src/librustc/ty/print/pretty.rs

   1 use crate::hir;
   2 use crate::hir::def::Namespace;
   3 use crate::hir::map::{DefPathData, DisambiguatedDefPathData};
   4 use crate::hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
   5 use crate::middle::cstore::{ExternCrate, ExternCrateSource};
   6 use crate::middle::region;
   7 use crate::ty::{self, DefIdTree, ParamConst, Ty, TyCtxt, TypeFoldable};
   8 use crate::ty::subst::{Kind, Subst, UnpackedKind};
   9 use crate::mir::interpret::ConstValue;
  10 use rustc_target::spec::abi::Abi;
  11 use syntax::symbol::{kw, InternedString};
  12
  13 use std::cell::Cell;
  14 use std::fmt::{self, Write as _};
  15 use std::ops::{Deref, DerefMut};
  16
  17 // `pretty` is a separate module only for organization.
  18 use super::*;
  19
  20 macro_rules! p {
  21     (@write($($data:expr),+)) => {
  22         write!(scoped_cx!(), $($data),+)?
  23     };
  24     (@print($x:expr)) => {
  25         scoped_cx!() = $x.print(scoped_cx!())?
  26     };
  27     (@$method:ident($($arg:expr),*)) => {
  28         scoped_cx!() = scoped_cx!().$method($($arg),*)?
  29     };
  30     ($($kind:ident $data:tt),+) => {{
  31         $(p!(@$kind $data);)+
  32     }};
  33 }
  34 macro_rules! define_scoped_cx {
  35     ($cx:ident) => {
  36         #[allow(unused_macros)]
  37         macro_rules! scoped_cx {
  38             () => ($cx)
  39         }
  40     };
  41 }
  42
  43 thread_local! {
  44     static FORCE_IMPL_FILENAME_LINE: Cell<bool> = Cell::new(false);
  45     static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = Cell::new(false);
  46 }
  47
  48 /// Force us to name impls with just the filename/line number. We
  49 /// normally try to use types. But at some points, notably while printing
  50 /// cycle errors, this can result in extra or suboptimal error output,
  51 /// so this variable disables that check.
  52 pub fn with_forced_impl_filename_line<F: FnOnce() -> R, R>(f: F) -> R {
  53     FORCE_IMPL_FILENAME_LINE.with(|force| {
  54         let old = force.get();
  55         force.set(true);
  56         let result = f();
  57         force.set(old);
  58         result
  59     })
  60 }
  61
  62 /// Adds the `crate::` prefix to paths where appropriate.
  63 pub fn with_crate_prefix<F: FnOnce() -> R, R>(f: F) -> R {
  64     SHOULD_PREFIX_WITH_CRATE.with(|flag| {
  65         let old = flag.get();
  66         flag.set(true);
  67         let result = f();
  68         flag.set(old);
  69         result
  70     })
  71 }
  72
  73 /// The "region highlights" are used to control region printing during
  74 /// specific error messages. When a "region highlight" is enabled, it
  75 /// gives an alternate way to print specific regions. For now, we
  76 /// always print those regions using a number, so something like "`'0`".
  77 ///
  78 /// Regions not selected by the region highlight mode are presently
  79 /// unaffected.
  80 #[derive(Copy, Clone, Default)]
  81 pub struct RegionHighlightMode {
  82     /// If enabled, when we see the selected region, use "`'N`"
  83     /// instead of the ordinary behavior.
  84     highlight_regions: [Option<(ty::RegionKind, usize)>; 3],
  85
  86     /// If enabled, when printing a "free region" that originated from
  87     /// the given `ty::BoundRegion`, print it as "`'1`". Free regions that would ordinarily
  88     /// have names print as normal.
  89     ///
  90     /// This is used when you have a signature like `fn foo(x: &u32,
  91     /// y: &'a u32)` and we want to give a name to the region of the
  92     /// reference `x`.
  93     highlight_bound_region: Option<(ty::BoundRegion, usize)>,
  94 }
  95
  96 impl RegionHighlightMode {
  97     /// If `region` and `number` are both `Some`, invokes
  98     /// `highlighting_region`.
  99     pub fn maybe_highlighting_region(
 100         &mut self,
 101         region: Option<ty::Region<'_>>,
 102         number: Option<usize>,
 103     ) {
 104         if let Some(k) = region {
 105             if let Some(n) = number {
 106                 self.highlighting_region(k, n);
 107             }
 108         }
 109     }
 110
 111     /// Highlights the region inference variable `vid` as `'N`.
 112     pub fn highlighting_region(
 113         &mut self,
 114         region: ty::Region<'_>,
 115         number: usize,
 116     ) {
 117         let num_slots = self.highlight_regions.len();
 118         let first_avail_slot = self.highlight_regions.iter_mut()
 119             .filter(|s| s.is_none())
 120             .next()
 121             .unwrap_or_else(|| {
 122                 bug!(
 123                     "can only highlight {} placeholders at a time",
 124                     num_slots,
 125                 )
 126             });
 127         *first_avail_slot = Some((*region, number));
 128     }
 129
 130     /// Convenience wrapper for `highlighting_region`.
 131     pub fn highlighting_region_vid(
 132         &mut self,
 133         vid: ty::RegionVid,
 134         number: usize,
 135     ) {
 136         self.highlighting_region(&ty::ReVar(vid), number)
 137     }
 138
 139     /// Returns `Some(n)` with the number to use for the given region, if any.
 140     fn region_highlighted(&self, region: ty::Region<'_>) -> Option<usize> {
 141         self
 142             .highlight_regions
 143             .iter()
 144             .filter_map(|h| match h {
 145                 Some((r, n)) if r == region => Some(*n),
 146                 _ => None,
 147             })
 148             .next()
 149     }
 150
 151     /// Highlight the given bound region.
 152     /// We can only highlight one bound region at a time. See
 153     /// the field `highlight_bound_region` for more detailed notes.
 154     pub fn highlighting_bound_region(
 155         &mut self,
 156         br: ty::BoundRegion,
 157         number: usize,
 158     ) {
 159         assert!(self.highlight_bound_region.is_none());
 160         self.highlight_bound_region = Some((br, number));
 161     }
 162 }
 163
 164 /// Trait for printers that pretty-print using `fmt::Write` to the printer.
 165 pub trait PrettyPrinter<'gcx: 'tcx, 'tcx>:
 166     Printer<'gcx, 'tcx,
 167         Error = fmt::Error,
 168         Path = Self,
 169         Region = Self,
 170         Type = Self,
 171         DynExistential = Self,
 172     > +
 173     fmt::Write
 174 {
 175     /// Like `print_def_path` but for value paths.
 176     fn print_value_path(
 177         self,
 178         def_id: DefId,
 179         substs: &'tcx [Kind<'tcx>],
 180     ) -> Result<Self::Path, Self::Error> {
 181         self.print_def_path(def_id, substs)
 182     }
 183
 184     fn in_binder<T>(
 185         self,
 186         value: &ty::Binder<T>,
 187     ) -> Result<Self, Self::Error>
 188         where T: Print<'gcx, 'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>
 189     {
 190         value.skip_binder().print(self)
 191     }
 192
 193     /// Print comma-separated elements.
 194     fn comma_sep<T>(
 195         mut self,
 196         mut elems: impl Iterator<Item = T>,
 197     ) -> Result<Self, Self::Error>
 198         where T: Print<'gcx, 'tcx, Self, Output = Self, Error = Self::Error>
 199     {
 200         if let Some(first) = elems.next() {
 201             self = first.print(self)?;
 202             for elem in elems {
 203                 self.write_str(", ")?;
 204                 self = elem.print(self)?;
 205             }
 206         }
 207         Ok(self)
 208     }
 209
 210     /// Print `<...>` around what `f` prints.
