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 use hir::def_id::DefId;
  12 use hir::map::definitions::DefPathData;
  13 use middle::const_val::ConstVal;
  14 use middle::region::{self, BlockRemainder};
  15 use ty::subst::{self, Subst};
  16 use ty::{BrAnon, BrEnv, BrFresh, BrNamed};
  17 use ty::{TyBool, TyChar, TyAdt};
  18 use ty::{TyError, TyStr, TyArray, TySlice, TyFloat, TyFnDef, TyFnPtr};
  19 use ty::{TyParam, TyRawPtr, TyRef, TyNever, TyTuple};
  20 use ty::{TyClosure, TyGenerator, TyGeneratorWitness, TyForeign, TyProjection, TyAnon};
  21 use ty::{TyDynamic, TyInt, TyUint, TyInfer};
  22 use ty::{self, Ty, TyCtxt, TypeFoldable, GenericParamCount, GenericParamDefKind};
  23 use util::nodemap::FxHashSet;
  24
  25 use std::cell::Cell;
  26 use std::fmt;
  27 use std::usize;
  28
  29 use rustc_data_structures::indexed_vec::Idx;
  30 use rustc_target::spec::abi::Abi;
  31 use syntax::ast::CRATE_NODE_ID;
  32 use syntax::symbol::{Symbol, InternedString};
  33 use hir;
  34
  35 macro_rules! gen_display_debug_body {
  36     ( $with:path ) => {
  37         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  38             let mut cx = PrintContext::new();
  39             $with(self, f, &mut cx)
  40         }
  41     };
  42 }
  43 macro_rules! gen_display_debug {
  44     ( ($($x:tt)+) $target:ty, display yes ) => {
  45         impl<$($x)+> fmt::Display for $target {
  46             gen_display_debug_body! { Print::print_display }
  47         }
  48     };
  49     ( () $target:ty, display yes ) => {
  50         impl fmt::Display for $target {
  51             gen_display_debug_body! { Print::print_display }
  52         }
  53     };
  54     ( ($($x:tt)+) $target:ty, debug yes ) => {
  55         impl<$($x)+> fmt::Debug for $target {
  56             gen_display_debug_body! { Print::print_debug }
  57         }
  58     };
  59     ( () $target:ty, debug yes ) => {
  60         impl fmt::Debug for $target {
  61             gen_display_debug_body! { Print::print_debug }
  62         }
  63     };
  64     ( $generic:tt $target:ty, $t:ident no ) => {};
  65 }
  66 macro_rules! gen_print_impl {
  67     ( ($($x:tt)+) $target:ty, ($self:ident, $f:ident, $cx:ident) $disp:block $dbg:block ) => {
  68         impl<$($x)+> Print for $target {
  69             fn print<F: fmt::Write>(&$self, $f: &mut F, $cx: &mut PrintContext) -> fmt::Result {
  70                 if $cx.is_debug $dbg
  71                 else $disp
  72             }
  73         }
  74     };
  75     ( () $target:ty, ($self:ident, $f:ident, $cx:ident) $disp:block $dbg:block ) => {
  76         impl Print for $target {
  77             fn print<F: fmt::Write>(&$self, $f: &mut F, $cx: &mut PrintContext) -> fmt::Result {
  78                 if $cx.is_debug $dbg
  79                 else $disp
  80             }
  81         }
  82     };
  83     ( $generic:tt $target:ty,
  84       $vars:tt $gendisp:ident $disp:block $gendbg:ident $dbg:block ) => {
  85         gen_print_impl! { $generic $target, $vars $disp $dbg }
  86         gen_display_debug! { $generic $target, display $gendisp }
  87         gen_display_debug! { $generic $target, debug $gendbg }
  88     }
  89 }
  90 macro_rules! define_print {
  91     ( $generic:tt $target:ty,
  92       $vars:tt { display $disp:block debug $dbg:block } ) => {
  93         gen_print_impl! { $generic $target, $vars yes $disp yes $dbg }
  94     };
  95     ( $generic:tt $target:ty,
  96       $vars:tt { debug $dbg:block display $disp:block } ) => {
  97         gen_print_impl! { $generic $target, $vars yes $disp yes $dbg }
  98     };
  99     ( $generic:tt $target:ty,
 100       $vars:tt { debug $dbg:block } ) => {
 101         gen_print_impl! { $generic $target, $vars no {
 102             bug!(concat!("display not implemented for ", stringify!($target)));
 103         } yes $dbg }
 104     };
 105     ( $generic:tt $target:ty,
 106       ($self:ident, $f:ident, $cx:ident) { display $disp:block } ) => {
 107         gen_print_impl! { $generic $target, ($self, $f, $cx) yes $disp no {
 108             write!($f, "{:?}", $self)
 109         } }
 110     };
 111 }
 112 macro_rules! define_print_multi {
 113     ( [ $($generic:tt $target:ty),* ] $vars:tt $def:tt ) => {
 114         $(define_print! { $generic $target, $vars $def })*
 115     };
 116 }
 117 macro_rules! print_inner {
 118     ( $f:expr, $cx:expr, write ($($data:expr),+) ) => {
 119         write!($f, $($data),+)
 120     };
 121     ( $f:expr, $cx:expr, $kind:ident ($data:expr) ) => {
 122         $data.$kind($f, $cx)
 123     };
 124 }
 125 macro_rules! print {
 126     ( $f:expr, $cx:expr $(, $kind:ident $data:tt)+ ) => {
 127         Ok(())$(.and_then(|_| print_inner!($f, $cx, $kind $data)))+
 128     };
 129 }
 130
 131
 132 struct LateBoundRegionNameCollector(FxHashSet<InternedString>);
 133 impl<'tcx> ty::fold::TypeVisitor<'tcx> for LateBoundRegionNameCollector {
 134     fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool {
 135         match *r {
 136             ty::ReLateBound(_, ty::BrNamed(_, name)) => {
 137                 self.0.insert(name);
 138             },
 139             _ => {},
 140         }
 141         r.super_visit_with(self)
 142     }
 143 }
 144
 145 #[derive(Debug)]
 146 pub struct PrintContext {
 147     is_debug: bool,
 148     is_verbose: bool,
 149     identify_regions: bool,
 150     used_region_names: Option<FxHashSet<InternedString>>,
 151     region_index: usize,
 152     binder_depth: usize,
 153 }
 154 impl PrintContext {
 155     fn new() -> Self {
 156         ty::tls::with_opt(|tcx| {
 157             let (is_verbose, identify_regions) = tcx.map(
 158                 |tcx| (tcx.sess.verbose(), tcx.sess.opts.debugging_opts.identify_regions)
 159             ).unwrap_or((false, false));
 160             PrintContext {
 161                 is_debug: false,
 162                 is_verbose: is_verbose,
 163                 identify_regions: identify_regions,
 164                 used_region_names: None,
 165                 region_index: 0,
 166                 binder_depth: 0,
 167             }
 168         })
 169     }
 170     fn prepare_late_bound_region_info<'tcx, T>(&mut self, value: &ty::Binder<T>)
 171     where T: TypeFoldable<'tcx>
 172     {
