src/librustc_mir/transform/type_check.rs

   1 // Copyright 2016 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 //! This pass type-checks the MIR to ensure it is not broken.
  12 #![allow(unreachable_code)]
  13
  14 use rustc::infer::{self, InferCtxt, InferOk};
  15 use rustc::traits::{self, Reveal};
  16 use rustc::ty::fold::TypeFoldable;
  17 use rustc::ty::{self, Ty, TyCtxt, TypeVariants};
  18 use rustc::mir::repr::*;
  19 use rustc::mir::tcx::LvalueTy;
  20 use rustc::mir::transform::{MirPass, MirSource, Pass};
  21 use rustc::mir::visit::{self, Visitor};
  22 use std::fmt;
  23 use syntax_pos::{Span, DUMMY_SP};
  24
  25 use rustc_data_structures::indexed_vec::Idx;
  26
  27 macro_rules! span_mirbug {
  28     ($context:expr, $elem:expr, $($message:tt)*) => ({
  29         $context.tcx().sess.span_warn(
  30             $context.last_span,
  31             &format!("broken MIR ({:?}): {}", $elem, format!($($message)*))
  32         )
  33     })
  34 }
  35
  36 macro_rules! span_mirbug_and_err {
  37     ($context:expr, $elem:expr, $($message:tt)*) => ({
  38         {
  39             $context.tcx().sess.span_warn(
  40                 $context.last_span,
  41                 &format!("broken MIR ({:?}): {:?}", $elem, format!($($message)*))
  42             );
  43             $context.error()
  44         }
  45     })
  46 }
  47
  48 enum FieldAccessError {
  49     OutOfRange { field_count: usize }
  50 }
  51
  52 /// Verifies that MIR types are sane to not crash further checks.
  53 ///
  54 /// The sanitize_XYZ methods here take an MIR object and compute its
  55 /// type, calling `span_mirbug` and returning an error type if there
  56 /// is a problem.
  57 struct TypeVerifier<'a, 'b: 'a, 'gcx: 'b+'tcx, 'tcx: 'b> {
  58     cx: &'a mut TypeChecker<'b, 'gcx, 'tcx>,
  59     mir: &'a Mir<'tcx>,
  60     last_span: Span,
  61     errors_reported: bool
  62 }
  63
  64 impl<'a, 'b, 'gcx, 'tcx> Visitor<'tcx> for TypeVerifier<'a, 'b, 'gcx, 'tcx> {
  65     fn visit_span(&mut self, span: &Span) {
  66         if *span != DUMMY_SP {
  67             self.last_span = *span;
  68         }
  69     }
  70
  71     fn visit_lvalue(&mut self,
  72                     lvalue: &Lvalue<'tcx>,
  73                     _context: visit::LvalueContext,
  74                     location: Location) {
  75         self.sanitize_lvalue(lvalue, location);
  76     }
  77
  78     fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location) {
  79         self.super_constant(constant, location);
  80         self.sanitize_type(constant, constant.ty);
  81     }
  82
  83     fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
  84         self.super_rvalue(rvalue, location);
  85         if let Some(ty) = rvalue.ty(self.mir, self.tcx()) {
  86             self.sanitize_type(rvalue, ty);
  87         }
  88     }
  89
  90     fn visit_mir(&mut self, mir: &Mir<'tcx>) {
  91         self.sanitize_type(&"return type", mir.return_ty);
  92         for var_decl in &mir.var_decls {
  93             self.sanitize_type(var_decl, var_decl.ty);
  94         }
  95         for (n, arg_decl) in mir.arg_decls.iter().enumerate() {
  96             self.sanitize_type(&(n, arg_decl), arg_decl.ty);
  97         }
  98         for (n, tmp_decl) in mir.temp_decls.iter().enumerate() {
  99             self.sanitize_type(&(n, tmp_decl), tmp_decl.ty);
 100         }
 101         if self.errors_reported {
 102             return;
 103         }
 104         self.super_mir(mir);
 105     }
 106 }
 107
 108 impl<'a, 'b, 'gcx, 'tcx> TypeVerifier<'a, 'b, 'gcx, 'tcx> {
 109     fn new(cx: &'a mut TypeChecker<'b, 'gcx, 'tcx>, mir: &'a Mir<'tcx>) -> Self {
 110         TypeVerifier {
 111             cx: cx,
 112             mir: mir,
 113             last_span: mir.span,
 114             errors_reported: false
 115         }
 116     }
 117
 118     fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
 119         self.cx.infcx.tcx
 120     }
 121