 211     fn generic_delimiters(
 212         self,
 213         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
 214     ) -> Result<Self, Self::Error>;
 215
 216     /// Return `true` if the region should be printed in
 217     /// optional positions, e.g. `&'a T` or `dyn Tr + 'b`.
 218     /// This is typically the case for all non-`'_` regions.
 219     fn region_should_not_be_omitted(
 220         &self,
 221         region: ty::Region<'_>,
 222     ) -> bool;
 223
 224     // Defaults (should not be overriden):
 225
 226     /// If possible, this returns a global path resolving to `def_id` that is visible
 227     /// from at least one local module and returns true. If the crate defining `def_id` is
 228     /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`.
 229     fn try_print_visible_def_path(
 230         mut self,
 231         def_id: DefId,
 232     ) -> Result<(Self, bool), Self::Error> {
 233         define_scoped_cx!(self);
 234
 235         debug!("try_print_visible_def_path: def_id={:?}", def_id);
 236
 237         // If `def_id` is a direct or injected extern crate, return the
 238         // path to the crate followed by the path to the item within the crate.
 239         if def_id.index == CRATE_DEF_INDEX {
 240             let cnum = def_id.krate;
 241
 242             if cnum == LOCAL_CRATE {
 243                 return Ok((self.path_crate(cnum)?, true));
 244             }
 245
 246             // In local mode, when we encounter a crate other than
 247             // LOCAL_CRATE, execution proceeds in one of two ways:
 248             //
 249             // 1. for a direct dependency, where user added an
 250             //    `extern crate` manually, we put the `extern
 251             //    crate` as the parent. So you wind up with
 252             //    something relative to the current crate.
 253             // 2. for an extern inferred from a path or an indirect crate,
 254             //    where there is no explicit `extern crate`, we just prepend
 255             //    the crate name.
 256             match self.tcx().extern_crate(def_id) {
 257                 Some(&ExternCrate {
 258                     src: ExternCrateSource::Extern(def_id),
 259                     direct: true,
 260                     span,
 261                     ..
 262                 }) => {
 263                     debug!("try_print_visible_def_path: def_id={:?}", def_id);
 264                     return Ok((if !span.is_dummy() {
 265                         self.print_def_path(def_id, &[])?
 266                     } else {
 267                         self.path_crate(cnum)?
 268                     }, true));
 269                 }
 270                 None => {
 271                     return Ok((self.path_crate(cnum)?, true));
 272                 }
 273                 _ => {},
 274             }
 275         }
 276
 277         if def_id.is_local() {
 278             return Ok((self, false));
 279         }
 280
 281         let visible_parent_map = self.tcx().visible_parent_map(LOCAL_CRATE);
 282
 283         let mut cur_def_key = self.tcx().def_key(def_id);
 284         debug!("try_print_visible_def_path: cur_def_key={:?}", cur_def_key);
 285
 286         // For a constructor we want the name of its parent rather than <unnamed>.
 287         match cur_def_key.disambiguated_data.data {
 288             DefPathData::Ctor => {
 289                 let parent = DefId {
 290                     krate: def_id.krate,
 291                     index: cur_def_key.parent
 292                         .expect("DefPathData::Ctor/VariantData missing a parent"),
 293                 };
 294
 295                 cur_def_key = self.tcx().def_key(parent);
 296             },
 297             _ => {},
 298         }
 299
 300         let visible_parent = match visible_parent_map.get(&def_id).cloned() {
 301             Some(parent) => parent,
 302             None => return Ok((self, false)),
 303         };
 304         // HACK(eddyb) this bypasses `path_append`'s prefix printing to avoid
 305         // knowing ahead of time whether the entire path will succeed or not.
 306         // To support printers that do not implement `PrettyPrinter`, a `Vec` or
 307         // linked list on the stack would need to be built, before any printing.
 308         match self.try_print_visible_def_path(visible_parent)? {
 309             (cx, false) => return Ok((cx, false)),
 310             (cx, true) => self = cx,
 311         }
 312         let actual_parent = self.tcx().parent(def_id);
 313         debug!(
 314             "try_print_visible_def_path: visible_parent={:?} actual_parent={:?}",
 315             visible_parent, actual_parent,
 316         );
 317
 318         let mut data = cur_def_key.disambiguated_data.data;
 319         debug!(
 320             "try_print_visible_def_path: data={:?} visible_parent={:?} actual_parent={:?}",
 321             data, visible_parent, actual_parent,
 322         );
 323
 324         match data {
 325             // In order to output a path that could actually be imported (valid and visible),
 326             // we need to handle re-exports correctly.
 327             //
 328             // For example, take `std::os::unix::process::CommandExt`, this trait is actually
 329             // defined at `std::sys::unix::ext::process::CommandExt` (at time of writing).
 330             //
 331             // `std::os::unix` rexports the contents of `std::sys::unix::ext`. `std::sys` is
 332             // private so the "true" path to `CommandExt` isn't accessible.
 333             //
 334             // In this case, the `visible_parent_map` will look something like this:
 335             //
 336             // (child) -> (parent)
 337             // `std::sys::unix::ext::process::CommandExt` -> `std::sys::unix::ext::process`
 338             // `std::sys::unix::ext::process` -> `std::sys::unix::ext`
 339             // `std::sys::unix::ext` -> `std::os`
 340             //
 341             // This is correct, as the visible parent of `std::sys::unix::ext` is in fact
 342             // `std::os`.
 343             //
 344             // When printing the path to `CommandExt` and looking at the `cur_def_key` that
 345             // corresponds to `std::sys::unix::ext`, we would normally print `ext` and then go
 346             // to the parent - resulting in a mangled path like
 347             // `std::os::ext::process::CommandExt`.
 348             //
 349             // Instead, we must detect that there was a re-export and instead print `unix`
 350             // (which is the name `std::sys::unix::ext` was re-exported as in `std::os`). To
 351             // do this, we compare the parent of `std::sys::unix::ext` (`std::sys::unix`) with
 352             // the visible parent (`std::os`). If these do not match, then we iterate over
 353             // the children of the visible parent (as was done when computing
 354             // `visible_parent_map`), looking for the specific child we currently have and then
 355             // have access to the re-exported name.
 356             DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => {
 357                 let reexport = self.tcx().item_children(visible_parent)
 358                     .iter()
 359                     .find(|child| child.res.def_id() == def_id)
 360                     .map(|child| child.ident.as_interned_str());
 361                 if let Some(reexport) = reexport {
 362                     *name = reexport;
 363                 }
 364             }
 365             // Re-exported `extern crate` (#43189).
 366             DefPathData::CrateRoot => {
 367                 data = DefPathData::TypeNs(
 368                     self.tcx().original_crate_name(def_id.krate).as_interned_str(),
 369                 );
 370             }
 371             _ => {}
 372         }
 373         debug!("try_print_visible_def_path: data={:?}", data);
 374
 375         Ok((self.path_append(Ok, &DisambiguatedDefPathData {
 376             data,
 377             disambiguator: 0,
 378         })?, true))
 379     }
 380
 381     fn pretty_path_qualified(
 382         self,
 383         self_ty: Ty<'tcx>,
 384         trait_ref: Option<ty::TraitRef<'tcx>>,
 385     ) -> Result<Self::Path, Self::Error> {
 386         if trait_ref.is_none() {
 387             // Inherent impls. Try to print `Foo::bar` for an inherent
 388             // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is
 389             // anything other than a simple path.
