self.word_space("=");
2339                     self.print_type(rhs_ty);
2340                 }
2341             }
2342         }
2343     }
2344
2345     pub fn print_mutability(&mut self, mutbl: hir::Mutability, print_const: bool) {
2346         match mutbl {
2347             hir::Mutability::Mut => self.word_nbsp("mut"),
2348             hir::Mutability::Not => {
2349                 if print_const {
2350                     self.word_nbsp("const")
2351                 }
2352             }
2353         }
2354     }
2355
2356     pub fn print_mt(&mut self, mt: &hir::MutTy<'_>, print_const: bool) {
2357         self.print_mutability(mt.mutbl, print_const);
2358         self.print_type(&mt.ty)
2359     }
2360
2361     pub fn print_fn_output(&mut self, decl: &hir::FnDecl<'_>) {
2362         if let hir::FnRetTy::DefaultReturn(..) = decl.output {
2363             return;
2364         }
2365
2366         self.space_if_not_bol();
2367         self.ibox(INDENT_UNIT);
2368         self.word_space("->");
2369         match decl.output {
2370             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
2371             hir::FnRetTy::Return(ref ty) => self.print_type(&ty),
2372         }
2373         self.end();
2374
2375         if let hir::FnRetTy::Return(ref output) = decl.output {
2376             self.maybe_print_comment(output.span.lo())
2377         }
2378     }
2379
2380     pub fn print_ty_fn(
2381         &mut self,
2382         abi: Abi,
2383         unsafety: hir::Unsafety,
2384         decl: &hir::FnDecl<'_>,
2385         name: Option<Symbol>,
2386         generic_params: &[hir::GenericParam<'_>],
2387         arg_names: &[Ident],
2388     ) {
2389         self.ibox(INDENT_UNIT);
2390         if !generic_params.is_empty() {
2391             self.s.word("for");
2392             self.print_generic_params(generic_params);
2393         }
2394         let generics = hir::Generics {
2395             params: &[],
2396             where_clause: hir::WhereClause { predicates: &[], span: rustc_span::DUMMY_SP },
2397             span: rustc_span::DUMMY_SP,
2398         };
2399         self.print_fn(
2400             decl,
2401             hir::FnHeader {
2402                 unsafety,
2403                 abi,
2404                 constness: hir::Constness::NotConst,
2405                 asyncness: hir::IsAsync::NotAsync,
2406             },
2407             name,
2408             &generics,
2409             &Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Inherited },
2410             arg_names,
2411             None,
2412         );
2413         self.end();
2414     }
2415
2416     pub fn maybe_print_trailing_comment(
2417         &mut self,
2418         span: rustc_span::Span,
2419         next_pos: Option<BytePos>,
2420     ) {
2421         if let Some(cmnts) = self.comments() {
2422             if let Some(cmnt) = cmnts.trailing_comment(span, next_pos) {
2423                 self.print_comment(&cmnt);
2424             }
2425         }
2426     }
2427
2428     pub fn print_remaining_comments(&mut self) {
2429         // If there aren't any remaining comments, then we need to manually
2430         // make sure there is a line break at the end.
2431         if self.next_comment().is_none() {
2432             self.s.hardbreak();
2433         }
2434         while let Some(ref cmnt) = self.next_comment() {
2435             self.print_comment(cmnt)
2436         }
2437     }
2438
2439     pub fn print_fn_header_info(&mut self, header: hir::FnHeader, vis: &hir::Visibility<'_>) {
2440         self.s.word(visibility_qualified(vis, ""));
2441
2442         match header.constness {
2443             hir::Constness::NotConst => {}
2444             hir::Constness::Const => self.word_nbsp("const"),
2445         }
2446
2447         match header.asyncness {
2448             hir::IsAsync::NotAsync => {}
2449             hir::IsAsync::Async => self.word_nbsp("async"),
2450         }
2451
2452         self.print_unsafety(header.unsafety);
2453
2454         if header.abi != Abi::Rust {
2455             self.word_nbsp("extern");
2456             self.word_nbsp(header.abi.to_string());
2457         }
2458
2459         self.s.word("fn")
2460     }
2461
2462     pub fn print_unsafety(&mut self, s: hir::Unsafety) {
2463         match s {
2464             hir::Unsafety::Normal => {}
2465             hir::Unsafety::Unsafe => self.word_nbsp("unsafe"),
2466         }
2467     }
2468
2469     pub fn print_is_auto(&mut self, s: hir::IsAuto) {
2470         match s {
2471             hir::IsAuto::Yes => self.word_nbsp("auto"),
2472             hir::IsAuto::No => {}
2473         }
2474     }
2475 }
2476
2477 /// Does this expression require a semicolon to be treated
2478 /// as a statement? The negation of this: 'can this expression
2479 /// be used as a statement without a semicolon' -- is used
2480 /// as an early-bail-out in the parser so that, for instance,
2481 ///     if true {...} else {...}
2482 ///      |x| 5
2483 /// isn't parsed as (if true {...} else {...} | x) | 5
2484 //
2485 // Duplicated from `parse::classify`, but adapted for the HIR.
