src/librustc/ty/maps.rs

   1 // Copyright 2012-2015 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 dep_graph::{DepNode, DepTrackingMapConfig};
  12 use hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefId, LOCAL_CRATE};
  13 use hir::def::Def;
  14 use hir;
  15 use middle::const_val;
  16 use middle::privacy::AccessLevels;
  17 use middle::region::RegionMaps;
  18 use mir;
  19 use mir::transform::{MirSuite, MirPassIndex};
  20 use session::CompileResult;
  21 use traits::specialization_graph;
  22 use ty::{self, CrateInherentImpls, Ty, TyCtxt};
  23 use ty::layout::{Layout, LayoutError};
  24 use ty::item_path;
  25 use ty::steal::Steal;
  26 use ty::subst::Substs;
  27 use ty::fast_reject::SimplifiedType;
  28 use util::nodemap::{DefIdSet, NodeSet};
  29
  30 use rustc_data_structures::indexed_vec::IndexVec;
  31 use rustc_data_structures::fx::FxHashMap;
  32 use std::cell::{RefCell, RefMut};
  33 use std::fmt::Debug;
  34 use std::hash::Hash;
  35 use std::marker::PhantomData;
  36 use std::mem;
  37 use std::collections::BTreeMap;
  38 use std::ops::Deref;
  39 use std::rc::Rc;
  40 use syntax_pos::{Span, DUMMY_SP};
  41 use syntax::attr;
  42 use syntax::ast;
  43 use syntax::symbol::Symbol;
  44
  45 pub trait Key: Clone + Hash + Eq + Debug {
  46     fn map_crate(&self) -> CrateNum;
  47     fn default_span(&self, tcx: TyCtxt) -> Span;
  48 }
  49
  50 impl<'tcx> Key for ty::InstanceDef<'tcx> {
  51     fn map_crate(&self) -> CrateNum {
  52         LOCAL_CRATE
  53     }
  54
  55     fn default_span(&self, tcx: TyCtxt) -> Span {
  56         tcx.def_span(self.def_id())
  57     }
  58 }
  59
  60 impl<'tcx> Key for ty::Instance<'tcx> {
  61     fn map_crate(&self) -> CrateNum {
  62         LOCAL_CRATE
  63     }
  64
  65     fn default_span(&self, tcx: TyCtxt) -> Span {
  66         tcx.def_span(self.def_id())
  67     }
  68 }
  69
  70 impl Key for CrateNum {
  71     fn map_crate(&self) -> CrateNum {
  72         *self
  73     }
  74     fn default_span(&self, _: TyCtxt) -> Span {
  75         DUMMY_SP
  76     }
  77 }
  78
  79 impl Key for DefId {
  80     fn map_crate(&self) -> CrateNum {
  81         self.krate
  82     }
  83     fn default_span(&self, tcx: TyCtxt) -> Span {
  84         tcx.def_span(*self)
  85     }
  86 }
  87
  88 impl Key for (DefId, DefId) {
  89     fn map_crate(&self) -> CrateNum {
  90         self.0.krate
  91     }
  92     fn default_span(&self, tcx: TyCtxt) -> Span {
  93         self.1.default_span(tcx)
  94     }
  95 }
  96
  97 impl Key for (CrateNum, DefId) {
  98     fn map_crate(&self) -> CrateNum {
  99         self.0
 100     }
 101     fn default_span(&self, tcx: TyCtxt) -> Span {
 102         self.1.default_span(tcx)
 103     }
 104 }
 105
 106 impl Key for (DefId, SimplifiedType) {
 107     fn map_crate(&self) -> CrateNum {
 108         self.0.krate
 109     }
 110     fn default_span(&self, tcx: TyCtxt) -> Span {
 111         self.0.default_span(tcx)
 112     }
 113 }
 114
 115 impl<'tcx> Key for (DefId, &'tcx Substs<'tcx>) {
 116     fn map_crate(&self) -> CrateNum {
 117         self.0.krate
 118     }
 119     fn default_span(&self, tcx: TyCtxt) -> Span {
 120         self.0.default_span(tcx)
 121     }
 122 }
 123
 124 impl Key for (MirSuite, DefId) {
 125     fn map_crate(&self) -> CrateNum {
 126         self.1.map_crate()
 127     }
 128     fn default_span(&self, tcx: TyCtxt) -> Span {
 129         self.1.default_span(tcx)
 130     }
 131 }
 132
 133 impl Key for (MirSuite, MirPassIndex, DefId) {
 134     fn map_crate(&self) -> CrateNum {
 135         self.2.map_crate()
 136     }
 137     fn default_span(&self, tcx: TyCtxt) -> Span {
 138         self.2.default_span(tcx)
 139     }
 140 }
 141
 142 impl<'tcx, T: Clone + Hash + Eq + Debug> Key for ty::ParamEnvAnd<'tcx, T> {
 143     fn map_crate(&self) -> CrateNum {
 144         LOCAL_CRATE
 145     }
 146     fn default_span(&self, _: TyCtxt) -> Span {
 147         DUMMY_SP
 148     }
 149 }
 150
 151 trait Value<'tcx>: Sized {
 152     fn from_cycle_error<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Self;
 153 }
 154
 155 impl<'tcx, T> Value<'tcx> for T {
 156     default fn from_cycle_error<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> T {
 157         tcx.sess.abort_if_errors();
 158         bug!("Value::from_cycle_error called without errors");
 159     }
 160 }
 161
 162 impl<'tcx, T: Default> Value<'tcx> for T {
 163     default fn from_cycle_error<'a>(_: TyCtxt<'a, 'tcx, 'tcx>) -> T {
 164         T::default()
 165     }
 166 }
 167
 168 impl<'tcx> Value<'tcx> for Ty<'tcx> {
 169     fn from_cycle_error<'a>(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Ty<'tcx> {
 170         tcx.types.err
 171     }
 172 }
 173
 174 impl<'tcx> Value<'tcx> for ty::DtorckConstraint<'tcx> {
 175     fn from_cycle_error<'a>(_: TyCtxt<'a, 'tcx, 'tcx>) -> Self {
 176         Self::empty()
 177     }
 178 }
 179
