src/librustc/util/ppaux.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11
  12 use middle::def_id::DefId;
  13 use middle::subst::{self, Subst};
  14 use middle::ty::{BoundRegion, BrAnon, BrNamed};
  15 use middle::ty::{ReEarlyBound, BrFresh, ctxt};
  16 use middle::ty::{ReFree, ReScope, ReStatic, Region, ReEmpty};
  17 use middle::ty::{ReSkolemized, ReVar, BrEnv};
  18 use middle::ty::{TyBool, TyChar, TyStruct, TyEnum};
  19 use middle::ty::{TyError, TyStr, TyArray, TySlice, TyFloat, TyBareFn};
  20 use middle::ty::{TyParam, TyRawPtr, TyRef, TyTuple};
  21 use middle::ty::TyClosure;
  22 use middle::ty::{TyBox, TyTrait, TyInt, TyUint, TyInfer};
  23 use middle::ty::{self, TypeAndMut, Ty, HasTypeFlags};
  24 use middle::ty::fold::TypeFoldable;
  25
  26 use std::fmt;
  27 use syntax::abi;
  28 use syntax::ast;
  29 use syntax::parse::token;
  30 use syntax::ast::CRATE_NODE_ID;
  31 use rustc_front::hir;
  32
  33 pub fn verbose() -> bool {
  34     ty::tls::with(|tcx| tcx.sess.verbose())
  35 }
  36
  37 fn fn_sig(f: &mut fmt::Formatter,
  38           inputs: &[Ty],
  39           variadic: bool,
  40           output: ty::FnOutput)
  41           -> fmt::Result {
  42     try!(write!(f, "("));
  43     let mut inputs = inputs.iter();
  44     if let Some(&ty) = inputs.next() {
  45         try!(write!(f, "{}", ty));
  46         for &ty in inputs {
  47             try!(write!(f, ", {}", ty));
  48         }
  49         if variadic {
  50             try!(write!(f, ", ..."));
  51         }
  52     }
  53     try!(write!(f, ")"));
  54
  55     match output {
  56         ty::FnConverging(ty) => {
  57             if !ty.is_nil() {
  58                 try!(write!(f, " -> {}", ty));
  59             }
  60             Ok(())
  61         }
  62         ty::FnDiverging => {
  63             write!(f, " -> !")
  64         }
  65     }
  66 }
  67
  68 fn parameterized<GG>(f: &mut fmt::Formatter,
  69                      substs: &subst::Substs,
  70                      did: DefId,
  71                      projections: &[ty::ProjectionPredicate],
  72                      get_generics: GG)
  73                      -> fmt::Result
  74     where GG: for<'tcx> FnOnce(&ty::ctxt<'tcx>) -> ty::Generics<'tcx>
  75 {
  76     let (fn_trait_kind, verbose) = try!(ty::tls::with(|tcx| {
  77         try!(write!(f, "{}", tcx.item_path_str(did)));
  78         Ok((tcx.lang_items.fn_trait_kind(did), tcx.sess.verbose()))
  79     }));
  80
  81     let mut empty = true;
  82     let mut start_or_continue = |f: &mut fmt::Formatter, start: &str, cont: &str| {
  83         if empty {
  84             empty = false;
  85             write!(f, "{}", start)
  86         } else {
  87             write!(f, "{}", cont)
  88         }
  89     };
  90
  91     if verbose {
  92         match substs.regions {
  93             subst::ErasedRegions => {
  94                 try!(start_or_continue(f, "<", ", "));
  95                 try!(write!(f, ".."));
  96             }
  97             subst::NonerasedRegions(ref regions) => {
  98                 for region in regions {
  99                     try!(start_or_continue(f, "<", ", "));
 100                     try!(write!(f, "{:?}", region));
 101                 }
 102             }
 103         }
 104         for &ty in &substs.types {
 105             try!(start_or_continue(f, "<", ", "));
 106             try!(write!(f, "{}", ty));
 107         }
 108         for projection in projections {
 109             try!(start_or_continue(f, "<", ", "));
 110             try!(write!(f, "{}={}",
 111                         projection.projection_ty.item_name,
 112                         projection.ty));
 113         }
 114         return start_or_continue(f, "", ">");
 115     }
 116
 117     if fn_trait_kind.is_some() && projections.len() == 1 {
 118         let projection_ty = projections[0].ty;
 119         if let TyTuple(ref args) = substs.types.get_slice(subst::TypeSpace)[0].sty {
 120             return fn_sig(f, args, false, ty::FnConverging(projection_ty));
 121         }
 122     }
 123
 124     match substs.regions {
 125         subst::ErasedRegions => { }
 126         subst::NonerasedRegions(ref regions) => {
 127             for &r in regions {
 128                 try!(start_or_continue(f, "<", ", "));
 129                 let s = r.to_string();
 130                 if s.is_empty() {
 131                     // This happens when the value of the region
 132                     // parameter is not easily serialized. This may be
 133                     // because the user omitted it in the first place,
 134                     // or because it refers to some block in the code,
 135                     // etc. I'm not sure how best to serialize this.