 390             match self_ty.sty {
 391                 ty::Adt(..) | ty::Foreign(_) |
 392                 ty::Bool | ty::Char | ty::Str |
 393                 ty::Int(_) | ty::Uint(_) | ty::Float(_) => {
 394                     return self_ty.print(self);
 395                 }
 396
 397                 _ => {}
 398             }
 399         }
 400
 401         self.generic_delimiters(|mut cx| {
 402             define_scoped_cx!(cx);
 403
 404             p!(print(self_ty));
 405             if let Some(trait_ref) = trait_ref {
 406                 p!(write(" as "), print(trait_ref));
 407             }
 408             Ok(cx)
 409         })
 410     }
 411
 412     fn pretty_path_append_impl(
 413         mut self,
 414         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
 415         self_ty: Ty<'tcx>,
 416         trait_ref: Option<ty::TraitRef<'tcx>>,
 417     ) -> Result<Self::Path, Self::Error> {
 418         self = print_prefix(self)?;
 419
 420         self.generic_delimiters(|mut cx| {
 421             define_scoped_cx!(cx);
 422
 423             p!(write("impl "));
 424             if let Some(trait_ref) = trait_ref {
 425                 p!(print(trait_ref), write(" for "));
 426             }
 427             p!(print(self_ty));
 428
 429             Ok(cx)
 430         })
 431     }
 432
 433     fn pretty_print_type(
 434         mut self,
 435         ty: Ty<'tcx>,
 436     ) -> Result<Self::Type, Self::Error> {
 437         define_scoped_cx!(self);
 438
 439         match ty.sty {
 440             ty::Bool => p!(write("bool")),
 441             ty::Char => p!(write("char")),
 442             ty::Int(t) => p!(write("{}", t.ty_to_string())),
 443             ty::Uint(t) => p!(write("{}", t.ty_to_string())),
 444             ty::Float(t) => p!(write("{}", t.ty_to_string())),
 445             ty::RawPtr(ref tm) => {
 446                 p!(write("*{} ", match tm.mutbl {
 447                     hir::MutMutable => "mut",
 448                     hir::MutImmutable => "const",
 449                 }));
 450                 p!(print(tm.ty))
 451             }
 452             ty::Ref(r, ty, mutbl) => {
 453                 p!(write("&"));
 454                 if self.region_should_not_be_omitted(r) {
 455                     p!(print(r), write(" "));
 456                 }
 457                 p!(print(ty::TypeAndMut { ty, mutbl }))
 458             }
 459             ty::Never => p!(write("!")),
 460             ty::Tuple(ref tys) => {
 461                 p!(write("("));
 462                 let mut tys = tys.iter();
 463                 if let Some(&ty) = tys.next() {
 464                     p!(print(ty), write(","));
 465                     if let Some(&ty) = tys.next() {
 466                         p!(write(" "), print(ty));
 467                         for &ty in tys {
 468                             p!(write(", "), print(ty));
 469                         }
 470                     }
 471                 }
 472                 p!(write(")"))
 473             }
 474             ty::FnDef(def_id, substs) => {
 475                 let sig = self.tcx().fn_sig(def_id).subst(self.tcx(), substs);
 476                 p!(print(sig), write(" {{"), print_value_path(def_id, substs), write("}}"));
 477             }
 478             ty::FnPtr(ref bare_fn) => {
 479                 p!(print(bare_fn))
 480             }
 481             ty::Infer(infer_ty) => p!(write("{}", infer_ty)),
 482             ty::Error => p!(write("[type error]")),
 483             ty::Param(ref param_ty) => p!(write("{}", param_ty)),
 484             ty::Bound(debruijn, bound_ty) => {
 485                 match bound_ty.kind {
 486                     ty::BoundTyKind::Anon => {
 487                         if debruijn == ty::INNERMOST {
 488                             p!(write("^{}", bound_ty.var.index()))
 489                         } else {
 490                             p!(write("^{}_{}", debruijn.index(), bound_ty.var.index()))
 491                         }
 492                     }
 493
 494                     ty::BoundTyKind::Param(p) => p!(write("{}", p)),
 495                 }
 496             }
 497             ty::Adt(def, substs) => {
 498                 p!(print_def_path(def.did, substs));
 499             }
 500             ty::Dynamic(data, r) => {
 501                 let print_r = self.region_should_not_be_omitted(r);
 502                 if print_r {
 503                     p!(write("("));
 504                 }
 505                 p!(write("dyn "), print(data));
 506                 if print_r {
 507                     p!(write(" + "), print(r), write(")"));
 508                 }
 509             }
 510             ty::Foreign(def_id) => {
 511                 p!(print_def_path(def_id, &[]));
 512             }
 513             ty::Projection(ref data) => p!(print(data)),
 514             ty::UnnormalizedProjection(ref data) => {
 515                 p!(write("Unnormalized("), print(data), write(")"))
 516             }
 517             ty::Placeholder(placeholder) => {
 518                 p!(write("Placeholder({:?})", placeholder))
 519             }
 520             ty::Opaque(def_id, substs) => {
 521                 // FIXME(eddyb) print this with `print_def_path`.
 522                 if self.tcx().sess.verbose() {
 523                     p!(write("Opaque({:?}, {:?})", def_id, substs));
 524                     return Ok(self);
 525                 }
 526
 527                 let def_key = self.tcx().def_key(def_id);
 528                 if let Some(name) = def_key.disambiguated_data.data.get_opt_name() {
 529                     p!(write("{}", name));
 530                     let mut substs = substs.iter();
 531                     // FIXME(eddyb) print this with `print_def_path`.
 532                     if let Some(first) = substs.next() {
 533                         p!(write("::<"));
 534                         p!(print(first));
 535                         for subst in substs {
 536                             p!(write(", "), print(subst));
 537                         }
 538                         p!(write(">"));
 539                     }
 540                     return Ok(self);
 541                 }
 542                 // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
 543                 // by looking up the projections associated with the def_id.
 544                 let bounds = self.tcx().predicates_of(def_id).instantiate(self.tcx(), substs);
 545
 546                 let mut first = true;
 547                 let mut is_sized = false;
 548                 p!(write("impl"));
 549                 for predicate in bounds.predicates {
 550                     if let Some(trait_ref) = predicate.to_opt_poly_trait_ref() {
 551                         // Don't print +Sized, but rather +?Sized if absent.
 552                         if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() {
 553                             is_sized = true;
 554                             continue;
 555                         }
 556
 557                         p!(
 558                                 write("{}", if first { " " } else { "+" }),
 559                                 print(trait_ref));
 560                         first = false;
 561                     }
 562                 }
 563                 if !is_sized {
 564                     p!(write("{}?Sized", if first { " " } else { "+" }));
 565                 } else if first {
 566                     p!(write(" Sized"));
 567                 }
 568             }
 569             ty::Str => p!(write("str")),
 570             ty::Generator(did, substs, movability) => {
 571                 let upvar_tys = substs.upvar_tys(did, self.tcx());
 572                 let witness = substs.witness(did, self.tcx());
 573                 if movability == hir::GeneratorMovability::Movable {
 574                     p!(write("[generator"));
 575                 } else {
 576                     p!(write("[static generator"));
 577                 }
 578
 579                 // FIXME(eddyb) should use `def_span`.
 580                 if let Some(hir_id) = self.tcx().hir().as_local_hir_id(did) {
 581                     p!(write("@{:?}", self.tcx().hir().span_by_hir_id(hir_id)));
 582                     let mut sep = " ";
 583                     for (upvar, upvar_ty) in self.tcx().upvars(did)
 584                         .as_ref()
 585                         .map_or(&[][..], |v| &v[..])
