1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! MIR datatypes and passes. See the [rustc guide] for more info.
13 //! [rustc guide]: https://rust-lang.github.io/rustc-guide/mir/index.html
15 use hir::def::CtorKind;
16 use hir::def_id::DefId;
17 use hir::{self, HirId, InlineAsm};
18 use mir::interpret::{ConstValue, EvalErrorKind, Scalar};
19 use mir::visit::MirVisitable;
20 use rustc_apfloat::ieee::{Double, Single};
21 use rustc_apfloat::Float;
22 use rustc_data_structures::fx::FxHashSet;
23 use rustc_data_structures::graph::dominators::{dominators, Dominators};
24 use rustc_data_structures::graph::{self, GraphPredecessors, GraphSuccessors};
25 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
26 use rustc_data_structures::sync::Lrc;
27 use rustc_data_structures::sync::MappedReadGuard;
28 use rustc_serialize as serialize;
29 use smallvec::SmallVec;
31 use std::fmt::{self, Debug, Formatter, Write};
32 use std::ops::{Index, IndexMut};
34 use std::vec::IntoIter;
35 use std::{iter, mem, option, u32};
36 use syntax::ast::{self, Name};
37 use syntax::symbol::InternedString;
38 use syntax_pos::{Span, DUMMY_SP};
39 use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
40 use ty::subst::{CanonicalUserSubsts, Subst, Substs};
41 use ty::{self, AdtDef, CanonicalTy, ClosureSubsts, GeneratorSubsts, Region, Ty, TyCtxt};
42 use ty::layout::VariantIdx;
45 pub use mir::interpret::AssertMessage;
55 type LocalDecls<'tcx> = IndexVec<Local, LocalDecl<'tcx>>;
57 pub trait HasLocalDecls<'tcx> {
58 fn local_decls(&self) -> &LocalDecls<'tcx>;
61 impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> {
62 fn local_decls(&self) -> &LocalDecls<'tcx> {
67 impl<'tcx> HasLocalDecls<'tcx> for Mir<'tcx> {
68 fn local_decls(&self) -> &LocalDecls<'tcx> {
73 /// The various "big phases" that MIR goes through.
75 /// Warning: ordering of variants is significant
76 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, PartialEq, Eq, PartialOrd, Ord)]
85 /// Gets the index of the current MirPhase within the set of all MirPhases.
86 pub fn phase_index(&self) -> usize {
91 /// Lowered representation of a single function.
92 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
93 pub struct Mir<'tcx> {
94 /// List of basic blocks. References to basic block use a newtyped index type `BasicBlock`
95 /// that indexes into this vector.
96 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
98 /// Records how far through the "desugaring and optimization" process this particular
99 /// MIR has traversed. This is particularly useful when inlining, since in that context
100 /// we instantiate the promoted constants and add them to our promoted vector -- but those
101 /// promoted items have already been optimized, whereas ours have not. This field allows
102 /// us to see the difference and forego optimization on the inlined promoted items.
105 /// List of source scopes; these are referenced by statements
106 /// and used for debuginfo. Indexed by a `SourceScope`.
107 pub source_scopes: IndexVec<SourceScope, SourceScopeData>,
109 /// Crate-local information for each source scope, that can't (and
110 /// needn't) be tracked across crates.
111 pub source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
113 /// Rvalues promoted from this function, such as borrows of constants.
114 /// Each of them is the Mir of a constant with the fn's type parameters
115 /// in scope, but a separate set of locals.
116 pub promoted: IndexVec<Promoted, Mir<'tcx>>,
118 /// Yield type of the function, if it is a generator.
119 pub yield_ty: Option<Ty<'tcx>>,
121 /// Generator drop glue
122 pub generator_drop: Option<Box<Mir<'tcx>>>,
124 /// The layout of a generator. Produced by the state transformation.
125 pub generator_layout: Option<GeneratorLayout<'tcx>>,
127 /// Declarations of locals.
129 /// The first local is the return value pointer, followed by `arg_count`
130 /// locals for the function arguments, followed by any user-declared
131 /// variables and temporaries.
132 pub local_decls: LocalDecls<'tcx>,
134 /// Number of arguments this function takes.
136 /// Starting at local 1, `arg_count` locals will be provided by the caller
137 /// and can be assumed to be initialized.
139 /// If this MIR was built for a constant, this will be 0.
140 pub arg_count: usize,
142 /// Names and capture modes of all the closure upvars, assuming
143 /// the first argument is either the closure or a reference to it.
144 pub upvar_decls: Vec<UpvarDecl>,
146 /// Mark an argument local (which must be a tuple) as getting passed as
147 /// its individual components at the LLVM level.
149 /// This is used for the "rust-call" ABI.
150 pub spread_arg: Option<Local>,
152 /// A span representing this MIR, for error reporting
155 /// A cache for various calculations
159 impl<'tcx> Mir<'tcx> {
161 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
162 source_scopes: IndexVec<SourceScope, SourceScopeData>,
163 source_scope_local_data: ClearCrossCrate<IndexVec<SourceScope, SourceScopeLocalData>>,
164 promoted: IndexVec<Promoted, Mir<'tcx>>,
165 yield_ty: Option<Ty<'tcx>>,
166 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
168 upvar_decls: Vec<UpvarDecl>,
171 // We need `arg_count` locals, and one for the return place
173 local_decls.len() >= arg_count + 1,
174 "expected at least {} locals, got {}",
180 phase: MirPhase::Build,
183 source_scope_local_data,
186 generator_drop: None,
187 generator_layout: None,
193 cache: cache::Cache::new(),
198 pub fn basic_blocks(&self) -> &IndexVec<BasicBlock, BasicBlockData<'tcx>> {
203 pub fn basic_blocks_mut(&mut self) -> &mut IndexVec<BasicBlock, BasicBlockData<'tcx>> {
204 self.cache.invalidate();
205 &mut self.basic_blocks
209 pub fn basic_blocks_and_local_decls_mut(
212 &mut IndexVec<BasicBlock, BasicBlockData<'tcx>>,
213 &mut LocalDecls<'tcx>,
215 self.cache.invalidate();
216 (&mut self.basic_blocks, &mut self.local_decls)
220 pub fn predecessors(&self) -> MappedReadGuard<'_, IndexVec<BasicBlock, Vec<BasicBlock>>> {
221 self.cache.predecessors(self)
225 pub fn predecessors_for(&self, bb: BasicBlock) -> MappedReadGuard<'_, Vec<BasicBlock>> {
226 MappedReadGuard::map(self.predecessors(), |p| &p[bb])
230 pub fn predecessor_locations(&self, loc: Location) -> impl Iterator<Item = Location> + '_ {
231 let if_zero_locations = if loc.statement_index == 0 {
232 let predecessor_blocks = self.predecessors_for(loc.block);
233 let num_predecessor_blocks = predecessor_blocks.len();
235 (0..num_predecessor_blocks)
236 .map(move |i| predecessor_blocks[i])
237 .map(move |bb| self.terminator_loc(bb)),
243 let if_not_zero_locations = if loc.statement_index == 0 {
248 statement_index: loc.statement_index - 1,
255 .chain(if_not_zero_locations)
259 pub fn dominators(&self) -> Dominators<BasicBlock> {
264 pub fn local_kind(&self, local: Local) -> LocalKind {
265 let index = local.as_usize();
268 self.local_decls[local].mutability == Mutability::Mut,
269 "return place should be mutable"
272 LocalKind::ReturnPointer
273 } else if index < self.arg_count + 1 {
275 } else if self.local_decls[local].name.is_some() {
282 /// Returns an iterator over all temporaries.
284 pub fn temps_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
285 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
286 let local = Local::new(index);
287 if self.local_decls[local].is_user_variable.is_some() {
295 /// Returns an iterator over all user-declared locals.
297 pub fn vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
298 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
299 let local = Local::new(index);
300 if self.local_decls[local].is_user_variable.is_some() {
308 /// Returns an iterator over all user-declared mutable locals.
310 pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
311 (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
312 let local = Local::new(index);
313 let decl = &self.local_decls[local];
314 if decl.is_user_variable.is_some() && decl.mutability == Mutability::Mut {
322 /// Returns an iterator over all user-declared mutable arguments and locals.
324 pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator<Item = Local> + 'a {
325 (1..self.local_decls.len()).filter_map(move |index| {
326 let local = Local::new(index);
327 let decl = &self.local_decls[local];
328 if (decl.is_user_variable.is_some() || index < self.arg_count + 1)
329 && decl.mutability == Mutability::Mut
338 /// Returns an iterator over all function arguments.
340 pub fn args_iter(&self) -> impl Iterator<Item = Local> {
341 let arg_count = self.arg_count;
342 (1..arg_count + 1).map(Local::new)
345 /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all
346 /// locals that are neither arguments nor the return place).
348 pub fn vars_and_temps_iter(&self) -> impl Iterator<Item = Local> {
349 let arg_count = self.arg_count;
350 let local_count = self.local_decls.len();
351 (arg_count + 1..local_count).map(Local::new)
354 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
355 /// invalidating statement indices in `Location`s.
356 pub fn make_statement_nop(&mut self, location: Location) {
357 let block = &mut self[location.block];
358 debug_assert!(location.statement_index < block.statements.len());
359 block.statements[location.statement_index].make_nop()
362 /// Returns the source info associated with `location`.
363 pub fn source_info(&self, location: Location) -> &SourceInfo {
364 let block = &self[location.block];
365 let stmts = &block.statements;
366 let idx = location.statement_index;
367 if idx < stmts.len() {
368 &stmts[idx].source_info
370 assert_eq!(idx, stmts.len());
371 &block.terminator().source_info
375 /// Check if `sub` is a sub scope of `sup`
376 pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool {
378 match self.source_scopes[sub].parent_scope {
379 None => return false,
386 /// Return the return type, it always return first element from `local_decls` array
387 pub fn return_ty(&self) -> Ty<'tcx> {
388 self.local_decls[RETURN_PLACE].ty
391 /// Get the location of the terminator for the given block
392 pub fn terminator_loc(&self, bb: BasicBlock) -> Location {
395 statement_index: self[bb].statements.len(),
400 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
403 /// Unsafe because of a PushUnsafeBlock
405 /// Unsafe because of an unsafe fn
407 /// Unsafe because of an `unsafe` block
408 ExplicitUnsafe(ast::NodeId),
411 impl_stable_hash_for!(struct Mir<'tcx> {
415 source_scope_local_data,
428 impl<'tcx> Index<BasicBlock> for Mir<'tcx> {
429 type Output = BasicBlockData<'tcx>;
432 fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> {
433 &self.basic_blocks()[index]
437 impl<'tcx> IndexMut<BasicBlock> for Mir<'tcx> {
439 fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> {
440 &mut self.basic_blocks_mut()[index]
444 #[derive(Copy, Clone, Debug)]
445 pub enum ClearCrossCrate<T> {
450 impl<T> ClearCrossCrate<T> {
451 pub fn assert_crate_local(self) -> T {
453 ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"),
454 ClearCrossCrate::Set(v) => v,
459 impl<T: serialize::Encodable> serialize::UseSpecializedEncodable for ClearCrossCrate<T> {}
460 impl<T: serialize::Decodable> serialize::UseSpecializedDecodable for ClearCrossCrate<T> {}
462 /// Grouped information about the source code origin of a MIR entity.
