src/librustc/util/ppaux.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11
  12 use middle::def;
  13 use middle::region;
  14 use middle::subst::{VecPerParamSpace,Subst};
  15 use middle::subst;
  16 use middle::ty::{BoundRegion, BrAnon, BrNamed};
  17 use middle::ty::{ReEarlyBound, BrFresh, ctxt};
  18 use middle::ty::{ReFree, ReScope, ReInfer, ReStatic, Region, ReEmpty};
  19 use middle::ty::{ReSkolemized, ReVar, BrEnv};
  20 use middle::ty::{mt, Ty, ParamTy};
  21 use middle::ty::{ty_bool, ty_char, ty_struct, ty_enum};
  22 use middle::ty::{ty_err, ty_str, ty_vec, ty_float, ty_bare_fn};
  23 use middle::ty::{ty_param, ty_ptr, ty_rptr, ty_tup};
  24 use middle::ty::ty_closure;
  25 use middle::ty::{ty_uniq, ty_trait, ty_int, ty_uint, ty_infer};
  26 use middle::ty;
  27 use middle::ty_fold::TypeFoldable;
  28
  29 use std::collections::HashMap;
  30 use std::collections::hash_state::HashState;
  31 use std::hash::Hash;
  32 use std::rc::Rc;
  33 use syntax::abi;
  34 use syntax::ast_map;
  35 use syntax::codemap::{Span, Pos};
  36 use syntax::parse::token;
  37 use syntax::print::pprust;
  38 use syntax::ptr::P;
  39 use syntax::{ast, ast_util};
  40 use syntax::owned_slice::OwnedSlice;
  41
  42 /// Produces a string suitable for debugging output.
  43 pub trait Repr<'tcx> {
  44     fn repr(&self, tcx: &ctxt<'tcx>) -> String;
  45 }
  46
  47 /// Produces a string suitable for showing to the user.
  48 pub trait UserString<'tcx> : Repr<'tcx> {
  49     fn user_string(&self, tcx: &ctxt<'tcx>) -> String;
  50 }
  51
  52 pub fn note_and_explain_region(cx: &ctxt,
  53                                prefix: &str,
  54                                region: ty::Region,
  55                                suffix: &str) -> Option<Span> {
  56     match explain_region_and_span(cx, region) {
  57       (ref str, Some(span)) => {
  58         cx.sess.span_note(
  59             span,
  60             &format!("{}{}{}", prefix, *str, suffix));
  61         Some(span)
  62       }
  63       (ref str, None) => {
  64         cx.sess.note(
  65             &format!("{}{}{}", prefix, *str, suffix));
  66         None
  67       }
  68     }
  69 }
  70
  71 /// When a free region is associated with `item`, how should we describe the item in the error
  72 /// message.
  73 fn item_scope_tag(item: &ast::Item) -> &'static str {
  74     match item.node {
  75         ast::ItemImpl(..) => "impl",
  76         ast::ItemStruct(..) => "struct",
  77         ast::ItemEnum(..) => "enum",
  78         ast::ItemTrait(..) => "trait",
  79         ast::ItemFn(..) => "function body",
  80         _ => "item"
  81     }
  82 }
  83
  84 pub fn explain_region_and_span(cx: &ctxt, region: ty::Region)
  85                             -> (String, Option<Span>) {
  86     return match region {
  87       ReScope(scope) => {
  88         let new_string;
  89         let on_unknown_scope = || {
  90           (format!("unknown scope: {:?}.  Please report a bug.", scope), None)
  91         };
  92         let span = match scope.span(&cx.map) {
  93           Some(s) => s,
  94           None => return on_unknown_scope(),
  95         };
  96         let tag = match cx.map.find(scope.node_id()) {
  97           Some(ast_map::NodeBlock(_)) => "block",
  98           Some(ast_map::NodeExpr(expr)) => match expr.node {
  99               ast::ExprCall(..) => "call",
 100               ast::ExprMethodCall(..) => "method call",
 101               ast::ExprMatch(_, _, ast::MatchSource::IfLetDesugar { .. }) => "if let",
 102               ast::ExprMatch(_, _, ast::MatchSource::WhileLetDesugar) =>  "while let",
 103               ast::ExprMatch(_, _, ast::MatchSource::ForLoopDesugar) =>  "for",
 104               ast::ExprMatch(..) => "match",
 105               _ => "expression",
 106           },
 107           Some(ast_map::NodeStmt(_)) => "statement",
 108           Some(ast_map::NodeItem(it)) => item_scope_tag(&*it),
 109           Some(_) | None => {
 110             // this really should not happen
 111             return on_unknown_scope();
 112           }
 113         };
 114         let scope_decorated_tag = match scope {
 115             region::CodeExtent::Misc(_) => tag,
 116             region::CodeExtent::ParameterScope { .. } => {
 117                 "scope of parameters for function"
 118             }
 119             region::CodeExtent::DestructionScope(_) => {
 120                 new_string = format!("destruction scope surrounding {}", tag);
 121                 &*new_string
 122             }
 123             region::CodeExtent::Remainder(r) => {
 124                 new_string = format!("block suffix following statement {}",
 125                                      r.first_statement_index);
 126                 &*new_string
 127             }
 128         };
 129         explain_span(cx, scope_decorated_tag, span)
 130
 131       }
 132
 133       ReFree(ref fr) => {
 134         let prefix = match fr.bound_region {
 135           BrAnon(idx) => {
 136               format!("the anonymous lifetime #{} defined on", idx + 1)
 137           }
 138           BrFresh(_) => "an anonymous lifetime defined on".to_string(),
 139           _ => {
 140               format!("the lifetime {} as defined on",
 141                       bound_region_ptr_to_string(cx, fr.bound_region))
 142           }
 143         };
 144
 145         match cx.map.find(fr.scope.node_id) {
 146           Some(ast_map::NodeBlock(ref blk)) => {
 147               let (msg, opt_span) = explain_span(cx, "block", blk.span);
 148               (format!("{} {}", prefix, msg), opt_span)
 149           }
 150           Some(ast_map::NodeItem(it)) => {
 151               let tag = item_scope_tag(&*it);
 152               let (msg, opt_span) = explain_span(cx, tag, it.span);
 153               (format!("{} {}", prefix, msg), opt_span)
 154           }
 155           Some(_) | None => {
 156               // this really should not happen
 157               (format!("{} unknown free region bounded by scope {:?}", prefix, fr.scope), None)
 158           }
 159         }
 160       }
 161
 162       ReStatic => { ("the static lifetime".to_string(), None) }
 163
 164       ReEmpty => { ("the empty lifetime".to_string(), None) }
 165
 166       ReEarlyBound(ref data) => {
 167         (format!("{}", token::get_name(data.name)), None)
 168       }
 169
 170       // I believe these cases should not occur (except when debugging,
 171       // perhaps)
 172       ty::ReInfer(_) | ty::ReLateBound(..) => {
 173         (format!("lifetime {:?}", region), None)
 174       }
 175     };
 176
 177     fn explain_span(cx: &ctxt, heading: &str, span: Span)
 178                     -> (String, Option<Span>) {
 179         let lo = cx.sess.codemap().lookup_char_pos_adj(span.lo);
 180         (format!("the {} at {}:{}", heading, lo.line, lo.col.to_usize()),
 181          Some(span))
 182     }
 183 }
 184
 185 pub fn bound_region_ptr_to_string(cx: &ctxt, br: BoundRegion) -> String {
 186     bound_region_to_string(cx, "", false, br)
 187 }
 188
 189 pub fn bound_region_to_string(cx: &ctxt,
 190                            prefix: &str, space: bool,
 191                            br: BoundRegion) -> String {
 192     let space_str = if space { " " } else { "" };
 193
 194     if cx.sess.verbose() {
 195         return format!("{}{}{}", prefix, br.repr(cx), space_str)
 196     }
 197
 198     match br {
 199         BrNamed(_, name) => {
 200             format!("{}{}{}", prefix, token::get_name(name), space_str)
 201         }
 202         BrAnon(_) | BrFresh(_) | BrEnv => prefix.to_string()
 203     }
 204 }
 205
 206 // In general, if you are giving a region error message,
 207 // you should use `explain_region()` or, better yet,
 208 // `note_and_explain_region()`
 209 pub fn region_ptr_to_string(cx: &ctxt, region: Region) -> String {
 210     region_to_string(cx, "&", true, region)
 211 }
 212
 213 pub fn region_to_string(cx: &ctxt, prefix: &str, space: bool, region: Region) -> String {
 214     let space_str = if space { " " } else { "" };
 215
 216     if cx.sess.verbose() {
 217         return format!("{}{}{}", prefix, region.repr(cx), space_str)
 218     }
 219
 220     // These printouts are concise.  They do not contain all the information
 221     // the user might want to diagnose an error, but there is basically no way
 222     // to fit that into a short string.  Hence the recommendation to use
 223     // `explain_region()` or `note_and_explain_region()`.