 586                         .iter()
 587                         .zip(upvar_tys)
 588                     {
 589                         p!(
 590                             write("{}{}:",
 591                                     sep,
 592                                     self.tcx().hir().name_by_hir_id(upvar.var_id())),
 593                             print(upvar_ty));
 594                         sep = ", ";
 595                     }
 596                 } else {
 597                     // cross-crate closure types should only be
 598                     // visible in codegen bug reports, I imagine.
 599                     p!(write("@{:?}", did));
 600                     let mut sep = " ";
 601                     for (index, upvar_ty) in upvar_tys.enumerate() {
 602                         p!(
 603                                 write("{}{}:", sep, index),
 604                                 print(upvar_ty));
 605                         sep = ", ";
 606                     }
 607                 }
 608
 609                 p!(write(" "), print(witness), write("]"))
 610             },
 611             ty::GeneratorWitness(types) => {
 612                 p!(in_binder(&types));
 613             }
 614             ty::Closure(did, substs) => {
 615                 let upvar_tys = substs.upvar_tys(did, self.tcx());
 616                 p!(write("[closure"));
 617
 618                 // FIXME(eddyb) should use `def_span`.
 619                 if let Some(hir_id) = self.tcx().hir().as_local_hir_id(did) {
 620                     if self.tcx().sess.opts.debugging_opts.span_free_formats {
 621                         p!(write("@{:?}", hir_id));
 622                     } else {
 623                         p!(write("@{:?}", self.tcx().hir().span_by_hir_id(hir_id)));
 624                     }
 625                     let mut sep = " ";
 626                     for (upvar, upvar_ty) in self.tcx().upvars(did)
 627                         .as_ref()
 628                         .map_or(&[][..], |v| &v[..])
 629                         .iter()
 630                         .zip(upvar_tys)
 631                     {
 632                         p!(
 633                             write("{}{}:",
 634                                     sep,
 635                                     self.tcx().hir().name_by_hir_id(upvar.var_id())),
 636                             print(upvar_ty));
 637                         sep = ", ";
 638                     }
 639                 } else {
 640                     // cross-crate closure types should only be
 641                     // visible in codegen bug reports, I imagine.
 642                     p!(write("@{:?}", did));
 643                     let mut sep = " ";
 644                     for (index, upvar_ty) in upvar_tys.enumerate() {
 645                         p!(
 646                                 write("{}{}:", sep, index),
 647                                 print(upvar_ty));
 648                         sep = ", ";
 649                     }
 650                 }
 651
 652                 if self.tcx().sess.verbose() {
 653                     p!(write(
 654                         " closure_kind_ty={:?} closure_sig_ty={:?}",
 655                         substs.closure_kind_ty(did, self.tcx()),
 656                         substs.closure_sig_ty(did, self.tcx())
 657                     ));
 658                 }
 659
 660                 p!(write("]"))
 661             },
 662             ty::Array(ty, sz) => {
 663                 p!(write("["), print(ty), write("; "));
 664                 match sz.val {
 665                     ConstValue::Unevaluated(..) |
 666                     ConstValue::Infer(..) => p!(write("_")),
 667                     ConstValue::Param(ParamConst { name, .. }) =>
 668                         p!(write("{}", name)),
 669                     _ => p!(write("{}", sz.unwrap_usize(self.tcx()))),
 670                 }
 671                 p!(write("]"))
 672             }
 673             ty::Slice(ty) => {
 674                 p!(write("["), print(ty), write("]"))
 675             }
 676         }
 677
 678         Ok(self)
 679     }
 680
 681     fn pretty_print_dyn_existential(
 682         mut self,
 683         predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
 684     ) -> Result<Self::DynExistential, Self::Error> {
 685         define_scoped_cx!(self);
 686
 687         // Generate the main trait ref, including associated types.
 688         let mut first = true;
 689
 690         if let Some(principal) = predicates.principal() {
 691             p!(print_def_path(principal.def_id, &[]));
 692
 693             let mut resugared = false;
 694
 695             // Special-case `Fn(...) -> ...` and resugar it.
 696             let fn_trait_kind = self.tcx().lang_items().fn_trait_kind(principal.def_id);
 697             if !self.tcx().sess.verbose() && fn_trait_kind.is_some() {
 698                 if let ty::Tuple(ref args) = principal.substs.type_at(0).sty {
 699                     let mut projections = predicates.projection_bounds();
 700                     if let (Some(proj), None) = (projections.next(), projections.next()) {
 701                         let tys: Vec<_> = args.iter().map(|k| k.expect_ty()).collect();
 702                         p!(pretty_fn_sig(&tys, false, proj.ty));
 703                         resugared = true;
 704                     }
 705                 }
 706             }
 707
 708             // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`,
 709             // in order to place the projections inside the `<...>`.
 710             if !resugared {
 711                 // Use a type that can't appear in defaults of type parameters.
 712                 let dummy_self = self.tcx().mk_ty_infer(ty::FreshTy(0));
 713                 let principal = principal.with_self_ty(self.tcx(), dummy_self);
 714
 715                 let args = self.generic_args_to_print(
 716                     self.tcx().generics_of(principal.def_id),
 717                     principal.substs,
 718                 );
 719
 720                 // Don't print `'_` if there's no unerased regions.
 721                 let print_regions = args.iter().any(|arg| {
 722                     match arg.unpack() {
 723                         UnpackedKind::Lifetime(r) => *r != ty::ReErased,
 724                         _ => false,
 725                     }
 726                 });
 727                 let mut args = args.iter().cloned().filter(|arg| {
 728                     match arg.unpack() {
 729                         UnpackedKind::Lifetime(_) => print_regions,
 730                         _ => true,
 731                     }
 732                 });
 733                 let mut projections = predicates.projection_bounds();
 734
 735                 let arg0 = args.next();
 736                 let projection0 = projections.next();
 737                 if arg0.is_some() || projection0.is_some() {
 738                     let args = arg0.into_iter().chain(args);
 739                     let projections = projection0.into_iter().chain(projections);
 740
 741                     p!(generic_delimiters(|mut cx| {
 742                         cx = cx.comma_sep(args)?;
 743                         if arg0.is_some() && projection0.is_some() {
 744                             write!(cx, ", ")?;
 745                         }
 746                         cx.comma_sep(projections)
 747                     }));
 748                 }
 749             }
 750             first = false;
 751         }
 752
 753         // Builtin bounds.
 754         // FIXME(eddyb) avoid printing twice (needed to ensure
 755         // that the auto traits are sorted *and* printed via cx).
 756         let mut auto_traits: Vec<_> = predicates.auto_traits().map(|did| {
 757             (self.tcx().def_path_str(did), did)
 758         }).collect();
 759
 760         // The auto traits come ordered by `DefPathHash`. While
 761         // `DefPathHash` is *stable* in the sense that it depends on
 762         // neither the host nor the phase of the moon, it depends
 763         // "pseudorandomly" on the compiler version and the target.
 764         //
 765         // To avoid that causing instabilities in compiletest
 766         // output, sort the auto-traits alphabetically.
