compiler/rustc_mir_build/src/thir/cx/expr.rs

   1 use crate::thir::cx::Cx;
   2 use crate::thir::util::UserAnnotatedTyHelpers;
   3 use rustc_data_structures::stack::ensure_sufficient_stack;
   4 use rustc_hir as hir;
   5 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
   6 use rustc_index::vec::Idx;
   7 use rustc_middle::hir::place::Place as HirPlace;
   8 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
   9 use rustc_middle::hir::place::ProjectionKind as HirProjectionKind;
  10 use rustc_middle::middle::region;
  11 use rustc_middle::mir::interpret::Scalar;
  12 use rustc_middle::mir::{BinOp, BorrowKind, Field, UnOp};
  13 use rustc_middle::thir::*;
  14 use rustc_middle::ty::adjustment::{
  15     Adjust, Adjustment, AutoBorrow, AutoBorrowMutability, PointerCast,
  16 };
  17 use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
  18 use rustc_middle::ty::{self, AdtKind, Ty, UpvarSubsts, UserType};
  19 use rustc_span::def_id::DefId;
  20 use rustc_span::Span;
  21 use rustc_target::abi::VariantIdx;
  22
  23 impl<'tcx> Cx<'tcx> {
  24     crate fn mirror_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) -> ExprId {
  25         // `mirror_expr` is recursing very deep. Make sure the stack doesn't overflow.
  26         ensure_sufficient_stack(|| self.mirror_expr_inner(expr))
  27     }
  28
  29     crate fn mirror_exprs(&mut self, exprs: &'tcx [hir::Expr<'tcx>]) -> Box<[ExprId]> {
  30         exprs.iter().map(|expr| self.mirror_expr_inner(expr)).collect()
  31     }
  32
  33     pub(super) fn mirror_expr_inner(&mut self, hir_expr: &'tcx hir::Expr<'tcx>) -> ExprId {
  34         let temp_lifetime = self.region_scope_tree.temporary_scope(hir_expr.hir_id.local_id);
  35         let expr_scope =
  36             region::Scope { id: hir_expr.hir_id.local_id, data: region::ScopeData::Node };
  37
  38         debug!("Expr::make_mirror(): id={}, span={:?}", hir_expr.hir_id, hir_expr.span);
  39
  40         let mut expr = self.make_mirror_unadjusted(hir_expr);
  41
  42         let adjustment_span = match self.adjustment_span {
  43             Some((hir_id, span)) if hir_id == hir_expr.hir_id => Some(span),
  44             _ => None,
  45         };
  46
  47         // Now apply adjustments, if any.
  48         for adjustment in self.typeck_results.expr_adjustments(hir_expr) {
  49             debug!("make_mirror: expr={:?} applying adjustment={:?}", expr, adjustment);
  50             let span = expr.span;
  51             expr =
  52                 self.apply_adjustment(hir_expr, expr, adjustment, adjustment_span.unwrap_or(span));
  53         }
  54
  55         // Next, wrap this up in the expr's scope.
  56         expr = Expr {
  57             temp_lifetime,
  58             ty: expr.ty,
  59             span: hir_expr.span,
  60             kind: ExprKind::Scope {
  61                 region_scope: expr_scope,
  62                 value: self.thir.exprs.push(expr),
  63                 lint_level: LintLevel::Explicit(hir_expr.hir_id),
  64             },
  65         };
  66
  67         // Finally, create a destruction scope, if any.
  68         if let Some(region_scope) =
  69             self.region_scope_tree.opt_destruction_scope(hir_expr.hir_id.local_id)
  70         {
  71             expr = Expr {
  72                 temp_lifetime,
  73                 ty: expr.ty,
  74                 span: hir_expr.span,
  75                 kind: ExprKind::Scope {
  76                     region_scope,
  77                     value: self.thir.exprs.push(expr),
  78                     lint_level: LintLevel::Inherited,
  79                 },
  80             };
  81         }
  82
  83         // OK, all done!
  84         self.thir.exprs.push(expr)
  85     }
  86
  87     fn apply_adjustment(
  88         &mut self,
  89         hir_expr: &'tcx hir::Expr<'tcx>,
  90         mut expr: Expr<'tcx>,
  91         adjustment: &Adjustment<'tcx>,
  92         mut span: Span,
  93     ) -> Expr<'tcx> {
  94         let Expr { temp_lifetime, .. } = expr;
  95
  96         // Adjust the span from the block, to the last expression of the
  97         // block. This is a better span when returning a mutable reference
  98         // with too short a lifetime. The error message will use the span
  99         // from the assignment to the return place, which should only point
 100         // at the returned value, not the entire function body.
 101         //
 102         // fn return_short_lived<'a>(x: &'a mut i32) -> &'static mut i32 {
 103         //      x
 104         //   // ^ error message points at this expression.
 105         // }
 106         let mut adjust_span = |expr: &mut Expr<'tcx>| {
 107             if let ExprKind::Block { body } = &expr.kind {
 108                 if let Some(last_expr) = body.expr {
 109                     span = self.thir[last_expr].span;
 110                     expr.span = span;
 111                 }
 112             }
 113         };
 114
 115         let kind = match adjustment.kind {
 116             Adjust::Pointer(PointerCast::Unsize) => {
 117                 adjust_span(&mut expr);
 118                 ExprKind::Pointer { cast: PointerCast::Unsize, source: self.thir.exprs.push(expr) }
 119             }
 120             Adjust::Pointer(cast) => ExprKind::Pointer { cast, source: self.thir.exprs.push(expr) },
 121             Adjust::NeverToAny => ExprKind::NeverToAny { source: self.thir.exprs.push(expr) },
 122             Adjust::Deref(None) => {
 123                 adjust_span(&mut expr);
 124                 ExprKind::Deref { arg: self.thir.exprs.push(expr) }
 125             }
 126             Adjust::Deref(Some(deref)) => {
 127                 // We don't need to do call adjust_span here since
 128                 // deref coercions always start with a built-in deref.