 224     match region {
 225         ty::ReScope(_) => prefix.to_string(),
 226         ty::ReEarlyBound(ref data) => {
 227             token::get_name(data.name).to_string()
 228         }
 229         ty::ReLateBound(_, br) => bound_region_to_string(cx, prefix, space, br),
 230         ty::ReFree(ref fr) => bound_region_to_string(cx, prefix, space, fr.bound_region),
 231         ty::ReInfer(ReSkolemized(_, br)) => {
 232             bound_region_to_string(cx, prefix, space, br)
 233         }
 234         ty::ReInfer(ReVar(_)) => prefix.to_string(),
 235         ty::ReStatic => format!("{}'static{}", prefix, space_str),
 236         ty::ReEmpty => format!("{}'<empty>{}", prefix, space_str),
 237     }
 238 }
 239
 240 pub fn mutability_to_string(m: ast::Mutability) -> String {
 241     match m {
 242         ast::MutMutable => "mut ".to_string(),
 243         ast::MutImmutable => "".to_string(),
 244     }
 245 }
 246
 247 pub fn mt_to_string<'tcx>(cx: &ctxt<'tcx>, m: &mt<'tcx>) -> String {
 248     format!("{}{}",
 249         mutability_to_string(m.mutbl),
 250         ty_to_string(cx, m.ty))
 251 }
 252
 253 pub fn vec_map_to_string<T, F>(ts: &[T], f: F) -> String where
 254     F: FnMut(&T) -> String,
 255 {
 256     let tstrs = ts.iter().map(f).collect::<Vec<String>>();
 257     format!("[{}]", tstrs.connect(", "))
 258 }
 259
 260 pub fn ty_to_string<'tcx>(cx: &ctxt<'tcx>, typ: &ty::TyS<'tcx>) -> String {
 261     fn bare_fn_to_string<'tcx>(cx: &ctxt<'tcx>,
 262                                opt_def_id: Option<ast::DefId>,
 263                                unsafety: ast::Unsafety,
 264                                abi: abi::Abi,
 265                                ident: Option<ast::Ident>,
 266                                sig: &ty::PolyFnSig<'tcx>)
 267                                -> String {
 268         let mut s = String::new();
 269
 270         match unsafety {
 271             ast::Unsafety::Normal => {}
 272             ast::Unsafety::Unsafe => {
 273                 s.push_str(&unsafety.to_string());
 274                 s.push(' ');
 275             }
 276         };
 277
 278         if abi != abi::Rust {
 279             s.push_str(&format!("extern {} ", abi.to_string()));
 280         };
 281
 282         s.push_str("fn");
 283
 284         match ident {
 285             Some(i) => {
 286                 s.push(' ');
 287                 s.push_str(&token::get_ident(i));
 288             }
 289             _ => { }
 290         }
 291
 292         push_sig_to_string(cx, &mut s, '(', ')', sig);
 293
 294         match opt_def_id {
 295             Some(def_id) => {
 296                 s.push_str(" {");
 297                 let path_str = ty::item_path_str(cx, def_id);
 298                 s.push_str(&path_str[..]);
 299                 s.push_str("}");
 300             }
 301             None => { }
 302         }
 303
 304         s
 305     }
 306
 307     fn closure_to_string<'tcx>(cx: &ctxt<'tcx>, cty: &ty::ClosureTy<'tcx>) -> String {
 308         let mut s = String::new();
 309         s.push_str("[closure");
 310         push_sig_to_string(cx, &mut s, '(', ')', &cty.sig);
 311         s.push(']');
 312         s
 313     }
 314
 315     fn push_sig_to_string<'tcx>(cx: &ctxt<'tcx>,
 316                                 s: &mut String,
 317                                 bra: char,
 318                                 ket: char,
 319                                 sig: &ty::PolyFnSig<'tcx>) {
 320         s.push(bra);
 321         let strs = sig.0.inputs
 322             .iter()
 323             .map(|a| ty_to_string(cx, *a))
 324             .collect::<Vec<_>>();
 325         s.push_str(&strs.connect(", "));
 326         if sig.0.variadic {
 327             s.push_str(", ...");
 328         }
 329         s.push(ket);
 330
 331         match sig.0.output {
 332             ty::FnConverging(t) => {
 333                 if !ty::type_is_nil(t) {
 334                    s.push_str(" -> ");
 335                    s.push_str(&ty_to_string(cx, t));
 336                 }
 337             }
 338             ty::FnDiverging => {
 339                 s.push_str(" -> !");
 340             }
 341         }
 342     }
 343
 344     fn infer_ty_to_string(cx: &ctxt, ty: ty::InferTy) -> String {
 345         let print_var_ids = cx.sess.verbose();
 346         match ty {
 347             ty::TyVar(ref vid) if print_var_ids => vid.repr(cx),
 348             ty::IntVar(ref vid) if print_var_ids => vid.repr(cx),
 349             ty::FloatVar(ref vid) if print_var_ids => vid.repr(cx),
 350             ty::TyVar(_) | ty::IntVar(_) | ty::FloatVar(_) => format!("_"),
 351             ty::FreshTy(v) => format!("FreshTy({})", v),
 352             ty::FreshIntTy(v) => format!("FreshIntTy({})", v),
 353             ty::FreshFloatTy(v) => format!("FreshFloatTy({})", v)
 354         }
 355     }
 356
 357     // pretty print the structural type representation:
 358     match typ.sty {
 359         ty_bool => "bool".to_string(),
 360         ty_char => "char".to_string(),
 361         ty_int(t) => ast_util::int_ty_to_string(t, None).to_string(),
 362         ty_uint(t) => ast_util::uint_ty_to_string(t, None).to_string(),
 363         ty_float(t) => ast_util::float_ty_to_string(t).to_string(),
 364         ty_uniq(typ) => format!("Box<{}>", ty_to_string(cx, typ)),
 365         ty_ptr(ref tm) => {
 366             format!("*{} {}", match tm.mutbl {
 367                 ast::MutMutable => "mut",
 368                 ast::MutImmutable => "const",
 369             }, ty_to_string(cx, tm.ty))
 370         }
 371         ty_rptr(r, ref tm) => {
 372             let mut buf = region_ptr_to_string(cx, *r);
 373             buf.push_str(&mt_to_string(cx, tm));
 374             buf
 375         }
 376         ty_tup(ref elems) => {
 377             let strs = elems
 378                 .iter()
 379                 .map(|elem| ty_to_string(cx, *elem))
 380                 .collect::<Vec<_>>();
 381             match &strs[..] {
 382                 [ref string] => format!("({},)", string),
 383                 strs => format!("({})", strs.connect(", "))
 384             }
 385         }
 386         ty_bare_fn(opt_def_id, ref f) => {
 387             bare_fn_to_string(cx, opt_def_id, f.unsafety, f.abi, None, &f.sig)
 388         }
 389         ty_infer(infer_ty) => infer_ty_to_string(cx, infer_ty),
 390         ty_err => "[type error]".to_string(),
 391         ty_param(ref param_ty) => param_ty.user_string(cx),
 392         ty_enum(did, substs) | ty_struct(did, substs) => {
 393             let base = ty::item_path_str(cx, did);
 394             parameterized(cx, &base, substs, did, &[],
 395                           || ty::lookup_item_type(cx, did).generics)
 396         }
 397         ty_trait(ref data) => {
 398             data.user_string(cx)
 399         }
 400         ty::ty_projection(ref data) => {