463 /// Intended to be inspected by diagnostics and debuginfo.
464 /// Most passes can work with it as a whole, within a single function.
465 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
466 pub struct SourceInfo {
467 /// Source span for the AST pertaining to this MIR entity.
470 /// The source scope, keeping track of which bindings can be
471 /// seen by debuginfo, active lint levels, `unsafe {...}`, etc.
472 pub scope: SourceScope,
475 ///////////////////////////////////////////////////////////////////////////
476 // Mutability and borrow kinds
478 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
479 pub enum Mutability {
484 impl From<Mutability> for hir::Mutability {
485 fn from(m: Mutability) -> Self {
487 Mutability::Mut => hir::MutMutable,
488 Mutability::Not => hir::MutImmutable,
493 #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)]
494 pub enum BorrowKind {
495 /// Data must be immutable and is aliasable.
498 /// The immediately borrowed place must be immutable, but projections from
499 /// it don't need to be. For example, a shallow borrow of `a.b` doesn't
500 /// conflict with a mutable borrow of `a.b.c`.
502 /// This is used when lowering matches: when matching on a place we want to
503 /// ensure that place have the same value from the start of the match until
504 /// an arm is selected. This prevents this code from compiling:
506 /// let mut x = &Some(0);
509 /// Some(_) if { x = &None; false } => (),
513 /// This can't be a shared borrow because mutably borrowing (*x as Some).0
514 /// should not prevent `if let None = x { ... }`, for example, because the
515 /// mutating `(*x as Some).0` can't affect the discriminant of `x`.
516 /// We can also report errors with this kind of borrow differently.
519 /// Data must be immutable but not aliasable. This kind of borrow
520 /// cannot currently be expressed by the user and is used only in
521 /// implicit closure bindings. It is needed when the closure is
522 /// borrowing or mutating a mutable referent, e.g.:
524 /// let x: &mut isize = ...;
525 /// let y = || *x += 5;
527 /// If we were to try to translate this closure into a more explicit
528 /// form, we'd encounter an error with the code as written:
530 /// struct Env { x: & &mut isize }
531 /// let x: &mut isize = ...;
532 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
533 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
535 /// This is then illegal because you cannot mutate an `&mut` found
536 /// in an aliasable location. To solve, you'd have to translate with
537 /// an `&mut` borrow:
539 /// struct Env { x: & &mut isize }
540 /// let x: &mut isize = ...;
541 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
542 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
544 /// Now the assignment to `**env.x` is legal, but creating a
545 /// mutable pointer to `x` is not because `x` is not mutable. We
546 /// could fix this by declaring `x` as `let mut x`. This is ok in
547 /// user code, if awkward, but extra weird for closures, since the
548 /// borrow is hidden.
550 /// So we introduce a "unique imm" borrow -- the referent is
551 /// immutable, but not aliasable. This solves the problem. For
552 /// simplicity, we don't give users the way to express this
553 /// borrow, it's just used when translating closures.
556 /// Data is mutable and not aliasable.
558 /// True if this borrow arose from method-call auto-ref
559 /// (i.e. `adjustment::Adjust::Borrow`)
560 allow_two_phase_borrow: bool,
565 pub fn allows_two_phase_borrow(&self) -> bool {
567 BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false,
568 BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
573 ///////////////////////////////////////////////////////////////////////////
574 // Variables and temps
578 DEBUG_FORMAT = "_{}",
579 const RETURN_PLACE = 0,
583 /// Classifies locals into categories. See `Mir::local_kind`.
584 #[derive(PartialEq, Eq, Debug)]
586 /// User-declared variable binding
588 /// Compiler-introduced temporary
590 /// Function argument
592 /// Location of function's return value
596 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
597 pub struct VarBindingForm<'tcx> {
598 /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`?
599 pub binding_mode: ty::BindingMode,
600 /// If an explicit type was provided for this variable binding,
601 /// this holds the source Span of that type.
603 /// NOTE: If you want to change this to a `HirId`, be wary that
604 /// doing so breaks incremental compilation (as of this writing),
605 /// while a `Span` does not cause our tests to fail.
606 pub opt_ty_info: Option<Span>,
607 /// Place of the RHS of the =, or the subject of the `match` where this
608 /// variable is initialized. None in the case of `let PATTERN;`.
609 /// Some((None, ..)) in the case of and `let [mut] x = ...` because
610 /// (a) the right-hand side isn't evaluated as a place expression.
611 /// (b) it gives a way to separate this case from the remaining cases
613 pub opt_match_place: Option<(Option<Place<'tcx>>, Span)>,
614 /// Span of the pattern in which this variable was bound.
618 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
619 pub enum BindingForm<'tcx> {
620 /// This is a binding for a non-`self` binding, or a `self` that has an explicit type.
621 Var(VarBindingForm<'tcx>),
622 /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit.
623 ImplicitSelf(ImplicitSelfKind),
624 /// Reference used in a guard expression to ensure immutability.
628 /// Represents what type of implicit self a function has, if any.
629 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
630 pub enum ImplicitSelfKind {
631 /// Represents a `fn x(self);`.
633 /// Represents a `fn x(mut self);`.
635 /// Represents a `fn x(&self);`.
637 /// Represents a `fn x(&mut self);`.
639 /// Represents when a function does not have a self argument or
640 /// when a function has a `self: X` argument.
644 CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, }
646 impl_stable_hash_for!(struct self::VarBindingForm<'tcx> {
653 impl_stable_hash_for!(enum self::ImplicitSelfKind {
661 impl_stable_hash_for!(enum self::MirPhase {
668 mod binding_form_impl {
669 use ich::StableHashingContext;
670 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableHasherResult};
672 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for super::BindingForm<'tcx> {
673 fn hash_stable<W: StableHasherResult>(
675 hcx: &mut StableHashingContext<'a>,
676 hasher: &mut StableHasher<W>,
678 use super::BindingForm::*;
679 ::std::mem::discriminant(self).hash_stable(hcx, hasher);
682 Var(binding) => binding.hash_stable(hcx, hasher),
683 ImplicitSelf(kind) => kind.hash_stable(hcx, hasher),
690 /// `BlockTailInfo` is attached to the `LocalDecl` for temporaries
691 /// created during evaluation of expressions in a block tail
692 /// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`.
694 /// It is used to improve diagnostics when such temporaries are
695 /// involved in borrow_check errors, e.g. explanations of where the
696 /// temporaries come from, when their destructors are run, and/or how
697 /// one might revise the code to satisfy the borrow checker's rules.
698 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
699 pub struct BlockTailInfo {
700 /// If `true`, then the value resulting from evaluating this tail
701 /// expression is ignored by the block's expression context.
703 /// Examples include `{ ...; tail };` and `let _ = { ...; tail };`
704 /// but not e.g. `let _x = { ...; tail };`
705 pub tail_result_is_ignored: bool,
708 impl_stable_hash_for!(struct BlockTailInfo { tail_result_is_ignored });
712 /// This can be a binding declared by the user, a temporary inserted by the compiler, a function
713 /// argument, or the return place.
714 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
715 pub struct LocalDecl<'tcx> {
716 /// `let mut x` vs `let x`.
718 /// Temporaries and the return place are always mutable.
719 pub mutability: Mutability,
721 /// Some(binding_mode) if this corresponds to a user-declared local variable.
723 /// This is solely used for local diagnostics when generating
724 /// warnings/errors when compiling the current crate, and
725 /// therefore it need not be visible across crates. pnkfelix
726 /// currently hypothesized we *need* to wrap this in a
727 /// `ClearCrossCrate` as long as it carries as `HirId`.
728 pub is_user_variable: Option<ClearCrossCrate<BindingForm<'tcx>>>,
730 /// True if this is an internal local
732 /// These locals are not based on types in the source code and are only used
733 /// for a few desugarings at the moment.
735 /// The generator transformation will sanity check the locals which are live
736 /// across a suspension point against the type components of the generator
737 /// which type checking knows are live across a suspension point. We need to
738 /// flag drop flags to avoid triggering this check as they are introduced
741 /// Unsafety checking will also ignore dereferences of these locals,
742 /// so they can be used for raw pointers only used in a desugaring.
744 /// This should be sound because the drop flags are fully algebraic, and
745 /// therefore don't affect the OIBIT or outlives properties of the
749 /// If this local is a temporary and `is_block_tail` is `Some`,
750 /// then it is a temporary created for evaluation of some
751 /// subexpression of some block's tail expression (with no
752 /// intervening statement context).
753 pub is_block_tail: Option<BlockTailInfo>,
755 /// Type of this local.
758 /// If the user manually ascribed a type to this variable,
759 /// e.g. via `let x: T`, then we carry that type here. The MIR
760 /// borrow checker needs this information since it can affect
761 /// region inference.
762 pub user_ty: UserTypeProjections<'tcx>,
764 /// Name of the local, used in debuginfo and pretty-printing.
766 /// Note that function arguments can also have this set to `Some(_)`
767 /// to generate better debuginfo.
768 pub name: Option<Name>,
770 /// The *syntactic* (i.e. not visibility) source scope the local is defined
771 /// in. If the local was defined in a let-statement, this
772 /// is *within* the let-statement, rather than outside
775 /// This is needed because the visibility source scope of locals within
776 /// a let-statement is weird.
778 /// The reason is that we want the local to be *within* the let-statement
779 /// for lint purposes, but we want the local to be *after* the let-statement
780 /// for names-in-scope purposes.
782 /// That's it, if we have a let-statement like the one in this
786 /// fn foo(x: &str) {
787 /// #[allow(unused_mut)]
788 /// let mut x: u32 = { // <- one unused mut
789 /// let mut y: u32 = x.parse().unwrap();
796 /// Then, from a lint point of view, the declaration of `x: u32`
797 /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the
798 /// lint scopes are the same as the AST/HIR nesting.
800 /// However, from a name lookup point of view, the scopes look more like
801 /// as if the let-statements were `match` expressions:
804 /// fn foo(x: &str) {
806 /// match x.parse().unwrap() {
815 /// We care about the name-lookup scopes for debuginfo - if the
816 /// debuginfo instruction pointer is at the call to `x.parse()`, we
817 /// want `x` to refer to `x: &str`, but if it is at the call to
818 /// `drop(x)`, we want it to refer to `x: u32`.