 767         auto_traits.sort();
 768
 769         for (_, def_id) in auto_traits {
 770             if !first {
 771                 p!(write(" + "));
 772             }
 773             first = false;
 774
 775             p!(print_def_path(def_id, &[]));
 776         }
 777
 778         Ok(self)
 779     }
 780
 781     fn pretty_fn_sig(
 782         mut self,
 783         inputs: &[Ty<'tcx>],
 784         c_variadic: bool,
 785         output: Ty<'tcx>,
 786     ) -> Result<Self, Self::Error> {
 787         define_scoped_cx!(self);
 788
 789         p!(write("("));
 790         let mut inputs = inputs.iter();
 791         if let Some(&ty) = inputs.next() {
 792             p!(print(ty));
 793             for &ty in inputs {
 794                 p!(write(", "), print(ty));
 795             }
 796             if c_variadic {
 797                 p!(write(", ..."));
 798             }
 799         }
 800         p!(write(")"));
 801         if !output.is_unit() {
 802             p!(write(" -> "), print(output));
 803         }
 804
 805         Ok(self)
 806     }
 807 }
 808
 809 // HACK(eddyb) boxed to avoid moving around a large struct by-value.
 810 pub struct FmtPrinter<'a, 'gcx, 'tcx, F>(Box<FmtPrinterData<'a, 'gcx, 'tcx, F>>);
 811
 812 pub struct FmtPrinterData<'a, 'gcx, 'tcx, F> {
 813     tcx: TyCtxt<'a, 'gcx, 'tcx>,
 814     fmt: F,
 815
 816     empty_path: bool,
 817     in_value: bool,
 818
 819     used_region_names: FxHashSet<InternedString>,
 820     region_index: usize,
 821     binder_depth: usize,
 822
 823     pub region_highlight_mode: RegionHighlightMode,
 824 }
 825
 826 impl<F> Deref for FmtPrinter<'a, 'gcx, 'tcx, F> {
 827     type Target = FmtPrinterData<'a, 'gcx, 'tcx, F>;
 828     fn deref(&self) -> &Self::Target {
 829         &self.0
 830     }
 831 }
 832
 833 impl<F> DerefMut for FmtPrinter<'_, '_, '_, F> {
 834     fn deref_mut(&mut self) -> &mut Self::Target {
 835         &mut self.0
 836     }
 837 }
 838
 839 impl<F> FmtPrinter<'a, 'gcx, 'tcx, F> {
 840     pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>, fmt: F, ns: Namespace) -> Self {
 841         FmtPrinter(Box::new(FmtPrinterData {
 842             tcx,
 843             fmt,
 844             empty_path: false,
 845             in_value: ns == Namespace::ValueNS,
 846             used_region_names: Default::default(),
 847             region_index: 0,
 848             binder_depth: 0,
 849             region_highlight_mode: RegionHighlightMode::default(),
 850         }))
 851     }
 852 }
 853
 854 impl TyCtxt<'_, '_, '_> {
 855     // HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
 856     // (but also some things just print a `DefId` generally so maybe we need this?)
 857     fn guess_def_namespace(self, def_id: DefId) -> Namespace {
 858         match self.def_key(def_id).disambiguated_data.data {
 859             DefPathData::TypeNs(..)
 860             | DefPathData::CrateRoot
 861             | DefPathData::ImplTrait => Namespace::TypeNS,
 862
 863             DefPathData::ValueNs(..)
 864             | DefPathData::AnonConst
 865             | DefPathData::ClosureExpr
 866             | DefPathData::Ctor => Namespace::ValueNS,
 867
 868             DefPathData::MacroNs(..) => Namespace::MacroNS,
 869
 870             _ => Namespace::TypeNS,
 871         }
 872     }
 873
 874     /// Returns a string identifying this `DefId`. This string is
 875     /// suitable for user output.
 876     pub fn def_path_str(self, def_id: DefId) -> String {
 877         let ns = self.guess_def_namespace(def_id);
 878         debug!("def_path_str: def_id={:?}, ns={:?}", def_id, ns);
 879         let mut s = String::new();
 880         let _ = FmtPrinter::new(self, &mut s, ns)
 881             .print_def_path(def_id, &[]);
 882         s
 883     }
 884 }
 885
 886 impl<F: fmt::Write> fmt::Write for FmtPrinter<'_, '_, '_, F> {
 887     fn write_str(&mut self, s: &str) -> fmt::Result {
 888         self.fmt.write_str(s)
 889     }
 890 }
 891
 892 impl<F: fmt::Write> Printer<'gcx, 'tcx> for FmtPrinter<'_, 'gcx, 'tcx, F> {
 893     type Error = fmt::Error;
 894
 895     type Path = Self;
 896     type Region = Self;
 897     type Type = Self;
 898     type DynExistential = Self;
 899
 900     fn tcx(&'a self) -> TyCtxt<'a, 'gcx, 'tcx> {
 901         self.tcx
 902     }
 903
 904     fn print_def_path(
 905         mut self,
 906         def_id: DefId,
 907         substs: &'tcx [Kind<'tcx>],
 908     ) -> Result<Self::Path, Self::Error> {
 909         define_scoped_cx!(self);
 910
 911         if substs.is_empty() {
 912             match self.try_print_visible_def_path(def_id)? {
 913                 (cx, true) => return Ok(cx),
 914                 (cx, false) => self = cx,
 915             }
 916         }
 917
 918         let key = self.tcx.def_key(def_id);
 919         if let DefPathData::Impl = key.disambiguated_data.data {
 920             // Always use types for non-local impls, where types are always
 921             // available, and filename/line-number is mostly uninteresting.
 922             let use_types =
 923                 !def_id.is_local() || {
 924                     // Otherwise, use filename/line-number if forced.
 925                     let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
 926                     !force_no_types
 927                 };
 928
 929             if !use_types {
 930                 // If no type info is available, fall back to
 931                 // pretty printing some span information. This should
 932                 // only occur very early in the compiler pipeline.
 933                 let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id };
 934                 let span = self.tcx.def_span(def_id);
 935
 936                 self = self.print_def_path(parent_def_id, &[])?;
 937
 938                 // HACK(eddyb) copy of `path_append` to avoid
 939                 // constructing a `DisambiguatedDefPathData`.
 940                 if !self.empty_path {
 941                     write!(self, "::")?;
 942                 }
 943                 write!(self, "<impl at {:?}>", span)?;
 944                 self.empty_path = false;
 945
 946                 return Ok(self);
 947             }
 948         }
 949
 950         self.default_print_def_path(def_id, substs)
 951     }
 952
 953     fn print_region(
 954         self,
 955         region: ty::Region<'_>,
 956     ) -> Result<Self::Region, Self::Error> {
 957         self.pretty_print_region(region)
 958     }
 959
 960     fn print_type(
 961         self,
 962         ty: Ty<'tcx>,
 963     ) -> Result<Self::Type, Self::Error> {
 964         self.pretty_print_type(ty)
 965     }
 966
 967     fn print_dyn_existential(
 968         self,
 969         predicates: &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
 970     ) -> Result<Self::DynExistential, Self::Error> {
 971         self.pretty_print_dyn_existential(predicates)
 972     }
 973
 974     fn path_crate(
 975         mut self,
 976         cnum: CrateNum,
 977     ) -> Result<Self::Path, Self::Error> {
 978         self.empty_path = true;
 979         if cnum == LOCAL_CRATE {
 980             if self.tcx.sess.rust_2018() {
 981                 // We add the `crate::` keyword on Rust 2018, only when desired.