 401             format!("<{} as {}>::{}",
 402                     data.trait_ref.self_ty().user_string(cx),
 403                     data.trait_ref.user_string(cx),
 404                     data.item_name.user_string(cx))
 405         }
 406         ty_str => "str".to_string(),
 407         ty_closure(ref did, substs) => {
 408             let closure_tys = cx.closure_tys.borrow();
 409             closure_tys.get(did).map(|closure_type| {
 410                 closure_to_string(cx, &closure_type.subst(cx, substs))
 411             }).unwrap_or_else(|| {
 412                 if did.krate == ast::LOCAL_CRATE {
 413                     let span = cx.map.span(did.node);
 414                     format!("[closure {}]", span.repr(cx))
 415                 } else {
 416                     format!("[closure]")
 417                 }
 418             })
 419         }
 420         ty_vec(t, sz) => {
 421             let inner_str = ty_to_string(cx, t);
 422             match sz {
 423                 Some(n) => format!("[{}; {}]", inner_str, n),
 424                 None => format!("[{}]", inner_str),
 425             }
 426         }
 427     }
 428 }
 429
 430 pub fn explicit_self_category_to_str(category: &ty::ExplicitSelfCategory)
 431                                      -> &'static str {
 432     match *category {
 433         ty::StaticExplicitSelfCategory => "static",
 434         ty::ByValueExplicitSelfCategory => "self",
 435         ty::ByReferenceExplicitSelfCategory(_, ast::MutMutable) => {
 436             "&mut self"
 437         }
 438         ty::ByReferenceExplicitSelfCategory(_, ast::MutImmutable) => "&self",
 439         ty::ByBoxExplicitSelfCategory => "Box<self>",
 440     }
 441 }
 442
 443 pub fn parameterized<'tcx,GG>(cx: &ctxt<'tcx>,
 444                               base: &str,
 445                               substs: &subst::Substs<'tcx>,
 446                               did: ast::DefId,
 447                               projections: &[ty::ProjectionPredicate<'tcx>],
 448                               get_generics: GG)
 449                               -> String
 450     where GG : FnOnce() -> ty::Generics<'tcx>
 451 {
 452     if cx.sess.verbose() {
 453         let mut strings = vec![];
 454         match substs.regions {
 455             subst::ErasedRegions => {
 456                 strings.push(format!(".."));
 457             }
 458             subst::NonerasedRegions(ref regions) => {
 459                 for region in regions.iter() {
 460                     strings.push(region.repr(cx));
 461                 }
 462             }
 463         }
 464         for ty in substs.types.iter() {
 465             strings.push(ty.repr(cx));
 466         }
 467         for projection in projections.iter() {
 468             strings.push(format!("{}={}",
 469                                  projection.projection_ty.item_name.user_string(cx),
 470                                  projection.ty.user_string(cx)));
 471         }
 472         return if strings.is_empty() {
 473             format!("{}", base)
 474         } else {
 475             format!("{}<{}>", base, strings.connect(","))
 476         };
 477     }
 478
 479     let mut strs = Vec::new();
 480
 481     match substs.regions {
 482         subst::ErasedRegions => { }
 483         subst::NonerasedRegions(ref regions) => {
 484             for &r in regions.iter() {
 485                 let s = region_to_string(cx, "", false, r);
 486                 if s.is_empty() {
 487                     // This happens when the value of the region
 488                     // parameter is not easily serialized. This may be
 489                     // because the user omitted it in the first place,
 490                     // or because it refers to some block in the code,
 491                     // etc. I'm not sure how best to serialize this.
 492                     strs.push(format!("'_"));
 493                 } else {
 494                     strs.push(s)
 495                 }
 496             }
 497         }
 498     }
 499
 500     // It is important to execute this conditionally, only if -Z
 501     // verbose is false. Otherwise, debug logs can sometimes cause
 502     // ICEs trying to fetch the generics early in the pipeline. This
 503     // is kind of a hacky workaround in that -Z verbose is required to
 504     // avoid those ICEs.
 505     let generics = get_generics();
 506
 507     let has_self = substs.self_ty().is_some();
 508     let tps = substs.types.get_slice(subst::TypeSpace);
 509     let ty_params = generics.types.get_slice(subst::TypeSpace);
 510     let has_defaults = ty_params.last().map_or(false, |def| def.default.is_some());
 511     let num_defaults = if has_defaults {
 512         ty_params.iter().zip(tps.iter()).rev().take_while(|&(def, &actual)| {
 513             match def.default {
 514                 Some(default) => {
 515                     if !has_self && ty::type_has_self(default) {
 516                         // In an object type, there is no `Self`, and
 517                         // thus if the default value references Self,
 518                         // the user will be required to give an
 519                         // explicit value. We can't even do the
 520                         // substitution below to check without causing
 521                         // an ICE. (#18956).
 522                         false
 523                     } else {
 524                         default.subst(cx, substs) == actual
 525                     }
 526                 }
 527                 None => false
 528             }
 529         }).count()
 530     } else {
 531         0
 532     };
 533
 534     for t in &tps[..tps.len() - num_defaults] {
 535         strs.push(ty_to_string(cx, *t))
 536     }
 537
 538     for projection in projections {
 539         strs.push(format!("{}={}",
 540                           projection.projection_ty.item_name.user_string(cx),
 541                           projection.ty.user_string(cx)));
 542     }
 543
 544     if cx.lang_items.fn_trait_kind(did).is_some() && projections.len() == 1 {
 545         let projection_ty = projections[0].ty;
 546         let tail =
 547             if ty::type_is_nil(projection_ty) {
 548                 format!("")
 549             } else {
 550                 format!(" -> {}", projection_ty.user_string(cx))
 551             };
 552         format!("{}({}){}",
 553                 base,
 554                 if strs[0].starts_with("(") && strs[0].ends_with(",)") {
 555                     &strs[0][1 .. strs[0].len() - 2] // Remove '(' and ',)'
 556                 } else if strs[0].starts_with("(") && strs[0].ends_with(")") {
 557                     &strs[0][1 .. strs[0].len() - 1] // Remove '(' and ')'
 558                 } else {
 559                     &strs[0][..]