820 /// To allow both uses to work, we need to have more than a single scope
821 /// for a local. We have the `source_info.scope` represent the
822 /// "syntactic" lint scope (with a variable being under its let
823 /// block) while the `visibility_scope` represents the "local variable"
824 /// scope (where the "rest" of a block is under all prior let-statements).
826 /// The end result looks like this:
830 /// │{ argument x: &str }
832 /// │ │{ #[allow(unused_mut)] } // this is actually split into 2 scopes
833 /// │ │ // in practice because I'm lazy.
835 /// │ │← x.source_info.scope
836 /// │ │← `x.parse().unwrap()`
838 /// │ │ │← y.source_info.scope
840 /// │ │ │{ let y: u32 }
842 /// │ │ │← y.visibility_scope
845 /// │ │{ let x: u32 }
846 /// │ │← x.visibility_scope
847 /// │ │← `drop(x)` // this accesses `x: u32`
849 pub source_info: SourceInfo,
851 /// Source scope within which the local is visible (for debuginfo)
852 /// (see `source_info` for more details).
853 pub visibility_scope: SourceScope,
856 impl<'tcx> LocalDecl<'tcx> {
857 /// Returns true only if local is a binding that can itself be
858 /// made mutable via the addition of the `mut` keyword, namely
859 /// something like the occurrences of `x` in:
860 /// - `fn foo(x: Type) { ... }`,
862 /// - or `match ... { C(x) => ... }`
863 pub fn can_be_made_mutable(&self) -> bool {
864 match self.is_user_variable {
865 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
866 binding_mode: ty::BindingMode::BindByValue(_),
872 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(ImplicitSelfKind::Imm)))
879 /// Returns true if local is definitely not a `ref ident` or
880 /// `ref mut ident` binding. (Such bindings cannot be made into
881 /// mutable bindings, but the inverse does not necessarily hold).
882 pub fn is_nonref_binding(&self) -> bool {
883 match self.is_user_variable {
884 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
885 binding_mode: ty::BindingMode::BindByValue(_),
891 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_))) => true,
897 /// Create a new `LocalDecl` for a temporary.
899 pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self {
900 Self::new_local(ty, Mutability::Mut, false, span)
903 /// Converts `self` into same `LocalDecl` except tagged as immutable.
905 pub fn immutable(mut self) -> Self {
906 self.mutability = Mutability::Not;
910 /// Converts `self` into same `LocalDecl` except tagged as internal temporary.
912 pub fn block_tail(mut self, info: BlockTailInfo) -> Self {
913 assert!(self.is_block_tail.is_none());
914 self.is_block_tail = Some(info);
918 /// Create a new `LocalDecl` for a internal temporary.
920 pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self {
921 Self::new_local(ty, Mutability::Mut, true, span)
927 mutability: Mutability,
934 user_ty: UserTypeProjections::none(),
936 source_info: SourceInfo {
938 scope: OUTERMOST_SOURCE_SCOPE,
940 visibility_scope: OUTERMOST_SOURCE_SCOPE,
942 is_user_variable: None,
947 /// Builds a `LocalDecl` for the return place.
949 /// This must be inserted into the `local_decls` list as the first local.
951 pub fn new_return_place(return_ty: Ty<'_>, span: Span) -> LocalDecl<'_> {
953 mutability: Mutability::Mut,
955 user_ty: UserTypeProjections::none(),
956 source_info: SourceInfo {
958 scope: OUTERMOST_SOURCE_SCOPE,
960 visibility_scope: OUTERMOST_SOURCE_SCOPE,
963 name: None, // FIXME maybe we do want some name here?
964 is_user_variable: None,
969 /// A closure capture, with its name and mode.
970 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
971 pub struct UpvarDecl {
972 pub debug_name: Name,
974 /// `HirId` of the captured variable
975 pub var_hir_id: ClearCrossCrate<HirId>,
977 /// If true, the capture is behind a reference.
980 pub mutability: Mutability,
983 ///////////////////////////////////////////////////////////////////////////
987 pub struct BasicBlock {
988 DEBUG_FORMAT = "bb{}",
989 const START_BLOCK = 0,
994 pub fn start_location(self) -> Location {
1002 ///////////////////////////////////////////////////////////////////////////
1003 // BasicBlockData and Terminator
1005 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1006 pub struct BasicBlockData<'tcx> {
1007 /// List of statements in this block.
1008 pub statements: Vec<Statement<'tcx>>,
1010 /// Terminator for this block.
1012 /// NB. This should generally ONLY be `None` during construction.
1013 /// Therefore, you should generally access it via the
1014 /// `terminator()` or `terminator_mut()` methods. The only
1015 /// exception is that certain passes, such as `simplify_cfg`, swap
1016 /// out the terminator temporarily with `None` while they continue
1017 /// to recurse over the set of basic blocks.
1018 pub terminator: Option<Terminator<'tcx>>,
1020 /// If true, this block lies on an unwind path. This is used
1021 /// during codegen where distinct kinds of basic blocks may be
1022 /// generated (particularly for MSVC cleanup). Unwind blocks must
1023 /// only branch to other unwind blocks.
1024 pub is_cleanup: bool,
1027 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1028 pub struct Terminator<'tcx> {
1029 pub source_info: SourceInfo,
1030 pub kind: TerminatorKind<'tcx>,
1033 #[derive(Clone, RustcEncodable, RustcDecodable)]
1034 pub enum TerminatorKind<'tcx> {
1035 /// block should have one successor in the graph; we jump there
1036 Goto { target: BasicBlock },
1038 /// operand evaluates to an integer; jump depending on its value
1039 /// to one of the targets, and otherwise fallback to `otherwise`
1041 /// discriminant value being tested
1042 discr: Operand<'tcx>,
1044 /// type of value being tested
1045 switch_ty: Ty<'tcx>,
1047 /// Possible values. The locations to branch to in each case
1048 /// are found in the corresponding indices from the `targets` vector.
1049 values: Cow<'tcx, [u128]>,
1051 /// Possible branch sites. The last element of this vector is used
1052 /// for the otherwise branch, so targets.len() == values.len() + 1
1054 // This invariant is quite non-obvious and also could be improved.
1055 // One way to make this invariant is to have something like this instead:
1057 // branches: Vec<(ConstInt, BasicBlock)>,
1058 // otherwise: Option<BasicBlock> // exhaustive if None
1060 // However we’ve decided to keep this as-is until we figure a case
1061 // where some other approach seems to be strictly better than other.
1062 targets: Vec<BasicBlock>,
1065 /// Indicates that the landing pad is finished and unwinding should
1066 /// continue. Emitted by build::scope::diverge_cleanup.
1069 /// Indicates that the landing pad is finished and that the process
1070 /// should abort. Used to prevent unwinding for foreign items.
1073 /// Indicates a normal return. The return place should have
1074 /// been filled in by now. This should occur at most once.
1077 /// Indicates a terminator that can never be reached.
1082 location: Place<'tcx>,
1084 unwind: Option<BasicBlock>,
1087 /// Drop the Place and assign the new value over it. This ensures
1088 /// that the assignment to `P` occurs *even if* the destructor for
1089 /// place unwinds. Its semantics are best explained by the
1094 /// DropAndReplace(P <- V, goto BB1, unwind BB2)
1102 /// Drop(P, goto BB1, unwind BB2)
1105 /// // P is now uninitialized
1109 /// // P is now uninitialized -- its dtor panicked
1114 location: Place<'tcx>,
1115 value: Operand<'tcx>,
1117 unwind: Option<BasicBlock>,
1120 /// Block ends with a call of a converging function
1122 /// The function that’s being called
1123 func: Operand<'tcx>,
1124 /// Arguments the function is called with.
1125 /// These are owned by the callee, which is free to modify them.
1126 /// This allows the memory occupied by "by-value" arguments to be
1127 /// reused across function calls without duplicating the contents.
1128 args: Vec<Operand<'tcx>>,
1129 /// Destination for the return value. If some, the call is converging.
1130 destination: Option<(Place<'tcx>, BasicBlock)>,
1131 /// Cleanups to be done if the call unwinds.
1132 cleanup: Option<BasicBlock>,
1133 /// Whether this is from a call in HIR, rather than from an overloaded
1134 /// operator. True for overloaded function call.
1135 from_hir_call: bool,
1138 /// Jump to the target if the condition has the expected value,
1139 /// otherwise panic with a message and a cleanup target.
1141 cond: Operand<'tcx>,
1143 msg: AssertMessage<'tcx>,
1145 cleanup: Option<BasicBlock>,
1150 /// The value to return
1151 value: Operand<'tcx>,
1152 /// Where to resume to
1154 /// Cleanup to be done if the generator is dropped at this suspend point
1155 drop: Option<BasicBlock>,
1158 /// Indicates the end of the dropping of a generator
1161 /// A block where control flow only ever takes one real path, but borrowck
1162 /// needs to be more conservative.
1164 /// The target normal control flow will take
1165 real_target: BasicBlock,
1166 /// The list of blocks control flow could conceptually take, but won't
1168 imaginary_targets: Vec<BasicBlock>,
1170 /// A terminator for blocks that only take one path in reality, but where we
1171 /// reserve the right to unwind in borrowck, even if it won't happen in practice.
1172 /// This can arise in infinite loops with no function calls for example.