 129                 let call = deref.method_call(self.tcx(), expr.ty);
 130
 131                 expr = Expr {
 132                     temp_lifetime,
 133                     ty: self
 134                         .tcx
 135                         .mk_ref(deref.region, ty::TypeAndMut { ty: expr.ty, mutbl: deref.mutbl }),
 136                     span,
 137                     kind: ExprKind::Borrow {
 138                         borrow_kind: deref.mutbl.to_borrow_kind(),
 139                         arg: self.thir.exprs.push(expr),
 140                     },
 141                 };
 142
 143                 let expr = Box::new([self.thir.exprs.push(expr)]);
 144
 145                 self.overloaded_place(hir_expr, adjustment.target, Some(call), expr, deref.span)
 146             }
 147             Adjust::Borrow(AutoBorrow::Ref(_, m)) => ExprKind::Borrow {
 148                 borrow_kind: m.to_borrow_kind(),
 149                 arg: self.thir.exprs.push(expr),
 150             },
 151             Adjust::Borrow(AutoBorrow::RawPtr(mutability)) => {
 152                 ExprKind::AddressOf { mutability, arg: self.thir.exprs.push(expr) }
 153             }
 154         };
 155
 156         Expr { temp_lifetime, ty: adjustment.target, span, kind }
 157     }
 158
 159     fn make_mirror_unadjusted(&mut self, expr: &'tcx hir::Expr<'tcx>) -> Expr<'tcx> {
 160         let expr_ty = self.typeck_results().expr_ty(expr);
 161         let expr_span = expr.span;
 162         let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
 163
 164         let kind = match expr.kind {
 165             // Here comes the interesting stuff:
 166             hir::ExprKind::MethodCall(_, method_span, ref args, fn_span) => {
 167                 // Rewrite a.b(c) into UFCS form like Trait::b(a, c)
 168                 let expr = self.method_callee(expr, method_span, None);
 169                 // When we apply adjustments to the receiver, use the span of
 170                 // the overall method call for better diagnostics. args[0]
 171                 // is guaranteed to exist, since a method call always has a receiver.
 172                 let old_adjustment_span = self.adjustment_span.replace((args[0].hir_id, expr_span));
 173                 tracing::info!("Using method span: {:?}", expr.span);
 174                 let args = self.mirror_exprs(args);
 175                 self.adjustment_span = old_adjustment_span;
 176                 ExprKind::Call {
 177                     ty: expr.ty,
 178                     fun: self.thir.exprs.push(expr),
 179                     args,
 180                     from_hir_call: true,
 181                     fn_span,
 182                 }
 183             }
 184
 185             hir::ExprKind::Call(ref fun, ref args) => {
 186                 if self.typeck_results().is_method_call(expr) {
 187                     // The callee is something implementing Fn, FnMut, or FnOnce.
 188                     // Find the actual method implementation being called and
 189                     // build the appropriate UFCS call expression with the
 190                     // callee-object as expr parameter.
 191
 192                     // rewrite f(u, v) into FnOnce::call_once(f, (u, v))
 193
 194                     let method = self.method_callee(expr, fun.span, None);
 195
 196                     let arg_tys = args.iter().map(|e| self.typeck_results().expr_ty_adjusted(e));
 197                     let tupled_args = Expr {
 198                         ty: self.tcx.mk_tup(arg_tys),
 199                         temp_lifetime,
 200                         span: expr.span,
 201                         kind: ExprKind::Tuple { fields: self.mirror_exprs(args) },
 202                     };
 203                     let tupled_args = self.thir.exprs.push(tupled_args);
 204
 205                     ExprKind::Call {
 206                         ty: method.ty,
 207                         fun: self.thir.exprs.push(method),
 208                         args: Box::new([self.mirror_expr(fun), tupled_args]),
 209                         from_hir_call: true,
 210                         fn_span: expr.span,
 211                     }
 212                 } else {
 213                     let adt_data =
 214                         if let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = fun.kind {
 215                             // Tuple-like ADTs are represented as ExprKind::Call. We convert them here.
 216                             expr_ty.ty_adt_def().and_then(|adt_def| match path.res {
 217                                 Res::Def(DefKind::Ctor(_, CtorKind::Fn), ctor_id) => {
 218                                     Some((adt_def, adt_def.variant_index_with_ctor_id(ctor_id)))
 219                                 }
 220                                 Res::SelfCtor(..) => Some((adt_def, VariantIdx::new(0))),
 221                                 _ => None,
 222                             })
 223                         } else {
 224                             None
 225                         };
 226                     if let Some((adt_def, index)) = adt_data {
 227                         let substs = self.typeck_results().node_substs(fun.hir_id);
 228                         let user_provided_types = self.typeck_results().user_provided_types();
 229                         let user_ty =
 230                             user_provided_types.get(fun.hir_id).copied().map(|mut u_ty| {
 231                                 if let UserType::TypeOf(ref mut did, _) = &mut u_ty.value {
 232                                     *did = adt_def.did;
 233                                 }
 234                                 u_ty
 235                             });
 236                         debug!("make_mirror_unadjusted: (call) user_ty={:?}", user_ty);
 237
 238                         let field_refs = args
 239                             .iter()
 240                             .enumerate()
 241                             .map(|(idx, e)| FieldExpr {
 242                                 name: Field::new(idx),
 243                                 expr: self.mirror_expr(e),
 244                             })
 245                             .collect();
 246                         ExprKind::Adt(Box::new(Adt {
 247                             adt_def,
 248                             substs,
 249                             variant_index: index,
 250                             fields: field_refs,
 251                             user_ty,
 252                             base: None,
 253                         }))
 254                     } else {
 255                         ExprKind::Call {
 256                             ty: self.typeck_results().node_type(fun.hir_id),
 257                             fun: self.mirror_expr(fun),
 258                             args: self.mirror_exprs(args),
 259                             from_hir_call: true,
 260                             fn_span: expr.span,
 261                         }
 262                     }
 263                 }
 264             }
 265
 266             hir::ExprKind::AddrOf(hir::BorrowKind::Ref, mutbl, ref arg) => {
 267                 ExprKind::Borrow { borrow_kind: mutbl.to_borrow_kind(), arg: self.mirror_expr(arg) }
 268             }
 269
 270             hir::ExprKind::AddrOf(hir::BorrowKind::Raw, mutability, ref arg) => {
 271                 ExprKind::AddressOf { mutability, arg: self.mirror_expr(arg) }
 272             }
 273
 274             hir::ExprKind::Block(ref blk, _) => ExprKind::Block { body: self.mirror_block(blk) },
 275
 276             hir::ExprKind::Assign(ref lhs, ref rhs, _) => {
 277                 ExprKind::Assign { lhs: self.mirror_expr(lhs), rhs: self.mirror_expr(rhs) }
 278             }
 279
 280             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
 281                 if self.typeck_results().is_method_call(expr) {
 282                     let lhs = self.mirror_expr(lhs);
 283                     let rhs = self.mirror_expr(rhs);
 284                     self.overloaded_operator(expr, Box::new([lhs, rhs]))
 285                 } else {
 286                     ExprKind::AssignOp {
 287                         op: bin_op(op.node),
 288                         lhs: self.mirror_expr(lhs),
 289                         rhs: self.mirror_expr(rhs),
 290                     }