 122     fn sanitize_type(&mut self, parent: &fmt::Debug, ty: Ty<'tcx>) -> Ty<'tcx> {
 123         if ty.needs_infer() || ty.has_escaping_regions() || ty.references_error() {
 124             span_mirbug_and_err!(self, parent, "bad type {:?}", ty)
 125         } else {
 126             ty
 127         }
 128     }
 129
 130     fn sanitize_lvalue(&mut self, lvalue: &Lvalue<'tcx>, location: Location) -> LvalueTy<'tcx> {
 131         debug!("sanitize_lvalue: {:?}", lvalue);
 132         match *lvalue {
 133             Lvalue::Var(index) => LvalueTy::Ty { ty: self.mir.var_decls[index].ty },
 134             Lvalue::Temp(index) => LvalueTy::Ty { ty: self.mir.temp_decls[index].ty },
 135             Lvalue::Arg(index) => LvalueTy::Ty { ty: self.mir.arg_decls[index].ty },
 136             Lvalue::Static(def_id) =>
 137                 LvalueTy::Ty { ty: self.tcx().lookup_item_type(def_id).ty },
 138             Lvalue::ReturnPointer => {
 139                 LvalueTy::Ty { ty: self.mir.return_ty }
 140             }
 141             Lvalue::Projection(ref proj) => {
 142                 let base_ty = self.sanitize_lvalue(&proj.base, location);
 143                 if let LvalueTy::Ty { ty } = base_ty {
 144                     if ty.references_error() {
 145                         assert!(self.errors_reported);
 146                         return LvalueTy::Ty { ty: self.tcx().types.err };
 147                     }
 148                 }
 149                 self.sanitize_projection(base_ty, &proj.elem, lvalue, location)
 150             }
 151         }
 152     }
 153
 154     fn sanitize_projection(&mut self,
 155                            base: LvalueTy<'tcx>,
 156                            pi: &LvalueElem<'tcx>,
 157                            lvalue: &Lvalue<'tcx>,
 158                            location: Location)
 159                            -> LvalueTy<'tcx> {
 160         debug!("sanitize_projection: {:?} {:?} {:?}", base, pi, lvalue);
 161         let tcx = self.tcx();
 162         let base_ty = base.to_ty(tcx);
 163         let span = self.last_span;
 164         match *pi {
 165             ProjectionElem::Deref => {
 166                 let deref_ty = base_ty.builtin_deref(true, ty::LvaluePreference::NoPreference);
 167                 LvalueTy::Ty {
 168                     ty: deref_ty.map(|t| t.ty).unwrap_or_else(|| {
 169                         span_mirbug_and_err!(
 170                             self, lvalue, "deref of non-pointer {:?}", base_ty)
 171                     })
 172                 }
 173             }
 174             ProjectionElem::Index(ref i) => {
 175                 self.visit_operand(i, location);
 176                 let index_ty = i.ty(self.mir, tcx);
 177                 if index_ty != tcx.types.usize {
 178                     LvalueTy::Ty {
 179                         ty: span_mirbug_and_err!(self, i, "index by non-usize {:?}", i)
 180                     }
 181                 } else {
 182                     LvalueTy::Ty {
 183                         ty: base_ty.builtin_index().unwrap_or_else(|| {
 184                             span_mirbug_and_err!(
 185                                 self, lvalue, "index of non-array {:?}", base_ty)
 186                         })
 187                     }
 188                 }
 189             }
 190             ProjectionElem::ConstantIndex { .. } => {
 191                 // consider verifying in-bounds
 192                 LvalueTy::Ty {
 193                     ty: base_ty.builtin_index().unwrap_or_else(|| {
 194                         span_mirbug_and_err!(
 195                             self, lvalue, "index of non-array {:?}", base_ty)
 196                     })
 197                 }
 198             }
 199             ProjectionElem::Subslice { from, to } => {
 200                 LvalueTy::Ty {
 201                     ty: match base_ty.sty {
 202                         ty::TyArray(inner, size) => {
 203                             let min_size = (from as usize) + (to as usize);
