src/librustc/util/ppaux.rs

   1 use crate::hir::def_id::DefId;
   2 use crate::hir::map::definitions::DefPathData;
   3 use crate::middle::region;
   4 use crate::ty::subst::{self, Subst, SubstsRef};
   5 use crate::ty::{BrAnon, BrEnv, BrFresh, BrNamed};
   6 use crate::ty::{Bool, Char, Adt};
   7 use crate::ty::{Error, Str, Array, Slice, Float, FnDef, FnPtr};
   8 use crate::ty::{Param, Bound, RawPtr, Ref, Never, Tuple};
   9 use crate::ty::{Closure, Generator, GeneratorWitness, Foreign, Projection, Opaque};
  10 use crate::ty::{Placeholder, UnnormalizedProjection, Dynamic, Int, Uint, Infer};
  11 use crate::ty::{self, Ty, TyCtxt, TypeFoldable, GenericParamCount, GenericParamDefKind, ParamConst};
  12 use crate::ty::print::{PrintCx, Print};
  13 use crate::mir::interpret::ConstValue;
  14
  15 use std::cell::Cell;
  16 use std::fmt;
  17 use std::usize;
  18
  19 use rustc_target::spec::abi::Abi;
  20 use syntax::ast::CRATE_NODE_ID;
  21 use syntax::symbol::{Symbol, InternedString};
  22 use crate::hir;
  23
  24 /// The "region highlights" are used to control region printing during
  25 /// specific error messages. When a "region highlight" is enabled, it
  26 /// gives an alternate way to print specific regions. For now, we
  27 /// always print those regions using a number, so something like "`'0`".
  28 ///
  29 /// Regions not selected by the region highlight mode are presently
  30 /// unaffected.
  31 #[derive(Copy, Clone, Default)]
  32 pub struct RegionHighlightMode {
  33     /// If enabled, when we see the selected region, use "`'N`"
  34     /// instead of the ordinary behavior.
  35     highlight_regions: [Option<(ty::RegionKind, usize)>; 3],
  36
  37     /// If enabled, when printing a "free region" that originated from
  38     /// the given `ty::BoundRegion`, print it as "`'1`". Free regions that would ordinarily
  39     /// have names print as normal.
  40     ///
  41     /// This is used when you have a signature like `fn foo(x: &u32,
  42     /// y: &'a u32)` and we want to give a name to the region of the
  43     /// reference `x`.
  44     highlight_bound_region: Option<(ty::BoundRegion, usize)>,
  45 }
  46
  47 thread_local! {
  48     /// Mechanism for highlighting of specific regions for display in NLL region inference errors.
  49     /// Contains region to highlight and counter for number to use when highlighting.
  50     static REGION_HIGHLIGHT_MODE: Cell<RegionHighlightMode> =
  51         Cell::new(RegionHighlightMode::default())
  52 }
  53
  54 impl RegionHighlightMode {
  55     /// Reads and returns the current region highlight settings (accesses thread-local state).
  56     pub fn get() -> Self {
  57         REGION_HIGHLIGHT_MODE.with(|c| c.get())
  58     }
  59
  60     // Internal helper to update current settings during the execution of `op`.
  61     fn set<R>(
  62         old_mode: Self,
  63         new_mode: Self,
  64         op: impl FnOnce() -> R,
  65     ) -> R {
  66         REGION_HIGHLIGHT_MODE.with(|c| {
  67             c.set(new_mode);
  68             let result = op();
  69             c.set(old_mode);
  70             result
  71         })
  72     }
  73
  74     /// If `region` and `number` are both `Some`, invokes
  75     /// `highlighting_region`; otherwise, just invokes `op` directly.
  76     pub fn maybe_highlighting_region<R>(
  77         region: Option<ty::Region<'_>>,
  78         number: Option<usize>,
  79         op: impl FnOnce() -> R,
  80     ) -> R {
  81         if let Some(k) = region {
  82             if let Some(n) = number {
  83                 return Self::highlighting_region(k, n, op);
  84             }
  85         }
  86
  87         op()
  88     }
  89
  90     /// During the execution of `op`, highlights the region inference
  91     /// variable `vid` as `'N`. We can only highlight one region `vid`
  92     /// at a time.
  93     pub fn highlighting_region<R>(
  94         region: ty::Region<'_>,
  95         number: usize,
  96         op: impl FnOnce() -> R,
  97     ) -> R {
  98         let old_mode = Self::get();
  99         let mut new_mode = old_mode;
 100         let first_avail_slot = new_mode.highlight_regions.iter_mut()
 101             .filter(|s| s.is_none())
 102             .next()
 103             .unwrap_or_else(|| {
 104                 panic!(
 105                     "can only highlight {} placeholders at a time",
 106                     old_mode.highlight_regions.len(),
 107                 )
 108             });
 109         *first_avail_slot = Some((*region, number));
 110         Self::set(old_mode, new_mode, op)
 111     }
 112
 113     /// Convenience wrapper for `highlighting_region`.
 114     pub fn highlighting_region_vid<R>(
 115         vid: ty::RegionVid,
 116         number: usize,
 117         op: impl FnOnce() -> R,
 118     ) -> R {
 119         Self::highlighting_region(&ty::ReVar(vid), number, op)
 120     }
 121
 122     /// Returns `true` if any placeholders are highlighted, and `false` otherwise.
 123     fn any_region_vids_highlighted(&self) -> bool {
 124         Self::get()
 125             .highlight_regions
 126             .iter()
 127             .any(|h| match h {
 128                 Some((ty::ReVar(_), _)) => true,
 129                 _ => false,
 130             })
 131     }
 132
 133     /// Returns `Some(n)` with the number to use for the given region, if any.
 134     fn region_highlighted(&self, region: ty::Region<'_>) -> Option<usize> {
 135         Self::get()
 136             .highlight_regions
 137             .iter()
 138             .filter_map(|h| match h {
 139                 Some((r, n)) if r == region => Some(*n),
 140                 _ => None,
 141             })
 142             .next()
 143     }
 144
 145     /// During the execution of `op`, highlight the given bound
 146     /// region. We can only highlight one bound region at a time. See
 147     /// the field `highlight_bound_region` for more detailed notes.
 148     pub fn highlighting_bound_region<R>(
 149         br: ty::BoundRegion,
 150         number: usize,
 151         op: impl FnOnce() -> R,
 152     ) -> R {
 153         let old_mode = Self::get();
 154         assert!(old_mode.highlight_bound_region.is_none());
 155         Self::set(
 156             old_mode,
 157             Self {
 158                 highlight_bound_region: Some((br, number)),
 159                 ..old_mode
 160             },
 161             op,
 162         )
 163     }
 164
 165     /// Returns `true` if any placeholders are highlighted, and `false` otherwise.
 166     pub fn any_placeholders_highlighted(&self) -> bool {
 167         Self::get()
 168             .highlight_regions
 169             .iter()
 170             .any(|h| match h {
 171                 Some((ty::RePlaceholder(_), _)) => true,
 172                 _ => false,
 173             })
 174     }
 175
 176     /// Returns `Some(N)` if the placeholder `p` is highlighted to print as "`'N`".