 291                 }
 292             }
 293
 294             hir::ExprKind::Lit(ref lit) => ExprKind::Literal {
 295                 literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, false),
 296                 user_ty: None,
 297                 const_id: None,
 298             },
 299
 300             hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
 301                 if self.typeck_results().is_method_call(expr) {
 302                     let lhs = self.mirror_expr(lhs);
 303                     let rhs = self.mirror_expr(rhs);
 304                     self.overloaded_operator(expr, Box::new([lhs, rhs]))
 305                 } else {
 306                     // FIXME overflow
 307                     match op.node {
 308                         hir::BinOpKind::And => ExprKind::LogicalOp {
 309                             op: LogicalOp::And,
 310                             lhs: self.mirror_expr(lhs),
 311                             rhs: self.mirror_expr(rhs),
 312                         },
 313                         hir::BinOpKind::Or => ExprKind::LogicalOp {
 314                             op: LogicalOp::Or,
 315                             lhs: self.mirror_expr(lhs),
 316                             rhs: self.mirror_expr(rhs),
 317                         },
 318
 319                         _ => {
 320                             let op = bin_op(op.node);
 321                             ExprKind::Binary {
 322                                 op,
 323                                 lhs: self.mirror_expr(lhs),
 324                                 rhs: self.mirror_expr(rhs),
 325                             }
 326                         }
 327                     }
 328                 }
 329             }
 330
 331             hir::ExprKind::Index(ref lhs, ref index) => {
 332                 if self.typeck_results().is_method_call(expr) {
 333                     let lhs = self.mirror_expr(lhs);
 334                     let index = self.mirror_expr(index);
 335                     self.overloaded_place(expr, expr_ty, None, Box::new([lhs, index]), expr.span)
 336                 } else {
 337                     ExprKind::Index { lhs: self.mirror_expr(lhs), index: self.mirror_expr(index) }
 338                 }
 339             }
 340
 341             hir::ExprKind::Unary(hir::UnOp::Deref, ref arg) => {
 342                 if self.typeck_results().is_method_call(expr) {
 343                     let arg = self.mirror_expr(arg);
 344                     self.overloaded_place(expr, expr_ty, None, Box::new([arg]), expr.span)
 345                 } else {
 346                     ExprKind::Deref { arg: self.mirror_expr(arg) }
 347                 }
 348             }
 349
 350             hir::ExprKind::Unary(hir::UnOp::Not, ref arg) => {
 351                 if self.typeck_results().is_method_call(expr) {
 352                     let arg = self.mirror_expr(arg);
 353                     self.overloaded_operator(expr, Box::new([arg]))
 354                 } else {
 355                     ExprKind::Unary { op: UnOp::Not, arg: self.mirror_expr(arg) }
 356                 }
 357             }
 358
 359             hir::ExprKind::Unary(hir::UnOp::Neg, ref arg) => {
 360                 if self.typeck_results().is_method_call(expr) {
 361                     let arg = self.mirror_expr(arg);
 362                     self.overloaded_operator(expr, Box::new([arg]))
 363                 } else if let hir::ExprKind::Lit(ref lit) = arg.kind {
 364                     ExprKind::Literal {
 365                         literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, true),
 366                         user_ty: None,
 367                         const_id: None,
 368                     }
 369                 } else {
 370                     ExprKind::Unary { op: UnOp::Neg, arg: self.mirror_expr(arg) }
 371                 }
 372             }
 373
 374             hir::ExprKind::Struct(ref qpath, ref fields, ref base) => match expr_ty.kind() {
 375                 ty::Adt(adt, substs) => match adt.adt_kind() {
 376                     AdtKind::Struct | AdtKind::Union => {
 377                         let user_provided_types = self.typeck_results().user_provided_types();
 378                         let user_ty = user_provided_types.get(expr.hir_id).copied();
 379                         debug!("make_mirror_unadjusted: (struct/union) user_ty={:?}", user_ty);
 380                         ExprKind::Adt(Box::new(Adt {
 381                             adt_def: adt,
 382                             variant_index: VariantIdx::new(0),
 383                             substs,
 384                             user_ty,
 385                             fields: self.field_refs(fields),
 386                             base: base.as_ref().map(|base| FruInfo {
 387                                 base: self.mirror_expr(base),
 388                                 field_types: self.typeck_results().fru_field_types()[expr.hir_id]
 389                                     .iter()
 390                                     .copied()
 391                                     .collect(),
 392                             }),
 393                         }))
 394                     }
 395                     AdtKind::Enum => {
 396                         let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
 397                         match res {
 398                             Res::Def(DefKind::Variant, variant_id) => {
 399                                 assert!(base.is_none());
 400
 401                                 let index = adt.variant_index_with_id(variant_id);
 402                                 let user_provided_types =
 403                                     self.typeck_results().user_provided_types();
 404                                 let user_ty = user_provided_types.get(expr.hir_id).copied();
 405                                 debug!("make_mirror_unadjusted: (variant) user_ty={:?}", user_ty);
 406                                 ExprKind::Adt(Box::new(Adt {
 407                                     adt_def: adt,
 408                                     variant_index: index,
 409                                     substs,
 410                                     user_ty,
 411                                     fields: self.field_refs(fields),
 412                                     base: None,
 413                                 }))
 414                             }
 415                             _ => {
 416                                 span_bug!(expr.span, "unexpected res: {:?}", res);
 417                             }
 418                         }
 419                     }
 420                 },
 421                 _ => {
 422                     span_bug!(expr.span, "unexpected type for struct literal: {:?}", expr_ty);
 423                 }
 424             },
 425
 426             hir::ExprKind::Closure(..) => {
 427                 let closure_ty = self.typeck_results().expr_ty(expr);
 428                 let (def_id, substs, movability) = match *closure_ty.kind() {
 429                     ty::Closure(def_id, substs) => (def_id, UpvarSubsts::Closure(substs), None),
 430                     ty::Generator(def_id, substs, movability) => {
 431                         (def_id, UpvarSubsts::Generator(substs), Some(movability))
 432                     }
 433                     _ => {
 434                         span_bug!(expr.span, "closure expr w/o closure type: {:?}", closure_ty);
 435                     }
 436                 };
 437
 438                 let upvars = self
 439                     .typeck_results
 440                     .closure_min_captures_flattened(def_id)
 441                     .zip(substs.upvar_tys())
 442                     .map(|(captured_place, ty)| {
 443                         let upvars = self.capture_upvar(expr, captured_place, ty);
 444                         self.thir.exprs.push(upvars)
 445                     })
 446                     .collect();
 447
 448                 // Convert the closure fake reads, if any, from hir `Place` to ExprRef
 449                 let fake_reads = match self.typeck_results.closure_fake_reads.get(&def_id) {
 450                     Some(fake_reads) => fake_reads
 451                         .iter()
 452                         .map(|(place, cause, hir_id)| {