 173         let mut collector = LateBoundRegionNameCollector(FxHashSet());
 174         value.visit_with(&mut collector);
 175         self.used_region_names = Some(collector.0);
 176         self.region_index = 0;
 177     }
 178 }
 179
 180 pub trait Print {
 181     fn print<F: fmt::Write>(&self, f: &mut F, cx: &mut PrintContext) -> fmt::Result;
 182     fn print_to_string(&self, cx: &mut PrintContext) -> String {
 183         let mut result = String::new();
 184         let _ = self.print(&mut result, cx);
 185         result
 186     }
 187     fn print_display<F: fmt::Write>(&self, f: &mut F, cx: &mut PrintContext) -> fmt::Result {
 188         let old_debug = cx.is_debug;
 189         cx.is_debug = false;
 190         let result = self.print(f, cx);
 191         cx.is_debug = old_debug;
 192         result
 193     }
 194     fn print_display_to_string(&self, cx: &mut PrintContext) -> String {
 195         let mut result = String::new();
 196         let _ = self.print_display(&mut result, cx);
 197         result
 198     }
 199     fn print_debug<F: fmt::Write>(&self, f: &mut F, cx: &mut PrintContext) -> fmt::Result {
 200         let old_debug = cx.is_debug;
 201         cx.is_debug = true;
 202         let result = self.print(f, cx);
 203         cx.is_debug = old_debug;
 204         result
 205     }
 206     fn print_debug_to_string(&self, cx: &mut PrintContext) -> String {
 207         let mut result = String::new();
 208         let _ = self.print_debug(&mut result, cx);
 209         result
 210     }
 211 }
 212
 213 impl PrintContext {
 214     fn fn_sig<F: fmt::Write>(&mut self,
 215                              f: &mut F,
 216                              inputs: &[Ty],
 217                              variadic: bool,
 218                              output: Ty)
 219                              -> fmt::Result {
 220         write!(f, "(")?;
 221         let mut inputs = inputs.iter();
 222         if let Some(&ty) = inputs.next() {
 223             print!(f, self, print_display(ty))?;
 224             for &ty in inputs {
 225                 print!(f, self, write(", "), print_display(ty))?;
 226             }
 227             if variadic {
 228                 write!(f, ", ...")?;
 229             }
 230         }
 231         write!(f, ")")?;
 232         if !output.is_nil() {
 233             print!(f, self, write(" -> "), print_display(output))?;
 234         }
 235
 236         Ok(())
 237     }
 238
 239     fn parameterized<F: fmt::Write>(&mut self,
 240                                     f: &mut F,
 241                                     substs: &subst::Substs,
 242                                     mut did: DefId,
 243                                     projections: &[ty::ProjectionPredicate])
 244                                     -> fmt::Result {
 245         let key = ty::tls::with(|tcx| tcx.def_key(did));
 246         let mut item_name = if let Some(name) = key.disambiguated_data.data.get_opt_name() {
 247             Some(name)
 248         } else {
 249             did.index = key.parent.unwrap_or_else(
 250                 || bug!("finding type for {:?}, encountered def-id {:?} with no parent",
 251                         did, did));
 252             self.parameterized(f, substs, did, projections)?;
 253             return write!(f, "::{}", key.disambiguated_data.data.as_interned_str());
 254         };
 255
 256         let verbose = self.is_verbose;
 257         let mut num_supplied_defaults = 0;
 258         let mut has_self = false;
 259         let mut own_counts = GenericParamCount {
 260             lifetimes: 0,
 261             types: 0,
 262         };
 263         let mut is_value_path = false;
 264         let fn_trait_kind = ty::tls::with(|tcx| {
 265             // Unfortunately, some kinds of items (e.g., closures) don't have
 266             // generics. So walk back up the find the closest parent that DOES
 267             // have them.
 268             let mut item_def_id = did;
 269             loop {
 270                 let key = tcx.def_key(item_def_id);
 271                 match key.disambiguated_data.data {
 272                     DefPathData::AssocTypeInTrait(_) |
 273                     DefPathData::AssocTypeInImpl(_) |
 274                     DefPathData::Trait(_) |
 275                     DefPathData::TypeNs(_) => {
 276                         break;
 277                     }
 278                     DefPathData::ValueNs(_) |
 279                     DefPathData::EnumVariant(_) => {
 280                         is_value_path = true;
 281                         break;
 282                     }
 283                     DefPathData::CrateRoot |
 284                     DefPathData::Misc |
 285                     DefPathData::Impl |
 286                     DefPathData::Module(_) |
 287                     DefPathData::MacroDef(_) |
 288                     DefPathData::ClosureExpr |
 289                     DefPathData::TypeParam(_) |
 290                     DefPathData::LifetimeParam(_) |
 291                     DefPathData::Field(_) |
 292                     DefPathData::StructCtor |
 293                     DefPathData::AnonConst |
 294                     DefPathData::ExistentialImplTrait |
 295                     DefPathData::UniversalImplTrait |
 296                     DefPathData::GlobalMetaData(_) => {
 297                         // if we're making a symbol for something, there ought
 298                         // to be a value or type-def or something in there
 299                         // *somewhere*
 300                         item_def_id.index = key.parent.unwrap_or_else(|| {
 301                             bug!("finding type for {:?}, encountered def-id {:?} with no \
 302                                  parent", did, item_def_id);
 303                         });
 304                     }
 305                 }
 306             }
 307             let mut generics = tcx.generics_of(item_def_id);
 308             let child_own_counts = generics.own_counts();
 309             let mut path_def_id = did;
 310             has_self = generics.has_self;
 311
 312             let mut child_types = 0;
 313             if let Some(def_id) = generics.parent {
 314                 // Methods.