 180 impl<'tcx> Value<'tcx> for ty::SymbolName {
 181     fn from_cycle_error<'a>(_: TyCtxt<'a, 'tcx, 'tcx>) -> Self {
 182         ty::SymbolName { name: Symbol::intern("<error>").as_str() }
 183     }
 184 }
 185
 186 struct QueryMap<D: QueryDescription> {
 187     phantom: PhantomData<D>,
 188     map: FxHashMap<D::Key, D::Value>,
 189 }
 190
 191 impl<M: QueryDescription> QueryMap<M> {
 192     fn new() -> QueryMap<M> {
 193         QueryMap {
 194             phantom: PhantomData,
 195             map: FxHashMap(),
 196         }
 197     }
 198 }
 199
 200 pub struct CycleError<'a, 'tcx: 'a> {
 201     span: Span,
 202     cycle: RefMut<'a, [(Span, Query<'tcx>)]>,
 203 }
 204
 205 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 206     pub fn report_cycle(self, CycleError { span, cycle }: CycleError) {
 207         // Subtle: release the refcell lock before invoking `describe()`
 208         // below by dropping `cycle`.
 209         let stack = cycle.to_vec();
 210         mem::drop(cycle);
 211
 212         assert!(!stack.is_empty());
 213
 214         // Disable naming impls with types in this path, since that
 215         // sometimes cycles itself, leading to extra cycle errors.
 216         // (And cycle errors around impls tend to occur during the
 217         // collect/coherence phases anyhow.)
 218         item_path::with_forced_impl_filename_line(|| {
 219             let mut err =
 220                 struct_span_err!(self.sess, span, E0391,
 221                                  "unsupported cyclic reference between types/traits detected");
 222             err.span_label(span, "cyclic reference");
 223
 224             err.span_note(stack[0].0, &format!("the cycle begins when {}...",
 225                                                stack[0].1.describe(self)));
 226
 227             for &(span, ref query) in &stack[1..] {
 228                 err.span_note(span, &format!("...which then requires {}...",
 229                                              query.describe(self)));
 230             }
 231
 232             err.note(&format!("...which then again requires {}, completing the cycle.",
 233                               stack[0].1.describe(self)));
 234
 235             err.emit();
 236         });
 237     }
 238
 239     fn cycle_check<F, R>(self, span: Span, query: Query<'gcx>, compute: F)
 240                          -> Result<R, CycleError<'a, 'gcx>>
 241         where F: FnOnce() -> R
 242     {
 243         {
 244             let mut stack = self.maps.query_stack.borrow_mut();
 245             if let Some((i, _)) = stack.iter().enumerate().rev()
 246                                        .find(|&(_, &(_, ref q))| *q == query) {
 247                 return Err(CycleError {
 248                     span: span,
 249                     cycle: RefMut::map(stack, |stack| &mut stack[i..])
 250                 });
 251             }
 252             stack.push((span, query));
 253         }
 254
 255         let result = compute();
 256
 257         self.maps.query_stack.borrow_mut().pop();
 258
 259         Ok(result)
 260     }
 261 }
 262
 263 trait QueryDescription: DepTrackingMapConfig {
 264     fn describe(tcx: TyCtxt, key: Self::Key) -> String;
 265 }
 266
 267 impl<M: DepTrackingMapConfig<Key=DefId>> QueryDescription for M {
 268     default fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 269         format!("processing `{}`", tcx.item_path_str(def_id))
 270     }
 271 }
 272
 273 impl<'tcx> QueryDescription for queries::is_copy_raw<'tcx> {
 274     fn describe(_tcx: TyCtxt, env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> String {
 275         format!("computing whether `{}` is `Copy`", env.value)
 276     }
 277 }
 278
 279 impl<'tcx> QueryDescription for queries::is_sized_raw<'tcx> {
 280     fn describe(_tcx: TyCtxt, env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> String {
 281         format!("computing whether `{}` is `Sized`", env.value)
 282     }
 283 }
 284
 285 impl<'tcx> QueryDescription for queries::is_freeze_raw<'tcx> {
 286     fn describe(_tcx: TyCtxt, env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> String {
 287         format!("computing whether `{}` is freeze", env.value)
 288     }
 289 }
 290
 291 impl<'tcx> QueryDescription for queries::needs_drop_raw<'tcx> {
 292     fn describe(_tcx: TyCtxt, env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> String {
 293         format!("computing whether `{}` needs drop", env.value)
 294     }
 295 }
 296
 297 impl<'tcx> QueryDescription for queries::layout_raw<'tcx> {
 298     fn describe(_tcx: TyCtxt, env: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> String {
 299         format!("computing layout of `{}`", env.value)
 300     }
 301 }
 302
 303 impl<'tcx> QueryDescription for queries::super_predicates_of<'tcx> {
 304     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 305         format!("computing the supertraits of `{}`",