 136                     try!(write!(f, "'_"));
 137                 } else {
 138                     try!(write!(f, "{}", s));
 139                 }
 140             }
 141         }
 142     }
 143
 144     // It is important to execute this conditionally, only if -Z
 145     // verbose is false. Otherwise, debug logs can sometimes cause
 146     // ICEs trying to fetch the generics early in the pipeline. This
 147     // is kind of a hacky workaround in that -Z verbose is required to
 148     // avoid those ICEs.
 149     let tps = substs.types.get_slice(subst::TypeSpace);
 150     let num_defaults = ty::tls::with(|tcx| {
 151         let generics = get_generics(tcx);
 152
 153         let has_self = substs.self_ty().is_some();
 154         let ty_params = generics.types.get_slice(subst::TypeSpace);
 155         if ty_params.last().map_or(false, |def| def.default.is_some()) {
 156             let substs = tcx.lift(&substs);
 157             ty_params.iter().zip(tps).rev().take_while(|&(def, &actual)| {
 158                 match def.default {
 159                     Some(default) => {
 160                         if !has_self && default.has_self_ty() {
 161                             // In an object type, there is no `Self`, and
 162                             // thus if the default value references Self,
 163                             // the user will be required to give an
 164                             // explicit value. We can't even do the
 165                             // substitution below to check without causing
 166                             // an ICE. (#18956).
 167                             false
 168                         } else {
 169                             let default = tcx.lift(&default);
 170                             substs.and_then(|substs| default.subst(tcx, substs)) == Some(actual)
 171                         }
 172                     }
 173                     None => false
 174                 }
 175             }).count()
 176         } else {
 177             0
 178         }
 179     });
 180
 181     for &ty in &tps[..tps.len() - num_defaults] {
 182         try!(start_or_continue(f, "<", ", "));
 183         try!(write!(f, "{}", ty));
 184     }
 185
 186     for projection in projections {
 187         try!(start_or_continue(f, "<", ", "));
 188         try!(write!(f, "{}={}",
 189                     projection.projection_ty.item_name,
 190                     projection.ty));
 191     }
 192
 193     start_or_continue(f, "", ">")
 194 }
 195
 196 fn in_binder<'tcx, T, U>(f: &mut fmt::Formatter,
 197                          tcx: &ty::ctxt<'tcx>,
 198                          original: &ty::Binder<T>,
 199                          lifted: Option<ty::Binder<U>>) -> fmt::Result
 200     where T: fmt::Display, U: fmt::Display + TypeFoldable<'tcx>
 201 {
 202     // Replace any anonymous late-bound regions with named
 203     // variants, using gensym'd identifiers, so that we can
 204     // clearly differentiate between named and unnamed regions in
 205     // the output. We'll probably want to tweak this over time to
 206     // decide just how much information to give.
 207     let value = if let Some(v) = lifted {
 208         v
 209     } else {
 210         return write!(f, "{}", original.0);
 211     };
 212
 213     let mut empty = true;
 214     let mut start_or_continue = |f: &mut fmt::Formatter, start: &str, cont: &str| {
 215         if empty {
 216             empty = false;
 217             write!(f, "{}", start)
 218         } else {
 219             write!(f, "{}", cont)
 220         }
 221     };
 222
 223     let new_value = tcx.replace_late_bound_regions(&value, |br| {
 224         let _ = start_or_continue(f, "for<", ", ");
 225         ty::ReLateBound(ty::DebruijnIndex::new(1), match br {
 226             ty::BrNamed(_, name) => {
 227                 let _ = write!(f, "{}", name);
 228                 br
 229             }
 230             ty::BrAnon(_) |
 231             ty::BrFresh(_) |
 232             ty::BrEnv => {
 233                 let name = token::intern("'r");
 234                 let _ = write!(f, "{}", name);
 235                 ty::BrNamed(tcx.map.local_def_id(CRATE_NODE_ID), name)
 236             }
 237         })
 238     }).0;
 239
 240     try!(start_or_continue(f, "", "> "));
 241     write!(f, "{}", new_value)
 242 }
 243
 244 /// This curious type is here to help pretty-print trait objects. In
 245 /// a trait object, the projections are stored separately from the
 246 /// main trait bound, but in fact we want to package them together
 247 /// when printing out; they also have separate binders, but we want
 248 /// them to share a binder when we print them out. (And the binder
 249 /// pretty-printing logic is kind of clever and we don't want to
 250 /// reproduce it.) So we just repackage up the structure somewhat.
 251 ///
 252 /// Right now there is only one trait in an object that can have
 253 /// projection bounds, so we just stuff them altogether. But in
 254 /// reality we should eventually sort things out better.