 453                             let expr = self.convert_captured_hir_place(expr, place.clone());
 454                             (self.thir.exprs.push(expr), *cause, *hir_id)
 455                         })
 456                         .collect(),
 457                     None => Vec::new(),
 458                 };
 459
 460                 ExprKind::Closure { closure_id: def_id, substs, upvars, movability, fake_reads }
 461             }
 462
 463             hir::ExprKind::Path(ref qpath) => {
 464                 let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
 465                 self.convert_path_expr(expr, res)
 466             }
 467
 468             hir::ExprKind::InlineAsm(ref asm) => ExprKind::InlineAsm {
 469                 template: asm.template,
 470                 operands: asm
 471                     .operands
 472                     .iter()
 473                     .map(|(op, _op_sp)| {
 474                         match *op {
 475                             hir::InlineAsmOperand::In { reg, ref expr } => {
 476                                 InlineAsmOperand::In { reg, expr: self.mirror_expr(expr) }
 477                             }
 478                             hir::InlineAsmOperand::Out { reg, late, ref expr } => {
 479                                 InlineAsmOperand::Out {
 480                                     reg,
 481                                     late,
 482                                     expr: expr.as_ref().map(|expr| self.mirror_expr(expr)),
 483                                 }
 484                             }
 485                             hir::InlineAsmOperand::InOut { reg, late, ref expr } => {
 486                                 InlineAsmOperand::InOut { reg, late, expr: self.mirror_expr(expr) }
 487                             }
 488                             hir::InlineAsmOperand::SplitInOut {
 489                                 reg,
 490                                 late,
 491                                 ref in_expr,
 492                                 ref out_expr,
 493                             } => InlineAsmOperand::SplitInOut {
 494                                 reg,
 495                                 late,
 496                                 in_expr: self.mirror_expr(in_expr),
 497                                 out_expr: out_expr.as_ref().map(|expr| self.mirror_expr(expr)),
 498                             },
 499                             hir::InlineAsmOperand::Const { ref anon_const } => {
 500                                 let anon_const_def_id =
 501                                     self.tcx.hir().local_def_id(anon_const.hir_id);
 502                                 let value = ty::Const::from_anon_const(self.tcx, anon_const_def_id);
 503                                 let span = self.tcx.hir().span(anon_const.hir_id);
 504
 505                                 InlineAsmOperand::Const { value, span }
 506                             }
 507                             hir::InlineAsmOperand::Sym { ref expr } => {
 508                                 let qpath = match expr.kind {
 509                                     hir::ExprKind::Path(ref qpath) => qpath,
 510                                     _ => span_bug!(
 511                                         expr.span,
 512                                         "asm `sym` operand should be a path, found {:?}",
 513                                         expr.kind
 514                                     ),
 515                                 };
 516                                 let temp_lifetime =
 517                                     self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
 518                                 let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
 519                                 let ty;
 520                                 match res {
 521                                     Res::Def(DefKind::Fn, _) | Res::Def(DefKind::AssocFn, _) => {
 522                                         ty = self.typeck_results().node_type(expr.hir_id);
 523                                         let user_ty =
 524                                             self.user_substs_applied_to_res(expr.hir_id, res);
 525                                         InlineAsmOperand::SymFn {
 526                                             expr: self.thir.exprs.push(Expr {
 527                                                 ty,
 528                                                 temp_lifetime,
 529                                                 span: expr.span,
 530                                                 kind: ExprKind::Literal {
 531                                                     literal: ty::Const::zero_sized(self.tcx, ty),
 532                                                     user_ty,
 533                                                     const_id: None,
 534                                                 },
 535                                             }),
 536                                         }
 537                                     }
 538
 539                                     Res::Def(DefKind::Static, def_id) => {
 540                                         InlineAsmOperand::SymStatic { def_id }
 541                                     }
 542
 543                                     _ => {
 544                                         self.tcx.sess.span_err(
 545                                             expr.span,
 546                                             "asm `sym` operand must point to a fn or static",
 547                                         );
 548
 549                                         // Not a real fn, but we're not reaching codegen anyways...
 550                                         ty = self.tcx.ty_error();
 551                                         InlineAsmOperand::SymFn {
 552                                             expr: self.thir.exprs.push(Expr {
 553                                                 ty,
 554                                                 temp_lifetime,
 555                                                 span: expr.span,
 556                                                 kind: ExprKind::Literal {
 557                                                     literal: ty::Const::zero_sized(self.tcx, ty),
 558                                                     user_ty: None,
 559                                                     const_id: None,
 560                                                 },
 561                                             }),
 562                                         }
 563                                     }
 564                                 }
 565                             }
 566                         }
 567                     })
 568                     .collect(),
 569                 options: asm.options,
 570                 line_spans: asm.line_spans,
 571             },
 572
 573             hir::ExprKind::LlvmInlineAsm(ref asm) => ExprKind::LlvmInlineAsm {
 574                 asm: &asm.inner,
 575                 outputs: self.mirror_exprs(asm.outputs_exprs),
 576                 inputs: self.mirror_exprs(asm.inputs_exprs),
 577             },
 578
 579             hir::ExprKind::ConstBlock(ref anon_const) => {
 580                 let anon_const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
 581                 let value = ty::Const::from_inline_const(self.tcx, anon_const_def_id);
 582
 583                 ExprKind::ConstBlock { value }
 584             }
 585             // Now comes the rote stuff:
 586             hir::ExprKind::Repeat(ref v, ref count) => {
 587                 let count_def_id = self.tcx.hir().local_def_id(count.hir_id);
 588                 let count = ty::Const::from_anon_const(self.tcx, count_def_id);
 589
 590                 ExprKind::Repeat { value: self.mirror_expr(v), count }
 591             }
 592             hir::ExprKind::Ret(ref v) => {
 593                 ExprKind::Return { value: v.as_ref().map(|v| self.mirror_expr(v)) }
 594             }
 595             hir::ExprKind::Break(dest, ref value) => match dest.target_id {
 596                 Ok(target_id) => ExprKind::Break {
 597                     label: region::Scope { id: target_id.local_id, data: region::ScopeData::Node },