 306                 tcx.item_path_str(def_id))
 307     }
 308 }
 309
 310 impl<'tcx> QueryDescription for queries::type_param_predicates<'tcx> {
 311     fn describe(tcx: TyCtxt, (_, def_id): (DefId, DefId)) -> String {
 312         let id = tcx.hir.as_local_node_id(def_id).unwrap();
 313         format!("computing the bounds for type parameter `{}`",
 314                 tcx.hir.ty_param_name(id))
 315     }
 316 }
 317
 318 impl<'tcx> QueryDescription for queries::coherent_trait<'tcx> {
 319     fn describe(tcx: TyCtxt, (_, def_id): (CrateNum, DefId)) -> String {
 320         format!("coherence checking all impls of trait `{}`",
 321                 tcx.item_path_str(def_id))
 322     }
 323 }
 324
 325 impl<'tcx> QueryDescription for queries::crate_inherent_impls<'tcx> {
 326     fn describe(_: TyCtxt, k: CrateNum) -> String {
 327         format!("all inherent impls defined in crate `{:?}`", k)
 328     }
 329 }
 330
 331 impl<'tcx> QueryDescription for queries::crate_inherent_impls_overlap_check<'tcx> {
 332     fn describe(_: TyCtxt, _: CrateNum) -> String {
 333         format!("check for overlap between inherent impls defined in this crate")
 334     }
 335 }
 336
 337 impl<'tcx> QueryDescription for queries::crate_variances<'tcx> {
 338     fn describe(_tcx: TyCtxt, _: CrateNum) -> String {
 339         format!("computing the variances for items in this crate")
 340     }
 341 }
 342
 343 impl<'tcx> QueryDescription for queries::mir_shims<'tcx> {
 344     fn describe(tcx: TyCtxt, def: ty::InstanceDef<'tcx>) -> String {
 345         format!("generating MIR shim for `{}`",
 346                 tcx.item_path_str(def.def_id()))
 347     }
 348 }
 349
 350 impl<'tcx> QueryDescription for queries::privacy_access_levels<'tcx> {
 351     fn describe(_: TyCtxt, _: CrateNum) -> String {
 352         format!("privacy access levels")
 353     }
 354 }
 355
 356 impl<'tcx> QueryDescription for queries::typeck_item_bodies<'tcx> {
 357     fn describe(_: TyCtxt, _: CrateNum) -> String {
 358         format!("type-checking all item bodies")
 359     }
 360 }
 361
 362 impl<'tcx> QueryDescription for queries::reachable_set<'tcx> {
 363     fn describe(_: TyCtxt, _: CrateNum) -> String {
 364         format!("reachability")
 365     }
 366 }
 367
 368 impl<'tcx> QueryDescription for queries::const_eval<'tcx> {
 369     fn describe(tcx: TyCtxt, (def_id, _): (DefId, &'tcx Substs<'tcx>)) -> String {
 370         format!("const-evaluating `{}`", tcx.item_path_str(def_id))
 371     }
 372 }
 373
 374 impl<'tcx> QueryDescription for queries::mir_keys<'tcx> {
 375     fn describe(_: TyCtxt, _: CrateNum) -> String {
 376         format!("getting a list of all mir_keys")
 377     }
 378 }
 379
 380 impl<'tcx> QueryDescription for queries::symbol_name<'tcx> {
 381     fn describe(_tcx: TyCtxt, instance: ty::Instance<'tcx>) -> String {
 382         format!("computing the symbol for `{}`", instance)
 383     }
 384 }
 385
 386 impl<'tcx> QueryDescription for queries::describe_def<'tcx> {
 387     fn describe(_: TyCtxt, _: DefId) -> String {
 388         bug!("describe_def")
 389     }
 390 }
 391
 392 impl<'tcx> QueryDescription for queries::def_span<'tcx> {
 393     fn describe(_: TyCtxt, _: DefId) -> String {
 394         bug!("def_span")
 395     }
 396 }
 397
 398
 399 impl<'tcx> QueryDescription for queries::stability<'tcx> {
 400     fn describe(_: TyCtxt, _: DefId) -> String {
 401         bug!("stability")
 402     }
 403 }
 404
 405 impl<'tcx> QueryDescription for queries::deprecation<'tcx> {
 406     fn describe(_: TyCtxt, _: DefId) -> String {
 407         bug!("deprecation")
 408     }
 409 }
 410
 411 impl<'tcx> QueryDescription for queries::item_attrs<'tcx> {
 412     fn describe(_: TyCtxt, _: DefId) -> String {
 413         bug!("item_attrs")
 414     }
 415 }
 416
 417 impl<'tcx> QueryDescription for queries::is_exported_symbol<'tcx> {
 418     fn describe(_: TyCtxt, _: DefId) -> String {
 419         bug!("is_exported_symbol")
 420     }
 421 }
 422
 423 impl<'tcx> QueryDescription for queries::fn_arg_names<'tcx> {
 424     fn describe(_: TyCtxt, _: DefId) -> String {
 425         bug!("fn_arg_names")
 426     }
 427 }
 428
 429 impl<'tcx> QueryDescription for queries::impl_parent<'tcx> {
 430     fn describe(_: TyCtxt, _: DefId) -> String {
 431         bug!("impl_parent")
 432     }
 433 }
 434
 435 impl<'tcx> QueryDescription for queries::trait_of_item<'tcx> {
 436     fn describe(_: TyCtxt, _: DefId) -> String {
 437         bug!("trait_of_item")
 438     }
 439 }
 440
 441 impl<'tcx> QueryDescription for queries::item_body_nested_bodies<'tcx> {
 442     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 443         format!("nested item bodies of `{}`", tcx.item_path_str(def_id))
 444     }
 445 }
 446
 447 impl<'tcx> QueryDescription for queries::const_is_rvalue_promotable_to_static<'tcx> {