 204                             if let Some(rest_size) = size.checked_sub(min_size) {
 205                                 tcx.mk_array(inner, rest_size)
 206                             } else {
 207                                 span_mirbug_and_err!(
 208                                     self, lvalue, "taking too-small slice of {:?}", base_ty)
 209                             }
 210                         }
 211                         ty::TySlice(..) => base_ty,
 212                         _ => {
 213                             span_mirbug_and_err!(
 214                                 self, lvalue, "slice of non-array {:?}", base_ty)
 215                         }
 216                     }
 217                 }
 218             }
 219             ProjectionElem::Downcast(adt_def1, index) =>
 220                 match base_ty.sty {
 221                     ty::TyEnum(adt_def, substs) if adt_def == adt_def1 => {
 222                         if index >= adt_def.variants.len() {
 223                             LvalueTy::Ty {
 224                                 ty: span_mirbug_and_err!(
 225                                     self,
 226                                     lvalue,
 227                                     "cast to variant #{:?} but enum only has {:?}",
 228                                     index,
 229                                     adt_def.variants.len())
 230                             }
 231                         } else {
 232                             LvalueTy::Downcast {
 233                                 adt_def: adt_def,
 234                                 substs: substs,
 235                                 variant_index: index
 236                             }
 237                         }
 238                     }
 239                     _ => LvalueTy::Ty {
 240                         ty: span_mirbug_and_err!(
 241                             self, lvalue, "can't downcast {:?} as {:?}",
 242                             base_ty, adt_def1)
 243                     }
 244                 },
 245             ProjectionElem::Field(field, fty) => {
 246                 let fty = self.sanitize_type(lvalue, fty);
 247                 match self.field_ty(lvalue, base, field) {
 248                     Ok(ty) => {
 249                         if let Err(terr) = self.cx.eq_types(span, ty, fty) {
 250                             span_mirbug!(
 251                                 self, lvalue, "bad field access ({:?}: {:?}): {:?}",
 252                                 ty, fty, terr);
 253                         }
 254                     }
 255                     Err(FieldAccessError::OutOfRange { field_count }) => {
 256                         span_mirbug!(
 257                             self, lvalue, "accessed field #{} but variant only has {}",
 258                             field.index(), field_count)
 259                     }
 260                 }
 261                 LvalueTy::Ty { ty: fty }
 262             }
 263         }
 264     }
 265
 266     fn error(&mut self) -> Ty<'tcx> {
 267         self.errors_reported = true;
 268         self.tcx().types.err
 269     }
 270
 271     fn field_ty(&mut self,
 272                 parent: &fmt::Debug,
 273                 base_ty: LvalueTy<'tcx>,
 274                 field: Field)
 275                 -> Result<Ty<'tcx>, FieldAccessError>
 276     {
 277         let tcx = self.tcx();
 278
 279         let (variant, substs) = match base_ty {
 280             LvalueTy::Downcast { adt_def, substs, variant_index } => {
 281                 (&adt_def.variants[variant_index], substs)
 282             }
 283             LvalueTy::Ty { ty } => match ty.sty {
 284                 ty::TyStruct(adt_def, substs) | ty::TyEnum(adt_def, substs)
 285                     if adt_def.is_univariant() => {
 286                         (&adt_def.variants[0], substs)
 287                     }
 288                 ty::TyTuple(tys) | ty::TyClosure(_, ty::ClosureSubsts {
 289                     upvar_tys: tys, ..