2486 fn expr_requires_semi_to_be_stmt(e: &hir::Expr<'_>) -> bool {
2487     !matches!(
2488         e.kind,
2489         hir::ExprKind::If(..)
2490             | hir::ExprKind::Match(..)
2491             | hir::ExprKind::Block(..)
2492             | hir::ExprKind::Loop(..)
2493     )
2494 }
2495
2496 /// This statement requires a semicolon after it.
2497 /// note that in one case (stmt_semi), we've already
2498 /// seen the semicolon, and thus don't need another.
2499 fn stmt_ends_with_semi(stmt: &hir::StmtKind<'_>) -> bool {
2500     match *stmt {
2501         hir::StmtKind::Local(_) => true,
2502         hir::StmtKind::Item(_) => false,
2503         hir::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(&e),
2504         hir::StmtKind::Semi(..) => false,
2505     }
2506 }
2507
2508 fn bin_op_to_assoc_op(op: hir::BinOpKind) -> AssocOp {
2509     use crate::hir::BinOpKind::*;
2510     match op {
2511         Add => AssocOp::Add,
2512         Sub => AssocOp::Subtract,
2513         Mul => AssocOp::Multiply,
2514         Div => AssocOp::Divide,
2515         Rem => AssocOp::Modulus,
2516
2517         And => AssocOp::LAnd,
2518         Or => AssocOp::LOr,
2519
2520         BitXor => AssocOp::BitXor,
2521         BitAnd => AssocOp::BitAnd,
2522         BitOr => AssocOp::BitOr,
2523         Shl => AssocOp::ShiftLeft,
2524         Shr => AssocOp::ShiftRight,
2525
2526         Eq => AssocOp::Equal,
2527         Lt => AssocOp::Less,
2528         Le => AssocOp::LessEqual,
2529         Ne => AssocOp::NotEqual,
2530         Ge => AssocOp::GreaterEqual,
2531         Gt => AssocOp::Greater,
2532     }
2533 }
2534
2535 /// Expressions that syntactically contain an "exterior" struct literal, i.e., not surrounded by any
2536 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
2537 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
2538 fn contains_exterior_struct_lit(value: &hir::Expr<'_>) -> bool {
2539     match value.kind {
2540         hir::ExprKind::Struct(..) => true,
2541
2542         hir::ExprKind::Assign(ref lhs, ref rhs, _)
2543         | hir::ExprKind::AssignOp(_, ref lhs, ref rhs)
2544         | hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
2545             // `X { y: 1 } + X { y: 2 }`
2546             contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
2547         }
2548         hir::ExprKind::Unary(_, ref x)
2549         | hir::ExprKind::Cast(ref x, _)
2550         | hir::ExprKind::Type(ref x, _)
2551         | hir::ExprKind::Field(ref x, _)
2552         | hir::ExprKind::Index(ref x, _) => {
2553             // `&X { y: 1 }, X { y: 1 }.y`
2554             contains_exterior_struct_lit(&x)
2555         }
2556
2557         hir::ExprKind::MethodCall(.., ref exprs, _) => {
2558             // `X { y: 1 }.bar(...)`
2559             contains_exterior_struct_lit(&exprs[0])
2560         }
2561
2562         _ => false,
2563     }
2564 }