 255 #[derive(Clone, Debug)]
 256 struct TraitAndProjections<'tcx>(ty::TraitRef<'tcx>, Vec<ty::ProjectionPredicate<'tcx>>);
 257
 258 impl<'tcx> TypeFoldable<'tcx> for TraitAndProjections<'tcx> {
 259     fn fold_with<F:ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F)
 260                                               -> TraitAndProjections<'tcx> {
 261         TraitAndProjections(self.0.fold_with(folder), self.1.fold_with(folder))
 262     }
 263 }
 264
 265 impl<'tcx> fmt::Display for TraitAndProjections<'tcx> {
 266     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 267         let TraitAndProjections(ref trait_ref, ref projection_bounds) = *self;
 268         parameterized(f, trait_ref.substs,
 269                       trait_ref.def_id,
 270                       projection_bounds,
 271                       |tcx| tcx.lookup_trait_def(trait_ref.def_id).generics.clone())
 272     }
 273 }
 274
 275 impl<'tcx> fmt::Display for ty::TraitTy<'tcx> {
 276     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 277         let bounds = &self.bounds;
 278
 279         // Generate the main trait ref, including associated types.
 280         try!(ty::tls::with(|tcx| {
 281             let principal = tcx.lift(&self.principal.0)
 282                                .expect("could not lift TraitRef for printing");
 283             let projections = tcx.lift(&bounds.projection_bounds[..])
 284                                  .expect("could not lift projections for printing");
 285             let projections = projections.into_iter().map(|p| p.0).collect();
 286
 287             let tap = ty::Binder(TraitAndProjections(principal, projections));
 288             in_binder(f, tcx, &ty::Binder(""), Some(tap))
 289         }));
 290
 291         // Builtin bounds.
 292         for bound in &bounds.builtin_bounds {
 293             try!(write!(f, " + {:?}", bound));
 294         }
 295
 296         // FIXME: It'd be nice to compute from context when this bound
 297         // is implied, but that's non-trivial -- we'd perhaps have to
 298         // use thread-local data of some kind? There are also
 299         // advantages to just showing the region, since it makes
 300         // people aware that it's there.
 301         let bound = bounds.region_bound.to_string();
 302         if !bound.is_empty() {
 303             try!(write!(f, " + {}", bound));
 304         }
 305
 306         Ok(())
 307     }
 308 }
 309
 310 impl<'tcx> fmt::Debug for ty::TypeParameterDef<'tcx> {
 311     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 312         write!(f, "TypeParameterDef({}, {:?}, {:?}/{})",
 313                self.name,
 314                self.def_id,
 315                self.space, self.index)
 316     }
 317 }
 318
 319 impl fmt::Debug for ty::RegionParameterDef {
 320     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 321         write!(f, "RegionParameterDef({}, {:?}, {:?}/{}, {:?})",
 322                self.name,
 323                self.def_id,
 324                self.space, self.index,
 325                self.bounds)
 326     }
 327 }
 328
 329 impl<'tcx> fmt::Debug for ty::TyS<'tcx> {
 330     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 331         write!(f, "{}", *self)
 332     }
 333 }
 334
 335 impl<'tcx> fmt::Display for ty::TypeAndMut<'tcx> {
 336     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 337         write!(f, "{}{}",
 338                if self.mutbl == hir::MutMutable { "mut " } else { "" },
 339                self.ty)
 340     }
 341 }
 342
 343 impl<'tcx> fmt::Debug for subst::Substs<'tcx> {
 344     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 345         write!(f, "Substs[types={:?}, regions={:?}]",
 346                self.types, self.regions)
 347     }
 348 }
 349
 350 impl<'tcx> fmt::Debug for ty::ItemSubsts<'tcx> {
 351     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 352         write!(f, "ItemSubsts({:?})", self.substs)
 353     }
 354 }
 355
 356 impl fmt::Debug for subst::RegionSubsts {
 357     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 358         match *self {
 359             subst::ErasedRegions => write!(f, "erased"),
 360             subst::NonerasedRegions(ref regions) => write!(f, "{:?}", regions)
 361         }
 362     }
 363 }
 364
 365 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
 366     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 367         // when printing out the debug representation, we don't need
 368         // to enumerate the `for<...>` etc because the debruijn index
 369         // tells you everything you need to know.
