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

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