 177     pub fn placeholder_highlight(&self, p: ty::PlaceholderRegion) -> Option<usize> {
 178         self.region_highlighted(&ty::RePlaceholder(p))
 179     }
 180 }
 181
 182 macro_rules! gen_display_debug_body {
 183     ( $with:path ) => {
 184         fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 185             let mut cx = PrintCx::new();
 186             $with(self, f, &mut cx)
 187         }
 188     };
 189 }
 190 macro_rules! gen_display_debug {
 191     ( ($($x:tt)+) $target:ty, display yes ) => {
 192         impl<$($x)+> fmt::Display for $target {
 193             gen_display_debug_body! { Print::print_display }
 194         }
 195     };
 196     ( () $target:ty, display yes ) => {
 197         impl fmt::Display for $target {
 198             gen_display_debug_body! { Print::print_display }
 199         }
 200     };
 201     ( ($($x:tt)+) $target:ty, debug yes ) => {
 202         impl<$($x)+> fmt::Debug for $target {
 203             gen_display_debug_body! { Print::print_debug }
 204         }
 205     };
 206     ( () $target:ty, debug yes ) => {
 207         impl fmt::Debug for $target {
 208             gen_display_debug_body! { Print::print_debug }
 209         }
 210     };
 211     ( $generic:tt $target:ty, $t:ident no ) => {};
 212 }
 213 macro_rules! gen_print_impl {
 214     ( ($($x:tt)+) $target:ty, ($self:ident, $f:ident, $cx:ident) $disp:block $dbg:block ) => {
 215         impl<$($x)+> Print<'tcx> for $target {
 216             fn print<F: fmt::Write>(&$self, $f: &mut F, $cx: &mut PrintCx) -> fmt::Result {
 217                 if $cx.is_debug $dbg
 218                 else $disp
 219             }
 220         }
 221     };
 222     ( () $target:ty, ($self:ident, $f:ident, $cx:ident) $disp:block $dbg:block ) => {
 223         impl Print<'tcx> for $target {
 224             fn print<F: fmt::Write>(&$self, $f: &mut F, $cx: &mut PrintCx) -> fmt::Result {
 225                 if $cx.is_debug $dbg
 226                 else $disp
 227             }
 228         }
 229     };
 230     ( $generic:tt $target:ty,
 231       $vars:tt $gendisp:ident $disp:block $gendbg:ident $dbg:block ) => {
 232         gen_print_impl! { $generic $target, $vars $disp $dbg }
 233         gen_display_debug! { $generic $target, display $gendisp }
 234         gen_display_debug! { $generic $target, debug $gendbg }
 235     }
 236 }
 237 macro_rules! define_print {
 238     ( $generic:tt $target:ty,
 239       $vars:tt { display $disp:block debug $dbg:block } ) => {
 240         gen_print_impl! { $generic $target, $vars yes $disp yes $dbg }
 241     };
 242     ( $generic:tt $target:ty,
 243       $vars:tt { debug $dbg:block display $disp:block } ) => {
 244         gen_print_impl! { $generic $target, $vars yes $disp yes $dbg }
 245     };
 246     ( $generic:tt $target:ty,
 247       $vars:tt { debug $dbg:block } ) => {
 248         gen_print_impl! { $generic $target, $vars no {
 249             bug!(concat!("display not implemented for ", stringify!($target)));
 250         } yes $dbg }
 251     };
 252     ( $generic:tt $target:ty,
 253       ($self:ident, $f:ident, $cx:ident) { display $disp:block } ) => {
 254         gen_print_impl! { $generic $target, ($self, $f, $cx) yes $disp no {
 255             write!($f, "{:?}", $self)
 256         } }
 257     };
 258 }
 259 macro_rules! define_print_multi {
 260     ( [ $($generic:tt $target:ty),* ] $vars:tt $def:tt ) => {
 261         $(define_print! { $generic $target, $vars $def })*
 262     };
 263 }
 264 macro_rules! print_inner {
 265     ( $f:expr, $cx:expr, write ($($data:expr),+) ) => {
 266         write!($f, $($data),+)
 267     };
 268     ( $f:expr, $cx:expr, $kind:ident ($data:expr) ) => {
 269         $data.$kind($f, $cx)
 270     };
 271 }
 272 macro_rules! print {
 273     ( $f:expr, $cx:expr $(, $kind:ident $data:tt)+ ) => {
 274         Ok(())$(.and_then(|_| print_inner!($f, $cx, $kind $data)))+
 275     };
 276 }
 277
 278 impl PrintCx {
 279     fn fn_sig<F: fmt::Write>(&mut self,
 280                              f: &mut F,
 281                              inputs: &[Ty<'_>],
 282                              c_variadic: bool,
 283                              output: Ty<'_>)
 284                              -> fmt::Result {
 285         write!(f, "(")?;
 286         let mut inputs = inputs.iter();
 287         if let Some(&ty) = inputs.next() {
 288             print!(f, self, print_display(ty))?;
 289             for &ty in inputs {
 290                 print!(f, self, write(", "), print_display(ty))?;
 291             }
 292             if c_variadic {
 293                 write!(f, ", ...")?;
 294             }
 295         }
 296         write!(f, ")")?;
 297         if !output.is_unit() {
 298             print!(f, self, write(" -> "), print_display(output))?;
 299         }
 300
 301         Ok(())
 302     }
 303
 304     fn parameterized<F: fmt::Write>(&mut self,
 305                                     f: &mut F,
 306                                     substs: SubstsRef<'_>,
 307                                     did: DefId,
 308                                     projections: &[ty::ProjectionPredicate<'_>])
 309                                     -> fmt::Result {
 310         let key = ty::tls::with(|tcx| tcx.def_key(did));
 311
 312         let verbose = self.is_verbose;
 313         let mut num_supplied_defaults = 0;
 314         let mut has_self = false;
 315         let mut own_counts: GenericParamCount = Default::default();
 316         let mut is_value_path = false;
 317         let mut item_name = Some(key.disambiguated_data.data.as_interned_str());
 318         let fn_trait_kind = ty::tls::with(|tcx| {
 319             // Unfortunately, some kinds of items (e.g., closures) don't have
 320             // generics. So walk back up the find the closest parent that DOES
 321             // have them.
 322             let mut item_def_id = did;
 323             loop {
 324                 let key = tcx.def_key(item_def_id);
 325                 match key.disambiguated_data.data {
 326                     DefPathData::AssocTypeInTrait(_) |
 327                     DefPathData::AssocTypeInImpl(_) |
 328                     DefPathData::AssocExistentialInImpl(_) |
 329                     DefPathData::Trait(_) |
 330                     DefPathData::TraitAlias(_) |
 331                     DefPathData::Impl |
 332                     DefPathData::TypeNs(_) => {
 333                         break;
 334                     }
 335                     DefPathData::ValueNs(_) |
 336                     DefPathData::EnumVariant(_) => {
 337                         is_value_path = true;
 338                         break;
 339                     }
 340                     DefPathData::CrateRoot |
 341                     DefPathData::Misc |
 342                     DefPathData::Module(_) |
 343                     DefPathData::MacroDef(_) |
 344                     DefPathData::ClosureExpr |
 345                     DefPathData::TypeParam(_) |
 346                     DefPathData::LifetimeParam(_) |
 347                     DefPathData::ConstParam(_) |
 348                     DefPathData::Field(_) |
 349                     DefPathData::StructCtor |
 350                     DefPathData::AnonConst |
 351                     DefPathData::ImplTrait |
 352                     DefPathData::GlobalMetaData(_) => {
 353                         // if we're making a symbol for something, there ought
 354                         // to be a value or type-def or something in there
 355                         // *somewhere*
 356                         item_def_id.index = key.parent.unwrap_or_else(|| {
 357                             bug!("finding type for {:?}, encountered def-id {:?} with no \
 358                                  parent", did, item_def_id);
 359                         });
 360                     }
 361                 }
 362             }
 363             let mut generics = tcx.generics_of(item_def_id);
 364             let child_own_counts = generics.own_counts();
 365             let mut path_def_id = did;
 366             has_self = generics.has_self;
 367
 368             let mut child_types = 0;
 369             if let Some(def_id) = generics.parent {
 370                 // Methods.