 370         match self.substs.self_ty() {
 371             None => write!(f, "{}", *self),
 372             Some(self_ty) => write!(f, "<{:?} as {}>", self_ty, *self)
 373         }
 374     }
 375 }
 376
 377 impl<'tcx> fmt::Debug for ty::TraitDef<'tcx> {
 378     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 379         write!(f, "TraitDef(generics={:?}, trait_ref={:?})",
 380                self.generics, self.trait_ref)
 381     }
 382 }
 383
 384 impl<'tcx, 'container> fmt::Debug for ty::AdtDefData<'tcx, 'container> {
 385     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 386         ty::tls::with(|tcx| {
 387             write!(f, "{}", tcx.item_path_str(self.did))
 388         })
 389     }
 390 }
 391
 392 impl<'tcx> fmt::Debug for ty::adjustment::AutoAdjustment<'tcx> {
 393     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 394         match *self {
 395             ty::adjustment::AdjustReifyFnPointer => {
 396                 write!(f, "AdjustReifyFnPointer")
 397             }
 398             ty::adjustment::AdjustUnsafeFnPointer => {
 399                 write!(f, "AdjustUnsafeFnPointer")
 400             }
 401             ty::adjustment::AdjustDerefRef(ref data) => {
 402                 write!(f, "{:?}", data)
 403             }
 404         }
 405     }
 406 }
 407
 408 impl<'tcx> fmt::Debug for ty::adjustment::AutoDerefRef<'tcx> {
 409     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 410         write!(f, "AutoDerefRef({}, unsize={:?}, {:?})",
 411                self.autoderefs, self.unsize, self.autoref)
 412     }
 413 }
 414
 415 impl<'tcx> fmt::Debug for ty::TraitTy<'tcx> {
 416     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 417         write!(f, "TraitTy({:?},{:?})",
 418                self.principal,
 419                self.bounds)
 420     }
 421 }
 422
 423 impl<'tcx> fmt::Debug for ty::Predicate<'tcx> {
 424     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 425         match *self {
 426             ty::Predicate::Trait(ref a) => write!(f, "{:?}", a),
 427             ty::Predicate::Equate(ref pair) => write!(f, "{:?}", pair),
 428             ty::Predicate::RegionOutlives(ref pair) => write!(f, "{:?}", pair),
 429             ty::Predicate::TypeOutlives(ref pair) => write!(f, "{:?}", pair),
 430             ty::Predicate::Projection(ref pair) => write!(f, "{:?}", pair),
 431             ty::Predicate::WellFormed(ty) => write!(f, "WF({:?})", ty),
 432             ty::Predicate::ObjectSafe(trait_def_id) => {
 433                 write!(f, "ObjectSafe({:?})", trait_def_id)
 434             }
 435         }
 436     }
 437 }
 438
 439 impl fmt::Display for ty::BoundRegion {
 440     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 441         if verbose() {
 442             return write!(f, "{:?}", *self);
 443         }
 444
 445         match *self {
 446             BrNamed(_, name) => write!(f, "{}", name),
 447             BrAnon(_) | BrFresh(_) | BrEnv => Ok(())
 448         }
 449     }
 450 }
 451
 452 impl fmt::Debug for ty::BoundRegion {
 453     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 454         match *self {
 455             BrAnon(n) => write!(f, "BrAnon({:?})", n),
 456             BrFresh(n) => write!(f, "BrFresh({:?})", n),
 457             BrNamed(did, name) => {
 458                 write!(f, "BrNamed({:?}, {:?})", did, name)
 459             }
 460             BrEnv => "BrEnv".fmt(f),
 461         }
 462     }
 463 }
 464
 465 impl fmt::Debug for ty::Region {
 466     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 467         match *self {
 468             ty::ReEarlyBound(ref data) => {
 469                 write!(f, "ReEarlyBound({:?}, {:?}, {}, {})",
 470                        data.def_id,
 471                        data.space,
 472                        data.index,
 473                        data.name)
 474             }
 475
 476             ty::ReLateBound(binder_id, ref bound_region) => {
 477                 write!(f, "ReLateBound({:?}, {:?})",
 478                        binder_id,
 479                        bound_region)
 480             }
 481
 482             ty::ReFree(ref fr) => write!(f, "{:?}", fr),
 483
 484             ty::ReScope(id) => {
 485                 write!(f, "ReScope({:?})", id)
 486             }
 487
 488             ty::ReStatic => write!(f, "ReStatic"),
 489
 490             ty::ReVar(ref vid) => {
 491                 write!(f, "{:?}", vid)
 492             }
 493
 494             ty::ReSkolemized(id, ref bound_region) => {
 495                 write!(f, "ReSkolemized({}, {:?})", id.index, bound_region)
 496             }
 497
 498             ty::ReEmpty => write!(f, "ReEmpty")
 499         }
 500     }
 501 }
 502
 503 impl<'tcx> fmt::Debug for ty::ClosureTy<'tcx> {
 504     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 505         write!(f, "ClosureTy({},{:?},{})",
 506                self.unsafety,
 507                self.sig,
 508                self.abi)
 509     }
 510 }
 511
 512 impl<'tcx> fmt::Debug for ty::ClosureUpvar<'tcx> {
 513     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 514         write!(f, "ClosureUpvar({:?},{:?})",
 515                self.def,
 516                self.ty)
 517     }
 518 }
 519
 520 impl<'a, 'tcx> fmt::Debug for ty::ParameterEnvironment<'a, 'tcx> {
 521     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 522         write!(f, "ParameterEnvironment(\
 523             free_substs={:?}, \
 524             implicit_region_bound={:?}, \
 525             caller_bounds={:?})",
 526             self.free_substs,
 527             self.implicit_region_bound,
 528             self.caller_bounds)
 529     }
 530 }
 531
 532 impl<'tcx> fmt::Debug for ty::ObjectLifetimeDefault {
 533     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 534         match *self {
 535             ty::ObjectLifetimeDefault::Ambiguous => write!(f, "Ambiguous"),
 536             ty::ObjectLifetimeDefault::BaseDefault => write!(f, "BaseDefault"),
 537             ty::ObjectLifetimeDefault::Specific(ref r) => write!(f, "{:?}", r),
 538         }
 539     }
 540 }
 541
 542 impl fmt::Display for ty::Region {
 543     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 544         if verbose() {
 545             return write!(f, "{:?}", *self);
 546         }
 547
 548         // These printouts are concise.  They do not contain all the information
 549         // the user might want to diagnose an error, but there is basically no way
 550         // to fit that into a short string.  Hence the recommendation to use
 551         // `explain_region()` or `note_and_explain_region()`.