 560                 },
 561                 tail)
 562     } else if !strs.is_empty() {
 563         format!("{}<{}>", base, strs.connect(", "))
 564     } else {
 565         format!("{}", base)
 566     }
 567 }
 568
 569 pub fn ty_to_short_str<'tcx>(cx: &ctxt<'tcx>, typ: Ty<'tcx>) -> String {
 570     let mut s = typ.repr(cx).to_string();
 571     if s.len() >= 32 {
 572         s = (&s[0..32]).to_string();
 573     }
 574     return s;
 575 }
 576
 577 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for Option<T> {
 578     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 579         match self {
 580             &None => "None".to_string(),
 581             &Some(ref t) => t.repr(tcx),
 582         }
 583     }
 584 }
 585
 586 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for P<T> {
 587     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 588         (**self).repr(tcx)
 589     }
 590 }
 591
 592 impl<'tcx,T:Repr<'tcx>,U:Repr<'tcx>> Repr<'tcx> for Result<T,U> {
 593     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 594         match self {
 595             &Ok(ref t) => t.repr(tcx),
 596             &Err(ref u) => format!("Err({})", u.repr(tcx))
 597         }
 598     }
 599 }
 600
 601 impl<'tcx> Repr<'tcx> for () {
 602     fn repr(&self, _tcx: &ctxt) -> String {
 603         "()".to_string()
 604     }
 605 }
 606
 607 impl<'a, 'tcx, T: ?Sized +Repr<'tcx>> Repr<'tcx> for &'a T {
 608     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 609         Repr::repr(*self, tcx)
 610     }
 611 }
 612
 613 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for Rc<T> {
 614     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 615         (&**self).repr(tcx)
 616     }
 617 }
 618
 619 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for Box<T> {
 620     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 621         (&**self).repr(tcx)
 622     }
 623 }
 624
 625 fn repr_vec<'tcx, T:Repr<'tcx>>(tcx: &ctxt<'tcx>, v: &[T]) -> String {
 626     vec_map_to_string(v, |t| t.repr(tcx))
 627 }
 628
 629 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for [T] {
 630     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 631         repr_vec(tcx, self)
 632     }
 633 }
 634
 635 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for OwnedSlice<T> {
 636     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 637         repr_vec(tcx, &self[..])
 638     }
 639 }
 640
 641 // This is necessary to handle types like Option<Vec<T>>, for which
 642 // autoderef cannot convert the &[T] handler
 643 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for Vec<T> {
 644     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 645         repr_vec(tcx, &self[..])
 646     }
 647 }
 648
 649 impl<'tcx, T:UserString<'tcx>> UserString<'tcx> for Vec<T> {
 650     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
 651         let strs: Vec<String> =
 652             self.iter().map(|t| t.user_string(tcx)).collect();
 653         strs.connect(", ")
 654     }
 655 }
 656
 657 impl<'tcx> Repr<'tcx> for def::Def {
 658     fn repr(&self, _tcx: &ctxt) -> String {
 659         format!("{:?}", *self)
 660     }
 661 }
 662
 663 /// This curious type is here to help pretty-print trait objects. In
 664 /// a trait object, the projections are stored separately from the
 665 /// main trait bound, but in fact we want to package them together
 666 /// when printing out; they also have separate binders, but we want
 667 /// them to share a binder when we print them out. (And the binder
 668 /// pretty-printing logic is kind of clever and we don't want to
 669 /// reproduce it.) So we just repackage up the structure somewhat.
 670 ///
 671 /// Right now there is only one trait in an object that can have
 672 /// projection bounds, so we just stuff them altogether. But in
 673 /// reality we should eventually sort things out better.
 674 type TraitAndProjections<'tcx> =
 675     (ty::TraitRef<'tcx>, Vec<ty::ProjectionPredicate<'tcx>>);
 676
 677 impl<'tcx> UserString<'tcx> for TraitAndProjections<'tcx> {
 678     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
 679         let &(ref trait_ref, ref projection_bounds) = self;
 680         let base = ty::item_path_str(tcx, trait_ref.def_id);
 681         parameterized(tcx,
 682                       &base,
 683                       trait_ref.substs,
 684                       trait_ref.def_id,
 685                       &projection_bounds[..],
 686                       || ty::lookup_trait_def(tcx, trait_ref.def_id).generics.clone())
 687     }
 688 }
 689
 690 impl<'tcx> UserString<'tcx> for ty::TyTrait<'tcx> {
 691     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
 692         let &ty::TyTrait { ref principal, ref bounds } = self;
 693
 694         let mut components = vec![];
 695
 696         let tap: ty::Binder<TraitAndProjections<'tcx>> =
 697             ty::Binder((principal.0.clone(),
 698                         bounds.projection_bounds.iter().map(|x| x.0.clone()).collect()));
 699
 700         // Generate the main trait ref, including associated types.
 701         components.push(tap.user_string(tcx));
 702
 703         // Builtin bounds.
 704         for bound in &bounds.builtin_bounds {
 705             components.push(bound.user_string(tcx));
 706         }
 707
 708         // Region, if not obviously implied by builtin bounds.
 709         if bounds.region_bound != ty::ReStatic {
 710             // Region bound is implied by builtin bounds:
 711             components.push(bounds.region_bound.user_string(tcx));
 712         }
 713
 714         components.retain(|s| !s.is_empty());
 715
 716         components.connect(" + ")
 717     }
 718 }
 719
 720 impl<'tcx> Repr<'tcx> for ty::TypeParameterDef<'tcx> {
 721     fn repr(&self, _tcx: &ctxt<'tcx>) -> String {
 722         format!("TypeParameterDef({:?}, {:?}/{})",
 723                 self.def_id,
 724                 self.space,
 725                 self.index)
 726     }
 727 }
 728
 729 impl<'tcx> Repr<'tcx> for ty::RegionParameterDef {
 730     fn repr(&self, tcx: &ctxt) -> String {
 731         format!("RegionParameterDef(name={}, def_id={}, bounds={})",
 732                 token::get_name(self.name),
 733                 self.def_id.repr(tcx),
 734                 self.bounds.repr(tcx))
 735     }
 736 }
 737
 738 impl<'tcx> Repr<'tcx> for ty::TyS<'tcx> {
 739     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 740         ty_to_string(tcx, self)
 741     }
 742 }
 743
 744 impl<'tcx> Repr<'tcx> for ty::mt<'tcx> {
 745     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 746         mt_to_string(tcx, self)
 747     }
 748 }
 749
 750 impl<'tcx> Repr<'tcx> for subst::Substs<'tcx> {
 751     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 752         format!("Substs[types={}, regions={}]",
 753                        self.types.repr(tcx),
 754                        self.regions.repr(tcx))
 755     }
 756 }
 757
 758 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for subst::VecPerParamSpace<T> {
 759     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 760         format!("[{};{};{}]",
 761                 self.get_slice(subst::TypeSpace).repr(tcx),
 762                 self.get_slice(subst::SelfSpace).repr(tcx),
 763                 self.get_slice(subst::FnSpace).repr(tcx))
 764     }
 765 }
 766
 767 impl<'tcx> Repr<'tcx> for ty::ItemSubsts<'tcx> {
 768     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 769         format!("ItemSubsts({})", self.substs.repr(tcx))
 770     }
 771 }
 772
 773 impl<'tcx> Repr<'tcx> for subst::RegionSubsts {
 774     fn repr(&self, tcx: &ctxt) -> String {
 775         match *self {
 776             subst::ErasedRegions => "erased".to_string(),
 777             subst::NonerasedRegions(ref regions) => regions.repr(tcx)
 778         }
 779     }
 780 }
 781
 782 impl<'tcx> Repr<'tcx> for ty::BuiltinBounds {
 783     fn repr(&self, _tcx: &ctxt) -> String {
 784         let mut res = Vec::new();
 785         for b in self {
 786             res.push(match b {
 787                 ty::BoundSend => "Send".to_string(),
 788                 ty::BoundSized => "Sized".to_string(),
 789                 ty::BoundCopy => "Copy".to_string(),
 790                 ty::BoundSync => "Sync".to_string(),
 791             });
 792         }
 793         res.connect("+")
 794     }
 795 }
 796
 797 impl<'tcx> Repr<'tcx> for ty::ParamBounds<'tcx> {
 798     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 799         let mut res = Vec::new();
 800         res.push(self.builtin_bounds.repr(tcx));
 801         for t in &self.trait_bounds {
 802             res.push(t.repr(tcx));
 803         }
 804         res.connect("+")
 805     }
 806 }
 807
 808 impl<'tcx> Repr<'tcx> for ty::TraitRef<'tcx> {
 809     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 810         // when printing out the debug representation, we don't need
 811         // to enumerate the `for<...>` etc because the debruijn index
 812         // tells you everything you need to know.