1174 /// The target normal control flow will take
1175 real_target: BasicBlock,
1176 /// The imaginary cleanup block link. This particular path will never be taken
1177 /// in practice, but in order to avoid fragility we want to always
1178 /// consider it in borrowck. We don't want to accept programs which
1179 /// pass borrowck only when panic=abort or some assertions are disabled
1180 /// due to release vs. debug mode builds. This needs to be an Option because
1181 /// of the remove_noop_landing_pads and no_landing_pads passes
1182 unwind: Option<BasicBlock>,
1186 pub type Successors<'a> =
1187 iter::Chain<option::IntoIter<&'a BasicBlock>, slice::Iter<'a, BasicBlock>>;
1188 pub type SuccessorsMut<'a> =
1189 iter::Chain<option::IntoIter<&'a mut BasicBlock>, slice::IterMut<'a, BasicBlock>>;
1191 impl<'tcx> Terminator<'tcx> {
1192 pub fn successors(&self) -> Successors<'_> {
1193 self.kind.successors()
1196 pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
1197 self.kind.successors_mut()
1200 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1204 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1205 self.kind.unwind_mut()
1209 impl<'tcx> TerminatorKind<'tcx> {
1210 pub fn if_<'a, 'gcx>(
1211 tcx: TyCtxt<'a, 'gcx, 'tcx>,
1212 cond: Operand<'tcx>,
1215 ) -> TerminatorKind<'tcx> {
1216 static BOOL_SWITCH_FALSE: &'static [u128] = &[0];
1217 TerminatorKind::SwitchInt {
1219 switch_ty: tcx.types.bool,
1220 values: From::from(BOOL_SWITCH_FALSE),
1221 targets: vec![f, t],
1225 pub fn successors(&self) -> Successors<'_> {
1226 use self::TerminatorKind::*;
1237 } => None.into_iter().chain(&[]),
1238 Goto { target: ref t }
1241 cleanup: Some(ref t),
1245 destination: Some((_, ref t)),
1272 } => Some(t).into_iter().chain(&[]),
1274 destination: Some((_, ref t)),
1275 cleanup: Some(ref u),
1285 unwind: Some(ref u),
1290 unwind: Some(ref u),
1295 cleanup: Some(ref u),
1300 unwind: Some(ref u),
1301 } => Some(t).into_iter().chain(slice::from_ref(u)),
1302 SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]),
1305 ref imaginary_targets,
1306 } => Some(real_target).into_iter().chain(&imaginary_targets[..]),
1310 pub fn successors_mut(&mut self) -> SuccessorsMut<'_> {
1311 use self::TerminatorKind::*;
1322 } => None.into_iter().chain(&mut []),
1323 Goto { target: ref mut t }
1326 cleanup: Some(ref mut t),
1330 destination: Some((_, ref mut t)),
1355 real_target: ref mut t,
1357 } => Some(t).into_iter().chain(&mut []),
1359 destination: Some((_, ref mut t)),
1360 cleanup: Some(ref mut u),
1365 drop: Some(ref mut u),
1370 unwind: Some(ref mut u),
1375 unwind: Some(ref mut u),
1380 cleanup: Some(ref mut u),
1384 real_target: ref mut t,
1385 unwind: Some(ref mut u),
1386 } => Some(t).into_iter().chain(slice::from_mut(u)),
1389 } => None.into_iter().chain(&mut targets[..]),
1391 ref mut real_target,
1392 ref mut imaginary_targets,
1393 } => Some(real_target)
1395 .chain(&mut imaginary_targets[..]),
1399 pub fn unwind(&self) -> Option<&Option<BasicBlock>> {
1401 TerminatorKind::Goto { .. }
1402 | TerminatorKind::Resume
1403 | TerminatorKind::Abort
1404 | TerminatorKind::Return
1405 | TerminatorKind::Unreachable
1406 | TerminatorKind::GeneratorDrop
1407 | TerminatorKind::Yield { .. }
1408 | TerminatorKind::SwitchInt { .. }
1409 | TerminatorKind::FalseEdges { .. } => None,
1410 TerminatorKind::Call {
1411 cleanup: ref unwind,
1414 | TerminatorKind::Assert {
1415 cleanup: ref unwind,
1418 | TerminatorKind::DropAndReplace { ref unwind, .. }
1419 | TerminatorKind::Drop { ref unwind, .. }
1420 | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind),
1424 pub fn unwind_mut(&mut self) -> Option<&mut Option<BasicBlock>> {
1426 TerminatorKind::Goto { .. }
1427 | TerminatorKind::Resume
1428 | TerminatorKind::Abort
1429 | TerminatorKind::Return
1430 | TerminatorKind::Unreachable
1431 | TerminatorKind::GeneratorDrop
1432 | TerminatorKind::Yield { .. }
1433 | TerminatorKind::SwitchInt { .. }
1434 | TerminatorKind::FalseEdges { .. } => None,
1435 TerminatorKind::Call {
1436 cleanup: ref mut unwind,
1439 | TerminatorKind::Assert {
1440 cleanup: ref mut unwind,
1443 | TerminatorKind::DropAndReplace { ref mut unwind, .. }
1444 | TerminatorKind::Drop { ref mut unwind, .. }
1445 | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind),
1450 impl<'tcx> BasicBlockData<'tcx> {
1451 pub fn new(terminator: Option<Terminator<'tcx>>) -> BasicBlockData<'tcx> {
1459 /// Accessor for terminator.
1461 /// Terminator may not be None after construction of the basic block is complete. This accessor
1462 /// provides a convenience way to reach the terminator.
1463 pub fn terminator(&self) -> &Terminator<'tcx> {
1464 self.terminator.as_ref().expect("invalid terminator state")
1467 pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> {
1468 self.terminator.as_mut().expect("invalid terminator state")
1471 pub fn retain_statements<F>(&mut self, mut f: F)
1473 F: FnMut(&mut Statement<'_>) -> bool,
1475 for s in &mut self.statements {
1482 pub fn expand_statements<F, I>(&mut self, mut f: F)
1484 F: FnMut(&mut Statement<'tcx>) -> Option<I>,
1485 I: iter::TrustedLen<Item = Statement<'tcx>>,
1487 // Gather all the iterators we'll need to splice in, and their positions.
1488 let mut splices: Vec<(usize, I)> = vec![];
1489 let mut extra_stmts = 0;
1490 for (i, s) in self.statements.iter_mut().enumerate() {
1491 if let Some(mut new_stmts) = f(s) {
1492 if let Some(first) = new_stmts.next() {
1493 // We can already store the first new statement.
1496 // Save the other statements for optimized splicing.
1497 let remaining = new_stmts.size_hint().0;
1499 splices.push((i + 1 + extra_stmts, new_stmts));
1500 extra_stmts += remaining;
1508 // Splice in the new statements, from the end of the block.
1509 // FIXME(eddyb) This could be more efficient with a "gap buffer"
1510 // where a range of elements ("gap") is left uninitialized, with
1511 // splicing adding new elements to the end of that gap and moving
1512 // existing elements from before the gap to the end of the gap.
1513 // For now, this is safe code, emulating a gap but initializing it.
1514 let mut gap = self.statements.len()..self.statements.len() + extra_stmts;
1515 self.statements.resize(
1518 source_info: SourceInfo {
1520 scope: OUTERMOST_SOURCE_SCOPE,
1522 kind: StatementKind::Nop,
1525 for (splice_start, new_stmts) in splices.into_iter().rev() {
1526 let splice_end = splice_start + new_stmts.size_hint().0;
1527 while gap.end > splice_end {
1530 self.statements.swap(gap.start, gap.end);
1532 self.statements.splice(splice_start..splice_end, new_stmts);
1533 gap.end = splice_start;
1537 pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> {
1538 if index < self.statements.len() {
1539 &self.statements[index]
1546 impl<'tcx> Debug for TerminatorKind<'tcx> {
1547 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1548 self.fmt_head(fmt)?;
1549 let successor_count = self.successors().count();
1550 let labels = self.fmt_successor_labels();
1551 assert_eq!(successor_count, labels.len());
1553 match successor_count {
1556 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()),
1559 write!(fmt, " -> [")?;
1560 for (i, target) in self.successors().enumerate() {
1564 write!(fmt, "{}: {:?}", labels[i], target)?;
1572 impl<'tcx> TerminatorKind<'tcx> {
1573 /// Write the "head" part of the terminator; that is, its name and the data it uses to pick the
1574 /// successor basic block, if any. The only information not included is the list of possible
1575 /// successors, which may be rendered differently between the text and the graphviz format.
1576 pub fn fmt_head<W: Write>(&self, fmt: &mut W) -> fmt::Result {
1577 use self::TerminatorKind::*;
1579 Goto { .. } => write!(fmt, "goto"),
1581 discr: ref place, ..
1582 } => write!(fmt, "switchInt({:?})", place),
1583 Return => write!(fmt, "return"),
1584 GeneratorDrop => write!(fmt, "generator_drop"),
1585 Resume => write!(fmt, "resume"),
1586 Abort => write!(fmt, "abort"),
1587 Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value),
1588 Unreachable => write!(fmt, "unreachable"),
1589 Drop { ref location, .. } => write!(fmt, "drop({:?})", location),
1594 } => write!(fmt, "replace({:?} <- {:?})", location, value),
1601 if let Some((ref destination, _)) = *destination {
1602 write!(fmt, "{:?} = ", destination)?;
1604 write!(fmt, "{:?}(", func)?;
1605 for (index, arg) in args.iter().enumerate() {
1609 write!(fmt, "{:?}", arg)?;
1619 write!(fmt, "assert(")?;
1623 write!(fmt, "{:?}, \"{:?}\")", cond, msg)
1625 FalseEdges { .. } => write!(fmt, "falseEdges"),
1626 FalseUnwind { .. } => write!(fmt, "falseUnwind"),
1630 /// Return the list of labels for the edges to the successor basic blocks.
1631 pub fn fmt_successor_labels(&self) -> Vec<Cow<'static, str>> {
1632 use self::TerminatorKind::*;
1634 Return | Resume | Abort | Unreachable | GeneratorDrop => vec![],
1635 Goto { .. } => vec!["".into()],
1641 let size = ty::tls::with(|tcx| {
1642 let param_env = ty::ParamEnv::empty();
1643 let switch_ty = tcx.lift_to_global(&switch_ty).unwrap();
1644 tcx.layout_of(param_env.and(switch_ty)).unwrap().size
1649 let mut s = String::new();
1651 val: ConstValue::Scalar(
1654 size: size.bytes() as u8,
1659 fmt_const_val(&mut s, &c).unwrap();
1661 }).chain(iter::once("otherwise".into()))
1665 destination: Some(_),
1668 } => vec!["return".into(), "unwind".into()],
1670 destination: Some(_),
1673 } => vec!["return".into()],
1678 } => vec!["unwind".into()],
1684 Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()],
1685 Yield { drop: None, .. } => vec!["resume".into()],
1686 DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => {
1687 vec!["return".into()]
1694 } => vec!["return".into(), "unwind".into()],
1695 Assert { cleanup: None, .. } => vec!["".into()],
1696 Assert { .. } => vec!["success".into(), "unwind".into()],
1698 ref imaginary_targets,
1701 let mut l = vec!["real".into()];
1702 l.resize(imaginary_targets.len() + 1, "imaginary".into());
1707 } => vec!["real".into(), "cleanup".into()],
1708 FalseUnwind { unwind: None, .. } => vec!["real".into()],
1713 ///////////////////////////////////////////////////////////////////////////
1716 #[derive(Clone, RustcEncodable, RustcDecodable)]
1717 pub struct Statement<'tcx> {
1718 pub source_info: SourceInfo,
1719 pub kind: StatementKind<'tcx>,
1722 // `Statement` is used a lot. Make sure it doesn't unintentionally get bigger.
1723 #[cfg(target_arch = "x86_64")]
1724 static_assert!(MEM_SIZE_OF_STATEMENT: mem::size_of::<Statement<'_>>() == 56);
1726 impl<'tcx> Statement<'tcx> {
1727 /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
1728 /// invalidating statement indices in `Location`s.
1729 pub fn make_nop(&mut self) {
1730 self.kind = StatementKind::Nop
1733 /// Changes a statement to a nop and returns the original statement.
1734 pub fn replace_nop(&mut self) -> Self {
1736 source_info: self.source_info,
1737 kind: mem::replace(&mut self.kind, StatementKind::Nop),
1742 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
1743 pub enum StatementKind<'tcx> {
1744 /// Write the RHS Rvalue to the LHS Place.