 598                     value: value.as_ref().map(|value| self.mirror_expr(value)),
 599                 },
 600                 Err(err) => bug!("invalid loop id for break: {}", err),
 601             },
 602             hir::ExprKind::Continue(dest) => match dest.target_id {
 603                 Ok(loop_id) => ExprKind::Continue {
 604                     label: region::Scope { id: loop_id.local_id, data: region::ScopeData::Node },
 605                 },
 606                 Err(err) => bug!("invalid loop id for continue: {}", err),
 607             },
 608             hir::ExprKind::Let(ref pat, ref expr, _) => {
 609                 ExprKind::Let { expr: self.mirror_expr(expr), pat: self.pattern_from_hir(pat) }
 610             }
 611             hir::ExprKind::If(cond, then, else_opt) => ExprKind::If {
 612                 if_then_scope: region::Scope {
 613                     id: then.hir_id.local_id,
 614                     data: region::ScopeData::IfThen,
 615                 },
 616                 cond: self.mirror_expr(cond),
 617                 then: self.mirror_expr(then),
 618                 else_opt: else_opt.map(|el| self.mirror_expr(el)),
 619             },
 620             hir::ExprKind::Match(ref discr, ref arms, _) => ExprKind::Match {
 621                 scrutinee: self.mirror_expr(discr),
 622                 arms: arms.iter().map(|a| self.convert_arm(a)).collect(),
 623             },
 624             hir::ExprKind::Loop(ref body, ..) => {
 625                 let block_ty = self.typeck_results().node_type(body.hir_id);
 626                 let temp_lifetime = self.region_scope_tree.temporary_scope(body.hir_id.local_id);
 627                 let block = self.mirror_block(body);
 628                 let body = self.thir.exprs.push(Expr {
 629                     ty: block_ty,
 630                     temp_lifetime,
 631                     span: block.span,
 632                     kind: ExprKind::Block { body: block },
 633                 });
 634                 ExprKind::Loop { body }
 635             }
 636             hir::ExprKind::Field(ref source, ..) => ExprKind::Field {
 637                 lhs: self.mirror_expr(source),
 638                 name: Field::new(self.tcx.field_index(expr.hir_id, self.typeck_results)),
 639             },
 640             hir::ExprKind::Cast(ref source, ref cast_ty) => {
 641                 // Check for a user-given type annotation on this `cast`
 642                 let user_provided_types = self.typeck_results.user_provided_types();
 643                 let user_ty = user_provided_types.get(cast_ty.hir_id);
 644
 645                 debug!(
 646                     "cast({:?}) has ty w/ hir_id {:?} and user provided ty {:?}",
 647                     expr, cast_ty.hir_id, user_ty,
 648                 );
 649
 650                 // Check to see if this cast is a "coercion cast", where the cast is actually done
 651                 // using a coercion (or is a no-op).
 652                 let cast = if self.typeck_results().is_coercion_cast(source.hir_id) {
 653                     // Convert the lexpr to a vexpr.
 654                     ExprKind::Use { source: self.mirror_expr(source) }
 655                 } else if self.typeck_results().expr_ty(source).is_region_ptr() {
 656                     // Special cased so that we can type check that the element
 657                     // type of the source matches the pointed to type of the
 658                     // destination.
 659                     ExprKind::Pointer {
 660                         source: self.mirror_expr(source),
 661                         cast: PointerCast::ArrayToPointer,
 662                     }
 663                 } else {
 664                     // check whether this is casting an enum variant discriminant
 665                     // to prevent cycles, we refer to the discriminant initializer
 666                     // which is always an integer and thus doesn't need to know the
 667                     // enum's layout (or its tag type) to compute it during const eval
 668                     // Example:
 669                     // enum Foo {
 670                     //     A,
 671                     //     B = A as isize + 4,
 672                     // }
 673                     // The correct solution would be to add symbolic computations to miri,
 674                     // so we wouldn't have to compute and store the actual value
 675                     let var = if let hir::ExprKind::Path(ref qpath) = source.kind {
 676                         let res = self.typeck_results().qpath_res(qpath, source.hir_id);
 677                         self.typeck_results().node_type(source.hir_id).ty_adt_def().and_then(
 678                             |adt_def| match res {
 679                                 Res::Def(
 680                                     DefKind::Ctor(CtorOf::Variant, CtorKind::Const),
 681                                     variant_ctor_id,
 682                                 ) => {
 683                                     let idx = adt_def.variant_index_with_ctor_id(variant_ctor_id);
 684                                     let (d, o) = adt_def.discriminant_def_for_variant(idx);
 685                                     use rustc_middle::ty::util::IntTypeExt;
 686                                     let ty = adt_def.repr.discr_type();
 687                                     let ty = ty.to_ty(self.tcx());
 688                                     Some((d, o, ty))
 689                                 }
 690                                 _ => None,
 691                             },
 692                         )
 693                     } else {
 694                         None
 695                     };
 696
 697                     let source = if let Some((did, offset, var_ty)) = var {
 698                         let mk_const = |literal| Expr {
 699                             temp_lifetime,
 700                             ty: var_ty,
 701                             span: expr.span,
 702                             kind: ExprKind::Literal { literal, user_ty: None, const_id: None },
 703                         };
 704                         let offset = self.thir.exprs.push(mk_const(ty::Const::from_bits(
 705                             self.tcx,
 706                             offset as u128,
 707                             self.param_env.and(var_ty),
 708                         )));
 709                         match did {
 710                             Some(did) => {
 711                                 // in case we are offsetting from a computed discriminant
 712                                 // and not the beginning of discriminants (which is always `0`)
 713                                 let substs = InternalSubsts::identity_for_item(self.tcx(), did);
 714                                 let lhs = ty::Const {
 715                                     val: ty::ConstKind::Unevaluated(ty::Unevaluated::new(
 716                                         ty::WithOptConstParam::unknown(did),
 717                                         substs,
 718                                     )),
 719                                     ty: var_ty,
 720                                 };
 721                                 let lhs = self.thir.exprs.push(mk_const(self.tcx().mk_const(lhs)));
 722                                 let bin =
 723                                     ExprKind::Binary { op: BinOp::Add, lhs: lhs, rhs: offset };
 724                                 self.thir.exprs.push(Expr {
 725                                     temp_lifetime,
 726                                     ty: var_ty,
 727                                     span: expr.span,
 728                                     kind: bin,
 729                                 })
 730                             }
 731                             None => offset,
 732                         }
 733                     } else {
 734                         self.mirror_expr(source)
 735                     };
 736
 737                     ExprKind::Cast { source: source }
 738                 };
 739
 740                 if let Some(user_ty) = user_ty {
 741                     // NOTE: Creating a new Expr and wrapping a Cast inside of it may be
 742                     //       inefficient, revisit this when performance becomes an issue.
