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