1use std::path::PathBuf;
2
3use hir::def::Namespace;
4use rustc_data_structures::fx::FxHashSet;
5use rustc_data_structures::sso::SsoHashSet;
6use rustc_hir as hir;
7use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
8use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
9use tracing::{debug, instrument, trace};
10
11use crate::ty::{self, GenericArg, ShortInstance, Ty, TyCtxt};
12
13// `pretty` is a separate module only for organization.
14mod pretty;
15pub use self::pretty::*;
16use super::Lift;
17
18pub type PrintError = std::fmt::Error;
19
20pub trait Print<'tcx, P> {
21 fn print(&self, cx: &mut P) -> Result<(), PrintError>;
22}
23
24/// Interface for outputting user-facing "type-system entities"
25/// (paths, types, lifetimes, constants, etc.) as a side-effect
26/// (e.g. formatting, like `PrettyPrinter` implementors do) or by
27/// constructing some alternative representation (e.g. an AST),
28/// which the associated types allow passing through the methods.
29///
30/// For pretty-printing/formatting in particular, see `PrettyPrinter`.
31//
32// FIXME(eddyb) find a better name; this is more general than "printing".
33pub trait Printer<'tcx>: Sized {
34 fn tcx<'a>(&'a self) -> TyCtxt<'tcx>;
35
36 fn print_def_path(
37 &mut self,
38 def_id: DefId,
39 args: &'tcx [GenericArg<'tcx>],
40 ) -> Result<(), PrintError> {
41 self.default_print_def_path(def_id, args)
42 }
43
44 fn print_impl_path(
45 &mut self,
46 impl_def_id: DefId,
47 args: &'tcx [GenericArg<'tcx>],
48 ) -> Result<(), PrintError> {
49 let tcx = self.tcx();
50 let self_ty = tcx.type_of(impl_def_id);
51 let impl_trait_ref = tcx.impl_trait_ref(impl_def_id);
52 let (self_ty, impl_trait_ref) = if tcx.generics_of(impl_def_id).count() <= args.len() {
53 (
54 self_ty.instantiate(tcx, args),
55 impl_trait_ref.map(|impl_trait_ref| impl_trait_ref.instantiate(tcx, args)),
56 )
57 } else {
58 // We are probably printing a nested item inside of an impl.
59 // Use the identity substitutions for the impl.
60 (
61 self_ty.instantiate_identity(),
62 impl_trait_ref.map(|impl_trait_ref| impl_trait_ref.instantiate_identity()),
63 )
64 };
65
66 self.default_print_impl_path(impl_def_id, self_ty, impl_trait_ref)
67 }
68
69 fn print_region(&mut self, region: ty::Region<'tcx>) -> Result<(), PrintError>;
70
71 fn print_type(&mut self, ty: Ty<'tcx>) -> Result<(), PrintError>;
72
73 fn print_dyn_existential(
74 &mut self,
75 predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
76 ) -> Result<(), PrintError>;
77
78 fn print_const(&mut self, ct: ty::Const<'tcx>) -> Result<(), PrintError>;
79
80 fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError>;
81
82 fn path_qualified(
83 &mut self,
84 self_ty: Ty<'tcx>,
85 trait_ref: Option<ty::TraitRef<'tcx>>,
86 ) -> Result<(), PrintError>;
87
88 fn path_append_impl(
89 &mut self,
90 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
91 disambiguated_data: &DisambiguatedDefPathData,
92 self_ty: Ty<'tcx>,
93 trait_ref: Option<ty::TraitRef<'tcx>>,
94 ) -> Result<(), PrintError>;
95
96 fn path_append(
97 &mut self,
98 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
99 disambiguated_data: &DisambiguatedDefPathData,
100 ) -> Result<(), PrintError>;
101
102 fn path_generic_args(
103 &mut self,
104 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
105 args: &[GenericArg<'tcx>],
106 ) -> Result<(), PrintError>;
107
108 fn should_truncate(&mut self) -> bool {
109 false
110 }
111
112 // Defaults (should not be overridden):
113
114 #[instrument(skip(self), level = "debug")]
115 fn default_print_def_path(
116 &mut self,
117 def_id: DefId,
118 args: &'tcx [GenericArg<'tcx>],
119 ) -> Result<(), PrintError> {
120 let key = self.tcx().def_key(def_id);
121 debug!(?key);
122
123 match key.disambiguated_data.data {
124 DefPathData::CrateRoot => {
125 assert!(key.parent.is_none());
126 self.path_crate(def_id.krate)
127 }
128
129 DefPathData::Impl => self.print_impl_path(def_id, args),
130
131 _ => {
132 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
133
134 let mut parent_args = args;
135 let mut trait_qualify_parent = false;
136 if !args.is_empty() {
137 let generics = self.tcx().generics_of(def_id);
138 parent_args = &args[..generics.parent_count.min(args.len())];
139
140 match key.disambiguated_data.data {
141 DefPathData::Closure => {
142 // FIXME(async_closures): This is somewhat ugly.