 315                 assert!(is_value_path);
 316                 child_types = child_own_counts.types;
 317                 generics = tcx.generics_of(def_id);
 318                 own_counts = generics.own_counts();
 319
 320                 if has_self {
 321                     print!(f, self, write("<"), print_display(substs.type_at(0)), write(" as "))?;
 322                 }
 323
 324                 path_def_id = def_id;
 325             } else {
 326                 item_name = None;
 327
 328                 if is_value_path {
 329                     // Functions.
 330                     assert_eq!(has_self, false);
 331                 } else {
 332                     // Types and traits.
 333                     own_counts = child_own_counts;
 334                 }
 335             }
 336
 337             if !verbose {
 338                 let mut type_params =
 339                     generics.params.iter().rev().filter_map(|param| match param.kind {
 340                         GenericParamDefKind::Lifetime => None,
 341                         GenericParamDefKind::Type { has_default, .. } => {
 342                             Some((param.def_id, has_default))
 343                         }
 344                     }).peekable();
 345                 let has_default = {
 346                     let has_default = type_params.peek().map(|(_, has_default)| has_default);
 347                     *has_default.unwrap_or(&false)
 348                 };
 349                 if has_default {
 350                     if let Some(substs) = tcx.lift(&substs) {
 351                         let mut types = substs.types().rev().skip(child_types);
 352                         for ((def_id, has_default), actual) in type_params.zip(types) {
 353                             if !has_default {
 354                                 break;
 355                             }
 356                             if tcx.type_of(def_id).subst(tcx, substs) != actual {
 357                                 break;
 358                             }
 359                             num_supplied_defaults += 1;
 360                         }
 361                     }
 362                 }
 363             }
 364
 365             print!(f, self, write("{}", tcx.item_path_str(path_def_id)))?;
 366             Ok(tcx.lang_items().fn_trait_kind(path_def_id))
 367         })?;
 368
 369         if !verbose && fn_trait_kind.is_some() && projections.len() == 1 {
 370             let projection_ty = projections[0].ty;
 371             if let TyTuple(ref args) = substs.type_at(1).sty {
 372                 return self.fn_sig(f, args, false, projection_ty);
 373             }
 374         }
 375
 376         let empty = Cell::new(true);
 377         let start_or_continue = |f: &mut F, start: &str, cont: &str| {
 378             if empty.get() {
 379                 empty.set(false);
 380                 write!(f, "{}", start)
 381             } else {
 382                 write!(f, "{}", cont)
 383             }
 384         };
 385
 386         let print_regions = |f: &mut F, start: &str, skip, count| {
 387             // Don't print any regions if they're all erased.
 388             let regions = || substs.regions().skip(skip).take(count);
 389             if regions().all(|r: ty::Region| *r == ty::ReErased) {
 390                 return Ok(());
 391             }
 392
 393             for region in regions() {
 394                 let region: ty::Region = region;
 395                 start_or_continue(f, start, ", ")?;
 396                 if verbose {
 397                     write!(f, "{:?}", region)?;
 398                 } else {
 399                     let s = region.to_string();
 400                     if s.is_empty() {
 401                         // This happens when the value of the region
 402                         // parameter is not easily serialized. This may be
 403                         // because the user omitted it in the first place,
 404                         // or because it refers to some block in the code,
 405                         // etc. I'm not sure how best to serialize this.
 406                         write!(f, "'_")?;
 407                     } else {
 408                         write!(f, "{}", s)?;
 409                     }
 410                 }
 411             }
 412
 413             Ok(())
 414         };
 415
 416         print_regions(f, "<", 0, own_counts.lifetimes)?;
 417
 418         let tps = substs.types()
 419                         .take(own_counts.types - num_supplied_defaults)
 420                         .skip(has_self as usize);
 421
 422         for ty in tps {
 423             start_or_continue(f, "<", ", ")?;
 424             ty.print_display(f, self)?;
 425         }
 426
 427         for projection in projections {
 428             start_or_continue(f, "<", ", ")?;
 429             ty::tls::with(|tcx|
 430                 print!(f, self,
 431                        write("{}=",
 432                              tcx.associated_item(projection.projection_ty.item_def_id).name),
 433                        print_display(projection.ty))
 434             )?;
 435         }
 436
 437         start_or_continue(f, "", ">")?;
 438
 439         // For values, also print their name and type parameters.
 440         if is_value_path {
 441             empty.set(true);
 442
 443             if has_self {
 444                 write!(f, ">")?;
 445             }
 446
 447             if let Some(item_name) = item_name {
 448                 write!(f, "::{}", item_name)?;
 449             }
 450
 451             print_regions(f, "::<", own_counts.lifetimes, usize::MAX)?;
 452
 453             // FIXME: consider being smart with defaults here too
 454             for ty in substs.types().skip(own_counts.types) {
 455                 start_or_continue(f, "::<", ", ")?;
 456                 ty.print_display(f, self)?;
 457             }
 458
 459             start_or_continue(f, "", ">")?;
 460         }
 461
 462         Ok(())
 463     }
 464
 465     fn in_binder<'a, 'gcx, 'tcx, T, U, F>(&mut self,
 466                                           f: &mut F,
 467                                           tcx: TyCtxt<'a, 'gcx, 'tcx>,
 468                                           original: &ty::Binder<T>,
 469                                           lifted: Option<ty::Binder<U>>) -> fmt::Result
 470         where T: Print, U: Print + TypeFoldable<'tcx>, F: fmt::Write
 471     {
 472         fn name_by_region_index(index: usize) -> InternedString {
 473             match index {
 474                 0 => Symbol::intern("'r"),
 475                 1 => Symbol::intern("'s"),
 476                 i => Symbol::intern(&format!("'t{}", i-2)),
 477             }.as_interned_str()
 478         }
 479
 480         // Replace any anonymous late-bound regions with named
 481         // variants, using gensym'd identifiers, so that we can
 482         // clearly differentiate between named and unnamed regions in
 483         // the output. We'll probably want to tweak this over time to
 484         // decide just how much information to give.