 813         let base = ty::item_path_str(tcx, self.def_id);
 814         let result = parameterized(tcx, &base, self.substs, self.def_id, &[],
 815                       || ty::lookup_trait_def(tcx, self.def_id).generics.clone());
 816         match self.substs.self_ty() {
 817             None => result,
 818             Some(sty) => format!("<{} as {}>", sty.repr(tcx), result)
 819         }
 820     }
 821 }
 822
 823 impl<'tcx> Repr<'tcx> for ty::TraitDef<'tcx> {
 824     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
 825         format!("TraitDef(generics={}, trait_ref={})",
 826                 self.generics.repr(tcx),
 827                 self.trait_ref.repr(tcx))
 828     }
 829 }
 830
 831 impl<'tcx> Repr<'tcx> for ast::TraitItem {
 832     fn repr(&self, _tcx: &ctxt) -> String {
 833         let kind = match self.node {
 834             ast::ConstTraitItem(..) => "ConstTraitItem",
 835             ast::MethodTraitItem(..) => "MethodTraitItem",
 836             ast::TypeTraitItem(..) => "TypeTraitItem",
 837         };
 838         format!("{}({}, id={})", kind, self.ident, self.id)
 839     }
 840 }
 841
 842 impl<'tcx> Repr<'tcx> for ast::Expr {
 843     fn repr(&self, _tcx: &ctxt) -> String {
 844         format!("expr({}: {})", self.id, pprust::expr_to_string(self))
 845     }
 846 }
 847
 848 impl<'tcx> Repr<'tcx> for ast::Path {
 849     fn repr(&self, _tcx: &ctxt) -> String {
 850         format!("path({})", pprust::path_to_string(self))
 851     }
 852 }
 853
 854 impl<'tcx> UserString<'tcx> for ast::Path {
 855     fn user_string(&self, _tcx: &ctxt) -> String {
 856         pprust::path_to_string(self)
 857     }
 858 }
 859
 860 impl<'tcx> Repr<'tcx> for ast::Ty {
 861     fn repr(&self, _tcx: &ctxt) -> String {
 862         format!("type({})", pprust::ty_to_string(self))
 863     }
 864 }
 865
 866 impl<'tcx> Repr<'tcx> for ast::Item {
 867     fn repr(&self, tcx: &ctxt) -> String {
 868         format!("item({})", tcx.map.node_to_string(self.id))
 869     }
 870 }
 871
 872 impl<'tcx> Repr<'tcx> for ast::Lifetime {
 873     fn repr(&self, _tcx: &ctxt) -> String {
 874         format!("lifetime({}: {})", self.id, pprust::lifetime_to_string(self))
 875     }
 876 }
 877
 878 impl<'tcx> Repr<'tcx> for ast::Stmt {
 879     fn repr(&self, _tcx: &ctxt) -> String {
 880         format!("stmt({}: {})",
 881                 ast_util::stmt_id(self),
 882                 pprust::stmt_to_string(self))
 883     }
 884 }
 885
 886 impl<'tcx> Repr<'tcx> for ast::Pat {
 887     fn repr(&self, _tcx: &ctxt) -> String {
 888         format!("pat({}: {})", self.id, pprust::pat_to_string(self))
 889     }
 890 }
 891
 892 impl<'tcx> Repr<'tcx> for ty::BoundRegion {
 893     fn repr(&self, tcx: &ctxt) -> String {
 894         match *self {
 895             ty::BrAnon(id) => format!("BrAnon({})", id),
 896             ty::BrNamed(id, name) => {
 897                 format!("BrNamed({}, {})", id.repr(tcx), token::get_name(name))
 898             }
 899             ty::BrFresh(id) => format!("BrFresh({})", id),
 900             ty::BrEnv => "BrEnv".to_string()
 901         }
 902     }
 903 }
 904
 905 impl<'tcx> Repr<'tcx> for ty::Region {
 906     fn repr(&self, tcx: &ctxt) -> String {
 907         match *self {
 908             ty::ReEarlyBound(ref data) => {
 909                 format!("ReEarlyBound({}, {:?}, {}, {})",
 910                         data.param_id,
 911                         data.space,
 912                         data.index,
 913                         token::get_name(data.name))
 914             }
 915
 916             ty::ReLateBound(binder_id, ref bound_region) => {
 917                 format!("ReLateBound({:?}, {})",
 918                         binder_id,
 919                         bound_region.repr(tcx))
 920             }
 921
 922             ty::ReFree(ref fr) => fr.repr(tcx),
 923
 924             ty::ReScope(id) => {
 925                 format!("ReScope({:?})", id)
 926             }
 927
 928             ty::ReStatic => {
 929                 "ReStatic".to_string()
 930             }
 931
 932             ty::ReInfer(ReVar(ref vid)) => {
 933                 format!("{:?}", vid)
 934             }
 935
 936             ty::ReInfer(ReSkolemized(id, ref bound_region)) => {
 937                 format!("re_skolemized({}, {})", id, bound_region.repr(tcx))
 938             }
 939
 940             ty::ReEmpty => {
 941                 "ReEmpty".to_string()
 942             }
 943         }
 944     }
 945 }
 946
 947 impl<'tcx> UserString<'tcx> for ty::Region {
 948     fn user_string(&self, tcx: &ctxt) -> String {
 949         region_to_string(tcx, "", false, *self)
 950     }
 951 }
 952
 953 impl<'tcx> Repr<'tcx> for ty::FreeRegion {
 954     fn repr(&self, tcx: &ctxt) -> String {
 955         format!("ReFree({}, {})",
 956                 self.scope.repr(tcx),
 957                 self.bound_region.repr(tcx))
 958     }
 959 }
 960
 961 impl<'tcx> Repr<'tcx> for region::CodeExtent {
 962     fn repr(&self, _tcx: &ctxt) -> String {
 963         match *self {
 964             region::CodeExtent::ParameterScope { fn_id, body_id } =>
 965                 format!("ParameterScope({}, {})", fn_id, body_id),
 966             region::CodeExtent::Misc(node_id) =>
 967                 format!("Misc({})", node_id),
 968             region::CodeExtent::DestructionScope(node_id) =>
 969                 format!("DestructionScope({})", node_id),
 970             region::CodeExtent::Remainder(rem) =>
 971                 format!("Remainder({}, {})", rem.block, rem.first_statement_index),
 972         }
 973     }
 974 }
 975
 976 impl<'tcx> Repr<'tcx> for region::DestructionScopeData {
 977     fn repr(&self, _tcx: &ctxt) -> String {
 978         match *self {
 979             region::DestructionScopeData{ node_id } =>
 980                 format!("DestructionScopeData {{ node_id: {} }}", node_id),
 981         }
 982     }
 983 }
 984
 985 impl<'tcx> Repr<'tcx> for ast::DefId {
 986     fn repr(&self, tcx: &ctxt) -> String {
 987         // Unfortunately, there seems to be no way to attempt to print
 988         // a path for a def-id, so I'll just make a best effort for now
 989         // and otherwise fallback to just printing the crate/node pair
 990         if self.krate == ast::LOCAL_CRATE {
 991             match tcx.map.find(self.node) {
 992                 Some(ast_map::NodeItem(..)) |
 993                 Some(ast_map::NodeForeignItem(..)) |
 994                 Some(ast_map::NodeImplItem(..)) |
 995                 Some(ast_map::NodeTraitItem(..)) |