 290                 }) => {
 291                     return match tys.get(field.index()) {
 292                         Some(&ty) => Ok(ty),
 293                         None => Err(FieldAccessError::OutOfRange {
 294                             field_count: tys.len()
 295                         })
 296                     }
 297                 }
 298                 _ => return Ok(span_mirbug_and_err!(
 299                     self, parent, "can't project out of {:?}", base_ty))
 300             }
 301         };
 302
 303         if let Some(field) = variant.fields.get(field.index()) {
 304             Ok(self.cx.normalize(&field.ty(tcx, substs)))
 305         } else {
 306             Err(FieldAccessError::OutOfRange { field_count: variant.fields.len() })
 307         }
 308     }
 309 }
 310
 311 pub struct TypeChecker<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
 312     infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
 313     fulfillment_cx: traits::FulfillmentContext<'tcx>,
 314     last_span: Span
 315 }
 316
 317 impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
 318     fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self {
 319         TypeChecker {
 320             infcx: infcx,
 321             fulfillment_cx: traits::FulfillmentContext::new(),
 322             last_span: DUMMY_SP
 323         }
 324     }
 325
 326     fn sub_types(&self, span: Span, sup: Ty<'tcx>, sub: Ty<'tcx>)
 327                  -> infer::UnitResult<'tcx>
 328     {
 329         self.infcx.sub_types(false, infer::TypeOrigin::Misc(span), sup, sub)
 330             // FIXME(#32730) propagate obligations
 331             .map(|InferOk { obligations, .. }| assert!(obligations.is_empty()))
 332     }
 333
 334     fn eq_types(&self, span: Span, a: Ty<'tcx>, b: Ty<'tcx>)
 335                 -> infer::UnitResult<'tcx>
 336     {
 337         self.infcx.eq_types(false, infer::TypeOrigin::Misc(span), a, b)
 338             // FIXME(#32730) propagate obligations
 339             .map(|InferOk { obligations, .. }| assert!(obligations.is_empty()))
 340     }
 341
 342     fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
 343         self.infcx.tcx
 344     }
 345
 346     fn check_stmt(&mut self, mir: &Mir<'tcx>, stmt: &Statement<'tcx>) {
 347         debug!("check_stmt: {:?}", stmt);
 348         let tcx = self.tcx();
 349         match stmt.kind {
 350             StatementKind::Assign(ref lv, ref rv) => {
 351                 let lv_ty = lv.ty(mir, tcx).to_ty(tcx);
 352                 let rv_ty = rv.ty(mir, tcx);
 353                 if let Some(rv_ty) = rv_ty {
 354                     if let Err(terr) = self.sub_types(self.last_span, rv_ty, lv_ty) {
 355                         span_mirbug!(self, stmt, "bad assignment ({:?} = {:?}): {:?}",
 356                                      lv_ty, rv_ty, terr);
 357                     }
 358                 // FIXME: rvalue with undeterminable type - e.g. inline
 359                 // asm.
 360                 }
 361             }
 362             StatementKind::SetDiscriminant{ ref lvalue, variant_index } => {
 363                 let lvalue_type = lvalue.ty(mir, tcx).to_ty(tcx);
 364                 let adt = match lvalue_type.sty {
 365                     TypeVariants::TyEnum(adt, _) => adt,
 366                     _ => {
 367                         span_bug!(stmt.source_info.span,
 368                                   "bad set discriminant ({:?} = {:?}): lhs is not an enum",
 369                                   lvalue,
 370                                   variant_index);
 371                     }
 372                 };
 373                 if variant_index >= adt.variants.len() {
 374                      span_bug!(stmt.source_info.span,
 375                                "bad set discriminant ({:?} = {:?}): value of of range",
 376                                lvalue,
 377                                variant_index);
 378                 };
 379             }
 380             StatementKind::StorageLive(ref lv) |
 381             StatementKind::StorageDead(ref lv) => {
 382                 match *lv {
 383                     Lvalue::Temp(_) | Lvalue::Var(_) => {}
 384                     _ => {
 385                         span_mirbug!(self, stmt, "bad lvalue: expected temp or var");
 386                     }
 387                 }
 388             }
 389         }
 390     }
 391
 392     fn check_terminator(&mut self,
 393                         mir: &Mir<'tcx>,
 394                         term: &Terminator<'tcx>) {
 395         debug!("check_terminator: {:?}", term);
 396         let tcx = self.tcx();
 397         match term.kind {
 398             TerminatorKind::Goto { .. } |
 399             TerminatorKind::Resume |
 400             TerminatorKind::Return |
 401             TerminatorKind::Unreachable |
 402             TerminatorKind::Drop { .. } => {
 403                 // no checks needed for these
 404             }
 405
 406
 407             TerminatorKind::DropAndReplace {
 408                 ref location,
 409                 ref value,
 410                 ..