 485         let value = if let Some(v) = lifted {
 486             v
 487         } else {
 488             return original.skip_binder().print_display(f, self);
 489         };
 490
 491         if self.binder_depth == 0 {
 492             self.prepare_late_bound_region_info(&value);
 493         }
 494
 495         let mut empty = true;
 496         let mut start_or_continue = |f: &mut F, start: &str, cont: &str| {
 497             if empty {
 498                 empty = false;
 499                 write!(f, "{}", start)
 500             } else {
 501                 write!(f, "{}", cont)
 502             }
 503         };
 504
 505         let old_region_index = self.region_index;
 506         let mut region_index = old_region_index;
 507         let new_value = tcx.replace_late_bound_regions(&value, |br| {
 508             let _ = start_or_continue(f, "for<", ", ");
 509             let br = match br {
 510                 ty::BrNamed(_, name) => {
 511                     let _ = write!(f, "{}", name);
 512                     br
 513                 }
 514                 ty::BrAnon(_) |
 515                 ty::BrFresh(_) |
 516                 ty::BrEnv => {
 517                     let name = loop {
 518                         let name = name_by_region_index(region_index);
 519                         region_index += 1;
 520                         if !self.is_name_used(&name) {
 521                             break name;
 522                         }
 523                     };
 524                     let _ = write!(f, "{}", name);
 525                     ty::BrNamed(tcx.hir.local_def_id(CRATE_NODE_ID), name)
 526                 }
 527             };
 528             tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
 529         }).0;
 530         start_or_continue(f, "", "> ")?;
 531
 532         // Push current state to gcx, and restore after writing new_value.
 533         self.binder_depth += 1;
 534         self.region_index = region_index;
 535         let result = new_value.print_display(f, self);
 536         self.region_index = old_region_index;
 537         self.binder_depth -= 1;
 538         result
 539     }
 540
 541     fn is_name_used(&self, name: &InternedString) -> bool {
 542         match self.used_region_names {
 543             Some(ref names) => names.contains(name),
 544             None => false,
 545         }
 546     }
 547 }
 548
 549 pub fn verbose() -> bool {
 550     ty::tls::with(|tcx| tcx.sess.verbose())
 551 }
 552
 553 pub fn identify_regions() -> bool {
 554     ty::tls::with(|tcx| tcx.sess.opts.debugging_opts.identify_regions)
 555 }
 556
 557 pub fn parameterized<F: fmt::Write>(f: &mut F,
 558                                     substs: &subst::Substs,
 559                                     did: DefId,
 560                                     projections: &[ty::ProjectionPredicate])
 561                                     -> fmt::Result {
 562     PrintContext::new().parameterized(f, substs, did, projections)
 563 }
 564
 565
 566 impl<'a, T: Print> Print for &'a T {
 567     fn print<F: fmt::Write>(&self, f: &mut F, cx: &mut PrintContext) -> fmt::Result {
 568         (*self).print(f, cx)
 569     }
 570 }
 571
 572 define_print! {
 573     ('tcx) &'tcx ty::Slice<ty::ExistentialPredicate<'tcx>>, (self, f, cx) {
 574         display {
 575             // Generate the main trait ref, including associated types.
 576             ty::tls::with(|tcx| {
 577                 // Use a type that can't appear in defaults of type parameters.
 578                 let dummy_self = tcx.mk_infer(ty::FreshTy(0));
 579
 580                 if let Some(p) = self.principal() {
 581                     let principal = tcx.lift(&p).expect("could not lift TraitRef for printing")
 582                         .with_self_ty(tcx, dummy_self);
 583                     let projections = self.projection_bounds().map(|p| {
 584                         tcx.lift(&p)
 585                             .expect("could not lift projection for printing")
 586                             .with_self_ty(tcx, dummy_self)
 587                     }).collect::<Vec<_>>();
 588                     cx.parameterized(f, principal.substs, principal.def_id, &projections)?;
 589                 }
 590
 591                 // Builtin bounds.
 592                 for did in self.auto_traits() {
 593                     write!(f, " + {}", tcx.item_path_str(did))?;
 594                 }
 595
 596                 Ok(())
 597             })?;
 598
 599             Ok(())
 600         }
 601     }
 602 }
 603
 604 impl fmt::Debug for ty::GenericParamDef {
 605     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 606         let type_name = match self.kind {
 607             ty::GenericParamDefKind::Lifetime => "Lifetime",
 608             ty::GenericParamDefKind::Type {..} => "Type",
 609         };
 610         write!(f, "{}({}, {:?}, {})",
 611                type_name,
 612                self.name,
 613                self.def_id,
 614                self.index)
 615     }
 616 }
 617
 618 impl fmt::Debug for ty::TraitDef {
 619     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 620         ty::tls::with(|tcx| {
 621             write!(f, "{}", tcx.item_path_str(self.def_id))
 622         })
 623     }
 624 }
 625
 626 impl fmt::Debug for ty::AdtDef {
 627     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 628         ty::tls::with(|tcx| {
 629             write!(f, "{}", tcx.item_path_str(self.did))
 630         })
 631     }
 632 }
 633
 634 impl<'tcx> fmt::Debug for ty::ClosureUpvar<'tcx> {
 635     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 636         write!(f, "ClosureUpvar({:?},{:?})",
 637                self.def,
 638                self.ty)
 639     }
 640 }
 641
 642 impl fmt::Debug for ty::UpvarId {
 643     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 644         write!(f, "UpvarId({:?};`{}`;{:?})",
 645                self.var_id,
 646                ty::tls::with(|tcx| tcx.hir.name(tcx.hir.hir_to_node_id(self.var_id))),
 647                self.closure_expr_id)
 648     }
 649 }
 650
 651 impl<'tcx> fmt::Debug for ty::UpvarBorrow<'tcx> {