 371                 assert!(is_value_path);
 372                 child_types = child_own_counts.types;
 373                 generics = tcx.generics_of(def_id);
 374                 own_counts = generics.own_counts();
 375
 376                 if has_self {
 377                     print!(f, self, write("<"), print_display(substs.type_at(0)), write(" as "))?;
 378                 }
 379
 380                 path_def_id = def_id;
 381             } else {
 382                 item_name = None;
 383
 384                 if is_value_path {
 385                     // Functions.
 386                     assert_eq!(has_self, false);
 387                 } else {
 388                     // Types and traits.
 389                     own_counts = child_own_counts;
 390                 }
 391             }
 392
 393             if !verbose {
 394                 let mut type_params =
 395                     generics.params.iter().rev().filter_map(|param| match param.kind {
 396                         GenericParamDefKind::Lifetime => None,
 397                         GenericParamDefKind::Type { has_default, .. } => {
 398                             Some((param.def_id, has_default))
 399                         }
 400                         GenericParamDefKind::Const => None, // FIXME(const_generics:defaults)
 401                     }).peekable();
 402                 let has_default = {
 403                     let has_default = type_params.peek().map(|(_, has_default)| has_default);
 404                     *has_default.unwrap_or(&false)
 405                 };
 406                 if has_default {
 407                     let substs = tcx.lift(&substs).expect("could not lift for printing");
 408                     let types = substs.types().rev().skip(child_types);
 409                     for ((def_id, has_default), actual) in type_params.zip(types) {
 410                         if !has_default {
 411                             break;
 412                         }
 413                         if tcx.type_of(def_id).subst(tcx, substs) != actual {
 414                             break;
 415                         }
 416                         num_supplied_defaults += 1;
 417                     }
 418                 }
 419             }
 420
 421             print!(f, self, write("{}", tcx.item_path_str(path_def_id)))?;
 422             Ok(tcx.lang_items().fn_trait_kind(path_def_id))
 423         })?;
 424
 425         if !verbose && fn_trait_kind.is_some() && projections.len() == 1 {
 426             let projection_ty = projections[0].ty;
 427             if let Tuple(ref args) = substs.type_at(1).sty {
 428                 return self.fn_sig(f, args, false, projection_ty);
 429             }
 430         }
 431
 432         let empty = Cell::new(true);
 433         let start_or_continue = |f: &mut F, start: &str, cont: &str| {
 434             if empty.get() {
 435                 empty.set(false);
 436                 write!(f, "{}", start)
 437             } else {
 438                 write!(f, "{}", cont)
 439             }
 440         };
 441
 442         let print_regions = |f: &mut F, start: &str, skip, count| {
 443             // Don't print any regions if they're all erased.
 444             let regions = || substs.regions().skip(skip).take(count);
 445             if regions().all(|r: ty::Region<'_>| *r == ty::ReErased) {
 446                 return Ok(());
 447             }
 448
 449             for region in regions() {
 450                 let region: ty::Region<'_> = region;
 451                 start_or_continue(f, start, ", ")?;
 452                 if verbose {
 453                     write!(f, "{:?}", region)?;
 454                 } else {
 455                     let s = region.to_string();
 456                     if s.is_empty() {
 457                         // This happens when the value of the region
 458                         // parameter is not easily serialized. This may be
 459                         // because the user omitted it in the first place,
 460                         // or because it refers to some block in the code,
 461                         // etc. I'm not sure how best to serialize this.
 462                         write!(f, "'_")?;
 463                     } else {
 464                         write!(f, "{}", s)?;
 465                     }
 466                 }
 467             }
 468
 469             Ok(())
 470         };
 471
 472         print_regions(f, "<", 0, own_counts.lifetimes)?;
 473
 474         let tps = substs.types()
 475                         .take(own_counts.types - num_supplied_defaults)
 476                         .skip(has_self as usize);
 477
 478         for ty in tps {
 479             start_or_continue(f, "<", ", ")?;
 480             ty.print_display(f, self)?;
 481         }
 482
 483         for projection in projections {
 484             start_or_continue(f, "<", ", ")?;
 485             ty::tls::with(|tcx|
 486                 print!(f, self,
 487                        write("{}=",
 488                              tcx.associated_item(projection.projection_ty.item_def_id).ident),
 489                        print_display(projection.ty))
 490             )?;
 491         }
 492
 493         // FIXME(const_generics::defaults)
 494         let consts = substs.consts();
 495
 496         for ct in consts {
 497             start_or_continue(f, "<", ", ")?;
 498             ct.print_display(f, self)?;
 499         }
 500
 501         start_or_continue(f, "", ">")?;
 502
 503         // For values, also print their name and type parameters.
 504         if is_value_path {
 505             empty.set(true);
 506
 507             if has_self {
 508                 write!(f, ">")?;
 509             }
 510
 511             if let Some(item_name) = item_name {
 512                 write!(f, "::{}", item_name)?;
 513             }
 514
 515             print_regions(f, "::<", own_counts.lifetimes, usize::MAX)?;
 516
 517             // FIXME: consider being smart with defaults here too
 518             for ty in substs.types().skip(own_counts.types) {
 519                 start_or_continue(f, "::<", ", ")?;
 520                 ty.print_display(f, self)?;
 521             }
 522
 523             start_or_continue(f, "", ">")?;
 524         }
 525
 526         Ok(())
 527     }
 528
 529     fn in_binder<'a, 'gcx, 'tcx, T, F>(
 530         &mut self,
 531         f: &mut F,
 532         tcx: TyCtxt<'a, 'gcx, 'tcx>,
 533         value: ty::Binder<T>,
 534     ) -> fmt::Result
 535         where T: Print<'tcx> + TypeFoldable<'tcx>, F: fmt::Write
 536     {
 537         fn name_by_region_index(index: usize) -> InternedString {
 538             match index {
 539                 0 => Symbol::intern("'r"),
 540                 1 => Symbol::intern("'s"),
 541                 i => Symbol::intern(&format!("'t{}", i-2)),
 542             }.as_interned_str()
 543         }
 544
 545         // Replace any anonymous late-bound regions with named
 546         // variants, using gensym'd identifiers, so that we can
 547         // clearly differentiate between named and unnamed regions in
 548         // the output. We'll probably want to tweak this over time to
 549         // decide just how much information to give.