1745 Assign(Place<'tcx>, Box<Rvalue<'tcx>>),
1747 /// This represents all the reading that a pattern match may do
1748 /// (e.g. inspecting constants and discriminant values), and the
1749 /// kind of pattern it comes from. This is in order to adapt potential
1750 /// error messages to these specific patterns.
1751 FakeRead(FakeReadCause, Place<'tcx>),
1753 /// Write the discriminant for a variant to the enum Place.
1756 variant_index: VariantIdx,
1759 /// Start a live range for the storage of the local.
1762 /// End the current live range for the storage of the local.
1765 /// Execute a piece of inline Assembly.
1767 asm: Box<InlineAsm>,
1768 outputs: Box<[Place<'tcx>]>,
1769 inputs: Box<[(Span, Operand<'tcx>)]>,
1772 /// Retag references in the given place, ensuring they got fresh tags. This is
1773 /// part of the Stacked Borrows model. These statements are currently only interpreted
1774 /// by miri and only generated when "-Z mir-emit-retag" is passed.
1775 /// See <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/>
1776 /// for more details.
1778 /// `fn_entry` indicates whether this is the initial retag that happens in the
1779 /// function prolog.
1784 /// Escape the given reference to a raw pointer, so that it can be accessed
1785 /// without precise provenance tracking. These statements are currently only interpreted
1786 /// by miri and only generated when "-Z mir-emit-retag" is passed.
1787 /// See <https://internals.rust-lang.org/t/stacked-borrows-an-aliasing-model-for-rust/8153/>
1788 /// for more details.
1789 EscapeToRaw(Operand<'tcx>),
1791 /// Encodes a user's type ascription. These need to be preserved
1792 /// intact so that NLL can respect them. For example:
1796 /// The effect of this annotation is to relate the type `T_y` of the place `y`
1797 /// to the user-given type `T`. The effect depends on the specified variance:
1799 /// - `Covariant` -- requires that `T_y <: T`
1800 /// - `Contravariant` -- requires that `T_y :> T`
1801 /// - `Invariant` -- requires that `T_y == T`
1802 /// - `Bivariant` -- no effect
1803 AscribeUserType(Place<'tcx>, ty::Variance, Box<UserTypeProjection<'tcx>>),
1805 /// No-op. Useful for deleting instructions without affecting statement indices.
1809 /// The `FakeReadCause` describes the type of pattern why a `FakeRead` statement exists.
1810 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
1811 pub enum FakeReadCause {
1812 /// Inject a fake read of the borrowed input at the start of each arm's
1813 /// pattern testing code.
1815 /// This should ensure that you cannot change the variant for an enum
1816 /// while you are in the midst of matching on it.
1819 /// `let x: !; match x {}` doesn't generate any read of x so we need to
1820 /// generate a read of x to check that it is initialized and safe.
1823 /// Officially, the semantics of
1825 /// `let pattern = <expr>;`
1827 /// is that `<expr>` is evaluated into a temporary and then this temporary is
1828 /// into the pattern.
1830 /// However, if we see the simple pattern `let var = <expr>`, we optimize this to
1831 /// evaluate `<expr>` directly into the variable `var`. This is mostly unobservable,
1832 /// but in some cases it can affect the borrow checker, as in #53695.
1833 /// Therefore, we insert a "fake read" here to ensure that we get
1834 /// appropriate errors.
1838 impl<'tcx> Debug for Statement<'tcx> {
1839 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
1840 use self::StatementKind::*;
1842 Assign(ref place, ref rv) => write!(fmt, "{:?} = {:?}", place, rv),
1843 FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
1844 Retag { fn_entry, ref place } =>
1845 write!(fmt, "Retag({}{:?})", if fn_entry { "[fn entry] " } else { "" }, place),
1846 EscapeToRaw(ref place) => write!(fmt, "EscapeToRaw({:?})", place),
1847 StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place),
1848 StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place),
1852 } => write!(fmt, "discriminant({:?}) = {:?}", place, variant_index),
1857 } => write!(fmt, "asm!({:?} : {:?} : {:?})", asm, outputs, inputs),
1858 AscribeUserType(ref place, ref variance, ref c_ty) => {
1859 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
1861 Nop => write!(fmt, "nop"),
1866 ///////////////////////////////////////////////////////////////////////////
1869 /// A path to a value; something that can be evaluated without
1870 /// changing or disturbing program state.
1871 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1872 pub enum Place<'tcx> {
1876 /// static or static mut variable
1877 Static(Box<Static<'tcx>>),
1879 /// Constant code promoted to an injected static
1880 Promoted(Box<(Promoted, Ty<'tcx>)>),
1882 /// projection out of a place (access a field, deref a pointer, etc)
1883 Projection(Box<PlaceProjection<'tcx>>),
1886 /// The def-id of a static, along with its normalized type (which is
1887 /// stored to avoid requiring normalization when reading MIR).
1888 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1889 pub struct Static<'tcx> {
1894 impl_stable_hash_for!(struct Static<'tcx> {
1899 /// The `Projection` data structure defines things of the form `B.x`
1900 /// or `*B` or `B[index]`. Note that it is parameterized because it is
1901 /// shared between `Constant` and `Place`. See the aliases
1902 /// `PlaceProjection` etc below.
1903 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1904 pub struct Projection<'tcx, B, V, T> {
1906 pub elem: ProjectionElem<'tcx, V, T>,
1909 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1910 pub enum ProjectionElem<'tcx, V, T> {
1915 /// These indices are generated by slice patterns. Easiest to explain
1919 /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false },
1920 /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false },
1921 /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true },
1922 /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true },
1925 /// index or -index (in Python terms), depending on from_end
1927 /// thing being indexed must be at least this long
1929 /// counting backwards from end?
1933 /// These indices are generated by slice patterns.
1935 /// slice[from:-to] in Python terms.
1941 /// "Downcast" to a variant of an ADT. Currently, we only introduce
1942 /// this for ADTs with more than one variant. It may be better to
1943 /// just introduce it always, or always for enums.
1944 Downcast(&'tcx AdtDef, VariantIdx),
1947 /// Alias for projections as they appear in places, where the base is a place
1948 /// and the index is a local.
1949 pub type PlaceProjection<'tcx> = Projection<'tcx, Place<'tcx>, Local, Ty<'tcx>>;
1951 /// Alias for projections as they appear in places, where the base is a place
1952 /// and the index is a local.
1953 pub type PlaceElem<'tcx> = ProjectionElem<'tcx, Local, Ty<'tcx>>;
1955 // at least on 64 bit systems, `PlaceElem` should not be larger than two pointers
1956 static_assert!(PROJECTION_ELEM_IS_2_PTRS_LARGE:
1957 mem::size_of::<PlaceElem<'_>>() <= 16
1960 /// Alias for projections as they appear in `UserTypeProjection`, where we
1961 /// need neither the `V` parameter for `Index` nor the `T` for `Field`.
1962 pub type ProjectionKind<'tcx> = ProjectionElem<'tcx, (), ()>;
1966 DEBUG_FORMAT = "field[{}]"
1970 impl<'tcx> Place<'tcx> {
1971 pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
1972 self.elem(ProjectionElem::Field(f, ty))
1975 pub fn deref(self) -> Place<'tcx> {
1976 self.elem(ProjectionElem::Deref)
1979 pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx) -> Place<'tcx> {
1980 self.elem(ProjectionElem::Downcast(adt_def, variant_index))
1983 pub fn index(self, index: Local) -> Place<'tcx> {
1984 self.elem(ProjectionElem::Index(index))
1987 pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
1988 Place::Projection(Box::new(PlaceProjection { base: self, elem }))
1991 /// Find the innermost `Local` from this `Place`, *if* it is either a local itself or
1992 /// a single deref of a local.
1994 /// FIXME: can we safely swap the semantics of `fn base_local` below in here instead?
1995 pub fn local(&self) -> Option<Local> {
1997 Place::Local(local) |
1998 Place::Projection(box Projection {
1999 base: Place::Local(local),
2000 elem: ProjectionElem::Deref,
2006 /// Find the innermost `Local` from this `Place`.
2007 pub fn base_local(&self) -> Option<Local> {
2009 Place::Local(local) => Some(*local),
2010 Place::Projection(box Projection { base, elem: _ }) => base.base_local(),
2011 Place::Promoted(..) | Place::Static(..) => None,
2016 impl<'tcx> Debug for Place<'tcx> {
2017 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2021 Local(id) => write!(fmt, "{:?}", id),
2022 Static(box self::Static { def_id, ty }) => write!(
2025 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
2028 Promoted(ref promoted) => write!(fmt, "({:?}: {:?})", promoted.0, promoted.1),
2029 Projection(ref data) => match data.elem {
2030 ProjectionElem::Downcast(ref adt_def, index) => {
2031 write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
2033 ProjectionElem::Deref => write!(fmt, "(*{:?})", data.base),
2034 ProjectionElem::Field(field, ty) => {
2035 write!(fmt, "({:?}.{:?}: {:?})", data.base, field.index(), ty)
2037 ProjectionElem::Index(ref index) => write!(fmt, "{:?}[{:?}]", data.base, index),
2038 ProjectionElem::ConstantIndex {
2042 } => write!(fmt, "{:?}[{:?} of {:?}]", data.base, offset, min_length),
2043 ProjectionElem::ConstantIndex {
2047 } => write!(fmt, "{:?}[-{:?} of {:?}]", data.base, offset, min_length),
2048 ProjectionElem::Subslice { from, to } if to == 0 => {
2049 write!(fmt, "{:?}[{:?}:]", data.base, from)
2051 ProjectionElem::Subslice { from, to } if from == 0 => {
2052 write!(fmt, "{:?}[:-{:?}]", data.base, to)
2054 ProjectionElem::Subslice { from, to } => {
2055 write!(fmt, "{:?}[{:?}:-{:?}]", data.base, from, to)
2062 ///////////////////////////////////////////////////////////////////////////
2066 pub struct SourceScope {
2067 DEBUG_FORMAT = "scope[{}]",
2068 const OUTERMOST_SOURCE_SCOPE = 0,
2072 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2073 pub struct SourceScopeData {
2075 pub parent_scope: Option<SourceScope>,
2078 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2079 pub struct SourceScopeLocalData {
2080 /// A NodeId with lint levels equivalent to this scope's lint levels.
2081 pub lint_root: ast::NodeId,
2082 /// The unsafe block that contains this node.
2086 ///////////////////////////////////////////////////////////////////////////
2089 /// These are values that can appear inside an rvalue. They are intentionally
2090 /// limited to prevent rvalues from being nested in one another.
2091 #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
2092 pub enum Operand<'tcx> {
2093 /// Copy: The value must be available for use afterwards.