 411             } => {
 412                 let lv_ty = location.ty(mir, tcx).to_ty(tcx);
 413                 let rv_ty = value.ty(mir, tcx);
 414                 if let Err(terr) = self.sub_types(self.last_span, rv_ty, lv_ty) {
 415                     span_mirbug!(self, term, "bad DropAndReplace ({:?} = {:?}): {:?}",
 416                                  lv_ty, rv_ty, terr);
 417                 }
 418             }
 419
 420             TerminatorKind::If { ref cond, .. } => {
 421                 let cond_ty = cond.ty(mir, tcx);
 422                 match cond_ty.sty {
 423                     ty::TyBool => {}
 424                     _ => {
 425                         span_mirbug!(self, term, "bad If ({:?}, not bool", cond_ty);
 426                     }
 427                 }
 428             }
 429             TerminatorKind::SwitchInt { ref discr, switch_ty, .. } => {
 430                 let discr_ty = discr.ty(mir, tcx).to_ty(tcx);
 431                 if let Err(terr) = self.sub_types(self.last_span, discr_ty, switch_ty) {
 432                     span_mirbug!(self, term, "bad SwitchInt ({:?} on {:?}): {:?}",
 433                                  switch_ty, discr_ty, terr);
 434                 }
 435                 if !switch_ty.is_integral() && !switch_ty.is_char() &&
 436                     !switch_ty.is_bool()
 437                 {
 438                     span_mirbug!(self, term, "bad SwitchInt discr ty {:?}",switch_ty);
 439                 }
 440                 // FIXME: check the values
 441             }
 442             TerminatorKind::Switch { ref discr, adt_def, ref targets } => {
 443                 let discr_ty = discr.ty(mir, tcx).to_ty(tcx);
 444                 match discr_ty.sty {
 445                     ty::TyEnum(def, _)
 446                         if def == adt_def && adt_def.variants.len() == targets.len()
 447                         => {},
 448                     _ => {
 449                         span_mirbug!(self, term, "bad Switch ({:?} on {:?})",
 450                                      adt_def, discr_ty);
 451                     }
 452                 }
 453             }
 454             TerminatorKind::Call { ref func, ref args, ref destination, .. } => {
 455                 let func_ty = func.ty(mir, tcx);
 456                 debug!("check_terminator: call, func_ty={:?}", func_ty);
 457                 let func_ty = match func_ty.sty {
 458                     ty::TyFnDef(_, _, func_ty) | ty::TyFnPtr(func_ty) => func_ty,
 459                     _ => {
 460                         span_mirbug!(self, term, "call to non-function {:?}", func_ty);
 461                         return;
 462                     }
 463                 };
 464                 let sig = tcx.erase_late_bound_regions(&func_ty.sig);
 465                 let sig = self.normalize(&sig);
 466                 self.check_call_dest(mir, term, &sig, destination);
 467
 468                 if self.is_box_free(func) {
 469                     self.check_box_free_inputs(mir, term, &sig, args);
 470                 } else {
 471                     self.check_call_inputs(mir, term, &sig, args);
 472                 }
 473             }
 474             TerminatorKind::Assert { ref cond, ref msg, .. } => {
 475                 let cond_ty = cond.ty(mir, tcx);
 476                 if cond_ty != tcx.types.bool {
 477                     span_mirbug!(self, term, "bad Assert ({:?}, not bool", cond_ty);
 478                 }
 479
 480                 if let AssertMessage::BoundsCheck { ref len, ref index } = *msg {
 481                     if len.ty(mir, tcx) != tcx.types.usize {
 482                         span_mirbug!(self, len, "bounds-check length non-usize {:?}", len)
 483                     }
 484                     if index.ty(mir, tcx) != tcx.types.usize {
 485                         span_mirbug!(self, index, "bounds-check index non-usize {:?}", index)
 486                     }
 487                 }
 488             }
 489         }
 490     }
 491
 492     fn check_call_dest(&self,
 493                        mir: &Mir<'tcx>,
 494                        term: &Terminator<'tcx>,
 495                        sig: &ty::FnSig<'tcx>,
 496                        destination: &Option<(Lvalue<'tcx>, BasicBlock)>) {
 497         let tcx = self.tcx();
 498         match *destination {
 499             Some((ref dest, _)) => {
 500                 let dest_ty = dest.ty(mir, tcx).to_ty(tcx);
 501                 if let Err(terr) = self.sub_types(self.last_span, sig.output, dest_ty) {
 502                     span_mirbug!(self, term,
 503                                  "call dest mismatch ({:?} <- {:?}): {:?}",
 504                                  dest_ty, sig.output, terr);
 505                 }
 506             },
 507             None => {
 508                 // FIXME(canndrew): This is_never should probably be an is_uninhabited
 509                 if !sig.output.is_never() {
 510                     span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
 511                 }
 512             },
 513         }
 514     }
 515
 516     fn check_call_inputs(&self,
 517                          mir: &Mir<'tcx>,
 518                          term: &Terminator<'tcx>,
 519                          sig: &ty::FnSig<'tcx>,
 520                          args: &[Operand<'tcx>])
 521     {
 522         debug!("check_call_inputs({:?}, {:?})", sig, args);
 523         if args.len() < sig.inputs.len() ||
 524            (args.len() > sig.inputs.len() && !sig.variadic) {
 525             span_mirbug!(self, term, "call to {:?} with wrong # of args", sig);
 526         }
 527         for (n, (fn_arg, op_arg)) in sig.inputs.iter().zip(args).enumerate() {
 528             let op_arg_ty = op_arg.ty(mir, self.tcx());
 529             if let Err(terr) = self.sub_types(self.last_span, op_arg_ty, fn_arg) {
 530                 span_mirbug!(self, term, "bad arg #{:?} ({:?} <- {:?}): {:?}",
 531                              n, fn_arg, op_arg_ty, terr);
 532             }
 533         }
 534     }
 535
 536     fn is_box_free(&self, operand: &Operand<'tcx>) -> bool {
 537         match operand {
 538             &Operand::Constant(Constant {
 539                 literal: Literal::Item { def_id, .. }, ..