 743                     let cast_expr = self.thir.exprs.push(Expr {
 744                         temp_lifetime,
 745                         ty: expr_ty,
 746                         span: expr.span,
 747                         kind: cast,
 748                     });
 749                     debug!("make_mirror_unadjusted: (cast) user_ty={:?}", user_ty);
 750
 751                     ExprKind::ValueTypeAscription { source: cast_expr, user_ty: Some(*user_ty) }
 752                 } else {
 753                     cast
 754                 }
 755             }
 756             hir::ExprKind::Type(ref source, ref ty) => {
 757                 let user_provided_types = self.typeck_results.user_provided_types();
 758                 let user_ty = user_provided_types.get(ty.hir_id).copied();
 759                 debug!("make_mirror_unadjusted: (type) user_ty={:?}", user_ty);
 760                 let mirrored = self.mirror_expr(source);
 761                 if source.is_syntactic_place_expr() {
 762                     ExprKind::PlaceTypeAscription { source: mirrored, user_ty }
 763                 } else {
 764                     ExprKind::ValueTypeAscription { source: mirrored, user_ty }
 765                 }
 766             }
 767             hir::ExprKind::DropTemps(ref source) => {
 768                 ExprKind::Use { source: self.mirror_expr(source) }
 769             }
 770             hir::ExprKind::Box(ref value) => ExprKind::Box { value: self.mirror_expr(value) },
 771             hir::ExprKind::Array(ref fields) => {
 772                 ExprKind::Array { fields: self.mirror_exprs(fields) }
 773             }
 774             hir::ExprKind::Tup(ref fields) => ExprKind::Tuple { fields: self.mirror_exprs(fields) },
 775
 776             hir::ExprKind::Yield(ref v, _) => ExprKind::Yield { value: self.mirror_expr(v) },
 777             hir::ExprKind::Err => unreachable!(),
 778         };
 779
 780         Expr { temp_lifetime, ty: expr_ty, span: expr.span, kind }
 781     }
 782
 783     fn user_substs_applied_to_res(
 784         &mut self,
 785         hir_id: hir::HirId,
 786         res: Res,
 787     ) -> Option<ty::CanonicalUserType<'tcx>> {
 788         debug!("user_substs_applied_to_res: res={:?}", res);
 789         let user_provided_type = match res {
 790             // A reference to something callable -- e.g., a fn, method, or
 791             // a tuple-struct or tuple-variant. This has the type of a
 792             // `Fn` but with the user-given substitutions.
 793             Res::Def(DefKind::Fn, _)
 794             | Res::Def(DefKind::AssocFn, _)
 795             | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
 796             | Res::Def(DefKind::Const, _)
 797             | Res::Def(DefKind::AssocConst, _) => {
 798                 self.typeck_results().user_provided_types().get(hir_id).copied()
 799             }
 800
 801             // A unit struct/variant which is used as a value (e.g.,
 802             // `None`). This has the type of the enum/struct that defines
 803             // this variant -- but with the substitutions given by the
 804             // user.
 805             Res::Def(DefKind::Ctor(_, CtorKind::Const), _) => {
 806                 self.user_substs_applied_to_ty_of_hir_id(hir_id)
 807             }
 808
 809             // `Self` is used in expression as a tuple struct constructor or a unit struct constructor
 810             Res::SelfCtor(_) => self.user_substs_applied_to_ty_of_hir_id(hir_id),
 811
 812             _ => bug!("user_substs_applied_to_res: unexpected res {:?} at {:?}", res, hir_id),
 813         };
 814         debug!("user_substs_applied_to_res: user_provided_type={:?}", user_provided_type);
 815         user_provided_type
 816     }
 817
 818     fn method_callee(
 819         &mut self,
 820         expr: &hir::Expr<'_>,
 821         span: Span,
 822         overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
 823     ) -> Expr<'tcx> {
 824         let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
 825         let (def_id, substs, user_ty) = match overloaded_callee {
 826             Some((def_id, substs)) => (def_id, substs, None),
 827             None => {
 828                 let (kind, def_id) =
 829                     self.typeck_results().type_dependent_def(expr.hir_id).unwrap_or_else(|| {
 830                         span_bug!(expr.span, "no type-dependent def for method callee")
 831                     });
 832                 let user_ty = self.user_substs_applied_to_res(expr.hir_id, Res::Def(kind, def_id));
 833                 debug!("method_callee: user_ty={:?}", user_ty);
 834                 (def_id, self.typeck_results().node_substs(expr.hir_id), user_ty)
 835             }
 836         };
 837         let ty = self.tcx().mk_fn_def(def_id, substs);
 838         Expr {
 839             temp_lifetime,
 840             ty,
 841             span,
 842             kind: ExprKind::Literal {
 843                 literal: ty::Const::zero_sized(self.tcx(), ty),
 844                 user_ty,
 845                 const_id: None,
 846             },
 847         }
 848     }
 849
 850     fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> ArmId {
 851         let arm = Arm {
 852             pattern: self.pattern_from_hir(&arm.pat),
 853             guard: arm.guard.as_ref().map(|g| match g {
 854                 hir::Guard::If(ref e) => Guard::If(self.mirror_expr(e)),
 855                 hir::Guard::IfLet(ref pat, ref e) => {
 856                     Guard::IfLet(self.pattern_from_hir(pat), self.mirror_expr(e))
 857                 }
 858             }),
 859             body: self.mirror_expr(arm.body),
 860             lint_level: LintLevel::Explicit(arm.hir_id),
 861             scope: region::Scope { id: arm.hir_id.local_id, data: region::ScopeData::Node },
 862             span: arm.span,
 863         };
 864         self.thir.arms.push(arm)
 865     }
 866
 867     fn convert_path_expr(&mut self, expr: &'tcx hir::Expr<'tcx>, res: Res) -> ExprKind<'tcx> {
 868         let substs = self.typeck_results().node_substs(expr.hir_id);
 869         match res {
 870             // A regular function, constructor function or a constant.