 448     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 449         format!("const checking if rvalue is promotable to static `{}`",
 450             tcx.item_path_str(def_id))
 451     }
 452 }
 453
 454 impl<'tcx> QueryDescription for queries::is_mir_available<'tcx> {
 455     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 456         format!("checking if item is mir available: `{}`",
 457             tcx.item_path_str(def_id))
 458     }
 459 }
 460
 461 impl<'tcx> QueryDescription for queries::trait_impls_of<'tcx> {
 462     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 463         format!("trait impls of `{}`", tcx.item_path_str(def_id))
 464     }
 465 }
 466
 467 impl<'tcx> QueryDescription for queries::relevant_trait_impls_for<'tcx> {
 468     fn describe(tcx: TyCtxt, (def_id, ty): (DefId, SimplifiedType)) -> String {
 469         format!("relevant impls for: `({}, {:?})`", tcx.item_path_str(def_id), ty)
 470     }
 471 }
 472
 473 impl<'tcx> QueryDescription for queries::is_object_safe<'tcx> {
 474     fn describe(tcx: TyCtxt, def_id: DefId) -> String {
 475         format!("determine object safety of trait `{}`", tcx.item_path_str(def_id))
 476     }
 477 }
 478
 479 macro_rules! define_maps {
 480     (<$tcx:tt>
 481      $($(#[$attr:meta])*
 482        [$($modifiers:tt)*] $name:ident: $node:ident($K:ty) -> $V:ty,)*) => {
 483         define_map_struct! {
 484             tcx: $tcx,
 485             input: ($(([$($modifiers)*] [$($attr)*] [$name]))*)
 486         }
 487
 488         impl<$tcx> Maps<$tcx> {
 489             pub fn new(providers: IndexVec<CrateNum, Providers<$tcx>>)
 490                        -> Self {
 491                 Maps {
 492                     providers,
 493                     query_stack: RefCell::new(vec![]),
 494                     $($name: RefCell::new(QueryMap::new())),*
 495                 }
 496             }
 497         }
 498
 499         #[allow(bad_style)]
 500         #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 501         pub enum Query<$tcx> {
 502             $($(#[$attr])* $name($K)),*
 503         }
 504
 505         impl<$tcx> Query<$tcx> {
 506             pub fn describe(&self, tcx: TyCtxt) -> String {
 507                 match *self {
 508                     $(Query::$name(key) => queries::$name::describe(tcx, key)),*
 509                 }
 510             }
 511         }
 512
 513         pub mod queries {
 514             use std::marker::PhantomData;
 515
 516             $(#[allow(bad_style)]
 517             pub struct $name<$tcx> {
 518                 data: PhantomData<&$tcx ()>
 519             })*
 520         }
 521
 522         $(impl<$tcx> DepTrackingMapConfig for queries::$name<$tcx> {
 523             type Key = $K;
 524             type Value = $V;
 525
 526             #[allow(unused)]
 527             fn to_dep_node(key: &$K) -> DepNode<DefId> {
 528                 use dep_graph::DepNode::*;
 529
 530                 $node(*key)
 531             }
 532         }
 533         impl<'a, $tcx, 'lcx> queries::$name<$tcx> {
 534             fn try_get_with<F, R>(tcx: TyCtxt<'a, $tcx, 'lcx>,
 535                                   mut span: Span,
 536                                   key: $K,
 537                                   f: F)
 538                                   -> Result<R, CycleError<'a, $tcx>>
 539                 where F: FnOnce(&$V) -> R
 540             {
 541                 debug!("ty::queries::{}::try_get_with(key={:?}, span={:?})",
 542                        stringify!($name),
 543                        key,
 544                        span);
 545
 546                 if let Some(result) = tcx.maps.$name.borrow().map.get(&key) {
 547                     return Ok(f(result));
 548                 }
 549
 550                 // FIXME(eddyb) Get more valid Span's on queries.
 551                 // def_span guard is necesary to prevent a recursive loop,
 552                 // default_span calls def_span query internally.
 553                 if span == DUMMY_SP && stringify!($name) != "def_span" {
 554                     span = key.default_span(tcx)
 555                 }
 556
 557                 let _task = tcx.dep_graph.in_task(Self::to_dep_node(&key));
 558
 559                 let result = tcx.cycle_check(span, Query::$name(key), || {
 560                     let provider = tcx.maps.providers[key.map_crate()].$name;
 561                     provider(tcx.global_tcx(), key)
 562                 })?;
 563
 564                 Ok(f(tcx.maps.$name.borrow_mut().map.entry(key).or_insert(result)))
 565             }
 566
 567             pub fn try_get(tcx: TyCtxt<'a, $tcx, 'lcx>, span: Span, key: $K)
 568                            -> Result<$V, CycleError<'a, $tcx>> {
 569                 // We register the `read` here, but not in `force`, since
 570                 // `force` does not give access to the value produced (and thus
 571                 // we actually don't read it).