 652     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 653         write!(f, "UpvarBorrow({:?}, {:?})",
 654                self.kind, self.region)
 655     }
 656 }
 657
 658 define_print! {
 659     ('tcx) &'tcx ty::Slice<Ty<'tcx>>, (self, f, cx) {
 660         display {
 661             write!(f, "{{")?;
 662             let mut tys = self.iter();
 663             if let Some(&ty) = tys.next() {
 664                 print!(f, cx, print(ty))?;
 665                 for &ty in tys {
 666                     print!(f, cx, write(", "), print(ty))?;
 667                 }
 668             }
 669             write!(f, "}}")
 670         }
 671     }
 672 }
 673
 674 define_print! {
 675     ('tcx) ty::TypeAndMut<'tcx>, (self, f, cx) {
 676         display {
 677             print!(f, cx,
 678                    write("{}", if self.mutbl == hir::MutMutable { "mut " } else { "" }),
 679                    print(self.ty))
 680         }
 681     }
 682 }
 683
 684 define_print! {
 685     ('tcx) ty::ExistentialTraitRef<'tcx>, (self, f, cx) {
 686         debug {
 687             ty::tls::with(|tcx| {
 688                 let dummy_self = tcx.mk_infer(ty::FreshTy(0));
 689
 690                 let trait_ref = *tcx.lift(&ty::Binder::bind(*self))
 691                                    .expect("could not lift TraitRef for printing")
 692                                    .with_self_ty(tcx, dummy_self).skip_binder();
 693                 cx.parameterized(f, trait_ref.substs, trait_ref.def_id, &[])
 694             })
 695         }
 696     }
 697 }
 698
 699 define_print! {
 700     ('tcx) ty::adjustment::Adjustment<'tcx>, (self, f, cx) {
 701         debug {
 702             print!(f, cx, write("{:?} -> ", self.kind), print(self.target))
 703         }
 704     }
 705 }
 706
 707 define_print! {
 708     () ty::BoundRegion, (self, f, cx) {
 709         display {
 710             if cx.is_verbose {
 711                 return self.print_debug(f, cx);
 712             }
 713
 714             match *self {
 715                 BrNamed(_, name) => write!(f, "{}", name),
 716                 BrAnon(_) | BrFresh(_) | BrEnv => Ok(())
 717             }
 718         }
 719         debug {
 720             return match *self {
 721                 BrAnon(n) => write!(f, "BrAnon({:?})", n),
 722                 BrFresh(n) => write!(f, "BrFresh({:?})", n),
 723                 BrNamed(did, name) => {
 724                     write!(f, "BrNamed({:?}:{:?}, {})",
 725                            did.krate, did.index, name)
 726                 }
 727                 BrEnv => write!(f, "BrEnv"),
 728             };
 729         }
 730     }
 731 }
 732
 733 define_print! {
 734     () ty::RegionKind, (self, f, cx) {
 735         display {
 736             if cx.is_verbose {
 737                 return self.print_debug(f, cx);
 738             }
 739
 740             // These printouts are concise.  They do not contain all the information
 741             // the user might want to diagnose an error, but there is basically no way
 742             // to fit that into a short string.  Hence the recommendation to use
 743             // `explain_region()` or `note_and_explain_region()`.
 744             match *self {
 745                 ty::ReEarlyBound(ref data) => {
 746                     write!(f, "{}", data.name)
 747                 }
 748                 ty::ReCanonical(_) => {
 749                     write!(f, "'_")
 750                 }
 751                 ty::ReLateBound(_, br) |
 752                 ty::ReFree(ty::FreeRegion { bound_region: br, .. }) |
 753                 ty::ReSkolemized(_, br) => {
 754                     write!(f, "{}", br)
 755                 }
 756                 ty::ReScope(scope) if cx.identify_regions => {
 757                     match scope.data() {
 758                         region::ScopeData::Node(id) =>
 759                             write!(f, "'{}s", id.as_usize()),
 760                         region::ScopeData::CallSite(id) =>
 761                             write!(f, "'{}cs", id.as_usize()),
 762                         region::ScopeData::Arguments(id) =>
 763                             write!(f, "'{}as", id.as_usize()),
 764                         region::ScopeData::Destruction(id) =>
 765                             write!(f, "'{}ds", id.as_usize()),
 766                         region::ScopeData::Remainder(BlockRemainder
 767                                                      { block, first_statement_index }) =>
 768                             write!(f, "'{}_{}rs", block.as_usize(), first_statement_index.index()),
 769                     }
 770                 }
 771                 ty::ReVar(region_vid) if cx.identify_regions => {
 772                     write!(f, "'{}rv", region_vid.index())
 773                 }
 774                 ty::ReScope(_) |
 775                 ty::ReVar(_) |
 776                 ty::ReErased => Ok(()),
 777                 ty::ReStatic => write!(f, "'static"),
 778                 ty::ReEmpty => write!(f, "'<empty>"),
 779
 780                 // The user should never encounter these in unsubstituted form.
 781                 ty::ReClosureBound(vid) => write!(f, "{:?}", vid),
 782             }
 783         }
 784         debug {
 785             match *self {
 786                 ty::ReEarlyBound(ref data) => {
 787                     write!(f, "ReEarlyBound({}, {})",
 788                            data.index,
 789                            data.name)
 790                 }
 791
 792                 ty::ReClosureBound(ref vid) => {
 793                     write!(f, "ReClosureBound({:?})",
 794                            vid)
 795                 }
 796
 797                 ty::ReLateBound(binder_id, ref bound_region) => {
 798                     write!(f, "ReLateBound({:?}, {:?})",
 799                            binder_id,
 800                            bound_region)
 801                 }
 802
 803                 ty::ReFree(ref fr) => write!(f, "{:?}", fr),
 804
 805                 ty::ReScope(id) => {
 806                     write!(f, "ReScope({:?})", id)
 807                 }
 808
 809                 ty::ReStatic => write!(f, "ReStatic"),
 810
 811                 ty::ReVar(ref vid) => {