 552         match *self {
 553             ty::ReEarlyBound(ref data) => {
 554                 write!(f, "{}", data.name)
 555             }
 556             ty::ReLateBound(_, br) |
 557             ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
 558             ty::ReSkolemized(_, br) => {
 559                 write!(f, "{}", br)
 560             }
 561             ty::ReScope(_) |
 562             ty::ReVar(_) => Ok(()),
 563             ty::ReStatic => write!(f, "'static"),
 564             ty::ReEmpty => write!(f, "'<empty>"),
 565         }
 566     }
 567 }
 568
 569 impl fmt::Debug for ty::FreeRegion {
 570     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 571         write!(f, "ReFree({:?}, {:?})",
 572                self.scope, self.bound_region)
 573     }
 574 }
 575
 576 impl fmt::Debug for ty::Variance {
 577     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 578         f.write_str(match *self {
 579             ty::Covariant => "+",
 580             ty::Contravariant => "-",
 581             ty::Invariant => "o",
 582             ty::Bivariant => "*",
 583         })
 584     }
 585 }
 586
 587 impl fmt::Debug for ty::ItemVariances {
 588     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 589         write!(f, "ItemVariances(types={:?}, regions={:?})",
 590                self.types, self.regions)
 591     }
 592 }
 593
 594 impl<'tcx> fmt::Debug for ty::GenericPredicates<'tcx> {
 595     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 596         write!(f, "GenericPredicates({:?})", self.predicates)
 597     }
 598 }
 599
 600 impl<'tcx> fmt::Debug for ty::InstantiatedPredicates<'tcx> {
 601     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 602         write!(f, "InstantiatedPredicates({:?})",
 603                self.predicates)
 604     }
 605 }
 606
 607 impl<'tcx> fmt::Debug for ty::ImplOrTraitItem<'tcx> {
 608     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 609         try!(write!(f, "ImplOrTraitItem("));
 610         try!(match *self {
 611             ty::ImplOrTraitItem::MethodTraitItem(ref i) => write!(f, "{:?}", i),
 612             ty::ImplOrTraitItem::ConstTraitItem(ref i) => write!(f, "{:?}", i),
 613             ty::ImplOrTraitItem::TypeTraitItem(ref i) => write!(f, "{:?}", i),
 614         });
 615         write!(f, ")")
 616     }
 617 }
 618
 619 impl<'tcx> fmt::Display for ty::FnSig<'tcx> {
 620     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 621         try!(write!(f, "fn"));
 622         fn_sig(f, &self.inputs, self.variadic, self.output)
 623     }
 624 }
 625
 626 impl<'tcx> fmt::Debug for ty::ExistentialBounds<'tcx> {
 627     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 628         let mut empty = true;
 629         let mut maybe_continue = |f: &mut fmt::Formatter| {
 630             if empty {
 631                 empty = false;
 632                 Ok(())
 633             } else {
 634                 write!(f, " + ")
 635             }
 636         };
 637
 638         let region_str = format!("{:?}", self.region_bound);
 639         if !region_str.is_empty() {
 640             try!(maybe_continue(f));
 641             try!(write!(f, "{}", region_str));
 642         }
 643
 644         for bound in &self.builtin_bounds {
 645             try!(maybe_continue(f));
 646             try!(write!(f, "{:?}", bound));
 647         }
 648
 649         for projection_bound in &self.projection_bounds {
 650             try!(maybe_continue(f));
 651             try!(write!(f, "{:?}", projection_bound));
 652         }
 653
 654         Ok(())
 655     }
 656 }
 657
 658 impl fmt::Display for ty::BuiltinBounds {
 659     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 660         let mut bounds = self.iter();
 661         if let Some(bound) = bounds.next() {
 662             try!(write!(f, "{:?}", bound));
 663             for bound in bounds {
 664                 try!(write!(f, " + {:?}", bound));
 665             }
 666         }
 667         Ok(())
 668     }
 669 }
 670
 671 impl fmt::Debug for ty::TyVid {
 672     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 673         write!(f, "_#{}t", self.index)