 572                 tcx.dep_graph.read(Self::to_dep_node(&key));
 573                 Self::try_get_with(tcx, span, key, Clone::clone)
 574             }
 575
 576             pub fn force(tcx: TyCtxt<'a, $tcx, 'lcx>, span: Span, key: $K) {
 577                 match Self::try_get_with(tcx, span, key, |_| ()) {
 578                     Ok(()) => {}
 579                     Err(e) => tcx.report_cycle(e)
 580                 }
 581             }
 582         })*
 583
 584         #[derive(Copy, Clone)]
 585         pub struct TyCtxtAt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 586             pub tcx: TyCtxt<'a, 'gcx, 'tcx>,
 587             pub span: Span,
 588         }
 589
 590         impl<'a, 'gcx, 'tcx> Deref for TyCtxtAt<'a, 'gcx, 'tcx> {
 591             type Target = TyCtxt<'a, 'gcx, 'tcx>;
 592             fn deref(&self) -> &Self::Target {
 593                 &self.tcx
 594             }
 595         }
 596
 597         impl<'a, $tcx, 'lcx> TyCtxt<'a, $tcx, 'lcx> {
 598             /// Return a transparent wrapper for `TyCtxt` which uses
 599             /// `span` as the location of queries performed through it.
 600             pub fn at(self, span: Span) -> TyCtxtAt<'a, $tcx, 'lcx> {
 601                 TyCtxtAt {
 602                     tcx: self,
 603                     span
 604                 }
 605             }
 606
 607             $($(#[$attr])*
 608             pub fn $name(self, key: $K) -> $V {
 609                 self.at(DUMMY_SP).$name(key)
 610             })*
 611         }
 612
 613         impl<'a, $tcx, 'lcx> TyCtxtAt<'a, $tcx, 'lcx> {
 614             $($(#[$attr])*
 615             pub fn $name(self, key: $K) -> $V {
 616                 queries::$name::try_get(self.tcx, self.span, key).unwrap_or_else(|e| {
 617                     self.report_cycle(e);
 618                     Value::from_cycle_error(self.global_tcx())
 619                 })
 620             })*
 621         }
 622
 623         define_provider_struct! {
 624             tcx: $tcx,
 625             input: ($(([$($modifiers)*] [$name] [$K] [$V]))*),
 626             output: ()
 627         }
 628
 629         impl<$tcx> Copy for Providers<$tcx> {}
 630         impl<$tcx> Clone for Providers<$tcx> {
 631             fn clone(&self) -> Self { *self }
 632         }
 633     }
 634 }
 635
 636 macro_rules! define_map_struct {
 637     // Initial state
 638     (tcx: $tcx:tt,
 639      input: $input:tt) => {
 640         define_map_struct! {
 641             tcx: $tcx,
 642             input: $input,
 643             output: ()
 644         }
 645     };
 646
 647     // Final output
 648     (tcx: $tcx:tt,
 649      input: (),
 650      output: ($($output:tt)*)) => {
 651         pub struct Maps<$tcx> {
 652             providers: IndexVec<CrateNum, Providers<$tcx>>,
 653             query_stack: RefCell<Vec<(Span, Query<$tcx>)>>,
 654             $($output)*
 655         }
 656     };
 657
 658     // Field recognized and ready to shift into the output
 659     (tcx: $tcx:tt,
 660      ready: ([$($pub:tt)*] [$($attr:tt)*] [$name:ident]),
 661      input: $input:tt,
 662      output: ($($output:tt)*)) => {
 663         define_map_struct! {
 664             tcx: $tcx,
 665             input: $input,
 666             output: ($($output)*
 667                      $(#[$attr])* $($pub)* $name: RefCell<QueryMap<queries::$name<$tcx>>>,)
 668         }
 669     };
 670
 671     // No modifiers left? This is a private item.