 871             Res::Def(DefKind::Fn, _)
 872             | Res::Def(DefKind::AssocFn, _)
 873             | Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
 874             | Res::SelfCtor(..) => {
 875                 let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
 876                 debug!("convert_path_expr: user_ty={:?}", user_ty);
 877                 ExprKind::Literal {
 878                     literal: ty::Const::zero_sized(
 879                         self.tcx,
 880                         self.typeck_results().node_type(expr.hir_id),
 881                     ),
 882                     user_ty,
 883                     const_id: None,
 884                 }
 885             }
 886
 887             Res::Def(DefKind::ConstParam, def_id) => {
 888                 let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
 889                 let item_id = self.tcx.hir().get_parent_node(hir_id);
 890                 let item_def_id = self.tcx.hir().local_def_id(item_id);
 891                 let generics = self.tcx.generics_of(item_def_id);
 892                 let index = generics.param_def_id_to_index[&def_id];
 893                 let name = self.tcx.hir().name(hir_id);
 894                 let val = ty::ConstKind::Param(ty::ParamConst::new(index, name));
 895                 ExprKind::Literal {
 896                     literal: self.tcx.mk_const(ty::Const {
 897                         val,
 898                         ty: self.typeck_results().node_type(expr.hir_id),
 899                     }),
 900                     user_ty: None,
 901                     const_id: Some(def_id),
 902                 }
 903             }
 904
 905             Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => {
 906                 let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
 907                 debug!("convert_path_expr: (const) user_ty={:?}", user_ty);
 908                 ExprKind::Literal {
 909                     literal: self.tcx.mk_const(ty::Const {
 910                         val: ty::ConstKind::Unevaluated(ty::Unevaluated::new(
 911                             ty::WithOptConstParam::unknown(def_id),
 912                             substs,
 913                         )),
 914                         ty: self.typeck_results().node_type(expr.hir_id),
 915                     }),
 916                     user_ty,
 917                     const_id: Some(def_id),
 918                 }
 919             }
 920
 921             Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id) => {
 922                 let user_provided_types = self.typeck_results.user_provided_types();
 923                 let user_provided_type = user_provided_types.get(expr.hir_id).copied();
 924                 debug!("convert_path_expr: user_provided_type={:?}", user_provided_type);
 925                 let ty = self.typeck_results().node_type(expr.hir_id);
 926                 match ty.kind() {
 927                     // A unit struct/variant which is used as a value.
 928                     // We return a completely different ExprKind here to account for this special case.
 929                     ty::Adt(adt_def, substs) => ExprKind::Adt(Box::new(Adt {
 930                         adt_def,
 931                         variant_index: adt_def.variant_index_with_ctor_id(def_id),
 932                         substs,
 933                         user_ty: user_provided_type,
 934                         fields: Box::new([]),
 935                         base: None,
 936                     })),
 937                     _ => bug!("unexpected ty: {:?}", ty),
 938                 }
 939             }
 940
 941             // We encode uses of statics as a `*&STATIC` where the `&STATIC` part is
 942             // a constant reference (or constant raw pointer for `static mut`) in MIR
 943             Res::Def(DefKind::Static, id) => {
 944                 let ty = self.tcx.static_ptr_ty(id);
 945                 let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
 946                 let kind = if self.tcx.is_thread_local_static(id) {
 947                     ExprKind::ThreadLocalRef(id)
 948                 } else {
 949                     let ptr = self.tcx.create_static_alloc(id);
 950                     ExprKind::StaticRef {
 951                         literal: ty::Const::from_scalar(
 952                             self.tcx,
 953                             Scalar::from_pointer(ptr.into(), &self.tcx),
 954                             ty,
 955                         ),
 956                         def_id: id,
 957                     }
 958                 };
 959                 ExprKind::Deref {
 960                     arg: self.thir.exprs.push(Expr { ty, temp_lifetime, span: expr.span, kind }),
 961                 }
 962             }
 963
 964             Res::Local(var_hir_id) => self.convert_var(var_hir_id),
 965
 966             _ => span_bug!(expr.span, "res `{:?}` not yet implemented", res),
 967         }
 968     }
 969
 970     fn convert_var(&mut self, var_hir_id: hir::HirId) -> ExprKind<'tcx> {
 971         // We want upvars here not captures.
 972         // Captures will be handled in MIR.
 973         let is_upvar = self
 974             .tcx
 975             .upvars_mentioned(self.body_owner)
 976             .map_or(false, |upvars| upvars.contains_key(&var_hir_id));
 977
 978         debug!(
 979             "convert_var({:?}): is_upvar={}, body_owner={:?}",
 980             var_hir_id, is_upvar, self.body_owner
 981         );
 982
 983         if is_upvar {
 984             ExprKind::UpvarRef { closure_def_id: self.body_owner, var_hir_id }
 985         } else {
 986             ExprKind::VarRef { id: var_hir_id }
 987         }
 988     }
 989
 990     fn overloaded_operator(
 991         &mut self,
 992         expr: &'tcx hir::Expr<'tcx>,
 993         args: Box<[ExprId]>,
 994     ) -> ExprKind<'tcx> {
 995         let fun = self.method_callee(expr, expr.span, None);
 996         let fun = self.thir.exprs.push(fun);
 997         ExprKind::Call {
 998             ty: self.thir[fun].ty,
 999             fun,
1000             args,
1001             from_hir_call: false,
1002             fn_span: expr.span,
1003         }
1004     }
1005
1006     fn overloaded_place(
1007         &mut self,
1008         expr: &'tcx hir::Expr<'tcx>,
1009         place_ty: Ty<'tcx>,
1010         overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
1011         args: Box<[ExprId]>,
1012         span: Span,
1013     ) -> ExprKind<'tcx> {
1014         // For an overloaded *x or x[y] expression of type T, the method
1015         // call returns an &T and we must add the deref so that the types
1016         // line up (this is because `*x` and `x[y]` represent places):
1017
1018         // Reconstruct the output assuming it's a reference with the
1019         // same region and mutability as the receiver. This holds for
1020         // `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
1021         let (region, mutbl) = match *self.thir[args[0]].ty.kind() {
1022             ty::Ref(region, _, mutbl) => (region, mutbl),
1023             _ => span_bug!(span, "overloaded_place: receiver is not a reference"),
1024         };
1025         let ref_ty = self.tcx.mk_ref(region, ty::TypeAndMut { ty: place_ty, mutbl });
1026
1027         // construct the complete expression `foo()` for the overloaded call,
1028         // which will yield the &T type
1029         let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
1030         let fun = self.method_callee(expr, span, overloaded_callee);
1031         let fun = self.thir.exprs.push(fun);
1032         let fun_ty = self.thir[fun].ty;
1033         let ref_expr = self.thir.exprs.push(Expr {
1034             temp_lifetime,
1035             ty: ref_ty,
1036             span,
1037             kind: ExprKind::Call { ty: fun_ty, fun, args, from_hir_call: false, fn_span: span },
1038         });
1039
1040         // construct and return a deref wrapper `*foo()`
1041         ExprKind::Deref { arg: ref_expr }
1042     }
1043
1044     fn convert_captured_hir_place(
1045         &mut self,
1046         closure_expr: &'tcx hir::Expr<'tcx>,
1047         place: HirPlace<'tcx>,
1048     ) -> Expr<'tcx> {
1049         let temp_lifetime = self.region_scope_tree.temporary_scope(closure_expr.hir_id.local_id);
1050         let var_ty = place.base_ty;
1051
1052         // The result of capture analysis in `rustc_typeck/check/upvar.rs`represents a captured path
1053         // as it's seen for use within the closure and not at the time of closure creation.