 550         if self.binder_depth == 0 {
 551             self.prepare_late_bound_region_info(&value);
 552         }
 553
 554         let mut empty = true;
 555         let mut start_or_continue = |f: &mut F, start: &str, cont: &str| {
 556             if empty {
 557                 empty = false;
 558                 write!(f, "{}", start)
 559             } else {
 560                 write!(f, "{}", cont)
 561             }
 562         };
 563
 564         let old_region_index = self.region_index;
 565         let mut region_index = old_region_index;
 566         let new_value = tcx.replace_late_bound_regions(&value, |br| {
 567             let _ = start_or_continue(f, "for<", ", ");
 568             let br = match br {
 569                 ty::BrNamed(_, name) => {
 570                     let _ = write!(f, "{}", name);
 571                     br
 572                 }
 573                 ty::BrAnon(_) |
 574                 ty::BrFresh(_) |
 575                 ty::BrEnv => {
 576                     let name = loop {
 577                         let name = name_by_region_index(region_index);
 578                         region_index += 1;
 579                         if !self.is_name_used(&name) {
 580                             break name;
 581                         }
 582                     };
 583                     let _ = write!(f, "{}", name);
 584                     ty::BrNamed(tcx.hir().local_def_id(CRATE_NODE_ID), name)
 585                 }
 586             };
 587             tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br))
 588         }).0;
 589         start_or_continue(f, "", "> ")?;
 590
 591         // Push current state to gcx, and restore after writing new_value.
 592         self.binder_depth += 1;
 593         self.region_index = region_index;
 594         let result = new_value.print_display(f, self);
 595         self.region_index = old_region_index;
 596         self.binder_depth -= 1;
 597         result
 598     }
 599
 600     fn is_name_used(&self, name: &InternedString) -> bool {
 601         match self.used_region_names {
 602             Some(ref names) => names.contains(name),
 603             None => false,
 604         }
 605     }
 606 }
 607
 608 pub fn verbose() -> bool {
 609     ty::tls::with(|tcx| tcx.sess.verbose())
 610 }
 611
 612 pub fn identify_regions() -> bool {
 613     ty::tls::with(|tcx| tcx.sess.opts.debugging_opts.identify_regions)
 614 }
 615
 616 pub fn parameterized<F: fmt::Write>(f: &mut F,
 617                                     substs: SubstsRef<'_>,
 618                                     did: DefId,
 619                                     projections: &[ty::ProjectionPredicate<'_>])
 620                                     -> fmt::Result {
 621     PrintCx::new().parameterized(f, substs, did, projections)
 622 }
 623
 624 impl<'a, 'tcx, T: Print<'tcx>> Print<'tcx> for &'a T {
 625     fn print<F: fmt::Write>(&self, f: &mut F, cx: &mut PrintCx) -> fmt::Result {
 626         (*self).print(f, cx)
 627     }
 628 }
 629
 630 define_print! {
 631     ('tcx) &'tcx ty::List<ty::ExistentialPredicate<'tcx>>, (self, f, cx) {
 632         display {
 633             // Generate the main trait ref, including associated types.
 634             ty::tls::with(|tcx| {
 635                 // Use a type that can't appear in defaults of type parameters.
 636                 let dummy_self = tcx.mk_infer(ty::FreshTy(0));
 637                 let mut first = true;
 638
 639                 if let Some(principal) = self.principal() {
 640                     let principal = tcx
 641                         .lift(&principal)
 642                         .expect("could not lift for printing")
 643                         .with_self_ty(tcx, dummy_self);
 644                     let projections = self.projection_bounds().map(|p| {
 645                         tcx.lift(&p)
 646                             .expect("could not lift for printing")
 647                             .with_self_ty(tcx, dummy_self)
 648                     }).collect::<Vec<_>>();
 649                     cx.parameterized(f, principal.substs, principal.def_id, &projections)?;
 650                     first = false;
 651                 }
 652
 653                 // Builtin bounds.
 654                 let mut auto_traits: Vec<_> = self.auto_traits().map(|did| {
 655                     tcx.item_path_str(did)
 656                 }).collect();
 657
 658                 // The auto traits come ordered by `DefPathHash`. While
 659                 // `DefPathHash` is *stable* in the sense that it depends on
 660                 // neither the host nor the phase of the moon, it depends
 661                 // "pseudorandomly" on the compiler version and the target.
 662                 //
 663                 // To avoid that causing instabilities in compiletest
 664                 // output, sort the auto-traits alphabetically.
 665                 auto_traits.sort();
 666
 667                 for auto_trait in auto_traits {
 668                     if !first {
 669                         write!(f, " + ")?;
 670                     }
 671                     first = false;
 672
 673                     write!(f, "{}", auto_trait)?;
 674                 }
 675
 676                 Ok(())
 677             })?;
 678
 679             Ok(())
 680         }
 681     }
 682 }
 683
 684 impl fmt::Debug for ty::GenericParamDef {
 685     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 686         let type_name = match self.kind {
 687             ty::GenericParamDefKind::Lifetime => "Lifetime",
 688             ty::GenericParamDefKind::Type { .. } => "Type",
 689             ty::GenericParamDefKind::Const => "Const",
 690         };
 691         write!(f, "{}({}, {:?}, {})",
 692                type_name,
 693                self.name,
 694                self.def_id,
 695                self.index)
 696     }
 697 }
 698
 699 impl fmt::Debug for ty::TraitDef {
 700     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 701         ty::tls::with(|tcx| {
 702             write!(f, "{}", tcx.item_path_str(self.def_id))
 703         })
 704     }
 705 }
 706
 707 impl fmt::Debug for ty::AdtDef {
 708     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 709         ty::tls::with(|tcx| {
 710             write!(f, "{}", tcx.item_path_str(self.did))
 711         })
 712     }
 713 }
 714
 715 impl<'tcx> fmt::Debug for ty::ClosureUpvar<'tcx> {
 716     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 717         write!(f, "ClosureUpvar({:?},{:?})",
 718                self.def,
 719                self.ty)
 720     }
 721 }
 722
 723 impl fmt::Debug for ty::UpvarId {
 724     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 725         write!(f, "UpvarId({:?};`{}`;{:?})",
 726                self.var_path.hir_id,
 727                ty::tls::with(|tcx| tcx.hir().name_by_hir_id(self.var_path.hir_id)),
 728                self.closure_expr_id)
 729     }
 730 }
 731
 732 impl<'tcx> fmt::Debug for ty::UpvarBorrow<'tcx> {
 733     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 734         write!(f, "UpvarBorrow({:?}, {:?})",
 735                self.kind, self.region)
 736     }
 737 }
 738
 739 define_print! {
 740     ('tcx) &'tcx ty::List<Ty<'tcx>>, (self, f, cx) {
 741         display {
 742             write!(f, "{{")?;
 743             let mut tys = self.iter();
 744             if let Some(&ty) = tys.next() {
 745                 print!(f, cx, print(ty))?;
 746                 for &ty in tys {
 747                     print!(f, cx, write(", "), print(ty))?;
 748                 }
 749             }
 750             write!(f, "}}")
 751         }
 752     }
 753 }
 754
 755 define_print! {
 756     ('tcx) ty::TypeAndMut<'tcx>, (self, f, cx) {
 757         display {
 758             print!(f, cx,
 759                    write("{}", if self.mutbl == hir::MutMutable { "mut " } else { "" }),
 760                    print(self.ty))
 761         }
 762     }
 763 }
 764
 765 define_print! {
 766     ('tcx) ty::ExistentialTraitRef<'tcx>, (self, f, cx) {
 767         display {
 768             cx.parameterized(f, self.substs, self.def_id, &[])
 769         }