 674     }
 675 }
 676
 677 impl fmt::Debug for ty::IntVid {
 678     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 679         write!(f, "_#{}i", self.index)
 680     }
 681 }
 682
 683 impl fmt::Debug for ty::FloatVid {
 684     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 685         write!(f, "_#{}f", self.index)
 686     }
 687 }
 688
 689 impl fmt::Debug for ty::RegionVid {
 690     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 691         write!(f, "'_#{}r", self.index)
 692     }
 693 }
 694
 695 impl<'tcx> fmt::Debug for ty::FnSig<'tcx> {
 696     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 697         write!(f, "({:?}; variadic: {})->{:?}", self.inputs, self.variadic, self.output)
 698     }
 699 }
 700
 701 impl fmt::Debug for ty::InferTy {
 702     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 703         match *self {
 704             ty::TyVar(ref v) => v.fmt(f),
 705             ty::IntVar(ref v) => v.fmt(f),
 706             ty::FloatVar(ref v) => v.fmt(f),
 707             ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
 708             ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
 709             ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v)
 710         }
 711     }
 712 }
 713
 714 impl fmt::Debug for ty::IntVarValue {
 715     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 716         match *self {
 717             ty::IntType(ref v) => v.fmt(f),
 718             ty::UintType(ref v) => v.fmt(f),
 719         }
 720     }
 721 }
 722
 723 // The generic impl doesn't work yet because projections are not
 724 // normalized under HRTB.
 725 /*impl<T> fmt::Display for ty::Binder<T>
 726     where T: fmt::Display + for<'a> ty::Lift<'a>,
 727           for<'a> <T as ty::Lift<'a>>::Lifted: fmt::Display + TypeFoldable<'a>
 728 {
 729     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 730         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 731     }
 732 }*/
 733
 734 impl<'tcx> fmt::Display for ty::Binder<ty::TraitRef<'tcx>> {
 735     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 736         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 737     }
 738 }
 739
 740 impl<'tcx> fmt::Display for ty::Binder<ty::TraitPredicate<'tcx>> {
 741     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 742         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 743     }
 744 }
 745
 746 impl<'tcx> fmt::Display for ty::Binder<ty::EquatePredicate<'tcx>> {
 747     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 748         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 749     }
 750 }
 751
 752 impl<'tcx> fmt::Display for ty::Binder<ty::ProjectionPredicate<'tcx>> {
 753     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 754         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 755     }
 756 }
 757
 758 impl<'tcx> fmt::Display for ty::Binder<ty::OutlivesPredicate<Ty<'tcx>, ty::Region>> {
 759     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 760         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 761     }
 762 }
 763
 764 impl fmt::Display for ty::Binder<ty::OutlivesPredicate<ty::Region, ty::Region>> {
 765     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 766         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 767     }
 768 }
 769
 770 impl<'tcx> fmt::Display for ty::TraitRef<'tcx> {
 771     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 772         parameterized(f, self.substs, self.def_id, &[],
 773                       |tcx| tcx.lookup_trait_def(self.def_id).generics.clone())
 774     }
 775 }
 776
 777 pub fn int_ty_to_string(t: ast::IntTy, val: Option<i64>) -> String {
 778     let s = match t {
 779         ast::TyIs => "isize",
 780         ast::TyI8 => "i8",
 781         ast::TyI16 => "i16",
 782         ast::TyI32 => "i32",
 783         ast::TyI64 => "i64"
 784     };
 785
 786     match val {
 787         // cast to a u64 so we can correctly print INT64_MIN. All integral types
 788         // are parsed as u64, so we wouldn't want to print an extra negative
 789         // sign.