 812                     write!(f, "{:?}", vid)
 813                 }
 814
 815                 ty::ReCanonical(c) => {
 816                     write!(f, "'?{}", c.index())
 817                 }
 818
 819                 ty::ReSkolemized(universe, ref bound_region) => {
 820                     write!(f, "ReSkolemized({:?}, {:?})", universe, bound_region)
 821                 }
 822
 823                 ty::ReEmpty => write!(f, "ReEmpty"),
 824
 825                 ty::ReErased => write!(f, "ReErased")
 826             }
 827         }
 828     }
 829 }
 830
 831 define_print! {
 832     () ty::FreeRegion, (self, f, cx) {
 833         debug {
 834             write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 835         }
 836     }
 837 }
 838
 839 define_print! {
 840     () ty::Variance, (self, f, cx) {
 841         debug {
 842             f.write_str(match *self {
 843                 ty::Covariant => "+",
 844                 ty::Contravariant => "-",
 845                 ty::Invariant => "o",
 846                 ty::Bivariant => "*",
 847             })
 848         }
 849     }
 850 }
 851
 852 define_print! {
 853     ('tcx) ty::GenericPredicates<'tcx>, (self, f, cx) {
 854         debug {
 855             write!(f, "GenericPredicates({:?})", self.predicates)
 856         }
 857     }
 858 }
 859
 860 define_print! {
 861     ('tcx) ty::InstantiatedPredicates<'tcx>, (self, f, cx) {
 862         debug {
 863             write!(f, "InstantiatedPredicates({:?})", self.predicates)
 864         }
 865     }
 866 }
 867
 868 define_print! {
 869     ('tcx) ty::FnSig<'tcx>, (self, f, cx) {
 870         display {
 871             if self.unsafety == hir::Unsafety::Unsafe {
 872                 write!(f, "unsafe ")?;
 873             }
 874
 875             if self.abi != Abi::Rust {
 876                 write!(f, "extern {} ", self.abi)?;
 877             }
 878
 879             write!(f, "fn")?;
 880             cx.fn_sig(f, self.inputs(), self.variadic, self.output())
 881         }
 882         debug {
 883             write!(f, "({:?}; variadic: {})->{:?}", self.inputs(), self.variadic, self.output())
 884         }
 885     }
 886 }
 887
 888 impl fmt::Debug for ty::TyVid {
 889     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 890         write!(f, "_#{}t", self.index)
 891     }
 892 }
 893
 894 impl fmt::Debug for ty::IntVid {
 895     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 896         write!(f, "_#{}i", self.index)
 897     }
 898 }
 899
 900 impl fmt::Debug for ty::FloatVid {
 901     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 902         write!(f, "_#{}f", self.index)
 903     }
 904 }
 905
 906 impl fmt::Debug for ty::RegionVid {
 907     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 908         write!(f, "'_#{}r", self.index())
 909     }
 910 }
 911
 912 define_print! {
 913     () ty::InferTy, (self, f, cx) {
 914         display {
 915             if cx.is_verbose {
 916                 print!(f, cx, print_debug(self))
 917             } else {
 918                 match *self {
 919                     ty::TyVar(_) => write!(f, "_"),
 920                     ty::IntVar(_) => write!(f, "{}", "{integer}"),
 921                     ty::FloatVar(_) => write!(f, "{}", "{float}"),
 922                     ty::CanonicalTy(_) => write!(f, "_"),
 923                     ty::FreshTy(v) => write!(f, "FreshTy({})", v),
 924                     ty::FreshIntTy(v) => write!(f, "FreshIntTy({})", v),
 925                     ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({})", v)
 926                 }
 927             }
 928         }
 929         debug {
 930             match *self {
 931                 ty::TyVar(ref v) => write!(f, "{:?}", v),
 932                 ty::IntVar(ref v) => write!(f, "{:?}", v),
 933                 ty::FloatVar(ref v) => write!(f, "{:?}", v),
 934                 ty::CanonicalTy(v) => write!(f, "?{:?}", v.index()),
 935                 ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
 936                 ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
 937                 ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v)
 938             }
 939         }
 940     }
 941 }
 942
 943 impl fmt::Debug for ty::IntVarValue {
 944     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 945         match *self {
 946             ty::IntType(ref v) => v.fmt(f),
 947             ty::UintType(ref v) => v.fmt(f),
 948         }
 949     }
 950 }
 951
 952 impl fmt::Debug for ty::FloatVarValue {
 953     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 954         self.0.fmt(f)
 955     }
 956 }
 957
 958 // The generic impl doesn't work yet because projections are not
 959 // normalized under HRTB.
 960 /*impl<T> fmt::Display for ty::Binder<T>
 961     where T: fmt::Display + for<'a> ty::Lift<'a>,
 962           for<'a> <T as ty::Lift<'a>>::Lifted: fmt::Display + TypeFoldable<'a>
 963 {
 964     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 965         ty::tls::with(|tcx| in_binder(f, tcx, self, tcx.lift(self)))
 966     }
 967 }*/
 968
 969 define_print_multi! {
 970     [
 971     ('tcx) ty::Binder<&'tcx ty::Slice<ty::ExistentialPredicate<'tcx>>>,
 972     ('tcx) ty::Binder<ty::TraitRef<'tcx>>,
 973     ('tcx) ty::Binder<ty::FnSig<'tcx>>,
 974     ('tcx) ty::Binder<ty::TraitPredicate<'tcx>>,
 975     ('tcx) ty::Binder<ty::SubtypePredicate<'tcx>>,
 976     ('tcx) ty::Binder<ty::ProjectionPredicate<'tcx>>,
 977     ('tcx) ty::Binder<ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
 978     ('tcx) ty::Binder<ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>
 979     ]
 980     (self, f, cx) {
 981         display {
 982             ty::tls::with(|tcx| cx.in_binder(f, tcx, self, tcx.lift(self)))
 983         }
 984     }
 985 }
 986
 987 define_print! {
 988     ('tcx) ty::TraitRef<'tcx>, (self, f, cx) {
 989         display {
 990             cx.parameterized(f, self.substs, self.def_id, &[])
 991         }
 992         debug {
 993             // when printing out the debug representation, we don't need
 994             // to enumerate the `for<...>` etc because the debruijn index
 995             // tells you everything you need to know.