 672     (tcx: $tcx:tt,
 673      input: (([] $attrs:tt $name:tt) $($input:tt)*),
 674      output: $output:tt) => {
 675         define_map_struct! {
 676             tcx: $tcx,
 677             ready: ([] $attrs $name),
 678             input: ($($input)*),
 679             output: $output
 680         }
 681     };
 682
 683     // Skip other modifiers
 684     (tcx: $tcx:tt,
 685      input: (([$other_modifier:tt $($modifiers:tt)*] $($fields:tt)*) $($input:tt)*),
 686      output: $output:tt) => {
 687         define_map_struct! {
 688             tcx: $tcx,
 689             input: (([$($modifiers)*] $($fields)*) $($input)*),
 690             output: $output
 691         }
 692     };
 693 }
 694
 695 macro_rules! define_provider_struct {
 696     // Initial state:
 697     (tcx: $tcx:tt, input: $input:tt) => {
 698         define_provider_struct! {
 699             tcx: $tcx,
 700             input: $input,
 701             output: ()
 702         }
 703     };
 704
 705     // Final state:
 706     (tcx: $tcx:tt,
 707      input: (),
 708      output: ($(([$name:ident] [$K:ty] [$R:ty]))*)) => {
 709         pub struct Providers<$tcx> {
 710             $(pub $name: for<'a> fn(TyCtxt<'a, $tcx, $tcx>, $K) -> $R,)*
 711         }
 712
 713         impl<$tcx> Default for Providers<$tcx> {
 714             fn default() -> Self {
 715                 $(fn $name<'a, $tcx>(_: TyCtxt<'a, $tcx, $tcx>, key: $K) -> $R {
 716                     bug!("tcx.maps.{}({:?}) unsupported by its crate",
 717                          stringify!($name), key);
 718                 })*
 719                 Providers { $($name),* }
 720             }
 721         }
 722     };
 723
 724     // Something ready to shift:
 725     (tcx: $tcx:tt,
 726      ready: ($name:tt $K:tt $V:tt),
 727      input: $input:tt,
 728      output: ($($output:tt)*)) => {
 729         define_provider_struct! {
 730             tcx: $tcx,
 731             input: $input,
 732             output: ($($output)* ($name $K $V))
 733         }
 734     };
 735
 736     // Regular queries produce a `V` only.
 737     (tcx: $tcx:tt,
 738      input: (([] $name:tt $K:tt $V:tt) $($input:tt)*),
 739      output: $output:tt) => {
 740         define_provider_struct! {
 741             tcx: $tcx,
 742             ready: ($name $K $V),
 743             input: ($($input)*),
 744             output: $output
 745         }
 746     };
 747
 748     // Skip modifiers.
 749     (tcx: $tcx:tt,
 750      input: (([$other_modifier:tt $($modifiers:tt)*] $($fields:tt)*) $($input:tt)*),
 751      output: $output:tt) => {
 752         define_provider_struct! {
 753             tcx: $tcx,
 754             input: (([$($modifiers)*] $($fields)*) $($input)*),
 755             output: $output
 756         }
 757     };
 758 }
 759
 760 // Each of these maps also corresponds to a method on a
 761 // `Provider` trait for requesting a value of that type,
 762 // and a method on `Maps` itself for doing that in a
 763 // a way that memoizes and does dep-graph tracking,
 764 // wrapping around the actual chain of providers that
 765 // the driver creates (using several `rustc_*` crates).
 766 define_maps! { <'tcx>
 767     /// Records the type of every item.
 768     [] type_of: ItemSignature(DefId) -> Ty<'tcx>,
 769
 770     /// Maps from the def-id of an item (trait/struct/enum/fn) to its
 771     /// associated generics and predicates.
 772     [] generics_of: ItemSignature(DefId) -> &'tcx ty::Generics,
 773     [] predicates_of: ItemSignature(DefId) -> ty::GenericPredicates<'tcx>,
 774
 775     /// Maps from the def-id of a trait to the list of
 776     /// super-predicates. This is a subset of the full list of
 777     /// predicates. We store these in a separate map because we must
 778     /// evaluate them even during type conversion, often before the
 779     /// full predicates are available (note that supertraits have
 780     /// additional acyclicity requirements).
 781     [] super_predicates_of: ItemSignature(DefId) -> ty::GenericPredicates<'tcx>,
 782
 783     /// To avoid cycles within the predicates of a single item we compute
 784     /// per-type-parameter predicates for resolving `T::AssocTy`.
 785     [] type_param_predicates: TypeParamPredicates((DefId, DefId))
 786         -> ty::GenericPredicates<'tcx>,
 787
 788     [] trait_def: ItemSignature(DefId) -> &'tcx ty::TraitDef,
 789     [] adt_def: ItemSignature(DefId) -> &'tcx ty::AdtDef,
 790     [] adt_destructor: AdtDestructor(DefId) -> Option<ty::Destructor>,
 791     [] adt_sized_constraint: SizedConstraint(DefId) -> &'tcx [Ty<'tcx>],
 792     [] adt_dtorck_constraint: DtorckConstraint(DefId) -> ty::DtorckConstraint<'tcx>,
 793
 794     /// True if this is a foreign item (i.e., linked via `extern { ... }`).
 795     [] is_foreign_item: IsForeignItem(DefId) -> bool,
 796
 797     /// True if this is a default impl (aka impl Foo for ..)
 798     [] is_default_impl: ItemSignature(DefId) -> bool,
 799
 800     /// Get a map with the variance of every item; use `item_variance`
 801     /// instead.
 802     [] crate_variances: crate_variances(CrateNum) -> Rc<ty::CrateVariancesMap>,
 803
 804     /// Maps from def-id of a type or region parameter to its
 805     /// (inferred) variance.
 806     [] variances_of: ItemVariances(DefId) -> Rc<Vec<ty::Variance>>,
 807
 808     /// Maps from an impl/trait def-id to a list of the def-ids of its items
 809     [] associated_item_def_ids: AssociatedItemDefIds(DefId) -> Rc<Vec<DefId>>,
 810
 811     /// Maps from a trait item to the trait item "descriptor"
 812     [] associated_item: AssociatedItems(DefId) -> ty::AssociatedItem,
 813
 814     [] impl_trait_ref: ItemSignature(DefId) -> Option<ty::TraitRef<'tcx>>,
 815     [] impl_polarity: ItemSignature(DefId) -> hir::ImplPolarity,
 816
 817     /// Maps a DefId of a type to a list of its inherent impls.