 540             }) => {
 541                 Some(def_id) == self.tcx().lang_items.box_free_fn()
 542             }
 543             _ => false,
 544         }
 545     }
 546
 547     fn check_box_free_inputs(&self,
 548                              mir: &Mir<'tcx>,
 549                              term: &Terminator<'tcx>,
 550                              sig: &ty::FnSig<'tcx>,
 551                              args: &[Operand<'tcx>])
 552     {
 553         debug!("check_box_free_inputs");
 554
 555         // box_free takes a Box as a pointer. Allow for that.
 556
 557         if sig.inputs.len() != 1 {
 558             span_mirbug!(self, term, "box_free should take 1 argument");
 559             return;
 560         }
 561
 562         let pointee_ty = match sig.inputs[0].sty {
 563             ty::TyRawPtr(mt) => mt.ty,
 564             _ => {
 565                 span_mirbug!(self, term, "box_free should take a raw ptr");
 566                 return;
 567             }
 568         };
 569
 570         if args.len() != 1 {
 571             span_mirbug!(self, term, "box_free called with wrong # of args");
 572             return;
 573         }
 574
 575         let arg_ty = match args[0].ty(mir, self.tcx()).sty {
 576             ty::TyRawPtr(mt) => mt.ty,
 577             ty::TyBox(ty) => ty,
 578             _ => {
 579                 span_mirbug!(self, term, "box_free called with bad arg ty");
 580                 return;
 581             }
 582         };
 583
 584         if let Err(terr) = self.sub_types(self.last_span, arg_ty, pointee_ty) {
 585             span_mirbug!(self, term, "bad box_free arg ({:?} <- {:?}): {:?}",
 586                          pointee_ty, arg_ty, terr);
 587         }
 588     }
 589
 590     fn check_iscleanup(&mut self, mir: &Mir<'tcx>, block: &BasicBlockData<'tcx>)
 591     {
 592         let is_cleanup = block.is_cleanup;
 593         self.last_span = block.terminator().source_info.span;
 594         match block.terminator().kind {
 595             TerminatorKind::Goto { target } =>
 596                 self.assert_iscleanup(mir, block, target, is_cleanup),
 597             TerminatorKind::If { targets: (on_true, on_false), .. } => {
 598                 self.assert_iscleanup(mir, block, on_true, is_cleanup);
 599                 self.assert_iscleanup(mir, block, on_false, is_cleanup);
 600             }
 601             TerminatorKind::Switch { ref targets, .. } |
 602             TerminatorKind::SwitchInt { ref targets, .. } => {
 603                 for target in targets {
 604                     self.assert_iscleanup(mir, block, *target, is_cleanup);
 605                 }
 606             }
 607             TerminatorKind::Resume => {
 608                 if !is_cleanup {
 609                     span_mirbug!(self, block, "resume on non-cleanup block!")