 790         Some(n) => format!("{}{}", n as u64, s),
 791         None => s.to_string()
 792     }
 793 }
 794
 795 pub fn uint_ty_to_string(t: ast::UintTy, val: Option<u64>) -> String {
 796     let s = match t {
 797         ast::TyUs => "usize",
 798         ast::TyU8 => "u8",
 799         ast::TyU16 => "u16",
 800         ast::TyU32 => "u32",
 801         ast::TyU64 => "u64"
 802     };
 803
 804     match val {
 805         Some(n) => format!("{}{}", n, s),
 806         None => s.to_string()
 807     }
 808 }
 809
 810
 811 pub fn float_ty_to_string(t: ast::FloatTy) -> String {
 812     match t {
 813         ast::TyF32 => "f32".to_string(),
 814         ast::TyF64 => "f64".to_string(),
 815     }
 816 }
 817
 818 impl<'tcx> fmt::Display for ty::TypeVariants<'tcx> {
 819     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 820         match *self {
 821             TyBool => write!(f, "bool"),
 822             TyChar => write!(f, "char"),
 823             TyInt(t) => write!(f, "{}", int_ty_to_string(t, None)),
 824             TyUint(t) => write!(f, "{}", uint_ty_to_string(t, None)),
 825             TyFloat(t) => write!(f, "{}", float_ty_to_string(t)),
 826             TyBox(typ) => write!(f, "Box<{}>",  typ),
 827             TyRawPtr(ref tm) => {
 828                 write!(f, "*{} {}", match tm.mutbl {
 829                     hir::MutMutable => "mut",
 830                     hir::MutImmutable => "const",
 831                 },  tm.ty)
 832             }
 833             TyRef(r, ref tm) => {
 834                 try!(write!(f, "&"));
 835                 let s = r.to_string();
 836                 try!(write!(f, "{}", s));
 837                 if !s.is_empty() {
 838                     try!(write!(f, " "));
 839                 }
 840                 write!(f, "{}", tm)
 841             }
 842             TyTuple(ref tys) => {
 843                 try!(write!(f, "("));
 844                 let mut tys = tys.iter();
 845                 if let Some(&ty) = tys.next() {
 846                     try!(write!(f, "{},", ty));
 847                     if let Some(&ty) = tys.next() {
 848                         try!(write!(f, " {}", ty));
 849                         for &ty in tys {
 850                             try!(write!(f, ", {}", ty));
 851                         }
 852                     }
 853                 }
 854                 write!(f, ")")
 855             }
 856             TyBareFn(opt_def_id, ref bare_fn) => {
 857                 if bare_fn.unsafety == hir::Unsafety::Unsafe {
 858                     try!(write!(f, "unsafe "));
 859                 }
 860
 861                 if bare_fn.abi != abi::Rust {
 862                     try!(write!(f, "extern {} ", bare_fn.abi));
 863                 }
 864
 865                 try!(write!(f, "{}", bare_fn.sig.0));
 866
 867                 if let Some(def_id) = opt_def_id {
 868                     try!(write!(f, " {{{}}}", ty::tls::with(|tcx| {
 869                         tcx.item_path_str(def_id)
 870                     })));
 871                 }
 872                 Ok(())
 873             }
 874             TyInfer(infer_ty) => write!(f, "{}", infer_ty),
 875             TyError => write!(f, "[type error]"),
 876             TyParam(ref param_ty) => write!(f, "{}", param_ty),
 877             TyEnum(def, substs) | TyStruct(def, substs) => {
 878                 ty::tls::with(|tcx| {
 879                     if def.did.is_local() &&
 880                           !tcx.tcache.borrow().contains_key(&def.did) {
 881                         write!(f, "{}<..>", tcx.item_path_str(def.did))
 882                     } else {
 883                         parameterized(f, substs, def.did, &[],
 884                                       |tcx| tcx.lookup_item_type(def.did).generics)
 885                     }
 886                 })
 887             }
 888             TyTrait(ref data) => write!(f, "{}", data),
 889             ty::TyProjection(ref data) => write!(f, "{}", data),
 890             TyStr => write!(f, "str"),
 891             TyClosure(did, ref substs) => ty::tls::with(|tcx| {
 892                 try!(write!(f, "[closure"));
 893
 894                 if let Some(node_id) = tcx.map.as_local_node_id(did) {
 895                     try!(write!(f, "@{:?}", tcx.map.span(node_id)));
 896                     let mut sep = " ";
 897                     try!(tcx.with_freevars(node_id, |freevars| {
 898                         for (freevar, upvar_ty) in freevars.iter().zip(&substs.upvar_tys) {
 899                             let node_id = freevar.def.var_id();
 900                             try!(write!(f,
 901                                         "{}{}:{}",
 902                                         sep,
 903                                         tcx.local_var_name_str(node_id),
 904                                         upvar_ty));
 905                             sep = ", ";
 906                         }
 907                         Ok(())
 908                     }))
 909                 } else {
 910                     // cross-crate closure types should only be
 911                     // visible in trans bug reports, I imagine.