 818     /// Contains implementations of methods that are inherent to a type.
 819     /// Methods in these implementations don't need to be exported.
 820     [] inherent_impls: InherentImpls(DefId) -> Rc<Vec<DefId>>,
 821
 822     /// Set of all the def-ids in this crate that have MIR associated with
 823     /// them. This includes all the body owners, but also things like struct
 824     /// constructors.
 825     [] mir_keys: mir_keys(CrateNum) -> Rc<DefIdSet>,
 826
 827     /// Maps DefId's that have an associated Mir to the result
 828     /// of the MIR qualify_consts pass. The actual meaning of
 829     /// the value isn't known except to the pass itself.
 830     [] mir_const_qualif: Mir(DefId) -> u8,
 831
 832     /// Fetch the MIR for a given def-id up till the point where it is
 833     /// ready for const evaluation.
 834     ///
 835     /// See the README for the `mir` module for details.
 836     [] mir_const: Mir(DefId) -> &'tcx Steal<mir::Mir<'tcx>>,
 837
 838     [] mir_validated: Mir(DefId) -> &'tcx Steal<mir::Mir<'tcx>>,
 839
 840     /// MIR after our optimization passes have run. This is MIR that is ready
 841     /// for trans. This is also the only query that can fetch non-local MIR, at present.
 842     [] optimized_mir: Mir(DefId) -> &'tcx mir::Mir<'tcx>,
 843
 844     /// Records the type of each closure. The def ID is the ID of the
 845     /// expression defining the closure.
 846     [] closure_kind: ItemSignature(DefId) -> ty::ClosureKind,
 847
 848     /// Records the type of each closure. The def ID is the ID of the
 849     /// expression defining the closure.
 850     [] closure_type: ItemSignature(DefId) -> ty::PolyFnSig<'tcx>,
 851
 852     /// Caches CoerceUnsized kinds for impls on custom types.
 853     [] coerce_unsized_info: ItemSignature(DefId)
 854         -> ty::adjustment::CoerceUnsizedInfo,
 855
 856     [] typeck_item_bodies: typeck_item_bodies_dep_node(CrateNum) -> CompileResult,
 857
 858     [] typeck_tables_of: TypeckTables(DefId) -> &'tcx ty::TypeckTables<'tcx>,
 859
 860     [] has_typeck_tables: TypeckTables(DefId) -> bool,
 861
 862     [] coherent_trait: coherent_trait_dep_node((CrateNum, DefId)) -> (),
 863
 864     [] borrowck: BorrowCheck(DefId) -> (),
 865
 866     /// Gets a complete map from all types to their inherent impls.
 867     /// Not meant to be used directly outside of coherence.
 868     /// (Defined only for LOCAL_CRATE)
 869     [] crate_inherent_impls: crate_inherent_impls_dep_node(CrateNum) -> CrateInherentImpls,
 870
 871     /// Checks all types in the krate for overlap in their inherent impls. Reports errors.
 872     /// Not meant to be used directly outside of coherence.
 873     /// (Defined only for LOCAL_CRATE)
 874     [] crate_inherent_impls_overlap_check: crate_inherent_impls_dep_node(CrateNum) -> (),
 875
 876     /// Results of evaluating const items or constants embedded in
 877     /// other items (such as enum variant explicit discriminants).
 878     [] const_eval: const_eval_dep_node((DefId, &'tcx Substs<'tcx>))
 879         -> const_val::EvalResult<'tcx>,
 880
 881     /// Performs the privacy check and computes "access levels".
 882     [] privacy_access_levels: PrivacyAccessLevels(CrateNum) -> Rc<AccessLevels>,
 883
 884     [] reachable_set: reachability_dep_node(CrateNum) -> Rc<NodeSet>,
 885
 886     /// Per-function `RegionMaps`. The `DefId` should be the owner-def-id for the fn body;
 887     /// in the case of closures or "inline" expressions, this will be redirected to the enclosing
 888     /// fn item.
 889     [] region_maps: RegionMaps(DefId) -> Rc<RegionMaps>,
 890
 891     [] mir_shims: mir_shim_dep_node(ty::InstanceDef<'tcx>) -> &'tcx mir::Mir<'tcx>,
 892
 893     [] def_symbol_name: SymbolName(DefId) -> ty::SymbolName,
 894     [] symbol_name: symbol_name_dep_node(ty::Instance<'tcx>) -> ty::SymbolName,
 895
 896     [] describe_def: DescribeDef(DefId) -> Option<Def>,
 897     [] def_span: DefSpan(DefId) -> Span,
 898     [] stability: Stability(DefId) -> Option<attr::Stability>,
 899     [] deprecation: Deprecation(DefId) -> Option<attr::Deprecation>,
 900     [] item_attrs: ItemAttrs(DefId) -> Rc<[ast::Attribute]>,
 901     [] fn_arg_names: FnArgNames(DefId) -> Vec<ast::Name>,
 902     [] impl_parent: ImplParent(DefId) -> Option<DefId>,
 903     [] trait_of_item: TraitOfItem(DefId) -> Option<DefId>,
 904     [] is_exported_symbol: IsExportedSymbol(DefId) -> bool,
 905     [] item_body_nested_bodies: ItemBodyNestedBodies(DefId) -> Rc<BTreeMap<hir::BodyId, hir::Body>>,
 906     [] const_is_rvalue_promotable_to_static: ConstIsRvaluePromotableToStatic(DefId) -> bool,
 907     [] is_mir_available: IsMirAvailable(DefId) -> bool,
 908
 909     [] trait_impls_of: TraitImpls(DefId) -> ty::trait_def::TraitImpls,
 910     // Note that TraitDef::for_each_relevant_impl() will do type simplication for you.