 770         debug {
 771             ty::tls::with(|tcx| {
 772                 let dummy_self = tcx.mk_infer(ty::FreshTy(0));
 773
 774                 let trait_ref = *tcx.lift(&ty::Binder::bind(*self))
 775                                    .expect("could not lift for printing")
 776                                    .with_self_ty(tcx, dummy_self).skip_binder();
 777                 cx.parameterized(f, trait_ref.substs, trait_ref.def_id, &[])
 778             })
 779         }
 780     }
 781 }
 782
 783 define_print! {
 784     ('tcx) ty::adjustment::Adjustment<'tcx>, (self, f, cx) {
 785         debug {
 786             print!(f, cx, write("{:?} -> ", self.kind), print(self.target))
 787         }
 788     }
 789 }
 790
 791 define_print! {
 792     () ty::BoundRegion, (self, f, cx) {
 793         display {
 794             if cx.is_verbose {
 795                 return self.print_debug(f, cx);
 796             }
 797
 798             if let Some((region, counter)) = RegionHighlightMode::get().highlight_bound_region {
 799                 if *self == region {
 800                     return match *self {
 801                         BrNamed(_, name) => write!(f, "{}", name),
 802                         BrAnon(_) | BrFresh(_) | BrEnv => write!(f, "'{}", counter)
 803                     };
 804                 }
 805             }
 806
 807             match *self {
 808                 BrNamed(_, name) => write!(f, "{}", name),
 809                 BrAnon(_) | BrFresh(_) | BrEnv => Ok(())
 810             }
 811         }
 812         debug {
 813             return match *self {
 814                 BrAnon(n) => write!(f, "BrAnon({:?})", n),
 815                 BrFresh(n) => write!(f, "BrFresh({:?})", n),
 816                 BrNamed(did, name) => {
 817                     write!(f, "BrNamed({:?}:{:?}, {})",
 818                            did.krate, did.index, name)
 819                 }
 820                 BrEnv => write!(f, "BrEnv"),
 821             };
 822         }
 823     }
 824 }
 825
 826 define_print! {
 827     () ty::PlaceholderRegion, (self, f, cx) {
 828         display {
 829             if cx.is_verbose {
 830                 return self.print_debug(f, cx);
 831             }
 832
 833             let highlight = RegionHighlightMode::get();
 834             if let Some(counter) = highlight.placeholder_highlight(*self) {
 835                 write!(f, "'{}", counter)
 836             } else if highlight.any_placeholders_highlighted() {
 837                 write!(f, "'_")
 838             } else {
 839                 write!(f, "{}", self.name)
 840             }
 841         }
 842     }
 843 }
 844
 845 define_print! {
 846     () ty::RegionKind, (self, f, cx) {
 847         display {
 848             if cx.is_verbose {
 849                 return self.print_debug(f, cx);
 850             }
 851
 852             // Watch out for region highlights.
 853             if let Some(n) = RegionHighlightMode::get().region_highlighted(self) {
 854                 return write!(f, "'{:?}", n);
 855             }
 856
 857             // These printouts are concise.  They do not contain all the information
 858             // the user might want to diagnose an error, but there is basically no way
 859             // to fit that into a short string.  Hence the recommendation to use
 860             // `explain_region()` or `note_and_explain_region()`.
 861             match *self {
 862                 ty::ReEarlyBound(ref data) => {
 863                     write!(f, "{}", data.name)
 864                 }
 865                 ty::ReLateBound(_, br) |
 866                 ty::ReFree(ty::FreeRegion { bound_region: br, .. }) => {
 867                     write!(f, "{}", br)
 868                 }
 869                 ty::RePlaceholder(p) => {
 870                     write!(f, "{}", p)
 871                 }
 872                 ty::ReScope(scope) if cx.identify_regions => {
 873                     match scope.data {
 874                         region::ScopeData::Node =>
 875                             write!(f, "'{}s", scope.item_local_id().as_usize()),
 876                         region::ScopeData::CallSite =>
 877                             write!(f, "'{}cs", scope.item_local_id().as_usize()),
 878                         region::ScopeData::Arguments =>
 879                             write!(f, "'{}as", scope.item_local_id().as_usize()),
 880                         region::ScopeData::Destruction =>
 881                             write!(f, "'{}ds", scope.item_local_id().as_usize()),
 882                         region::ScopeData::Remainder(first_statement_index) => write!(
 883                             f,
 884                             "'{}_{}rs",
 885                             scope.item_local_id().as_usize(),
 886                             first_statement_index.index()
 887                         ),
 888                     }
 889                 }
 890                 ty::ReVar(region_vid) => {
 891                     if RegionHighlightMode::get().any_region_vids_highlighted() {
 892                         write!(f, "{:?}", region_vid)
 893                     } else if cx.identify_regions {
 894                         write!(f, "'{}rv", region_vid.index())
 895                     } else {
 896                         Ok(())
 897                     }
 898                 }
 899                 ty::ReScope(_) |
 900                 ty::ReErased => Ok(()),
 901                 ty::ReStatic => write!(f, "'static"),
 902                 ty::ReEmpty => write!(f, "'<empty>"),
 903
 904                 // The user should never encounter these in unsubstituted form.
 905                 ty::ReClosureBound(vid) => write!(f, "{:?}", vid),
 906             }
 907         }
 908         debug {
 909             match *self {
 910                 ty::ReEarlyBound(ref data) => {
 911                     write!(f, "ReEarlyBound({}, {})",
 912                            data.index,
 913                            data.name)
 914                 }
 915
 916                 ty::ReClosureBound(ref vid) => {
 917                     write!(f, "ReClosureBound({:?})",
 918                            vid)
 919                 }
 920
 921                 ty::ReLateBound(binder_id, ref bound_region) => {
 922                     write!(f, "ReLateBound({:?}, {:?})",
 923                            binder_id,
 924                            bound_region)
 925                 }
 926
 927                 ty::ReFree(ref fr) => write!(f, "{:?}", fr),
 928
 929                 ty::ReScope(id) => {
 930                     write!(f, "ReScope({:?})", id)
 931                 }
 932
 933                 ty::ReStatic => write!(f, "ReStatic"),
 934
 935                 ty::ReVar(ref vid) => {
 936                     write!(f, "{:?}", vid)
 937                 }
 938
 939                 ty::RePlaceholder(placeholder) => {
 940                     write!(f, "RePlaceholder({:?})", placeholder)
 941                 }
 942
 943                 ty::ReEmpty => write!(f, "ReEmpty"),
 944
 945                 ty::ReErased => write!(f, "ReErased")
 946             }
 947         }
 948     }
 949 }
 950
 951 define_print! {
 952     () ty::FreeRegion, (self, f, cx) {
 953         debug {
 954             write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 955         }
 956     }
 957 }
 958
 959 define_print! {
 960     () ty::Variance, (self, f, cx) {
 961         debug {
 962             f.write_str(match *self {
 963                 ty::Covariant => "+",
 964                 ty::Contravariant => "-",
 965                 ty::Invariant => "o",
 966                 ty::Bivariant => "*",
 967             })
 968         }
 969     }
 970 }
 971
 972 define_print! {
 973     ('tcx) ty::GenericPredicates<'tcx>, (self, f, cx) {
 974         debug {
 975             write!(f, "GenericPredicates({:?})", self.predicates)
 976         }
 977     }
 978 }
 979
 980 define_print! {
 981     ('tcx) ty::InstantiatedPredicates<'tcx>, (self, f, cx) {
 982         debug {
 983             write!(f, "InstantiatedPredicates({:?})", self.predicates)
 984         }
 985     }
 986 }
 987
 988 define_print! {