 996             print!(f, cx,
 997                    write("<"),
 998                    print(self.self_ty()),
 999                    write(" as "))?;
1000             cx.parameterized(f, self.substs, self.def_id, &[])?;
1001             write!(f, ">")
1002         }
1003     }
1004 }
1005
1006 define_print! {
1007     ('tcx) ty::TypeVariants<'tcx>, (self, f, cx) {
1008         display {
1009             match *self {
1010                 TyBool => write!(f, "bool"),
1011                 TyChar => write!(f, "char"),
1012                 TyInt(t) => write!(f, "{}", t.ty_to_string()),
1013                 TyUint(t) => write!(f, "{}", t.ty_to_string()),
1014                 TyFloat(t) => write!(f, "{}", t.ty_to_string()),
1015                 TyRawPtr(ref tm) => {
1016                     write!(f, "*{} ", match tm.mutbl {
1017                         hir::MutMutable => "mut",
1018                         hir::MutImmutable => "const",
1019                     })?;
1020                     tm.ty.print(f, cx)
1021                 }
1022                 TyRef(r, ty, mutbl) => {
1023                     write!(f, "&")?;
1024                     let s = r.print_to_string(cx);
1025                     write!(f, "{}", s)?;
1026                     if !s.is_empty() {
1027                         write!(f, " ")?;
1028                     }
1029                     ty::TypeAndMut { ty, mutbl }.print(f, cx)
1030                 }
1031                 TyNever => write!(f, "!"),
1032                 TyTuple(ref tys) => {
1033                     write!(f, "(")?;
1034                     let mut tys = tys.iter();
1035                     if let Some(&ty) = tys.next() {
1036                         print!(f, cx, print(ty), write(","))?;
1037                         if let Some(&ty) = tys.next() {
1038                             print!(f, cx, write(" "), print(ty))?;
1039                             for &ty in tys {
1040                                 print!(f, cx, write(", "), print(ty))?;
1041                             }
1042                         }
1043                     }
1044                     write!(f, ")")
1045                 }
1046                 TyFnDef(def_id, substs) => {
1047                     ty::tls::with(|tcx| {
1048                         let mut sig = tcx.fn_sig(def_id);
1049                         if let Some(substs) = tcx.lift(&substs) {
1050                             sig = sig.subst(tcx, substs);
1051                         }
1052                         print!(f, cx, print(sig), write(" {{"))
1053                     })?;
1054                     cx.parameterized(f, substs, def_id, &[])?;
1055                     write!(f, "}}")
1056                 }
1057                 TyFnPtr(ref bare_fn) => {
1058                     bare_fn.print(f, cx)
1059                 }
1060                 TyInfer(infer_ty) => write!(f, "{}", infer_ty),
1061                 TyError => write!(f, "[type error]"),
1062                 TyParam(ref param_ty) => write!(f, "{}", param_ty),
1063                 TyAdt(def, substs) => cx.parameterized(f, substs, def.did, &[]),
1064                 TyDynamic(data, r) => {
1065                     data.print(f, cx)?;
1066                     let r = r.print_to_string(cx);
1067                     if !r.is_empty() {
1068                         write!(f, " + {}", r)
1069                     } else {
1070                         Ok(())
1071                     }
1072                 }
1073                 TyForeign(def_id) => parameterized(f, subst::Substs::empty(), def_id, &[]),
1074                 TyProjection(ref data) => data.print(f, cx),
1075                 TyAnon(def_id, substs) => {
1076                     if cx.is_verbose {
1077                         return write!(f, "TyAnon({:?}, {:?})", def_id, substs);
1078                     }
1079
1080                     ty::tls::with(|tcx| {
1081                         // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1082                         // by looking up the projections associated with the def_id.
1083                         let predicates_of = tcx.predicates_of(def_id);
1084                         let substs = tcx.lift(&substs).unwrap_or_else(|| {
1085                             tcx.intern_substs(&[])
1086                         });
1087                         let bounds = predicates_of.instantiate(tcx, substs);
1088
1089                         let mut first = true;
1090                         let mut is_sized = false;
1091                         write!(f, "impl")?;
1092                         for predicate in bounds.predicates {
1093                             if let Some(trait_ref) = predicate.to_opt_poly_trait_ref() {
1094                                 // Don't print +Sized, but rather +?Sized if absent.
1095                                 if Some(trait_ref.def_id()) == tcx.lang_items().sized_trait() {
1096                                     is_sized = true;
1097                                     continue;
1098                                 }
1099
1100                                 print!(f, cx,
1101                                        write("{}", if first { " " } else { "+" }),
1102                                        print(trait_ref))?;
1103                                 first = false;
1104                             }
1105                         }
1106                         if !is_sized {
1107                             write!(f, "{}?Sized", if first { " " } else { "+" })?;
1108                         }
1109                         Ok(())
1110                     })
1111                 }
1112                 TyStr => write!(f, "str"),
1113                 TyGenerator(did, substs, movability) => ty::tls::with(|tcx| {
1114                     let upvar_tys = substs.upvar_tys(did, tcx);
1115                     let witness = substs.witness(did, tcx);
1116                     if movability == hir::GeneratorMovability::Movable {
1117                         write!(f, "[generator")?;
1118                     } else {
1119                         write!(f, "[static generator")?;
1120                     }
1121
1122                     if let Some(node_id) = tcx.hir.as_local_node_id(did) {
1123                         write!(f, "@{:?}", tcx.hir.span(node_id))?;
1124                         let mut sep = " ";
1125                         tcx.with_freevars(node_id, |freevars| {
1126                             for (freevar, upvar_ty) in freevars.iter().zip(upvar_tys) {
1127                                 print!(f, cx,
1128                                        write("{}{}:",
1129                                              sep,
1130                                              tcx.hir.name(freevar.var_id())),
1131                                        print(upvar_ty))?;
1132                                 sep = ", ";
1133                             }
1134                             Ok(())
1135                         })?
1136                     } else {
1137                         // cross-crate closure types should only be
1138                         // visible in codegen bug reports, I imagine.
1139                         write!(f, "@{:?}", did)?;
1140                         let mut sep = " ";
1141                         for (index, upvar_ty) in upvar_tys.enumerate() {
1142                             print!(f, cx,
1143                                    write("{}{}:", sep, index),
1144                                    print(upvar_ty))?;
1145                             sep = ", ";
1146                         }
1147                     }
1148
1149                     print!(f, cx, write(" "), print(witness), write("]"))
1150                 }),
1151                 TyGeneratorWitness(types) => {
1152                     ty::tls::with(|tcx| cx.in_binder(f, tcx, &types, tcx.lift(&types)))
1153                 }
1154                 TyClosure(did, substs) => ty::tls::with(|tcx| {
1155                     let upvar_tys = substs.upvar_tys(did, tcx);
1156                     write!(f, "[closure")?;
1157
1158                     if let Some(node_id) = tcx.hir.as_local_node_id(did) {
1159                         if tcx.sess.opts.debugging_opts.span_free_formats {
1160                             write!(f, "@{:?}", node_id)?;
1161                         } else {
1162                             write!(f, "@{:?}", tcx.hir.span(node_id))?;
1163                         }
1164                         let mut sep = " ";
1165                         tcx.with_freevars(node_id, |freevars| {
1166                             for (freevar, upvar_ty) in freevars.iter().zip(upvar_tys) {
1167                                 print!(f, cx,
1168                                        write("{}{}:",
1169                                              sep,
1170                                              tcx.hir.name(freevar.var_id())),
1171                                        print(upvar_ty))?;
1172                                 sep = ", ";
1173                             }
1174                             Ok(())
1175                         })?
1176                     } else {
1177                         // cross-crate closure types should only be
1178                         // visible in codegen bug reports, I imagine.