 610                 }
 611             }
 612             TerminatorKind::Return => {
 613                 if is_cleanup {
 614                     span_mirbug!(self, block, "return on cleanup block")
 615                 }
 616             }
 617             TerminatorKind::Unreachable => {}
 618             TerminatorKind::Drop { target, unwind, .. } |
 619             TerminatorKind::DropAndReplace { target, unwind, .. } |
 620             TerminatorKind::Assert { target, cleanup: unwind, .. } => {
 621                 self.assert_iscleanup(mir, block, target, is_cleanup);
 622                 if let Some(unwind) = unwind {
 623                     if is_cleanup {
 624                         span_mirbug!(self, block, "unwind on cleanup block")
 625                     }
 626                     self.assert_iscleanup(mir, block, unwind, true);
 627                 }
 628             }
 629             TerminatorKind::Call { ref destination, cleanup, .. } => {
 630                 if let &Some((_, target)) = destination {
 631                     self.assert_iscleanup(mir, block, target, is_cleanup);
 632                 }
 633                 if let Some(cleanup) = cleanup {
 634                     if is_cleanup {
 635                         span_mirbug!(self, block, "cleanup on cleanup block")
 636                     }
 637                     self.assert_iscleanup(mir, block, cleanup, true);
 638                 }
 639             }
 640         }
 641     }
 642
 643     fn assert_iscleanup(&mut self,
 644                         mir: &Mir<'tcx>,
 645                         ctxt: &fmt::Debug,
 646                         bb: BasicBlock,
 647                         iscleanuppad: bool)
 648     {
 649         if mir[bb].is_cleanup != iscleanuppad {
 650             span_mirbug!(self, ctxt, "cleanuppad mismatch: {:?} should be {:?}",
 651                          bb, iscleanuppad);
 652         }
 653     }
 654
 655     fn typeck_mir(&mut self, mir: &Mir<'tcx>) {
 656         self.last_span = mir.span;
 657         debug!("run_on_mir: {:?}", mir.span);
 658         for block in mir.basic_blocks() {
 659             for stmt in &block.statements {
 660                 if stmt.source_info.span != DUMMY_SP {
 661                     self.last_span = stmt.source_info.span;
 662                 }
 663                 self.check_stmt(mir, stmt);
 664             }
 665
 666             self.check_terminator(mir, block.terminator());
 667             self.check_iscleanup(mir, block);
 668         }
 669     }
 670
 671
 672     fn normalize<T>(&mut self, value: &T) -> T
 673         where T: fmt::Debug + TypeFoldable<'tcx>
 674     {
 675         let mut selcx = traits::SelectionContext::new(self.infcx);
 676         let cause = traits::ObligationCause::misc(self.last_span, 0);
 677         let traits::Normalized { value, obligations } =
 678             traits::normalize(&mut selcx, cause, value);
 679
 680         debug!("normalize: value={:?} obligations={:?}",
 681                value,
 682                obligations);
 683
 684         let mut fulfill_cx = &mut self.fulfillment_cx;
 685         for obligation in obligations {
 686             fulfill_cx.register_predicate_obligation(self.infcx, obligation);
 687         }
 688
 689         value
 690     }
 691
 692     fn verify_obligations(&mut self, mir: &Mir<'tcx>) {
 693         self.last_span = mir.span;
 694         if let Err(e) = self.fulfillment_cx.select_all_or_error(self.infcx) {
 695             span_mirbug!(self, "", "errors selecting obligation: {:?}",
 696                          e);
 697         }
 698     }
 699 }
 700
 701 pub struct TypeckMir;
 702
 703 impl TypeckMir {
 704     pub fn new() -> Self {
 705         TypeckMir
 706     }
 707 }
 708
 709 impl<'tcx> MirPass<'tcx> for TypeckMir {
 710     fn run_pass<'a>(&mut self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
 711                     src: MirSource, mir: &mut Mir<'tcx>) {
 712         if tcx.sess.err_count() > 0 {
 713             // compiling a broken program can obviously result in a
 714             // broken MIR, so try not to report duplicate errors.
 715             return;
 716         }
 717         let param_env = ty::ParameterEnvironment::for_item(tcx, src.item_id());
 718         tcx.infer_ctxt(None, Some(param_env), Reveal::NotSpecializable).enter(|infcx| {
 719             let mut checker = TypeChecker::new(&infcx);
 720             {
 721                 let mut verifier = TypeVerifier::new(&mut checker, mir);
 722                 verifier.visit_mir(mir);
 723                 if verifier.errors_reported {
 724                     // don't do further checks to avoid ICEs
 725                     return;
 726                 }
 727             }
 728             checker.typeck_mir(mir);
 729             checker.verify_obligations(mir);
 730         });
 731     }
 732 }
 733
 734 impl Pass for TypeckMir {
 735 }