 982                 if SHOULD_PREFIX_WITH_CRATE.with(|flag| flag.get()) {
 983                     write!(self, "{}", kw::Crate)?;
 984                     self.empty_path = false;
 985                 }
 986             }
 987         } else {
 988             write!(self, "{}", self.tcx.crate_name(cnum))?;
 989             self.empty_path = false;
 990         }
 991         Ok(self)
 992     }
 993     fn path_qualified(
 994         mut self,
 995         self_ty: Ty<'tcx>,
 996         trait_ref: Option<ty::TraitRef<'tcx>>,
 997     ) -> Result<Self::Path, Self::Error> {
 998         self = self.pretty_path_qualified(self_ty, trait_ref)?;
 999         self.empty_path = false;
1000         Ok(self)
1001     }
1002
1003     fn path_append_impl(
1004         mut self,
1005         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1006         _disambiguated_data: &DisambiguatedDefPathData,
1007         self_ty: Ty<'tcx>,
1008         trait_ref: Option<ty::TraitRef<'tcx>>,
1009     ) -> Result<Self::Path, Self::Error> {
1010         self = self.pretty_path_append_impl(|mut cx| {
1011             cx = print_prefix(cx)?;
1012             if !cx.empty_path {
1013                 write!(cx, "::")?;
1014             }
1015
1016             Ok(cx)
1017         }, self_ty, trait_ref)?;
1018         self.empty_path = false;
1019         Ok(self)
1020     }
1021     fn path_append(
1022         mut self,
1023         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1024         disambiguated_data: &DisambiguatedDefPathData,
1025     ) -> Result<Self::Path, Self::Error> {
1026         self = print_prefix(self)?;
1027
1028         // Skip `::{{constructor}}` on tuple/unit structs.
1029         match disambiguated_data.data {
1030             DefPathData::Ctor => return Ok(self),
1031             _ => {}
1032         }
1033
1034         // FIXME(eddyb) `name` should never be empty, but it
1035         // currently is for `extern { ... }` "foreign modules".
1036         let name = disambiguated_data.data.as_interned_str().as_str();
1037         if !name.is_empty() {
1038             if !self.empty_path {
1039                 write!(self, "::")?;
1040             }
1041             write!(self, "{}", name)?;
1042
1043             // FIXME(eddyb) this will print e.g. `{{closure}}#3`, but it
1044             // might be nicer to use something else, e.g. `{closure#3}`.
1045             let dis = disambiguated_data.disambiguator;
1046             let print_dis =
1047                 disambiguated_data.data.get_opt_name().is_none() ||
1048                 dis != 0 && self.tcx.sess.verbose();
1049             if print_dis {
1050                 write!(self, "#{}", dis)?;
1051             }
1052
1053             self.empty_path = false;
1054         }
1055
1056         Ok(self)
1057     }
1058     fn path_generic_args(
1059         mut self,
1060         print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>,
1061         args: &[Kind<'tcx>],
1062     ) -> Result<Self::Path, Self::Error> {
1063         self = print_prefix(self)?;
1064
1065         // Don't print `'_` if there's no unerased regions.
1066         let print_regions = args.iter().any(|arg| {
1067             match arg.unpack() {
1068                 UnpackedKind::Lifetime(r) => *r != ty::ReErased,
1069                 _ => false,
1070             }
1071         });
1072         let args = args.iter().cloned().filter(|arg| {
1073             match arg.unpack() {
1074                 UnpackedKind::Lifetime(_) => print_regions,
1075                 _ => true,
1076             }
1077         });
1078
1079         if args.clone().next().is_some() {
1080             if self.in_value {
1081                 write!(self, "::")?;
1082             }
1083             self.generic_delimiters(|cx| cx.comma_sep(args))
1084         } else {
1085             Ok(self)
1086         }
1087     }
1088 }
1089
1090 impl<F: fmt::Write> PrettyPrinter<'gcx, 'tcx> for FmtPrinter<'_, 'gcx, 'tcx, F> {
1091     fn print_value_path(
1092         mut self,
1093         def_id: DefId,
1094         substs: &'tcx [Kind<'tcx>],
1095     ) -> Result<Self::Path, Self::Error> {
1096         let was_in_value = std::mem::replace(&mut self.in_value, true);
1097         self = self.print_def_path(def_id, substs)?;
1098         self.in_value = was_in_value;
1099
1100         Ok(self)
1101     }
1102
1103     fn in_binder<T>(
1104         self,
1105         value: &ty::Binder<T>,
1106     ) -> Result<Self, Self::Error>
1107         where T: Print<'gcx, 'tcx, Self, Output = Self, Error = Self::Error> + TypeFoldable<'tcx>
1108     {
1109         self.pretty_in_binder(value)
1110     }
1111
1112     fn generic_delimiters(
1113         mut self,
1114         f: impl FnOnce(Self) -> Result<Self, Self::Error>,
1115     ) -> Result<Self, Self::Error> {
1116         write!(self, "<")?;
1117
1118         let was_in_value = std::mem::replace(&mut self.in_value, false);
1119         let mut inner = f(self)?;
1120         inner.in_value = was_in_value;
1121
1122         write!(inner, ">")?;
1123         Ok(inner)
1124     }
1125
1126     fn region_should_not_be_omitted(
1127         &self,
1128         region: ty::Region<'_>,
1129     ) -> bool {
1130         let highlight = self.region_highlight_mode;
1131         if highlight.region_highlighted(region).is_some() {
1132             return true;
1133         }
1134
1135         if self.tcx.sess.verbose() {
1136             return true;
1137         }
1138
1139         let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions;
1140
1141         match *region {
1142             ty::ReEarlyBound(ref data) => {
1143                 data.name.as_symbol() != kw::Invalid &&
1144                 data.name.as_symbol() != kw::UnderscoreLifetime
1145             }
1146
1147             ty::ReLateBound(_, br) |
1148             ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
1149             ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1150                 if let ty::BrNamed(_, name) = br {
1151                     if name.as_symbol() != kw::Invalid &&
1152                        name.as_symbol() != kw::UnderscoreLifetime {
1153                         return true;
1154                     }
1155                 }
1156
1157                 if let Some((region, _)) = highlight.highlight_bound_region {
1158                     if br == region {
1159                         return true;
1160                     }
1161                 }
1162
1163                 false
1164             }
1165
1166             ty::ReScope(_) |
1167             ty::ReVar(_) if identify_regions => true,
1168
1169             ty::ReVar(_) |
1170             ty::ReScope(_) |
1171             ty::ReErased => false,
1172
1173             ty::ReStatic |
1174             ty::ReEmpty |
1175             ty::ReClosureBound(_) => true,
1176         }
1177     }
1178 }
1179
1180 // HACK(eddyb) limited to `FmtPrinter` because of `region_highlight_mode`.
1181 impl<F: fmt::Write> FmtPrinter<'_, '_, '_, F> {
1182     pub fn pretty_print_region(
1183         mut self,
1184         region: ty::Region<'_>,
1185     ) -> Result<Self, fmt::Error> {
1186         define_scoped_cx!(self);
1187
1188         // Watch out for region highlights.
1189         let highlight = self.region_highlight_mode;
1190         if let Some(n) = highlight.region_highlighted(region) {
1191             p!(write("'{}", n));
1192             return Ok(self);
1193         }
1194
1195         if self.tcx.sess.verbose() {
1196             p!(write("{:?}", region));
1197             return Ok(self);
1198         }
1199
1200         let identify_regions = self.tcx.sess.opts.debugging_opts.identify_regions;
1201
1202         // These printouts are concise.  They do not contain all the information
1203         // the user might want to diagnose an error, but there is basically no way
1204         // to fit that into a short string.  Hence the recommendation to use
1205         // `explain_region()` or `note_and_explain_region()`.