1179                         write!(f, "@{:?}", did)?;
1180                         let mut sep = " ";
1181                         for (index, upvar_ty) in upvar_tys.enumerate() {
1182                             print!(f, cx,
1183                                    write("{}{}:", sep, index),
1184                                    print(upvar_ty))?;
1185                             sep = ", ";
1186                         }
1187                     }
1188
1189                     write!(f, "]")
1190                 }),
1191                 TyArray(ty, sz) => {
1192                     print!(f, cx, write("["), print(ty), write("; "))?;
1193                     match sz.val {
1194                         ConstVal::Value(..) => ty::tls::with(|tcx| {
1195                             write!(f, "{}", sz.unwrap_usize(tcx))
1196                         })?,
1197                         ConstVal::Unevaluated(_def_id, _substs) => {
1198                             write!(f, "_")?;
1199                         }
1200                     }
1201                     write!(f, "]")
1202                 }
1203                 TySlice(ty) => {
1204                     print!(f, cx, write("["), print(ty), write("]"))
1205                 }
1206             }
1207         }
1208     }
1209 }
1210
1211 define_print! {
1212     ('tcx) ty::TyS<'tcx>, (self, f, cx) {
1213         display {
1214             self.sty.print(f, cx)
1215         }
1216         debug {
1217             self.sty.print_display(f, cx)
1218         }
1219     }
1220 }
1221
1222 define_print! {
1223     () ty::ParamTy, (self, f, cx) {
1224         display {
1225             write!(f, "{}", self.name)
1226         }
1227         debug {
1228             write!(f, "{}/#{}", self.name, self.idx)
1229         }
1230     }
1231 }
1232
1233 define_print! {
1234     ('tcx, T: Print + fmt::Debug, U: Print + fmt::Debug) ty::OutlivesPredicate<T, U>,
1235     (self, f, cx) {
1236         display {
1237             print!(f, cx, print(self.0), write(" : "), print(self.1))
1238         }
1239     }
1240 }
1241
1242 define_print! {
1243     ('tcx) ty::SubtypePredicate<'tcx>, (self, f, cx) {
1244         display {
1245             print!(f, cx, print(self.a), write(" <: "), print(self.b))
1246         }
1247     }
1248 }
1249
1250 define_print! {
1251     ('tcx) ty::TraitPredicate<'tcx>, (self, f, cx) {
1252         debug {
1253             write!(f, "TraitPredicate({:?})",
1254                    self.trait_ref)
1255         }
1256         display {
1257             print!(f, cx, print(self.trait_ref.self_ty()), write(": "), print(self.trait_ref))
1258         }
1259     }
1260 }
1261
1262 define_print! {
1263     ('tcx) ty::ProjectionPredicate<'tcx>, (self, f, cx) {
1264         debug {
1265             print!(f, cx,
1266                    write("ProjectionPredicate("),
1267                    print(self.projection_ty),
1268                    write(", "),
1269                    print(self.ty),
1270                    write(")"))
1271         }
1272         display {
1273             print!(f, cx, print(self.projection_ty), write(" == "), print(self.ty))
1274         }
1275     }
1276 }
1277
1278 define_print! {
1279     ('tcx) ty::ProjectionTy<'tcx>, (self, f, cx) {
1280         display {
1281             // FIXME(tschottdorf): use something like
1282             //   parameterized(f, self.substs, self.item_def_id, &[])
1283             // (which currently ICEs).
1284             let (trait_ref, item_name) = ty::tls::with(|tcx|
1285                 (self.trait_ref(tcx), tcx.associated_item(self.item_def_id).name)
1286             );
1287             print!(f, cx, print_debug(trait_ref), write("::{}", item_name))
1288         }
1289     }
1290 }
1291
1292 define_print! {
1293     () ty::ClosureKind, (self, f, cx) {
1294         display {
1295             match *self {
1296                 ty::ClosureKind::Fn => write!(f, "Fn"),
1297                 ty::ClosureKind::FnMut => write!(f, "FnMut"),
1298                 ty::ClosureKind::FnOnce => write!(f, "FnOnce"),
1299             }
1300         }
1301     }
1302 }
1303
1304 define_print! {
1305     ('tcx) ty::Predicate<'tcx>, (self, f, cx) {
1306         display {
1307             match *self {
1308                 ty::Predicate::Trait(ref data) => data.print(f, cx),
1309                 ty::Predicate::Subtype(ref predicate) => predicate.print(f, cx),
1310                 ty::Predicate::RegionOutlives(ref predicate) => predicate.print(f, cx),
1311                 ty::Predicate::TypeOutlives(ref predicate) => predicate.print(f, cx),
1312                 ty::Predicate::Projection(ref predicate) => predicate.print(f, cx),
1313                 ty::Predicate::WellFormed(ty) => print!(f, cx, print(ty), write(" well-formed")),
1314                 ty::Predicate::ObjectSafe(trait_def_id) =>
1315                     ty::tls::with(|tcx| {
1316                         write!(f, "the trait `{}` is object-safe", tcx.item_path_str(trait_def_id))
1317                     }),
1318                 ty::Predicate::ClosureKind(closure_def_id, _closure_substs, kind) =>
1319                     ty::tls::with(|tcx| {
1320                         write!(f, "the closure `{}` implements the trait `{}`",
1321                                tcx.item_path_str(closure_def_id), kind)
1322                     }),
1323                 ty::Predicate::ConstEvaluatable(def_id, substs) => {
1324                     write!(f, "the constant `")?;
1325                     cx.parameterized(f, substs, def_id, &[])?;
1326                     write!(f, "` can be evaluated")
1327                 }
1328             }
1329         }
1330         debug {
1331             match *self {
1332                 ty::Predicate::Trait(ref a) => a.print(f, cx),
1333                 ty::Predicate::Subtype(ref pair) => pair.print(f, cx),
1334                 ty::Predicate::RegionOutlives(ref pair) => pair.print(f, cx),
1335                 ty::Predicate::TypeOutlives(ref pair) => pair.print(f, cx),
1336                 ty::Predicate::Projection(ref pair) => pair.print(f, cx),
1337                 ty::Predicate::WellFormed(ty) => ty.print(f, cx),
1338                 ty::Predicate::ObjectSafe(trait_def_id) => {
1339                     write!(f, "ObjectSafe({:?})", trait_def_id)
1340                 }
1341                 ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
1342                     write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
1343                 }
1344                 ty::Predicate::ConstEvaluatable(def_id, substs) => {
1345                     write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
1346                 }
1347             }
1348         }
1349     }
1350 }