1054         //
1055         // That is we see expect to see it start from a captured upvar and not something that is local
1056         // to the closure's parent.
1057         let var_hir_id = match place.base {
1058             HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
1059             base => bug!("Expected an upvar, found {:?}", base),
1060         };
1061
1062         let mut captured_place_expr = Expr {
1063             temp_lifetime,
1064             ty: var_ty,
1065             span: closure_expr.span,
1066             kind: self.convert_var(var_hir_id),
1067         };
1068
1069         for proj in place.projections.iter() {
1070             let kind = match proj.kind {
1071                 HirProjectionKind::Deref => {
1072                     ExprKind::Deref { arg: self.thir.exprs.push(captured_place_expr) }
1073                 }
1074                 HirProjectionKind::Field(field, ..) => {
1075                     // Variant index will always be 0, because for multi-variant
1076                     // enums, we capture the enum entirely.
1077                     ExprKind::Field {
1078                         lhs: self.thir.exprs.push(captured_place_expr),
1079                         name: Field::new(field as usize),
1080                     }
1081                 }
1082                 HirProjectionKind::Index | HirProjectionKind::Subslice => {
1083                     // We don't capture these projections, so we can ignore them here
1084                     continue;
1085                 }
1086             };
1087
1088             captured_place_expr =
1089                 Expr { temp_lifetime, ty: proj.ty, span: closure_expr.span, kind };
1090         }
1091
1092         captured_place_expr
1093     }
1094
1095     fn capture_upvar(
1096         &mut self,
1097         closure_expr: &'tcx hir::Expr<'tcx>,
1098         captured_place: &'tcx ty::CapturedPlace<'tcx>,
1099         upvar_ty: Ty<'tcx>,
1100     ) -> Expr<'tcx> {
1101         let upvar_capture = captured_place.info.capture_kind;
1102         let captured_place_expr =
1103             self.convert_captured_hir_place(closure_expr, captured_place.place.clone());
1104         let temp_lifetime = self.region_scope_tree.temporary_scope(closure_expr.hir_id.local_id);
1105
1106         match upvar_capture {
1107             ty::UpvarCapture::ByValue(_) => captured_place_expr,
1108             ty::UpvarCapture::ByRef(upvar_borrow) => {
1109                 let borrow_kind = match upvar_borrow.kind {
1110                     ty::BorrowKind::ImmBorrow => BorrowKind::Shared,
1111                     ty::BorrowKind::UniqueImmBorrow => BorrowKind::Unique,
1112                     ty::BorrowKind::MutBorrow => BorrowKind::Mut { allow_two_phase_borrow: false },
1113                 };
1114                 Expr {
1115                     temp_lifetime,
1116                     ty: upvar_ty,
1117                     span: closure_expr.span,
1118                     kind: ExprKind::Borrow {
1119                         borrow_kind,
1120                         arg: self.thir.exprs.push(captured_place_expr),
1121                     },
1122                 }
1123             }
1124         }
1125     }
1126
1127     /// Converts a list of named fields (i.e., for struct-like struct/enum ADTs) into FieldExpr.
1128     fn field_refs(&mut self, fields: &'tcx [hir::ExprField<'tcx>]) -> Box<[FieldExpr]> {
1129         fields
1130             .iter()
1131             .map(|field| FieldExpr {
1132                 name: Field::new(self.tcx.field_index(field.hir_id, self.typeck_results)),
1133                 expr: self.mirror_expr(field.expr),
1134             })
1135             .collect()
1136     }
1137 }
1138
1139 trait ToBorrowKind {
1140     fn to_borrow_kind(&self) -> BorrowKind;
1141 }
1142
1143 impl ToBorrowKind for AutoBorrowMutability {
1144     fn to_borrow_kind(&self) -> BorrowKind {
1145         use rustc_middle::ty::adjustment::AllowTwoPhase;
1146         match *self {
1147             AutoBorrowMutability::Mut { allow_two_phase_borrow } => BorrowKind::Mut {
1148                 allow_two_phase_borrow: match allow_two_phase_borrow {
1149                     AllowTwoPhase::Yes => true,
1150                     AllowTwoPhase::No => false,
1151                 },
1152             },
1153             AutoBorrowMutability::Not => BorrowKind::Shared,
1154         }
1155     }
1156 }
1157
1158 impl ToBorrowKind for hir::Mutability {
1159     fn to_borrow_kind(&self) -> BorrowKind {
1160         match *self {
1161             hir::Mutability::Mut => BorrowKind::Mut { allow_two_phase_borrow: false },
1162             hir::Mutability::Not => BorrowKind::Shared,
1163         }
1164     }
1165 }
1166
1167 fn bin_op(op: hir::BinOpKind) -> BinOp {
1168     match op {
1169         hir::BinOpKind::Add => BinOp::Add,
1170         hir::BinOpKind::Sub => BinOp::Sub,
1171         hir::BinOpKind::Mul => BinOp::Mul,
1172         hir::BinOpKind::Div => BinOp::Div,
1173         hir::BinOpKind::Rem => BinOp::Rem,
1174         hir::BinOpKind::BitXor => BinOp::BitXor,
1175         hir::BinOpKind::BitAnd => BinOp::BitAnd,
1176         hir::BinOpKind::BitOr => BinOp::BitOr,
1177         hir::BinOpKind::Shl => BinOp::Shl,
1178         hir::BinOpKind::Shr => BinOp::Shr,
1179         hir::BinOpKind::Eq => BinOp::Eq,
1180         hir::BinOpKind::Lt => BinOp::Lt,
1181         hir::BinOpKind::Le => BinOp::Le,
1182         hir::BinOpKind::Ne => BinOp::Ne,
1183         hir::BinOpKind::Ge => BinOp::Ge,
1184         hir::BinOpKind::Gt => BinOp::Gt,
1185         _ => bug!("no equivalent for ast binop {:?}", op),
1186     }
1187 }