143 // We need to additionally print the `kind` field of a closure if
144 // it is desugared from a coroutine-closure.
145 if let Some(hir::CoroutineKind::Desugared(
146 _,
147 hir::CoroutineSource::Closure,
148 )) = self.tcx().coroutine_kind(def_id)
149 && args.len() > parent_args.len()
150 {
151 return self.path_generic_args(
152 |cx| cx.print_def_path(def_id, parent_args),
153 &args[..parent_args.len() + 1][..1],
154 );
155 } else {
156 // Closures' own generics are only captures, don't print them.
157 }
158 }
159 // This covers both `DefKind::AnonConst` and `DefKind::InlineConst`.
160 // Anon consts doesn't have their own generics, and inline consts' own
161 // generics are their inferred types, so don't print them.
162 DefPathData::AnonConst => {}
163
164 // If we have any generic arguments to print, we do that
165 // on top of the same path, but without its own generics.
166 _ => {
167 if !generics.is_own_empty() && args.len() >= generics.count() {
168 let args = generics.own_args_no_defaults(self.tcx(), args);
169 return self.path_generic_args(
170 |cx| cx.print_def_path(def_id, parent_args),
171 args,
172 );
173 }
174 }
175 }
176
177 // FIXME(eddyb) try to move this into the parent's printing
178 // logic, instead of doing it when printing the child.
179 trait_qualify_parent = generics.has_self
180 && generics.parent == Some(parent_def_id)
181 && parent_args.len() == generics.parent_count
182 && self.tcx().generics_of(parent_def_id).parent_count == 0;
183 }
184
185 self.path_append(
186 |cx: &mut Self| {
187 if trait_qualify_parent {
188 let trait_ref = ty::TraitRef::new(
189 cx.tcx(),
190 parent_def_id,
191 parent_args.iter().copied(),
192 );
193 cx.path_qualified(trait_ref.self_ty(), Some(trait_ref))
194 } else {
195 cx.print_def_path(parent_def_id, parent_args)
196 }
197 },
198 &key.disambiguated_data,
199 )
200 }
201 }
202 }
203
204 fn default_print_impl_path(
205 &mut self,
206 impl_def_id: DefId,
207 self_ty: Ty<'tcx>,
208 impl_trait_ref: Option<ty::TraitRef<'tcx>>,
209 ) -> Result<(), PrintError> {
210 debug!(
211 "default_print_impl_path: impl_def_id={:?}, self_ty={}, impl_trait_ref={:?}",
212 impl_def_id, self_ty, impl_trait_ref
213 );
214
215 let key = self.tcx().def_key(impl_def_id);
216 let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id };
217
218 // Decide whether to print the parent path for the impl.
219 // Logically, since impls are global, it's never needed, but
220 // users may find it useful. Currently, we omit the parent if
221 // the impl is either in the same module as the self-type or
222 // as the trait.
223 let in_self_mod = match characteristic_def_id_of_type(self_ty) {
224 None => false,
225 Some(ty_def_id) => self.tcx().parent(ty_def_id) == parent_def_id,
226 };
227 let in_trait_mod = match impl_trait_ref {
228 None => false,
229 Some(trait_ref) => self.tcx().parent(trait_ref.def_id) == parent_def_id,
230 };
231
232 if !in_self_mod && !in_trait_mod {
233 // If the impl is not co-located with either self-type or
234 // trait-type, then fallback to a format that identifies
235 // the module more clearly.
236 self.path_append_impl(
237 |cx| cx.print_def_path(parent_def_id, &[]),
238 &key.disambiguated_data,
239 self_ty,
240 impl_trait_ref,
241 )
242 } else {
243 // Otherwise, try to give a good form that would be valid language
244 // syntax. Preferably using associated item notation.
245 self.path_qualified(self_ty, impl_trait_ref)
246 }
247 }
248}
249
250/// As a heuristic, when we see an impl, if we see that the
251/// 'self type' is a type defined in the same module as the impl,
252/// we can omit including the path to the impl itself. This
253/// function tries to find a "characteristic `DefId`" for a
254/// type. It's just a heuristic so it makes some questionable
255/// decisions and we may want to adjust it later.
256///
257/// Visited set is needed to avoid full iteration over
258/// deeply nested tuples that have no DefId.