 996                 Some(ast_map::NodeVariant(..)) |
 997                 Some(ast_map::NodeStructCtor(..)) => {
 998                     return format!(
 999                                 "{:?}:{}",
1000                                 *self,
1001                                 ty::item_path_str(tcx, *self))
1002                 }
1003                 _ => {}
1004             }
1005         }
1006         return format!("{:?}", *self)
1007     }
1008 }
1009
1010 impl<'tcx> Repr<'tcx> for ty::TypeScheme<'tcx> {
1011     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1012         format!("TypeScheme {{generics: {}, ty: {}}}",
1013                 self.generics.repr(tcx),
1014                 self.ty.repr(tcx))
1015     }
1016 }
1017
1018 impl<'tcx> Repr<'tcx> for ty::Generics<'tcx> {
1019     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1020         format!("Generics(types: {}, regions: {})",
1021                 self.types.repr(tcx),
1022                 self.regions.repr(tcx))
1023     }
1024 }
1025
1026 impl<'tcx> Repr<'tcx> for ty::GenericPredicates<'tcx> {
1027     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1028         format!("GenericPredicates(predicates: {})",
1029                 self.predicates.repr(tcx))
1030     }
1031 }
1032
1033 impl<'tcx> Repr<'tcx> for ty::InstantiatedPredicates<'tcx> {
1034     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1035         format!("InstantiatedPredicates({})",
1036                 self.predicates.repr(tcx))
1037     }
1038 }
1039
1040 impl<'tcx> Repr<'tcx> for ty::ItemVariances {
1041     fn repr(&self, tcx: &ctxt) -> String {
1042         format!("ItemVariances(types={}, \
1043                 regions={})",
1044                 self.types.repr(tcx),
1045                 self.regions.repr(tcx))
1046     }
1047 }
1048
1049 impl<'tcx> Repr<'tcx> for ty::Variance {
1050     fn repr(&self, _: &ctxt) -> String {
1051         // The first `.to_string()` returns a &'static str (it is not an implementation
1052         // of the ToString trait). Because of that, we need to call `.to_string()` again
1053         // if we want to have a `String`.
1054         let result: &'static str = (*self).to_string();
1055         result.to_string()
1056     }
1057 }
1058
1059 impl<'tcx> Repr<'tcx> for ty::ImplOrTraitItem<'tcx> {
1060     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1061         format!("ImplOrTraitItem({})",
1062                 match *self {
1063                     ty::ImplOrTraitItem::MethodTraitItem(ref i) => i.repr(tcx),
1064                     ty::ImplOrTraitItem::ConstTraitItem(ref i) => i.repr(tcx),
1065                     ty::ImplOrTraitItem::TypeTraitItem(ref i) => i.repr(tcx),
1066                 })
1067     }
1068 }
1069
1070 impl<'tcx> Repr<'tcx> for ty::AssociatedConst<'tcx> {
1071     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1072         format!("AssociatedConst(name: {}, ty: {}, vis: {}, def_id: {})",
1073                 self.name.repr(tcx),
1074                 self.ty.repr(tcx),
1075                 self.vis.repr(tcx),
1076                 self.def_id.repr(tcx))
1077     }
1078 }
1079
1080 impl<'tcx> Repr<'tcx> for ty::AssociatedType {
1081     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1082         format!("AssociatedType(name: {}, vis: {}, def_id: {})",
1083                 self.name.repr(tcx),
1084                 self.vis.repr(tcx),
1085                 self.def_id.repr(tcx))
1086     }
1087 }
1088
1089 impl<'tcx> Repr<'tcx> for ty::Method<'tcx> {
1090     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1091         format!("Method(name: {}, generics: {}, predicates: {}, fty: {}, \
1092                  explicit_self: {}, vis: {}, def_id: {})",
1093                 self.name.repr(tcx),
1094                 self.generics.repr(tcx),
1095                 self.predicates.repr(tcx),
1096                 self.fty.repr(tcx),
1097                 self.explicit_self.repr(tcx),
1098                 self.vis.repr(tcx),
1099                 self.def_id.repr(tcx))
1100     }
1101 }
1102
1103 impl<'tcx> Repr<'tcx> for ast::Name {
1104     fn repr(&self, _tcx: &ctxt) -> String {
1105         token::get_name(*self).to_string()
1106     }
1107 }
1108
1109 impl<'tcx> UserString<'tcx> for ast::Name {
1110     fn user_string(&self, _tcx: &ctxt) -> String {
1111         token::get_name(*self).to_string()
1112     }
1113 }
1114
1115 impl<'tcx> Repr<'tcx> for ast::Ident {
1116     fn repr(&self, _tcx: &ctxt) -> String {
1117         token::get_ident(*self).to_string()
1118     }
1119 }
1120
1121 impl<'tcx> Repr<'tcx> for ast::ExplicitSelf_ {
1122     fn repr(&self, _tcx: &ctxt) -> String {
1123         format!("{:?}", *self)
1124     }
1125 }
1126
1127 impl<'tcx> Repr<'tcx> for ast::Visibility {
1128     fn repr(&self, _tcx: &ctxt) -> String {
1129         format!("{:?}", *self)
1130     }
1131 }
1132
1133 impl<'tcx> Repr<'tcx> for ty::BareFnTy<'tcx> {
1134     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1135         format!("BareFnTy {{unsafety: {}, abi: {}, sig: {}}}",
1136                 self.unsafety,
1137                 self.abi.to_string(),
1138                 self.sig.repr(tcx))
1139     }
1140 }
1141
1142
1143 impl<'tcx> Repr<'tcx> for ty::FnSig<'tcx> {
1144     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1145         format!("fn{} -> {}", self.inputs.repr(tcx), self.output.repr(tcx))
1146     }
1147 }
1148
1149 impl<'tcx> Repr<'tcx> for ty::FnOutput<'tcx> {
1150     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1151         match *self {
1152             ty::FnConverging(ty) =>
1153                 format!("FnConverging({0})", ty.repr(tcx)),
1154             ty::FnDiverging =>
1155                 "FnDiverging".to_string()
1156         }
1157     }
1158 }
1159
1160 impl<'tcx> Repr<'tcx> for ty::MethodCallee<'tcx> {
1161     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1162         format!("MethodCallee {{origin: {}, ty: {}, {}}}",
1163                 self.origin.repr(tcx),
1164                 self.ty.repr(tcx),
1165                 self.substs.repr(tcx))
1166     }
1167 }
1168
1169 impl<'tcx> Repr<'tcx> for ty::MethodOrigin<'tcx> {
1170     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1171         match self {
1172             &ty::MethodStatic(def_id) => {
1173                 format!("MethodStatic({})", def_id.repr(tcx))
1174             }
1175             &ty::MethodStaticClosure(def_id) => {
1176                 format!("MethodStaticClosure({})", def_id.repr(tcx))
1177             }
1178             &ty::MethodTypeParam(ref p) => {