1206         match *region {
1207             ty::ReEarlyBound(ref data) => {
1208                 if data.name.as_symbol() != kw::Invalid {
1209                     p!(write("{}", data.name));
1210                     return Ok(self);
1211                 }
1212             }
1213             ty::ReLateBound(_, br) |
1214             ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
1215             ty::RePlaceholder(ty::Placeholder { name: br, .. }) => {
1216                 if let ty::BrNamed(_, name) = br {
1217                     if name.as_symbol() != kw::Invalid &&
1218                        name.as_symbol() != kw::UnderscoreLifetime {
1219                         p!(write("{}", name));
1220                         return Ok(self);
1221                     }
1222                 }
1223
1224                 if let Some((region, counter)) = highlight.highlight_bound_region {
1225                     if br == region {
1226                         p!(write("'{}", counter));
1227                         return Ok(self);
1228                     }
1229                 }
1230             }
1231             ty::ReScope(scope) if identify_regions => {
1232                 match scope.data {
1233                     region::ScopeData::Node =>
1234                         p!(write("'{}s", scope.item_local_id().as_usize())),
1235                     region::ScopeData::CallSite =>
1236                         p!(write("'{}cs", scope.item_local_id().as_usize())),
1237                     region::ScopeData::Arguments =>
1238                         p!(write("'{}as", scope.item_local_id().as_usize())),
1239                     region::ScopeData::Destruction =>
1240                         p!(write("'{}ds", scope.item_local_id().as_usize())),
1241                     region::ScopeData::Remainder(first_statement_index) => p!(write(
1242                         "'{}_{}rs",
1243                         scope.item_local_id().as_usize(),
1244                         first_statement_index.index()
1245                     )),
1246                 }
1247                 return Ok(self);
1248             }
1249             ty::ReVar(region_vid) if identify_regions => {
1250                 p!(write("{:?}", region_vid));
1251                 return Ok(self);
1252             }
1253             ty::ReVar(_) => {}
1254             ty::ReScope(_) |
1255             ty::ReErased => {}
1256             ty::ReStatic => {
1257                 p!(write("'static"));
1258                 return Ok(self);
1259             }
1260             ty::ReEmpty => {
1261                 p!(write("'<empty>"));
1262                 return Ok(self);
1263             }
1264
1265             // The user should never encounter these in unsubstituted form.
1266             ty::ReClosureBound(vid) => {
1267                 p!(write("{:?}", vid));
1268                 return Ok(self);
1269             }
1270         }
1271
1272         p!(write("'_"));
1273
1274         Ok(self)
1275     }
1276 }
1277
1278 // HACK(eddyb) limited to `FmtPrinter` because of `binder_depth`,
1279 // `region_index` and `used_region_names`.
1280 impl<F: fmt::Write> FmtPrinter<'_, 'gcx, 'tcx, F> {
1281     pub fn pretty_in_binder<T>(
1282         mut self,
1283         value: &ty::Binder<T>,
1284     ) -> Result<Self, fmt::Error>
1285         where T: Print<'gcx, 'tcx, Self, Output = Self, Error = fmt::Error> + TypeFoldable<'tcx>
1286     {
1287         fn name_by_region_index(index: usize) -> InternedString {
1288             match index {
1289                 0 => InternedString::intern("'r"),
1290                 1 => InternedString::intern("'s"),
1291                 i => InternedString::intern(&format!("'t{}", i-2)),
1292             }
1293         }
1294
1295         // Replace any anonymous late-bound regions with named
1296         // variants, using gensym'd identifiers, so that we can
1297         // clearly differentiate between named and unnamed regions in
1298         // the output. We'll probably want to tweak this over time to
1299         // decide just how much information to give.
1300         if self.binder_depth == 0 {
1301             self.prepare_late_bound_region_info(value);
1302         }
1303
1304         let mut empty = true;
1305         let mut start_or_continue = |cx: &mut Self, start: &str, cont: &str| {
1306             write!(cx, "{}", if empty {
1307                 empty = false;
1308                 start
1309             } else {
1310                 cont
1311             })
1312         };
1313
1314         define_scoped_cx!(self);
1315
1316         let old_region_index = self.region_index;
1317         let mut region_index = old_region_index;
1318         let new_value = self.tcx.replace_late_bound_regions(value, |br| {
1319             let _ = start_or_continue(&mut self, "for<", ", ");
1320             let br = match br {
1321                 ty::BrNamed(_, name) => {
1322                     let _ = write!(self, "{}", name);
1323                     br
1324                 }
1325                 ty::BrAnon(_) |
1326                 ty::BrFresh(_) |
1327                 ty::BrEnv => {
1328                     let name = loop {
1329                         let name = name_by_region_index(region_index);
1330                         region_index += 1;
1331                         if !self.used_region_names.contains(&name) {
1332                             break name;
1333                         }
1334                     };
1335                     let _ = write!(self, "{}", name);
1336                     ty::BrNamed(DefId::local(CRATE_DEF_INDEX), name)
1337                 }
1338             };
1339             self.tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
1340         }).0;
1341         start_or_continue(&mut self, "", "> ")?;
1342
1343         self.binder_depth += 1;
1344         self.region_index = region_index;
1345         let mut inner = new_value.print(self)?;
1346         inner.region_index = old_region_index;
1347         inner.binder_depth -= 1;
1348         Ok(inner)
1349     }
1350
1351     fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<T>)
1352         where T: TypeFoldable<'tcx>
1353     {
1354
1355         struct LateBoundRegionNameCollector<'a>(&'a mut FxHashSet<InternedString>);
1356         impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector<'_> {
1357             fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
1358                 match *r {
1359                     ty::ReLateBound(_, ty::BrNamed(_, name)) => {
1360                         self.0.insert(name);
1361                     },
1362                     _ => {},
1363                 }
1364                 r.super_visit_with(self)
1365             }
1366         }
1367
1368         self.used_region_names.clear();
1369         let mut collector = LateBoundRegionNameCollector(&mut self.used_region_names);
1370         value.visit_with(&mut collector);
1371         self.region_index = 0;
1372     }
1373 }
1374
1375 impl<'gcx: 'tcx, 'tcx, T, P: PrettyPrinter<'gcx, 'tcx>> Print<'gcx, 'tcx, P>
1376     for ty::Binder<T>
1377     where T: Print<'gcx, 'tcx, P, Output = P, Error = P::Error> + TypeFoldable<'tcx>
1378 {
1379     type Output = P;
1380     type Error = P::Error;
1381     fn print(&self, cx: P) -> Result<Self::Output, Self::Error> {
1382         cx.in_binder(self)
1383     }
1384 }
1385
1386 impl<'gcx: 'tcx, 'tcx, T, U, P: PrettyPrinter<'gcx, 'tcx>> Print<'gcx, 'tcx, P>
1387     for ty::OutlivesPredicate<T, U>
1388     where T: Print<'gcx, 'tcx, P, Output = P, Error = P::Error>,
1389           U: Print<'gcx, 'tcx, P, Output = P, Error = P::Error>,
1390 {
1391     type Output = P;
1392     type Error = P::Error;
1393     fn print(&self, mut cx: P) -> Result<Self::Output, Self::Error> {
1394         define_scoped_cx!(cx);
1395         p!(print(self.0), write(" : "), print(self.1));
1396         Ok(cx)
1397     }
1398 }
1399
1400 macro_rules! forward_display_to_print {
1401     ($($ty:ty),+) => {
1402         $(impl fmt::Display for $ty {
1403             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1404                 ty::tls::with(|tcx| {
1405                     tcx.lift(self)
1406                         .expect("could not lift for printing")
1407                         .print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?;
1408                     Ok(())
1409                 })
1410             }
1411         })+
1412     };
1413 }
1414
1415 macro_rules! define_print_and_forward_display {
1416     (($self:ident, $cx:ident): $($ty:ty $print:block)+) => {
1417         $(impl<'gcx: 'tcx, 'tcx, P: PrettyPrinter<'gcx, 'tcx>> Print<'gcx, 'tcx, P> for $ty {
1418             type Output = P;
1419             type Error = fmt::Error;
1420             fn print(&$self, $cx: P) -> Result<Self::Output, Self::Error> {
1421                 #[allow(unused_mut)]
1422                 let mut $cx = $cx;
1423                 define_scoped_cx!($cx);
1424                 let _: () = $print;
1425                 #[allow(unreachable_code)]
1426                 Ok($cx)
1427             }
1428         })+
1429
1430         forward_display_to_print!($($ty),+);
1431     };
1432 }
1433
1434 // HACK(eddyb) this is separate because `ty::RegionKind` doesn't need lifting.