 911     [] relevant_trait_impls_for: relevant_trait_impls_for((DefId, SimplifiedType))
 912         -> ty::trait_def::TraitImpls,
 913     [] specialization_graph_of: SpecializationGraph(DefId) -> Rc<specialization_graph::Graph>,
 914     [] is_object_safe: ObjectSafety(DefId) -> bool,
 915
 916     // Get the ParameterEnvironment for a given item; this environment
 917     // will be in "user-facing" mode, meaning that it is suitabe for
 918     // type-checking etc, and it does not normalize specializable
 919     // associated types. This is almost always what you want,
 920     // unless you are doing MIR optimizations, in which case you
 921     // might want to use `reveal_all()` method to change modes.
 922     [] param_env: ParamEnv(DefId) -> ty::ParamEnv<'tcx>,
 923
 924     // Trait selection queries. These are best used by invoking `ty.moves_by_default()`,
 925     // `ty.is_copy()`, etc, since that will prune the environment where possible.
 926     [] is_copy_raw: is_copy_dep_node(ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool,
 927     [] is_sized_raw: is_sized_dep_node(ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool,
 928     [] is_freeze_raw: is_freeze_dep_node(ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool,
 929     [] needs_drop_raw: needs_drop_dep_node(ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> bool,
 930     [] layout_raw: layout_dep_node(ty::ParamEnvAnd<'tcx, Ty<'tcx>>)
 931                                   -> Result<&'tcx Layout, LayoutError<'tcx>>,
 932 }
 933
 934 fn coherent_trait_dep_node((_, def_id): (CrateNum, DefId)) -> DepNode<DefId> {
 935     DepNode::CoherenceCheckTrait(def_id)
 936 }
 937
 938 fn crate_inherent_impls_dep_node(_: CrateNum) -> DepNode<DefId> {
 939     DepNode::Coherence
 940 }
 941
 942 fn reachability_dep_node(_: CrateNum) -> DepNode<DefId> {
 943     DepNode::Reachability
 944 }
 945
 946 fn mir_shim_dep_node(instance: ty::InstanceDef) -> DepNode<DefId> {
 947     instance.dep_node()
 948 }
 949
 950 fn symbol_name_dep_node(instance: ty::Instance) -> DepNode<DefId> {
 951     // symbol_name uses the substs only to traverse them to find the
 952     // hash, and that does not create any new dep-nodes.
 953     DepNode::SymbolName(instance.def.def_id())
 954 }
 955
 956 fn typeck_item_bodies_dep_node(_: CrateNum) -> DepNode<DefId> {
 957     DepNode::TypeckBodiesKrate
 958 }
 959
 960 fn const_eval_dep_node((def_id, _): (DefId, &Substs)) -> DepNode<DefId> {
 961     DepNode::ConstEval(def_id)
 962 }
 963
 964 fn mir_keys(_: CrateNum) -> DepNode<DefId> {
 965     DepNode::MirKeys
 966 }
 967
 968 fn crate_variances(_: CrateNum) -> DepNode<DefId> {
 969     DepNode::CrateVariances
 970 }
 971
 972 fn relevant_trait_impls_for((def_id, _): (DefId, SimplifiedType)) -> DepNode<DefId> {
 973     DepNode::TraitImpls(def_id)
 974 }
 975
 976 fn is_copy_dep_node<'tcx>(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> DepNode<DefId> {
 977     let def_id = ty::item_path::characteristic_def_id_of_type(key.value)
 978         .unwrap_or(DefId::local(CRATE_DEF_INDEX));
 979     DepNode::IsCopy(def_id)
 980 }
 981
 982 fn is_sized_dep_node<'tcx>(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> DepNode<DefId> {
 983     let def_id = ty::item_path::characteristic_def_id_of_type(key.value)
 984         .unwrap_or(DefId::local(CRATE_DEF_INDEX));
 985     DepNode::IsSized(def_id)
 986 }
 987
 988 fn is_freeze_dep_node<'tcx>(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> DepNode<DefId> {
 989     let def_id = ty::item_path::characteristic_def_id_of_type(key.value)
 990         .unwrap_or(DefId::local(CRATE_DEF_INDEX));
 991     DepNode::IsFreeze(def_id)
 992 }
 993
 994 fn needs_drop_dep_node<'tcx>(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> DepNode<DefId> {
 995     let def_id = ty::item_path::characteristic_def_id_of_type(key.value)
 996         .unwrap_or(DefId::local(CRATE_DEF_INDEX));
 997     DepNode::NeedsDrop(def_id)
 998 }
 999
1000 fn layout_dep_node<'tcx>(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> DepNode<DefId> {
1001     let def_id = ty::item_path::characteristic_def_id_of_type(key.value)
1002         .unwrap_or(DefId::local(CRATE_DEF_INDEX));
1003     DepNode::Layout(def_id)
1004 }