259fn characteristic_def_id_of_type_cached<'a>(
260 ty: Ty<'a>,
261 visited: &mut SsoHashSet<Ty<'a>>,
262) -> Option<DefId> {
263 match *ty.kind() {
264 ty::Adt(adt_def, _) => Some(adt_def.did()),
265
266 ty::Dynamic(data, ..) => data.principal_def_id(),
267
268 ty::Pat(subty, _) | ty::Array(subty, _) | ty::Slice(subty) => {
269 characteristic_def_id_of_type_cached(subty, visited)
270 }
271
272 ty::RawPtr(ty, _) => characteristic_def_id_of_type_cached(ty, visited),
273
274 ty::Ref(_, ty, _) => characteristic_def_id_of_type_cached(ty, visited),
275
276 ty::Tuple(tys) => tys.iter().find_map(|ty| {
277 if visited.insert(ty) {
278 return characteristic_def_id_of_type_cached(ty, visited);
279 }
280 return None;
281 }),
282
283 ty::FnDef(def_id, _)
284 | ty::Closure(def_id, _)
285 | ty::CoroutineClosure(def_id, _)
286 | ty::Coroutine(def_id, _)
287 | ty::CoroutineWitness(def_id, _)
288 | ty::Foreign(def_id) => Some(def_id),
289
290 ty::Bool
291 | ty::Char
292 | ty::Int(_)
293 | ty::Uint(_)
294 | ty::Str
295 | ty::FnPtr(..)
296 | ty::UnsafeBinder(_)
297 | ty::Alias(..)
298 | ty::Placeholder(..)
299 | ty::Param(_)
300 | ty::Infer(_)
301 | ty::Bound(..)
302 | ty::Error(_)
303 | ty::Never
304 | ty::Float(_) => None,
305 }
306}
307pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> {
308 characteristic_def_id_of_type_cached(ty, &mut SsoHashSet::new())
309}
310
311impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Region<'tcx> {
312 fn print(&self, cx: &mut P) -> Result<(), PrintError> {
313 cx.print_region(*self)
314 }
315}
316
317impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for Ty<'tcx> {
318 fn print(&self, cx: &mut P) -> Result<(), PrintError> {
319 cx.print_type(*self)
320 }
321}
322
323impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
324 fn print(&self, cx: &mut P) -> Result<(), PrintError> {
325 cx.print_dyn_existential(self)
326 }
327}
328
329impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Const<'tcx> {
330 fn print(&self, cx: &mut P) -> Result<(), PrintError> {
331 cx.print_const(*self)
332 }
333}
334
335// This is only used by query descriptions
336pub fn describe_as_module(def_id: impl Into<LocalDefId>, tcx: TyCtxt<'_>) -> String {
337 let def_id = def_id.into();
338 if def_id.is_top_level_module() {
339 "top-level module".to_string()
340 } else {
341 format!("module `{}`", tcx.def_path_str(def_id))
342 }
343}
344
345impl<T> rustc_type_ir::ir_print::IrPrint<T> for TyCtxt<'_>
346where
347 T: Copy + for<'a, 'tcx> dynLift<TyCtxt<'tcx>, Lifted: Print<'tcx, FmtPrinter<'a, 'tcx>>>,
348{
349 fn print(t: &T, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
350 ty::tls::with(|tcx: TyCtxt<'_>| {
351 let mut cx: FmtPrinter<'_, '_> = FmtPrinter::new(tcx, ns:Namespace::TypeNS);
352 tcx.lift(*t).expect(msg:"could not lift for printing").print(&mut cx)?;
353 fmt.write_str(&cx.into_buffer())?;
354 Ok(())
355 })
356 }
357
358 fn print_debug(t: &T, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
359 with_no_trimmed_paths!(Self::print(t, fmt))
360 }
361}
362
363/// Format instance name that is already known to be too long for rustc.
364/// Show only the first 2 types if it is longer than 32 characters to avoid blasting
365/// the user's terminal with thousands of lines of type-name.
366///
367/// If the type name is longer than before+after, it will be written to a file.
368pub fn shrunk_instance_name<'tcx>(
369 tcx: TyCtxt<'tcx>,
370 instance: ty::Instance<'tcx>,
371) -> (String, Option<PathBuf>) {
372 let s: String = instance.to_string();
373
374 // Only use the shrunk version if it's really shorter.
375 // This also avoids the case where before and after slices overlap.
376 if s.chars().nth(33).is_some() {
377 let shrunk: String = format!("{}", ShortInstance(instance, 4));
378 if shrunk == s {
379 return (s, None);
380 }
381
382 let path: PathBuf = tcx.output_filenames(()).temp_path_ext("long-type.txt", None);
383 let written_to_path: Option = std::fs::write(&path, contents:s).ok().map(|_| path);
384
385 (shrunk, written_to_path)
386 } else {
387 (s, None)
388 }
389}
390

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