1179                 p.repr(tcx)
1180             }
1181             &ty::MethodTraitObject(ref p) => {
1182                 p.repr(tcx)
1183             }
1184         }
1185     }
1186 }
1187
1188 impl<'tcx> Repr<'tcx> for ty::MethodParam<'tcx> {
1189     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1190         format!("MethodParam({},{})",
1191                 self.trait_ref.repr(tcx),
1192                 self.method_num)
1193     }
1194 }
1195
1196 impl<'tcx> Repr<'tcx> for ty::MethodObject<'tcx> {
1197     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1198         format!("MethodObject({},{},{})",
1199                 self.trait_ref.repr(tcx),
1200                 self.method_num,
1201                 self.vtable_index)
1202     }
1203 }
1204
1205 impl<'tcx> Repr<'tcx> for ty::BuiltinBound {
1206     fn repr(&self, _tcx: &ctxt) -> String {
1207         format!("{:?}", *self)
1208     }
1209 }
1210
1211 impl<'tcx> UserString<'tcx> for ty::BuiltinBound {
1212     fn user_string(&self, _tcx: &ctxt) -> String {
1213         match *self {
1214             ty::BoundSend => "Send".to_string(),
1215             ty::BoundSized => "Sized".to_string(),
1216             ty::BoundCopy => "Copy".to_string(),
1217             ty::BoundSync => "Sync".to_string(),
1218         }
1219     }
1220 }
1221
1222 impl<'tcx> Repr<'tcx> for Span {
1223     fn repr(&self, tcx: &ctxt) -> String {
1224         tcx.sess.codemap().span_to_string(*self).to_string()
1225     }
1226 }
1227
1228 impl<'tcx, A:UserString<'tcx>> UserString<'tcx> for Rc<A> {
1229     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1230         let this: &A = &**self;
1231         this.user_string(tcx)
1232     }
1233 }
1234
1235 impl<'tcx> UserString<'tcx> for ty::ParamBounds<'tcx> {
1236     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1237         let mut result = Vec::new();
1238         let s = self.builtin_bounds.user_string(tcx);
1239         if !s.is_empty() {
1240             result.push(s);
1241         }
1242         for n in &self.trait_bounds {
1243             result.push(n.user_string(tcx));
1244         }
1245         result.connect(" + ")
1246     }
1247 }
1248
1249 impl<'tcx> Repr<'tcx> for ty::ExistentialBounds<'tcx> {
1250     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1251         let mut res = Vec::new();
1252
1253         let region_str = self.region_bound.repr(tcx);
1254         if !region_str.is_empty() {
1255             res.push(region_str);
1256         }
1257
1258         for bound in &self.builtin_bounds {
1259             res.push(bound.repr(tcx));
1260         }
1261
1262         for projection_bound in &self.projection_bounds {
1263             res.push(projection_bound.repr(tcx));
1264         }
1265
1266         res.connect("+")
1267     }
1268 }
1269
1270 impl<'tcx> UserString<'tcx> for ty::BuiltinBounds {
1271     fn user_string(&self, tcx: &ctxt) -> String {
1272         self.iter()
1273             .map(|bb| bb.user_string(tcx))
1274             .collect::<Vec<String>>()
1275             .connect("+")
1276             .to_string()
1277     }
1278 }
1279
1280 impl<'tcx, T> UserString<'tcx> for ty::Binder<T>
1281     where T : UserString<'tcx> + TypeFoldable<'tcx>
1282 {
1283     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1284         // Replace any anonymous late-bound regions with named
1285         // variants, using gensym'd identifiers, so that we can
1286         // clearly differentiate between named and unnamed regions in
1287         // the output. We'll probably want to tweak this over time to
1288         // decide just how much information to give.
1289         let mut names = Vec::new();
1290         let (unbound_value, _) = ty::replace_late_bound_regions(tcx, self, |br| {
1291             ty::ReLateBound(ty::DebruijnIndex::new(1), match br {
1292                 ty::BrNamed(_, name) => {
1293                     names.push(token::get_name(name));
1294                     br
1295                 }
1296                 ty::BrAnon(_) |
1297                 ty::BrFresh(_) |
1298                 ty::BrEnv => {
1299                     let name = token::gensym("'r");
1300                     names.push(token::get_name(name));
1301                     ty::BrNamed(ast_util::local_def(ast::DUMMY_NODE_ID), name)
1302                 }
1303             })
1304         });
1305         let names: Vec<_> = names.iter().map(|s| &s[..]).collect();
1306
1307         let value_str = unbound_value.user_string(tcx);
1308         if names.is_empty() {
1309             value_str
1310         } else {
1311             format!("for<{}> {}", names.connect(","), value_str)
1312         }
1313     }
1314 }
1315
1316 impl<'tcx> UserString<'tcx> for ty::TraitRef<'tcx> {
1317     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1318         let path_str = ty::item_path_str(tcx, self.def_id);
1319         parameterized(tcx, &path_str, self.substs, self.def_id, &[],
1320                       || ty::lookup_trait_def(tcx, self.def_id).generics.clone())
1321     }
1322 }
1323
1324 impl<'tcx> UserString<'tcx> for Ty<'tcx> {
1325     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1326         ty_to_string(tcx, *self)
1327     }
1328 }
1329
1330 impl<'tcx> UserString<'tcx> for ast::Ident {
1331     fn user_string(&self, _tcx: &ctxt) -> String {
1332         token::get_name(self.name).to_string()
1333     }
1334 }
1335
1336 impl<'tcx> Repr<'tcx> for abi::Abi {
1337     fn repr(&self, _tcx: &ctxt) -> String {
1338         self.to_string()
1339     }
1340 }
1341
1342 impl<'tcx> UserString<'tcx> for abi::Abi {
1343     fn user_string(&self, _tcx: &ctxt) -> String {
1344         self.to_string()
1345     }
1346 }
1347
1348 impl<'tcx> Repr<'tcx> for ty::UpvarId {
1349     fn repr(&self, tcx: &ctxt) -> String {
1350         format!("UpvarId({};`{}`;{})",
1351                 self.var_id,
1352                 ty::local_var_name_str(tcx, self.var_id),
1353                 self.closure_expr_id)
1354     }
1355 }
1356
1357 impl<'tcx> Repr<'tcx> for ast::Mutability {
1358     fn repr(&self, _tcx: &ctxt) -> String {
1359         format!("{:?}", *self)
1360     }
1361 }
1362
1363 impl<'tcx> Repr<'tcx> for ty::BorrowKind {
1364     fn repr(&self, _tcx: &ctxt) -> String {
1365         format!("{:?}", *self)
1366     }
1367 }
1368
1369 impl<'tcx> Repr<'tcx> for ty::UpvarBorrow {
1370     fn repr(&self, tcx: &ctxt) -> String {
1371         format!("UpvarBorrow({}, {})",
1372                 self.kind.repr(tcx),
1373                 self.region.repr(tcx))
1374     }
1375 }
1376