2095 /// This implies that the type of the place must be `Copy`; this is true
2096 /// by construction during build, but also checked by the MIR type checker.
2099 /// Move: The value (including old borrows of it) will not be used again.
2101 /// Safe for values of all types (modulo future developments towards `?Move`).
2102 /// Correct usage patterns are enforced by the borrow checker for safe code.
2103 /// `Copy` may be converted to `Move` to enable "last-use" optimizations.
2106 /// Synthesizes a constant value.
2107 Constant(Box<Constant<'tcx>>),
2110 impl<'tcx> Debug for Operand<'tcx> {
2111 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2112 use self::Operand::*;
2114 Constant(ref a) => write!(fmt, "{:?}", a),
2115 Copy(ref place) => write!(fmt, "{:?}", place),
2116 Move(ref place) => write!(fmt, "move {:?}", place),
2121 impl<'tcx> Operand<'tcx> {
2122 /// Convenience helper to make a constant that refers to the fn
2123 /// with given def-id and substs. Since this is used to synthesize
2124 /// MIR, assumes `user_ty` is None.
2125 pub fn function_handle<'a>(
2126 tcx: TyCtxt<'a, 'tcx, 'tcx>,
2128 substs: &'tcx Substs<'tcx>,
2131 let ty = tcx.type_of(def_id).subst(tcx, substs);
2132 Operand::Constant(box Constant {
2136 literal: ty::Const::zero_sized(tcx, ty),
2140 pub fn to_copy(&self) -> Self {
2142 Operand::Copy(_) | Operand::Constant(_) => self.clone(),
2143 Operand::Move(ref place) => Operand::Copy(place.clone()),
2148 ///////////////////////////////////////////////////////////////////////////
2151 #[derive(Clone, RustcEncodable, RustcDecodable)]
2152 pub enum Rvalue<'tcx> {
2153 /// x (either a move or copy, depending on type of x)
2157 Repeat(Operand<'tcx>, u64),
2160 Ref(Region<'tcx>, BorrowKind, Place<'tcx>),
2162 /// length of a [X] or [X;n] value
2165 Cast(CastKind, Operand<'tcx>, Ty<'tcx>),
2167 BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2168 CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>),
2170 NullaryOp(NullOp, Ty<'tcx>),
2171 UnaryOp(UnOp, Operand<'tcx>),
2173 /// Read the discriminant of an ADT.
2175 /// Undefined (i.e. no effort is made to make it defined, but there’s no reason why it cannot
2176 /// be defined to return, say, a 0) if ADT is not an enum.
2177 Discriminant(Place<'tcx>),
2179 /// Create an aggregate value, like a tuple or struct. This is
2180 /// only needed because we want to distinguish `dest = Foo { x:
2181 /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case
2182 /// that `Foo` has a destructor. These rvalues can be optimized
2183 /// away after type-checking and before lowering.
2184 Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
2187 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2191 /// Convert unique, zero-sized type for a fn to fn()
2194 /// Convert non capturing closure to fn()
2197 /// Convert safe fn() to unsafe fn()
2200 /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
2201 /// codegen must figure out the details once full monomorphization
2202 /// is known. For example, this could be used to cast from a
2203 /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<dyn Trait>`
2204 /// (presuming `T: Trait`).
2208 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2209 pub enum AggregateKind<'tcx> {
2210 /// The type is of the element
2214 /// The second field is the variant index. It's equal to 0 for struct
2215 /// and union expressions. The fourth field is
2216 /// active field number and is present only for union expressions
2217 /// -- e.g. for a union expression `SomeUnion { c: .. }`, the
2218 /// active field index would identity the field `c`
2223 Option<UserTypeAnnotation<'tcx>>,
2227 Closure(DefId, ClosureSubsts<'tcx>),
2228 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
2231 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2233 /// The `+` operator (addition)
2235 /// The `-` operator (subtraction)
2237 /// The `*` operator (multiplication)
2239 /// The `/` operator (division)
2241 /// The `%` operator (modulus)
2243 /// The `^` operator (bitwise xor)
2245 /// The `&` operator (bitwise and)
2247 /// The `|` operator (bitwise or)
2249 /// The `<<` operator (shift left)
2251 /// The `>>` operator (shift right)
2253 /// The `==` operator (equality)
2255 /// The `<` operator (less than)
2257 /// The `<=` operator (less than or equal to)
2259 /// The `!=` operator (not equal to)
2261 /// The `>=` operator (greater than or equal to)
2263 /// The `>` operator (greater than)
2265 /// The `ptr.offset` operator
2270 pub fn is_checkable(self) -> bool {
2273 Add | Sub | Mul | Shl | Shr => true,
2279 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2281 /// Return the size of a value of that type
2283 /// Create a new uninitialized box for a value of that type
2287 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
2289 /// The `!` operator for logical inversion
2291 /// The `-` operator for negation
2295 impl<'tcx> Debug for Rvalue<'tcx> {
2296 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2297 use self::Rvalue::*;
2300 Use(ref place) => write!(fmt, "{:?}", place),
2301 Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b),
2302 Len(ref a) => write!(fmt, "Len({:?})", a),
2303 Cast(ref kind, ref place, ref ty) => {
2304 write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind)
2306 BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b),
2307 CheckedBinaryOp(ref op, ref a, ref b) => {
2308 write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b)
2310 UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a),
2311 Discriminant(ref place) => write!(fmt, "discriminant({:?})", place),
2312 NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t),
2313 Ref(region, borrow_kind, ref place) => {
2314 let kind_str = match borrow_kind {
2315 BorrowKind::Shared => "",
2316 BorrowKind::Shallow => "shallow ",
2317 BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ",
2320 // When printing regions, add trailing space if necessary.
2321 let region = if ppaux::verbose() || ppaux::identify_regions() {
2322 let mut region = region.to_string();
2323 if region.len() > 0 {
2328 // Do not even print 'static
2331 write!(fmt, "&{}{}{:?}", region, kind_str, place)
2334 Aggregate(ref kind, ref places) => {
2335 fn fmt_tuple(fmt: &mut Formatter<'_>, places: &[Operand<'_>]) -> fmt::Result {
2336 let mut tuple_fmt = fmt.debug_tuple("");
2337 for place in places {
2338 tuple_fmt.field(place);
2344 AggregateKind::Array(_) => write!(fmt, "{:?}", places),
2346 AggregateKind::Tuple => match places.len() {
2347 0 => write!(fmt, "()"),
2348 1 => write!(fmt, "({:?},)", places[0]),
2349 _ => fmt_tuple(fmt, places),
2352 AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => {
2353 let variant_def = &adt_def.variants[variant];
2355 ppaux::parameterized(fmt, substs, variant_def.did, &[])?;
2357 match variant_def.ctor_kind {
2358 CtorKind::Const => Ok(()),
2359 CtorKind::Fn => fmt_tuple(fmt, places),
2360 CtorKind::Fictive => {
2361 let mut struct_fmt = fmt.debug_struct("");
2362 for (field, place) in variant_def.fields.iter().zip(places) {
2363 struct_fmt.field(&field.ident.as_str(), place);
2370 AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| {
2371 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2372 let name = if tcx.sess.opts.debugging_opts.span_free_formats {
2373 format!("[closure@{:?}]", node_id)
2375 format!("[closure@{:?}]", tcx.hir.span(node_id))
2377 let mut struct_fmt = fmt.debug_struct(&name);
2379 tcx.with_freevars(node_id, |freevars| {
2380 for (freevar, place) in freevars.iter().zip(places) {
2381 let var_name = tcx.hir.name(freevar.var_id());
2382 struct_fmt.field(&var_name.as_str(), place);
2388 write!(fmt, "[closure]")
2392 AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| {
2393 if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
2394 let name = format!("[generator@{:?}]", tcx.hir.span(node_id));
2395 let mut struct_fmt = fmt.debug_struct(&name);
2397 tcx.with_freevars(node_id, |freevars| {
2398 for (freevar, place) in freevars.iter().zip(places) {
2399 let var_name = tcx.hir.name(freevar.var_id());
2400 struct_fmt.field(&var_name.as_str(), place);
2402 struct_fmt.field("$state", &places[freevars.len()]);
2403 for i in (freevars.len() + 1)..places.len() {
2405 .field(&format!("${}", i - freevars.len() - 1), &places[i]);
2411 write!(fmt, "[generator]")
2420 ///////////////////////////////////////////////////////////////////////////
2423 /// Two constants are equal if they are the same constant. Note that
2424 /// this does not necessarily mean that they are "==" in Rust -- in
2425 /// particular one must be wary of `NaN`!
2427 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2428 pub struct Constant<'tcx> {
2432 /// Optional user-given type: for something like
2433 /// `collect::<Vec<_>>`, this would be present and would
2434 /// indicate that `Vec<_>` was explicitly specified.
2436 /// Needed for NLL to impose user-given type constraints.
2437 pub user_ty: Option<UserTypeAnnotation<'tcx>>,
2439 pub literal: &'tcx ty::Const<'tcx>,
2442 /// A user-given type annotation attached to a constant. These arise
2443 /// from constants that are named via paths, like `Foo::<A>::new` and
2445 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2446 pub enum UserTypeAnnotation<'tcx> {
2447 Ty(CanonicalTy<'tcx>),
2449 /// The canonical type is the result of `type_of(def_id)` with the
2450 /// given substitutions applied.
2451 TypeOf(DefId, CanonicalUserSubsts<'tcx>),
2454 EnumTypeFoldableImpl! {
2455 impl<'tcx> TypeFoldable<'tcx> for UserTypeAnnotation<'tcx> {
2456 (UserTypeAnnotation::Ty)(ty),
2457 (UserTypeAnnotation::TypeOf)(def, substs),
2462 impl<'a, 'tcx> Lift<'tcx> for UserTypeAnnotation<'a> {
2463 type Lifted = UserTypeAnnotation<'tcx>;
2464 (UserTypeAnnotation::Ty)(ty),
2465 (UserTypeAnnotation::TypeOf)(def, substs),
2469 /// A collection of projections into user types.
2471 /// They are projections because a binding can occur a part of a
2472 /// parent pattern that has been ascribed a type.
2474 /// Its a collection because there can be multiple type ascriptions on
2475 /// the path from the root of the pattern down to the binding itself.
2480 /// struct S<'a>((i32, &'a str), String);
2481 /// let S((_, w): (i32, &'static str), _): S = ...;
2482 /// // ------ ^^^^^^^^^^^^^^^^^^^ (1)
2483 /// // --------------------------------- ^ (2)
2486 /// The highlights labelled `(1)` show the subpattern `(_, w)` being
2487 /// ascribed the type `(i32, &'static str)`.
2489 /// The highlights labelled `(2)` show the whole pattern being
2490 /// ascribed the type `S`.