 912                     try!(write!(f, "@{:?}", did));
 913                     let mut sep = " ";
 914                     for (index, upvar_ty) in substs.upvar_tys.iter().enumerate() {
 915                         try!(write!(f, "{}{}:{}", sep, index, upvar_ty));
 916                         sep = ", ";
 917                     }
 918                 }
 919
 920                 write!(f, "]")
 921             }),
 922             TyArray(ty, sz) => write!(f, "[{}; {}]",  ty, sz),
 923             TySlice(ty) => write!(f, "[{}]",  ty)
 924         }
 925     }
 926 }
 927
 928 impl<'tcx> fmt::Display for ty::TyS<'tcx> {
 929     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 930         write!(f, "{}", self.sty)
 931     }
 932 }
 933
 934 impl fmt::Debug for ty::UpvarId {
 935     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 936         write!(f, "UpvarId({};`{}`;{})",
 937                self.var_id,
 938                ty::tls::with(|tcx| tcx.local_var_name_str(self.var_id)),
 939                self.closure_expr_id)
 940     }
 941 }
 942
 943 impl fmt::Debug for ty::UpvarBorrow {
 944     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 945         write!(f, "UpvarBorrow({:?}, {:?})",
 946                self.kind, self.region)
 947     }
 948 }
 949
 950 impl fmt::Display for ty::InferTy {
 951     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 952         let print_var_ids = verbose();
 953         match *self {
 954             ty::TyVar(ref vid) if print_var_ids => write!(f, "{:?}", vid),
 955             ty::IntVar(ref vid) if print_var_ids => write!(f, "{:?}", vid),
 956             ty::FloatVar(ref vid) if print_var_ids => write!(f, "{:?}", vid),
 957             ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => write!(f, "_"),
 958             ty::FreshTy(v) => write!(f, "FreshTy({})", v),
 959             ty::FreshIntTy(v) => write!(f, "FreshIntTy({})", v),
 960             ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({})", v)
 961         }
 962     }
 963 }
 964
 965 impl fmt::Display for ty::ExplicitSelfCategory {
 966     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 967         f.write_str(match *self {
 968             ty::StaticExplicitSelfCategory => "static",
 969             ty::ByValueExplicitSelfCategory => "self",
 970             ty::ByReferenceExplicitSelfCategory(_, hir::MutMutable) => {
 971                 "&mut self"
 972             }
 973             ty::ByReferenceExplicitSelfCategory(_, hir::MutImmutable) => "&self",
 974             ty::ByBoxExplicitSelfCategory => "Box<self>",
 975         })
 976     }
 977 }
 978
 979 impl fmt::Display for ty::ParamTy {
 980     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 981         write!(f, "{}", self.name)
 982     }
 983 }
 984
 985 impl fmt::Debug for ty::ParamTy {
 986     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 987         write!(f, "{}/{:?}.{}", self, self.space, self.idx)
 988     }
 989 }
 990
 991 impl<'tcx, T, U> fmt::Display for ty::OutlivesPredicate<T,U>
 992     where T: fmt::Display, U: fmt::Display
 993 {
 994     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 995         write!(f, "{} : {}", self.0, self.1)
 996     }
 997 }
 998
 999 impl<'tcx> fmt::Display for ty::EquatePredicate<'tcx> {
1000     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1001         write!(f, "{} == {}", self.0, self.1)
1002     }
1003 }
1004
1005 impl<'tcx> fmt::Debug for ty::TraitPredicate<'tcx> {
1006     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1007         write!(f, "TraitPredicate({:?})",
1008                self.trait_ref)
1009     }
1010 }
1011
1012 impl<'tcx> fmt::Display for ty::TraitPredicate<'tcx> {
1013     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1014         write!(f, "{} : {}",
1015                self.trait_ref.self_ty(),
1016                self.trait_ref)
1017     }
1018 }
1019
1020 impl<'tcx> fmt::Debug for ty::ProjectionPredicate<'tcx> {
1021     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1022         write!(f, "ProjectionPredicate({:?}, {:?})",
1023                self.projection_ty,
1024                self.ty)
1025     }
1026 }
1027
1028 impl<'tcx> fmt::Display for ty::ProjectionPredicate<'tcx> {
1029     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1030         write!(f, "{} == {}",
1031                self.projection_ty,
1032                self.ty)
1033     }
1034 }
1035
1036 impl<'tcx> fmt::Display for ty::ProjectionTy<'tcx> {
1037     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1038         write!(f, "{:?}::{}",
1039                self.trait_ref,
1040                self.item_name)
1041     }
1042 }
1043
1044 impl<'tcx> fmt::Display for ty::Predicate<'tcx> {
1045     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1046         match *self {
1047             ty::Predicate::Trait(ref data) => write!(f, "{}", data),
1048             ty::Predicate::Equate(ref predicate) => write!(f, "{}", predicate),
1049             ty::Predicate::RegionOutlives(ref predicate) => write!(f, "{}", predicate),
1050             ty::Predicate::TypeOutlives(ref predicate) => write!(f, "{}", predicate),
1051             ty::Predicate::Projection(ref predicate) => write!(f, "{}", predicate),
1052             ty::Predicate::WellFormed(ty) => write!(f, "{} well-formed", ty),
1053             ty::Predicate::ObjectSafe(trait_def_id) =>
1054                 ty::tls::with(|tcx| {
1055                     write!(f, "the trait `{}` is object-safe", tcx.item_path_str(trait_def_id))
1056                 }),
1057         }
1058     }
1059 }