1435 impl fmt::Display for ty::RegionKind {
1436     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1437         ty::tls::with(|tcx| {
1438             self.print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?;
1439             Ok(())
1440         })
1441     }
1442 }
1443
1444 forward_display_to_print! {
1445     Ty<'tcx>,
1446     &'tcx ty::List<ty::ExistentialPredicate<'tcx>>,
1447
1448     // HACK(eddyb) these are exhaustive instead of generic,
1449     // because `for<'gcx: 'tcx, 'tcx>` isn't possible yet.
1450     ty::Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>,
1451     ty::Binder<ty::TraitRef<'tcx>>,
1452     ty::Binder<ty::FnSig<'tcx>>,
1453     ty::Binder<ty::TraitPredicate<'tcx>>,
1454     ty::Binder<ty::SubtypePredicate<'tcx>>,
1455     ty::Binder<ty::ProjectionPredicate<'tcx>>,
1456     ty::Binder<ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
1457     ty::Binder<ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>,
1458
1459     ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>,
1460     ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>
1461 }
1462
1463 define_print_and_forward_display! {
1464     (self, cx):
1465
1466     &'tcx ty::List<Ty<'tcx>> {
1467         p!(write("{{"));
1468         let mut tys = self.iter();
1469         if let Some(&ty) = tys.next() {
1470             p!(print(ty));
1471             for &ty in tys {
1472                 p!(write(", "), print(ty));
1473             }
1474         }
1475         p!(write("}}"))
1476     }
1477
1478     ty::TypeAndMut<'tcx> {
1479         p!(write("{}", if self.mutbl == hir::MutMutable { "mut " } else { "" }),
1480             print(self.ty))
1481     }
1482
1483     ty::ExistentialTraitRef<'tcx> {
1484         // Use a type that can't appear in defaults of type parameters.
1485         let dummy_self = cx.tcx().mk_ty_infer(ty::FreshTy(0));
1486         let trait_ref = self.with_self_ty(cx.tcx(), dummy_self);
1487         p!(print(trait_ref))
1488     }
1489
1490     ty::ExistentialProjection<'tcx> {
1491         let name = cx.tcx().associated_item(self.item_def_id).ident;
1492         p!(write("{} = ", name), print(self.ty))
1493     }
1494
1495     ty::ExistentialPredicate<'tcx> {
1496         match *self {
1497             ty::ExistentialPredicate::Trait(x) => p!(print(x)),
1498             ty::ExistentialPredicate::Projection(x) => p!(print(x)),
1499             ty::ExistentialPredicate::AutoTrait(def_id) => {
1500                 p!(print_def_path(def_id, &[]));
1501             }
1502         }
1503     }
1504
1505     ty::FnSig<'tcx> {
1506         if self.unsafety == hir::Unsafety::Unsafe {
1507             p!(write("unsafe "));
1508         }
1509
1510         if self.abi != Abi::Rust {
1511             p!(write("extern {} ", self.abi));
1512         }
1513
1514         p!(write("fn"), pretty_fn_sig(self.inputs(), self.c_variadic, self.output()));
1515     }
1516
1517     ty::InferTy {
1518         if cx.tcx().sess.verbose() {
1519             p!(write("{:?}", self));
1520             return Ok(cx);
1521         }
1522         match *self {
1523             ty::TyVar(_) => p!(write("_")),
1524             ty::IntVar(_) => p!(write("{}", "{integer}")),
1525             ty::FloatVar(_) => p!(write("{}", "{float}")),
1526             ty::FreshTy(v) => p!(write("FreshTy({})", v)),
1527             ty::FreshIntTy(v) => p!(write("FreshIntTy({})", v)),
1528             ty::FreshFloatTy(v) => p!(write("FreshFloatTy({})", v))
1529         }
1530     }
1531
1532     ty::TraitRef<'tcx> {
1533         p!(print_def_path(self.def_id, self.substs));
1534     }
1535
1536     &'tcx ty::Const<'tcx> {
1537         match self.val {
1538             ConstValue::Unevaluated(..) |
1539             ConstValue::Infer(..) => p!(write("_")),
1540             ConstValue::Param(ParamConst { name, .. }) => p!(write("{}", name)),
1541             _ => p!(write("{:?}", self)),
1542         }
1543     }
1544
1545     ty::ParamTy {
1546         p!(write("{}", self.name))
1547     }
1548
1549     ty::ParamConst {
1550         p!(write("{}", self.name))
1551     }
1552
1553     ty::SubtypePredicate<'tcx> {
1554         p!(print(self.a), write(" <: "), print(self.b))
1555     }
1556
1557     ty::TraitPredicate<'tcx> {
1558         p!(print(self.trait_ref.self_ty()), write(": "), print(self.trait_ref))
1559     }
1560
1561     ty::ProjectionPredicate<'tcx> {
1562         p!(print(self.projection_ty), write(" == "), print(self.ty))
1563     }
1564
1565     ty::ProjectionTy<'tcx> {
1566         p!(print_def_path(self.item_def_id, self.substs));
1567     }
1568
1569     ty::ClosureKind {
1570         match *self {
1571             ty::ClosureKind::Fn => p!(write("Fn")),
1572             ty::ClosureKind::FnMut => p!(write("FnMut")),
1573             ty::ClosureKind::FnOnce => p!(write("FnOnce")),
1574         }
1575     }
1576
1577     ty::Predicate<'tcx> {
1578         match *self {
1579             ty::Predicate::Trait(ref data) => p!(print(data)),
1580             ty::Predicate::Subtype(ref predicate) => p!(print(predicate)),
1581             ty::Predicate::RegionOutlives(ref predicate) => p!(print(predicate)),
1582             ty::Predicate::TypeOutlives(ref predicate) => p!(print(predicate)),
1583             ty::Predicate::Projection(ref predicate) => p!(print(predicate)),
1584             ty::Predicate::WellFormed(ty) => p!(print(ty), write(" well-formed")),
1585             ty::Predicate::ObjectSafe(trait_def_id) => {
1586                 p!(write("the trait `"),
1587                    print_def_path(trait_def_id, &[]),
1588                    write("` is object-safe"))
1589             }
1590             ty::Predicate::ClosureKind(closure_def_id, _closure_substs, kind) => {
1591                 p!(write("the closure `"),
1592                    print_value_path(closure_def_id, &[]),
1593                    write("` implements the trait `{}`", kind))
1594             }
1595             ty::Predicate::ConstEvaluatable(def_id, substs) => {
1596                 p!(write("the constant `"),
1597                    print_value_path(def_id, substs),
1598                    write("` can be evaluated"))
1599             }
1600         }
1601     }
1602
1603     Kind<'tcx> {
1604         match self.unpack() {
1605             UnpackedKind::Lifetime(lt) => p!(print(lt)),
1606             UnpackedKind::Type(ty) => p!(print(ty)),
1607             UnpackedKind::Const(ct) => p!(print(ct)),
1608         }
1609     }
1610 }