1377 impl<'tcx> Repr<'tcx> for ty::UpvarCapture {
1378     fn repr(&self, tcx: &ctxt) -> String {
1379         match *self {
1380             ty::UpvarCapture::ByValue => format!("ByValue"),
1381             ty::UpvarCapture::ByRef(ref data) => format!("ByRef({})", data.repr(tcx)),
1382         }
1383     }
1384 }
1385
1386 impl<'tcx> Repr<'tcx> for ty::IntVid {
1387     fn repr(&self, _tcx: &ctxt) -> String {
1388         format!("{:?}", self)
1389     }
1390 }
1391
1392 impl<'tcx> Repr<'tcx> for ty::FloatVid {
1393     fn repr(&self, _tcx: &ctxt) -> String {
1394         format!("{:?}", self)
1395     }
1396 }
1397
1398 impl<'tcx> Repr<'tcx> for ty::RegionVid {
1399     fn repr(&self, _tcx: &ctxt) -> String {
1400         format!("{:?}", self)
1401     }
1402 }
1403
1404 impl<'tcx> Repr<'tcx> for ty::TyVid {
1405     fn repr(&self, _tcx: &ctxt) -> String {
1406         format!("{:?}", self)
1407     }
1408 }
1409
1410 impl<'tcx> Repr<'tcx> for ty::IntVarValue {
1411     fn repr(&self, _tcx: &ctxt) -> String {
1412         format!("{:?}", *self)
1413     }
1414 }
1415
1416 impl<'tcx> Repr<'tcx> for ast::IntTy {
1417     fn repr(&self, _tcx: &ctxt) -> String {
1418         format!("{:?}", *self)
1419     }
1420 }
1421
1422 impl<'tcx> Repr<'tcx> for ast::UintTy {
1423     fn repr(&self, _tcx: &ctxt) -> String {
1424         format!("{:?}", *self)
1425     }
1426 }
1427
1428 impl<'tcx> Repr<'tcx> for ast::FloatTy {
1429     fn repr(&self, _tcx: &ctxt) -> String {
1430         format!("{:?}", *self)
1431     }
1432 }
1433
1434 impl<'tcx> Repr<'tcx> for ty::ExplicitSelfCategory {
1435     fn repr(&self, _: &ctxt) -> String {
1436         explicit_self_category_to_str(self).to_string()
1437     }
1438 }
1439
1440 impl<'tcx> UserString<'tcx> for ParamTy {
1441     fn user_string(&self, _tcx: &ctxt) -> String {
1442         format!("{}", token::get_name(self.name))
1443     }
1444 }
1445
1446 impl<'tcx> Repr<'tcx> for ParamTy {
1447     fn repr(&self, tcx: &ctxt) -> String {
1448         let ident = self.user_string(tcx);
1449         format!("{}/{:?}.{}", ident, self.space, self.idx)
1450     }
1451 }
1452
1453 impl<'tcx, A:Repr<'tcx>, B:Repr<'tcx>> Repr<'tcx> for (A,B) {
1454     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1455         let &(ref a, ref b) = self;
1456         format!("({},{})", a.repr(tcx), b.repr(tcx))
1457     }
1458 }
1459
1460 impl<'tcx, T:Repr<'tcx>> Repr<'tcx> for ty::Binder<T> {
1461     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1462         format!("Binder({})", self.0.repr(tcx))
1463     }
1464 }
1465
1466 impl<'tcx, S, K, V> Repr<'tcx> for HashMap<K, V, S>
1467     where K: Hash + Eq + Repr<'tcx>,
1468           V: Repr<'tcx>,
1469           S: HashState,
1470 {
1471     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1472         format!("HashMap({})",
1473                 self.iter()
1474                     .map(|(k,v)| format!("{} => {}", k.repr(tcx), v.repr(tcx)))
1475                     .collect::<Vec<String>>()
1476                     .connect(", "))
1477     }
1478 }
1479
1480 impl<'tcx, T, U> Repr<'tcx> for ty::OutlivesPredicate<T,U>
1481     where T : Repr<'tcx> + TypeFoldable<'tcx>,
1482           U : Repr<'tcx> + TypeFoldable<'tcx>,
1483 {
1484     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1485         format!("OutlivesPredicate({}, {})",
1486                 self.0.repr(tcx),
1487                 self.1.repr(tcx))
1488     }
1489 }
1490
1491 impl<'tcx, T, U> UserString<'tcx> for ty::OutlivesPredicate<T,U>
1492     where T : UserString<'tcx> + TypeFoldable<'tcx>,
1493           U : UserString<'tcx> + TypeFoldable<'tcx>,
1494 {
1495     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1496         format!("{} : {}",
1497                 self.0.user_string(tcx),
1498                 self.1.user_string(tcx))
1499     }
1500 }
1501
1502 impl<'tcx> Repr<'tcx> for ty::EquatePredicate<'tcx> {
1503     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1504         format!("EquatePredicate({}, {})",
1505                 self.0.repr(tcx),
1506                 self.1.repr(tcx))
1507     }
1508 }
1509
1510 impl<'tcx> UserString<'tcx> for ty::EquatePredicate<'tcx> {
1511     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1512         format!("{} == {}",
1513                 self.0.user_string(tcx),
1514                 self.1.user_string(tcx))
1515     }
1516 }
1517
1518 impl<'tcx> Repr<'tcx> for ty::TraitPredicate<'tcx> {
1519     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1520         format!("TraitPredicate({})",
1521                 self.trait_ref.repr(tcx))
1522     }
1523 }
1524
1525 impl<'tcx> UserString<'tcx> for ty::TraitPredicate<'tcx> {
1526     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1527         format!("{} : {}",
1528                 self.trait_ref.self_ty().user_string(tcx),
1529                 self.trait_ref.user_string(tcx))
1530     }
1531 }
1532
1533 impl<'tcx> UserString<'tcx> for ty::ProjectionPredicate<'tcx> {
1534     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1535         format!("{} == {}",
1536                 self.projection_ty.user_string(tcx),
1537                 self.ty.user_string(tcx))
1538     }
1539 }
1540
1541 impl<'tcx> Repr<'tcx> for ty::ProjectionTy<'tcx> {
1542     fn repr(&self, tcx: &ctxt<'tcx>) -> String {
1543         format!("{}::{}",
1544                 self.trait_ref.repr(tcx),
1545                 self.item_name.repr(tcx))
1546     }
1547 }
1548
1549 impl<'tcx> UserString<'tcx> for ty::ProjectionTy<'tcx> {
1550     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1551         format!("<{} as {}>::{}",
1552                 self.trait_ref.self_ty().user_string(tcx),
1553                 self.trait_ref.user_string(tcx),
1554                 self.item_name.user_string(tcx))
1555     }
1556 }
1557
1558 impl<'tcx> UserString<'tcx> for ty::Predicate<'tcx> {
1559     fn user_string(&self, tcx: &ctxt<'tcx>) -> String {
1560         match *self {
1561             ty::Predicate::Trait(ref data) => data.user_string(tcx),
1562             ty::Predicate::Equate(ref predicate) => predicate.user_string(tcx),
1563             ty::Predicate::RegionOutlives(ref predicate) => predicate.user_string(tcx),
1564             ty::Predicate::TypeOutlives(ref predicate) => predicate.user_string(tcx),
1565             ty::Predicate::Projection(ref predicate) => predicate.user_string(tcx),
1566         }
1567     }
1568 }
1569
1570 impl<'tcx> Repr<'tcx> for ast::Unsafety {
1571     fn repr(&self, _: &ctxt<'tcx>) -> String {
1572         format!("{:?}", *self)
1573     }
1574 }