 989     ('tcx) ty::FnSig<'tcx>, (self, f, cx) {
 990         display {
 991             if self.unsafety == hir::Unsafety::Unsafe {
 992                 write!(f, "unsafe ")?;
 993             }
 994
 995             if self.abi != Abi::Rust {
 996                 write!(f, "extern {} ", self.abi)?;
 997             }
 998
 999             write!(f, "fn")?;
1000             cx.fn_sig(f, self.inputs(), self.c_variadic, self.output())
1001         }
1002         debug {
1003             write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
1004         }
1005     }
1006 }
1007
1008 impl fmt::Debug for ty::TyVid {
1009     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1010         write!(f, "_#{}t", self.index)
1011     }
1012 }
1013
1014 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
1015     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1016         write!(f, "_#{}f", self.index)
1017     }
1018 }
1019
1020 impl fmt::Debug for ty::IntVid {
1021     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1022         write!(f, "_#{}i", self.index)
1023     }
1024 }
1025
1026 impl fmt::Debug for ty::FloatVid {
1027     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1028         write!(f, "_#{}f", self.index)
1029     }
1030 }
1031
1032 impl fmt::Debug for ty::RegionVid {
1033     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1034         if let Some(counter) = RegionHighlightMode::get().region_highlighted(&ty::ReVar(*self)) {
1035             return write!(f, "'{:?}", counter);
1036         } else if RegionHighlightMode::get().any_region_vids_highlighted() {
1037             return write!(f, "'_");
1038         }
1039
1040         write!(f, "'_#{}r", self.index())
1041     }
1042 }
1043
1044 define_print! {
1045     () ty::InferTy, (self, f, cx) {
1046         display {
1047             if cx.is_verbose {
1048                 print!(f, cx, print_debug(self))
1049             } else {
1050                 match *self {
1051                     ty::TyVar(_) => write!(f, "_"),
1052                     ty::IntVar(_) => write!(f, "{}", "{integer}"),
1053                     ty::FloatVar(_) => write!(f, "{}", "{float}"),
1054                     ty::FreshTy(v) => write!(f, "FreshTy({})", v),
1055                     ty::FreshIntTy(v) => write!(f, "FreshIntTy({})", v),
1056                     ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({})", v)
1057                 }
1058             }
1059         }
1060         debug {
1061             match *self {
1062                 ty::TyVar(ref v) => write!(f, "{:?}", v),
1063                 ty::IntVar(ref v) => write!(f, "{:?}", v),
1064                 ty::FloatVar(ref v) => write!(f, "{:?}", v),
1065                 ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
1066                 ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
1067                 ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v)
1068             }
1069         }
1070     }
1071 }
1072
1073 impl fmt::Debug for ty::IntVarValue {
1074     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1075         match *self {
1076             ty::IntType(ref v) => v.fmt(f),
1077             ty::UintType(ref v) => v.fmt(f),
1078         }
1079     }
1080 }
1081
1082 impl fmt::Debug for ty::FloatVarValue {
1083     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1084         self.0.fmt(f)
1085     }
1086 }
1087
1088 // The generic impl doesn't work yet because projections are not
1089 // normalized under HRTB.
1090 /*impl<T> fmt::Display for ty::Binder<T>
1091     where T: fmt::Display + for<'a> ty::Lift<'a>,
1092           for<'a> <T as ty::Lift<'a>>::Lifted: fmt::Display + TypeFoldable<'a>
1093 {
1094     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1095         ty::tls::with(|tcx| in_binder(f, tcx, tcx.lift(self)
1096             .expect("could not lift for printing")))
1097     }
1098 }*/
1099
1100 define_print_multi! {
1101     [
1102     ('tcx) ty::Binder<&'tcx ty::List<ty::ExistentialPredicate<'tcx>>>,
1103     ('tcx) ty::Binder<ty::TraitRef<'tcx>>,
1104     ('tcx) ty::Binder<ty::FnSig<'tcx>>,
1105     ('tcx) ty::Binder<ty::TraitPredicate<'tcx>>,
1106     ('tcx) ty::Binder<ty::SubtypePredicate<'tcx>>,
1107     ('tcx) ty::Binder<ty::ProjectionPredicate<'tcx>>,
1108     ('tcx) ty::Binder<ty::OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>>,
1109     ('tcx) ty::Binder<ty::OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>>
1110     ]
1111     (self, f, cx) {
1112         display {
1113             ty::tls::with(|tcx| cx.in_binder(f, tcx, tcx.lift(self)
1114                 .expect("could not lift for printing")))
1115         }
1116     }
1117 }
1118
1119 define_print! {
1120     ('tcx) ty::TraitRef<'tcx>, (self, f, cx) {
1121         display {
1122             cx.parameterized(f, self.substs, self.def_id, &[])
1123         }
1124         debug {
1125             // when printing out the debug representation, we don't need
1126             // to enumerate the `for<...>` etc because the debruijn index
1127             // tells you everything you need to know.
1128             print!(f, cx,
1129                    write("<"),
1130                    print(self.self_ty()),
1131                    write(" as "))?;
1132             cx.parameterized(f, self.substs, self.def_id, &[])?;
1133             write!(f, ">")
1134         }
1135     }
1136 }
1137
1138 define_print! {
1139     ('tcx) ty::TyKind<'tcx>, (self, f, cx) {
1140         display {
1141             match *self {
1142                 Bool => write!(f, "bool"),
1143                 Char => write!(f, "char"),
1144                 Int(t) => write!(f, "{}", t.ty_to_string()),
1145                 Uint(t) => write!(f, "{}", t.ty_to_string()),
1146                 Float(t) => write!(f, "{}", t.ty_to_string()),
1147                 RawPtr(ref tm) => {
1148                     write!(f, "*{} ", match tm.mutbl {
1149                         hir::MutMutable => "mut",
1150                         hir::MutImmutable => "const",
1151                     })?;
1152                     tm.ty.print(f, cx)
1153                 }
1154                 Ref(r, ty, mutbl) => {
1155                     write!(f, "&")?;
1156                     let s = r.print_to_string(cx);
1157                     if s != "'_" {
1158                         write!(f, "{}", s)?;
1159                         if !s.is_empty() {
1160                             write!(f, " ")?;
1161                         }
1162                     }
1163                     ty::TypeAndMut { ty, mutbl }.print(f, cx)
1164                 }
1165                 Never => write!(f, "!"),
1166                 Tuple(ref tys) => {
1167                     write!(f, "(")?;
1168                     let mut tys = tys.iter();
1169                     if let Some(&ty) = tys.next() {
1170                         print!(f, cx, print(ty), write(","))?;
1171                         if let Some(&ty) = tys.next() {
1172                             print!(f, cx, write(" "), print(ty))?;
1173                             for &ty in tys {
1174                                 print!(f, cx, write(", "), print(ty))?;
1175                             }
1176                         }
1177                     }
1178                     write!(f, ")")
1179                 }
1180                 FnDef(def_id, substs) => {
1181                     ty::tls::with(|tcx| {
1182                         let substs = tcx.lift(&substs)
1183                             .expect("could not lift for printing");
1184                         let sig = tcx.fn_sig(def_id).subst(tcx, substs);
1185                         print!(f, cx, print(sig), write(" {{"))
1186                     })?;
1187                     cx.parameterized(f, substs, def_id, &[])?;
1188                     write!(f, "}}")
1189                 }
1190                 FnPtr(ref bare_fn) => {
1191                     bare_fn.print(f, cx)
1192                 }
1193                 Infer(infer_ty) => write!(f, "{}", infer_ty),
1194                 Error => write!(f, "[type error]"),
1195                 Param(ref param_ty) => write!(f, "{}", param_ty),
1196                 Bound(debruijn, bound_ty) => {