2492 /// In this example, when we descend to `w`, we will have built up the
2493 /// following two projected types:
2495 /// * base: `S`, projection: `(base.0).1`
2496 /// * base: `(i32, &'static str)`, projection: `base.1`
2498 /// The first will lead to the constraint `w: &'1 str` (for some
2499 /// inferred region `'1`). The second will lead to the constraint `w:
2501 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2502 pub struct UserTypeProjections<'tcx> {
2503 pub(crate) contents: Vec<(UserTypeProjection<'tcx>, Span)>,
2506 BraceStructTypeFoldableImpl! {
2507 impl<'tcx> TypeFoldable<'tcx> for UserTypeProjections<'tcx> {
2512 impl<'tcx> UserTypeProjections<'tcx> {
2513 pub fn none() -> Self {
2514 UserTypeProjections { contents: vec![] }
2517 pub fn from_projections(projs: impl Iterator<Item=(UserTypeProjection<'tcx>, Span)>) -> Self {
2518 UserTypeProjections { contents: projs.collect() }
2521 pub fn projections_and_spans(&self) -> impl Iterator<Item=&(UserTypeProjection<'tcx>, Span)> {
2522 self.contents.iter()
2525 pub fn projections(&self) -> impl Iterator<Item=&UserTypeProjection<'tcx>> {
2526 self.contents.iter().map(|&(ref user_type, _span)| user_type)
2530 /// Encodes the effect of a user-supplied type annotation on the
2531 /// subcomponents of a pattern. The effect is determined by applying the
2532 /// given list of proejctions to some underlying base type. Often,
2533 /// the projection element list `projs` is empty, in which case this
2534 /// directly encodes a type in `base`. But in the case of complex patterns with
2535 /// subpatterns and bindings, we want to apply only a *part* of the type to a variable,
2536 /// in which case the `projs` vector is used.
2540 /// * `let x: T = ...` -- here, the `projs` vector is empty.
2542 /// * `let (x, _): T = ...` -- here, the `projs` vector would contain
2543 /// `field[0]` (aka `.0`), indicating that the type of `s` is
2544 /// determined by finding the type of the `.0` field from `T`.
2545 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2546 pub struct UserTypeProjection<'tcx> {
2547 pub base: UserTypeAnnotation<'tcx>,
2548 pub projs: Vec<ProjectionElem<'tcx, (), ()>>,
2551 impl<'tcx> Copy for ProjectionKind<'tcx> { }
2553 CloneTypeFoldableAndLiftImpls! { ProjectionKind<'tcx>, }
2555 impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection<'tcx> {
2556 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
2557 use mir::ProjectionElem::*;
2559 let base = self.base.fold_with(folder);
2560 let projs: Vec<_> = self.projs
2565 Field(f, ()) => Field(f.clone(), ()),
2566 Index(()) => Index(()),
2567 elem => elem.clone(),
2571 UserTypeProjection { base, projs }
2574 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
2575 self.base.visit_with(visitor)
2576 // Note: there's nothing in `self.proj` to visit.
2581 pub struct Promoted {
2582 DEBUG_FORMAT = "promoted[{}]"
2586 impl<'tcx> Debug for Constant<'tcx> {
2587 fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
2588 write!(fmt, "const ")?;
2589 fmt_const_val(fmt, self.literal)
2593 /// Write a `ConstValue` in a way closer to the original source code than the `Debug` output.
2594 pub fn fmt_const_val(f: &mut impl Write, const_val: &ty::Const<'_>) -> fmt::Result {
2596 let value = const_val.val;
2597 let ty = const_val.ty;
2598 // print some primitives
2599 if let ConstValue::Scalar(Scalar::Bits { bits, .. }) = value {
2601 Bool if bits == 0 => return write!(f, "false"),
2602 Bool if bits == 1 => return write!(f, "true"),
2603 Float(ast::FloatTy::F32) => return write!(f, "{}f32", Single::from_bits(bits)),
2604 Float(ast::FloatTy::F64) => return write!(f, "{}f64", Double::from_bits(bits)),
2605 Uint(ui) => return write!(f, "{:?}{}", bits, ui),
2607 let bit_width = ty::tls::with(|tcx| {
2608 let ty = tcx.lift_to_global(&ty).unwrap();
2609 tcx.layout_of(ty::ParamEnv::empty().and(ty))
2614 let shift = 128 - bit_width;
2615 return write!(f, "{:?}{}", ((bits as i128) << shift) >> shift, i);
2617 Char => return write!(f, "{:?}", ::std::char::from_u32(bits as u32).unwrap()),
2621 // print function definitions
2622 if let FnDef(did, _) = ty.sty {
2623 return write!(f, "{}", item_path_str(did));
2625 // print string literals
2626 if let ConstValue::ScalarPair(ptr, len) = value {
2627 if let Scalar::Ptr(ptr) = ptr {
2628 if let Scalar::Bits { bits: len, .. } = len {
2629 if let Ref(_, &ty::TyS { sty: Str, .. }, _) = ty.sty {
2630 return ty::tls::with(|tcx| {
2631 let alloc = tcx.alloc_map.lock().get(ptr.alloc_id);
2632 if let Some(interpret::AllocKind::Memory(alloc)) = alloc {
2633 assert_eq!(len as usize as u128, len);
2635 &alloc.bytes[(ptr.offset.bytes() as usize)..][..(len as usize)];
2636 let s = ::std::str::from_utf8(slice).expect("non utf8 str from miri");
2637 write!(f, "{:?}", s)
2639 write!(f, "pointer to erroneous constant {:?}, {:?}", ptr, len)
2646 // just raw dump everything else
2647 write!(f, "{:?}:{}", value, ty)
2650 fn item_path_str(def_id: DefId) -> String {
2651 ty::tls::with(|tcx| tcx.item_path_str(def_id))
2654 impl<'tcx> graph::DirectedGraph for Mir<'tcx> {
2655 type Node = BasicBlock;
2658 impl<'tcx> graph::WithNumNodes for Mir<'tcx> {
2659 fn num_nodes(&self) -> usize {
2660 self.basic_blocks.len()
2664 impl<'tcx> graph::WithStartNode for Mir<'tcx> {
2665 fn start_node(&self) -> Self::Node {
2670 impl<'tcx> graph::WithPredecessors for Mir<'tcx> {
2671 fn predecessors<'graph>(
2674 ) -> <Self as GraphPredecessors<'graph>>::Iter {
2675 self.predecessors_for(node).clone().into_iter()
2679 impl<'tcx> graph::WithSuccessors for Mir<'tcx> {
2680 fn successors<'graph>(
2683 ) -> <Self as GraphSuccessors<'graph>>::Iter {
2684 self.basic_blocks[node].terminator().successors().cloned()
2688 impl<'a, 'b> graph::GraphPredecessors<'b> for Mir<'a> {
2689 type Item = BasicBlock;
2690 type Iter = IntoIter<BasicBlock>;
2693 impl<'a, 'b> graph::GraphSuccessors<'b> for Mir<'a> {
2694 type Item = BasicBlock;
2695 type Iter = iter::Cloned<Successors<'b>>;
2698 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
2699 pub struct Location {
2700 /// the location is within this block
2701 pub block: BasicBlock,
2703 /// the location is the start of the statement; or, if `statement_index`
2704 /// == num-statements, then the start of the terminator.
2705 pub statement_index: usize,
2708 impl fmt::Debug for Location {
2709 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2710 write!(fmt, "{:?}[{}]", self.block, self.statement_index)
2715 pub const START: Location = Location {
2720 /// Returns the location immediately after this one within the enclosing block.
2722 /// Note that if this location represents a terminator, then the
2723 /// resulting location would be out of bounds and invalid.
2724 pub fn successor_within_block(&self) -> Location {
2727 statement_index: self.statement_index + 1,
2731 /// Returns `true` if `other` is earlier in the control flow graph than `self`.
2732 pub fn is_predecessor_of<'tcx>(&self, other: Location, mir: &Mir<'tcx>) -> bool {
2733 // If we are in the same block as the other location and are an earlier statement
2734 // then we are a predecessor of `other`.
2735 if self.block == other.block && self.statement_index < other.statement_index {
2739 // If we're in another block, then we want to check that block is a predecessor of `other`.
2740 let mut queue: Vec<BasicBlock> = mir.predecessors_for(other.block).clone();
2741 let mut visited = FxHashSet::default();
2743 while let Some(block) = queue.pop() {
2744 // If we haven't visited this block before, then make sure we visit it's predecessors.
2745 if visited.insert(block) {
2746 queue.append(&mut mir.predecessors_for(block).clone());
2751 // If we found the block that `self` is in, then we are a predecessor of `other` (since
2752 // we found that block by looking at the predecessors of `other`).
2753 if self.block == block {
2761 pub fn dominates(&self, other: Location, dominators: &Dominators<BasicBlock>) -> bool {
2762 if self.block == other.block {
2763 self.statement_index <= other.statement_index
2765 dominators.is_dominated_by(other.block, self.block)
2770 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2771 pub enum UnsafetyViolationKind {
2773 /// unsafety is not allowed at all in min const fn
2775 ExternStatic(ast::NodeId),
2776 BorrowPacked(ast::NodeId),
2779 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2780 pub struct UnsafetyViolation {
2781 pub source_info: SourceInfo,
2782 pub description: InternedString,
2783 pub details: InternedString,
2784 pub kind: UnsafetyViolationKind,
2787 #[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
2788 pub struct UnsafetyCheckResult {
2789 /// Violations that are propagated *upwards* from this function
2790 pub violations: Lrc<[UnsafetyViolation]>,
2791 /// unsafe blocks in this function, along with whether they are used. This is
2792 /// used for the "unused_unsafe" lint.
2793 pub unsafe_blocks: Lrc<[(ast::NodeId, bool)]>,
2796 /// The layout of generator state
2797 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2798 pub struct GeneratorLayout<'tcx> {
2799 pub fields: Vec<LocalDecl<'tcx>>,
2802 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2803 pub struct BorrowCheckResult<'gcx> {
2804 pub closure_requirements: Option<ClosureRegionRequirements<'gcx>>,
2805 pub used_mut_upvars: SmallVec<[Field; 8]>,
2808 /// After we borrow check a closure, we are left with various
2809 /// requirements that we have inferred between the free regions that
2810 /// appear in the closure's signature or on its field types. These
2811 /// requirements are then verified and proved by the closure's
2812 /// creating function. This struct encodes those requirements.
2814 /// The requirements are listed as being between various
2815 /// `RegionVid`. The 0th region refers to `'static`; subsequent region
2816 /// vids refer to the free regions that appear in the closure (or
2817 /// generator's) type, in order of appearance. (This numbering is
2818 /// actually defined by the `UniversalRegions` struct in the NLL
2819 /// region checker. See for example
2820 /// `UniversalRegions::closure_mapping`.) Note that we treat the free
2821 /// regions in the closure's type "as if" they were erased, so their
2822 /// precise identity is not important, only their position.