1197                     match bound_ty.kind {
1198                         ty::BoundTyKind::Anon => {
1199                             if debruijn == ty::INNERMOST {
1200                                 write!(f, "^{}", bound_ty.var.index())
1201                             } else {
1202                                 write!(f, "^{}_{}", debruijn.index(), bound_ty.var.index())
1203                             }
1204                         }
1205
1206                         ty::BoundTyKind::Param(p) => write!(f, "{}", p),
1207                     }
1208                 }
1209                 Adt(def, substs) => cx.parameterized(f, substs, def.did, &[]),
1210                 Dynamic(data, r) => {
1211                     let r = r.print_to_string(cx);
1212                     if !r.is_empty() {
1213                         write!(f, "(")?;
1214                     }
1215                     write!(f, "dyn ")?;
1216                     data.print(f, cx)?;
1217                     if !r.is_empty() {
1218                         write!(f, " + {})", r)
1219                     } else {
1220                         Ok(())
1221                     }
1222                 }
1223                 Foreign(def_id) => parameterized(f, subst::InternalSubsts::empty(), def_id, &[]),
1224                 Projection(ref data) => data.print(f, cx),
1225                 UnnormalizedProjection(ref data) => {
1226                     write!(f, "Unnormalized(")?;
1227                     data.print(f, cx)?;
1228                     write!(f, ")")
1229                 }
1230                 Placeholder(placeholder) => {
1231                     write!(f, "Placeholder({:?})", placeholder)
1232                 }
1233                 Opaque(def_id, substs) => {
1234                     if cx.is_verbose {
1235                         return write!(f, "Opaque({:?}, {:?})", def_id, substs);
1236                     }
1237
1238                     ty::tls::with(|tcx| {
1239                         let def_key = tcx.def_key(def_id);
1240                         if let Some(name) = def_key.disambiguated_data.data.get_opt_name() {
1241                             write!(f, "{}", name)?;
1242                             let mut substs = substs.iter();
1243                             if let Some(first) = substs.next() {
1244                                 write!(f, "::<")?;
1245                                 write!(f, "{}", first)?;
1246                                 for subst in substs {
1247                                     write!(f, ", {}", subst)?;
1248                                 }
1249                                 write!(f, ">")?;
1250                             }
1251                             return Ok(());
1252                         }
1253                         // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`,
1254                         // by looking up the projections associated with the def_id.
1255                         let substs = tcx.lift(&substs)
1256                             .expect("could not lift for printing");
1257                         let bounds = tcx.predicates_of(def_id).instantiate(tcx, substs);
1258
1259                         let mut first = true;
1260                         let mut is_sized = false;
1261                         write!(f, "impl")?;
1262                         for predicate in bounds.predicates {
1263                             if let Some(trait_ref) = predicate.to_opt_poly_trait_ref() {
1264                                 // Don't print +Sized, but rather +?Sized if absent.
1265                                 if Some(trait_ref.def_id()) == tcx.lang_items().sized_trait() {
1266                                     is_sized = true;
1267                                     continue;
1268                                 }
1269
1270                                 print!(f, cx,
1271                                        write("{}", if first { " " } else { "+" }),
1272                                        print(trait_ref))?;
1273                                 first = false;
1274                             }
1275                         }
1276                         if !is_sized {
1277                             write!(f, "{}?Sized", if first { " " } else { "+" })?;
1278                         } else if first {
1279                             write!(f, " Sized")?;
1280                         }
1281                         Ok(())
1282                     })
1283                 }
1284                 Str => write!(f, "str"),
1285                 Generator(did, substs, movability) => ty::tls::with(|tcx| {
1286                     let upvar_tys = substs.upvar_tys(did, tcx);
1287                     let witness = substs.witness(did, tcx);
1288                     if movability == hir::GeneratorMovability::Movable {
1289                         write!(f, "[generator")?;
1290                     } else {
1291                         write!(f, "[static generator")?;
1292                     }
1293
1294                     if let Some(hir_id) = tcx.hir().as_local_hir_id(did) {
1295                         write!(f, "@{:?}", tcx.hir().span_by_hir_id(hir_id))?;
1296                         let mut sep = " ";
1297                         tcx.with_freevars(hir_id, |freevars| {
1298                             for (freevar, upvar_ty) in freevars.iter().zip(upvar_tys) {
1299                                 print!(f, cx,
1300                                        write("{}{}:",
1301                                              sep,
1302                                              tcx.hir().name(freevar.var_id())),
1303                                        print(upvar_ty))?;
1304                                 sep = ", ";
1305                             }
1306                             Ok(())
1307                         })?
1308                     } else {
1309                         // cross-crate closure types should only be
1310                         // visible in codegen bug reports, I imagine.
1311                         write!(f, "@{:?}", did)?;
1312                         let mut sep = " ";
1313                         for (index, upvar_ty) in upvar_tys.enumerate() {
1314                             print!(f, cx,
1315                                    write("{}{}:", sep, index),
1316                                    print(upvar_ty))?;
1317                             sep = ", ";
1318                         }
1319                     }
1320
1321                     print!(f, cx, write(" "), print(witness), write("]"))
1322                 }),
1323                 GeneratorWitness(types) => {
1324                     ty::tls::with(|tcx| cx.in_binder(f, tcx, tcx.lift(&types)
1325                         .expect("could not lift for printing")))
1326                 }
1327                 Closure(did, substs) => ty::tls::with(|tcx| {
1328                     let upvar_tys = substs.upvar_tys(did, tcx);
1329                     write!(f, "[closure")?;
1330
1331                     if let Some(hir_id) = tcx.hir().as_local_hir_id(did) {
1332                         if tcx.sess.opts.debugging_opts.span_free_formats {
1333                             write!(f, "@{:?}", hir_id)?;
1334                         } else {
1335                             write!(f, "@{:?}", tcx.hir().span_by_hir_id(hir_id))?;
1336                         }
1337                         let mut sep = " ";
1338                         tcx.with_freevars(hir_id, |freevars| {
1339                             for (freevar, upvar_ty) in freevars.iter().zip(upvar_tys) {
1340                                 print!(f, cx,
1341                                        write("{}{}:",
1342                                              sep,
1343                                              tcx.hir().name(freevar.var_id())),
1344                                        print(upvar_ty))?;
1345                                 sep = ", ";
1346                             }
1347                             Ok(())
1348                         })?
1349                     } else {
1350                         // cross-crate closure types should only be
1351                         // visible in codegen bug reports, I imagine.
1352                         write!(f, "@{:?}", did)?;
1353                         let mut sep = " ";
1354                         for (index, upvar_ty) in upvar_tys.enumerate() {
1355                             print!(f, cx,
1356                                    write("{}{}:", sep, index),
1357                                    print(upvar_ty))?;
1358                             sep = ", ";
1359                         }
1360                     }
1361
1362                     if cx.is_verbose {
1363                         write!(
1364                             f,
1365                             " closure_kind_ty={:?} closure_sig_ty={:?}",
1366                             substs.closure_kind_ty(did, tcx),
1367                             substs.closure_sig_ty(did, tcx),
1368                         )?;
1369                     }
1370
1371                     write!(f, "]")
1372                 }),
1373                 Array(ty, sz) => {
1374                     print!(f, cx, write("["), print(ty), write("; "))?;
1375                     match sz {
1376                         ty::LazyConst::Unevaluated(_def_id, _substs) => {
1377                             write!(f, "_")?;
1378                         }
1379                         ty::LazyConst::Evaluated(c) => ty::tls::with(|tcx| {
1380                             match c.val {
1381                                 ConstValue::Infer(..) => write!(f, "_"),
1382                                 ConstValue::Param(ParamConst { name, .. }) =>
1383                                     write!(f, "{}", name),
1384                                 _ => write!(f, "{}", c.unwrap_usize(tcx)),
1385                             }
1386                         })?,
1387                     }
1388                     write!(f, "]")
1389                 }
1390                 Slice(ty) => {
1391                     print!(f, cx, write("["), print(ty), write("]"))
1392                 }
1393             }
1394         }
1395     }
1396 }
1397
1398 define_print! {
1399     ('tcx) ty::TyS<'tcx>, (self, f, cx) {
1400         display {
1401             self.sty.print(f, cx)
1402         }
1403         debug {
1404             self.sty.print_display(f, cx)
1405         }
1406     }
1407 }
1408
1409 define_print! {
1410     ('tcx) ConstValue<'tcx>, (self, f, cx) {
1411         display {
1412             match self {
1413                 ConstValue::Infer(..) => write!(f, "_"),
1414                 ConstValue::Param(ParamConst { name, .. }) => write!(f, "{}", name),
1415                 _ => write!(f, "{:?}", self),
1416             }
1417         }
1418     }
1419 }
1420
1421 define_print! {
1422     ('tcx) ty::Const<'tcx>, (self, f, cx) {
1423         display {
1424             write!(f, "{} : {}", self.val, self.ty)
1425         }
1426     }
1427 }
1428
1429 define_print! {
1430     ('tcx) ty::LazyConst<'tcx>, (self, f, cx) {
1431         display {
1432             match self {
1433                 ty::LazyConst::Unevaluated(..) => write!(f, "_ : _"),
1434                 ty::LazyConst::Evaluated(c) => write!(f, "{}", c),
1435             }
1436         }
1437     }
1438 }
1439
1440 define_print! {
1441     () ty::ParamTy, (self, f, cx) {
1442         display {
1443             write!(f, "{}", self.name)
1444         }
1445         debug {
1446             write!(f, "{}/#{}", self.name, self.idx)
1447         }
1448     }
1449 }
1450
1451 define_print! {
1452     () ty::ParamConst, (self, f, cx) {
1453         display {
1454             write!(f, "{}", self.name)
1455         }
1456         debug {
1457             write!(f, "{}/#{}", self.name, self.index)
1458         }
1459     }
1460 }
1461
1462 define_print! {
1463     ('tcx, T: Print<'tcx> + fmt::Debug, U: Print<'tcx> + fmt::Debug) ty::OutlivesPredicate<T, U>,
1464     (self, f, cx) {
1465         display {
1466             print!(f, cx, print(self.0), write(" : "), print(self.1))
1467         }
1468     }
1469 }
1470
1471 define_print! {
1472     ('tcx) ty::SubtypePredicate<'tcx>, (self, f, cx) {
1473         display {
1474             print!(f, cx, print(self.a), write(" <: "), print(self.b))
1475         }
1476     }
1477 }
1478
1479 define_print! {
1480     ('tcx) ty::TraitPredicate<'tcx>, (self, f, cx) {
1481         debug {
1482             write!(f, "TraitPredicate({:?})",
1483                    self.trait_ref)
1484         }
1485         display {
1486             print!(f, cx, print(self.trait_ref.self_ty()), write(": "), print(self.trait_ref))
1487         }
1488     }
1489 }
1490
1491 define_print! {
1492     ('tcx) ty::ProjectionPredicate<'tcx>, (self, f, cx) {
1493         debug {
1494             print!(f, cx,
1495                    write("ProjectionPredicate("),
1496                    print(self.projection_ty),
1497                    write(", "),
1498                    print(self.ty),
1499                    write(")"))
1500         }
1501         display {
1502             print!(f, cx, print(self.projection_ty), write(" == "), print(self.ty))
1503         }
1504     }
1505 }
1506
1507 define_print! {
1508     ('tcx) ty::ProjectionTy<'tcx>, (self, f, cx) {
1509         display {
1510             // FIXME(tschottdorf): use something like
1511             //   parameterized(f, self.substs, self.item_def_id, &[])
1512             // (which currently ICEs).
1513             let (trait_ref, item_name) = ty::tls::with(|tcx|
1514                 (self.trait_ref(tcx), tcx.associated_item(self.item_def_id).ident)
1515             );
1516             print!(f, cx, print_debug(trait_ref), write("::{}", item_name))
1517         }
1518     }
1519 }
1520
1521 define_print! {
1522     () ty::ClosureKind, (self, f, cx) {
1523         display {
1524             match *self {
1525                 ty::ClosureKind::Fn => write!(f, "Fn"),
1526                 ty::ClosureKind::FnMut => write!(f, "FnMut"),
1527                 ty::ClosureKind::FnOnce => write!(f, "FnOnce"),
1528             }
1529         }
1530     }
1531 }
1532
1533 define_print! {
1534     ('tcx) ty::Predicate<'tcx>, (self, f, cx) {
1535         display {
1536             match *self {
1537                 ty::Predicate::Trait(ref data) => data.print(f, cx),
1538                 ty::Predicate::Subtype(ref predicate) => predicate.print(f, cx),
1539                 ty::Predicate::RegionOutlives(ref predicate) => predicate.print(f, cx),
1540                 ty::Predicate::TypeOutlives(ref predicate) => predicate.print(f, cx),
1541                 ty::Predicate::Projection(ref predicate) => predicate.print(f, cx),
1542                 ty::Predicate::WellFormed(ty) => print!(f, cx, print(ty), write(" well-formed")),
1543                 ty::Predicate::ObjectSafe(trait_def_id) =>
1544                     ty::tls::with(|tcx| {
1545                         write!(f, "the trait `{}` is object-safe", tcx.item_path_str(trait_def_id))
1546                     }),
1547                 ty::Predicate::ClosureKind(closure_def_id, _closure_substs, kind) =>
1548                     ty::tls::with(|tcx| {
1549                         write!(f, "the closure `{}` implements the trait `{}`",
1550                                tcx.item_path_str(closure_def_id), kind)
1551                     }),
1552                 ty::Predicate::ConstEvaluatable(def_id, substs) => {
1553                     write!(f, "the constant `")?;
1554                     cx.parameterized(f, substs, def_id, &[])?;
1555                     write!(f, "` can be evaluated")
1556                 }
1557             }
1558         }
1559         debug {
1560             match *self {
1561                 ty::Predicate::Trait(ref a) => a.print(f, cx),
1562                 ty::Predicate::Subtype(ref pair) => pair.print(f, cx),
1563                 ty::Predicate::RegionOutlives(ref pair) => pair.print(f, cx),
1564                 ty::Predicate::TypeOutlives(ref pair) => pair.print(f, cx),
1565                 ty::Predicate::Projection(ref pair) => pair.print(f, cx),
1566                 ty::Predicate::WellFormed(ty) => ty.print(f, cx),
1567                 ty::Predicate::ObjectSafe(trait_def_id) => {
1568                     write!(f, "ObjectSafe({:?})", trait_def_id)
1569                 }
1570                 ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
1571                     write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
1572                 }
1573                 ty::Predicate::ConstEvaluatable(def_id, substs) => {
1574                     write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
1575                 }
1576             }
1577         }
1578     }
1579 }