2824 /// Example: If type check produces a closure with the closure substs:
2827 /// ClosureSubsts = [
2828 /// i8, // the "closure kind"
2829 /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature"
2830 /// &'a String, // some upvar
2834 /// here, there is one unique free region (`'a`) but it appears
2835 /// twice. We would "renumber" each occurrence to a unique vid, as follows:
2838 /// ClosureSubsts = [
2839 /// i8, // the "closure kind"
2840 /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature"
2841 /// &'2 String, // some upvar
2845 /// Now the code might impose a requirement like `'1: '2`. When an
2846 /// instance of the closure is created, the corresponding free regions
2847 /// can be extracted from its type and constrained to have the given
2848 /// outlives relationship.
2850 /// In some cases, we have to record outlives requirements between
2851 /// types and regions as well. In that case, if those types include
2852 /// any regions, those regions are recorded as `ReClosureBound`
2853 /// instances assigned one of these same indices. Those regions will
2854 /// be substituted away by the creator. We use `ReClosureBound` in
2855 /// that case because the regions must be allocated in the global
2856 /// TyCtxt, and hence we cannot use `ReVar` (which is what we use
2857 /// internally within the rest of the NLL code).
2858 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
2859 pub struct ClosureRegionRequirements<'gcx> {
2860 /// The number of external regions defined on the closure. In our
2861 /// example above, it would be 3 -- one for `'static`, then `'1`
2862 /// and `'2`. This is just used for a sanity check later on, to
2863 /// make sure that the number of regions we see at the callsite
2865 pub num_external_vids: usize,
2867 /// Requirements between the various free regions defined in
2869 pub outlives_requirements: Vec<ClosureOutlivesRequirement<'gcx>>,
2872 /// Indicates an outlives constraint between a type or between two
2873 /// free-regions declared on the closure.
2874 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2875 pub struct ClosureOutlivesRequirement<'tcx> {
2876 // This region or type ...
2877 pub subject: ClosureOutlivesSubject<'tcx>,
2879 // ... must outlive this one.
2880 pub outlived_free_region: ty::RegionVid,
2882 // If not, report an error here ...
2883 pub blame_span: Span,
2885 // ... due to this reason.
2886 pub category: ConstraintCategory,
2889 /// Outlives constraints can be categorized to determine whether and why they
2890 /// are interesting (for error reporting). Order of variants indicates sort
2891 /// order of the category, thereby influencing diagnostic output.
2893 /// See also [rustc_mir::borrow_check::nll::constraints]
2894 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
2895 pub enum ConstraintCategory {
2902 /// A constraint that came from checking the body of a closure.
2904 /// We try to get the category that the closure used when reporting this.
2912 /// A "boring" constraint (caused by the given location) is one that
2913 /// the user probably doesn't want to see described in diagnostics,
2914 /// because it is kind of an artifact of the type system setup.
2915 /// Example: `x = Foo { field: y }` technically creates
2916 /// intermediate regions representing the "type of `Foo { field: y
2917 /// }`", and data flows from `y` into those variables, but they
2918 /// are not very interesting. The assignment into `x` on the other
2921 // Boring and applicable everywhere.
2924 /// A constraint that doesn't correspond to anything the user sees.
2928 /// The subject of a ClosureOutlivesRequirement -- that is, the thing
2929 /// that must outlive some region.
2930 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
2931 pub enum ClosureOutlivesSubject<'tcx> {
2932 /// Subject is a type, typically a type parameter, but could also
2933 /// be a projection. Indicates a requirement like `T: 'a` being
2934 /// passed to the caller, where the type here is `T`.
2936 /// The type here is guaranteed not to contain any free regions at
2940 /// Subject is a free region from the closure. Indicates a requirement
2941 /// like `'a: 'b` being passed to the caller; the region here is `'a`.
2942 Region(ty::RegionVid),
2946 * TypeFoldable implementations for MIR types
2949 CloneTypeFoldableAndLiftImpls! {
2958 SourceScopeLocalData,
2961 BraceStructTypeFoldableImpl! {
2962 impl<'tcx> TypeFoldable<'tcx> for Mir<'tcx> {
2966 source_scope_local_data,
2980 BraceStructTypeFoldableImpl! {
2981 impl<'tcx> TypeFoldable<'tcx> for GeneratorLayout<'tcx> {
2986 BraceStructTypeFoldableImpl! {
2987 impl<'tcx> TypeFoldable<'tcx> for LocalDecl<'tcx> {
3000 BraceStructTypeFoldableImpl! {
3001 impl<'tcx> TypeFoldable<'tcx> for BasicBlockData<'tcx> {
3008 BraceStructTypeFoldableImpl! {
3009 impl<'tcx> TypeFoldable<'tcx> for Statement<'tcx> {
3014 EnumTypeFoldableImpl! {
3015 impl<'tcx> TypeFoldable<'tcx> for StatementKind<'tcx> {
3016 (StatementKind::Assign)(a, b),
3017 (StatementKind::FakeRead)(cause, place),
3018 (StatementKind::SetDiscriminant) { place, variant_index },
3019 (StatementKind::StorageLive)(a),
3020 (StatementKind::StorageDead)(a),
3021 (StatementKind::InlineAsm) { asm, outputs, inputs },
3022 (StatementKind::Retag) { fn_entry, place },
3023 (StatementKind::EscapeToRaw)(place),
3024 (StatementKind::AscribeUserType)(a, v, b),
3025 (StatementKind::Nop),
3029 EnumTypeFoldableImpl! {
3030 impl<'tcx, T> TypeFoldable<'tcx> for ClearCrossCrate<T> {
3031 (ClearCrossCrate::Clear),
3032 (ClearCrossCrate::Set)(a),
3033 } where T: TypeFoldable<'tcx>
3036 impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> {
3037 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3038 use mir::TerminatorKind::*;
3040 let kind = match self.kind {
3041 Goto { target } => Goto { target },
3048 discr: discr.fold_with(folder),
3049 switch_ty: switch_ty.fold_with(folder),
3050 values: values.clone(),
3051 targets: targets.clone(),
3058 location: location.fold_with(folder),
3067 } => DropAndReplace {
3068 location: location.fold_with(folder),
3069 value: value.fold_with(folder),
3078 value: value.fold_with(folder),
3089 let dest = destination
3091 .map(|&(ref loc, dest)| (loc.fold_with(folder), dest));
3094 func: func.fold_with(folder),
3095 args: args.fold_with(folder),
3108 let msg = if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
3109 EvalErrorKind::BoundsCheck {
3110 len: len.fold_with(folder),
3111 index: index.fold_with(folder),
3117 cond: cond.fold_with(folder),
3124 GeneratorDrop => GeneratorDrop,
3128 Unreachable => Unreachable,
3131 ref imaginary_targets,
3134 imaginary_targets: imaginary_targets.clone(),
3145 source_info: self.source_info,
3150 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3151 use mir::TerminatorKind::*;
3158 } => discr.visit_with(visitor) || switch_ty.visit_with(visitor),
3159 Drop { ref location, .. } => location.visit_with(visitor),
3164 } => location.visit_with(visitor) || value.visit_with(visitor),
3165 Yield { ref value, .. } => value.visit_with(visitor),
3172 let dest = if let Some((ref loc, _)) = *destination {
3173 loc.visit_with(visitor)
3177 dest || func.visit_with(visitor) || args.visit_with(visitor)
3180 ref cond, ref msg, ..
3182 if cond.visit_with(visitor) {
3183 if let EvalErrorKind::BoundsCheck { ref len, ref index } = *msg {
3184 len.visit_with(visitor) || index.visit_with(visitor)
3199 | FalseUnwind { .. } => false,
3204 impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> {
3205 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3207 &Place::Projection(ref p) => Place::Projection(p.fold_with(folder)),
3212 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3213 if let &Place::Projection(ref p) = self {
3214 p.visit_with(visitor)
3221 impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> {
3222 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3225 Use(ref op) => Use(op.fold_with(folder)),
3226 Repeat(ref op, len) => Repeat(op.fold_with(folder), len),
3227 Ref(region, bk, ref place) => {
3228 Ref(region.fold_with(folder), bk, place.fold_with(folder))
3230 Len(ref place) => Len(place.fold_with(folder)),
3231 Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)),
3232 BinaryOp(op, ref rhs, ref lhs) => {
3233 BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
3235 CheckedBinaryOp(op, ref rhs, ref lhs) => {
3236 CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder))
3238 UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)),
3239 Discriminant(ref place) => Discriminant(place.fold_with(folder)),
3240 NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)),
3241 Aggregate(ref kind, ref fields) => {
3242 let kind = box match **kind {
3243 AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)),
3244 AggregateKind::Tuple => AggregateKind::Tuple,
3245 AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt(
3248 substs.fold_with(folder),
3249 user_ty.fold_with(folder),
3252 AggregateKind::Closure(id, substs) => {
3253 AggregateKind::Closure(id, substs.fold_with(folder))
3255 AggregateKind::Generator(id, substs, movablity) => {
3256 AggregateKind::Generator(id, substs.fold_with(folder), movablity)
3259 Aggregate(kind, fields.fold_with(folder))
3264 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3267 Use(ref op) => op.visit_with(visitor),
3268 Repeat(ref op, _) => op.visit_with(visitor),
3269 Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor),
3270 Len(ref place) => place.visit_with(visitor),
3271 Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor),
3272 BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => {
3273 rhs.visit_with(visitor) || lhs.visit_with(visitor)
3275 UnaryOp(_, ref val) => val.visit_with(visitor),
3276 Discriminant(ref place) => place.visit_with(visitor),
3277 NullaryOp(_, ty) => ty.visit_with(visitor),
3278 Aggregate(ref kind, ref fields) => {
3280 AggregateKind::Array(ty) => ty.visit_with(visitor),
3281 AggregateKind::Tuple => false,
3282 AggregateKind::Adt(_, _, substs, user_ty, _) => {
3283 substs.visit_with(visitor) || user_ty.visit_with(visitor)
3285 AggregateKind::Closure(_, substs) => substs.visit_with(visitor),
3286 AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor),
3287 }) || fields.visit_with(visitor)
3293 impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> {
3294 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3296 Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)),
3297 Operand::Move(ref place) => Operand::Move(place.fold_with(folder)),
3298 Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)),
3302 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3304 Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor),
3305 Operand::Constant(ref c) => c.visit_with(visitor),
3310 impl<'tcx, B, V, T> TypeFoldable<'tcx> for Projection<'tcx, B, V, T>
3312 B: TypeFoldable<'tcx>,
3313 V: TypeFoldable<'tcx>,
3314 T: TypeFoldable<'tcx>,
3316 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3317 use mir::ProjectionElem::*;
3319 let base = self.base.fold_with(folder);
3320 let elem = match self.elem {
3322 Field(f, ref ty) => Field(f, ty.fold_with(folder)),
3323 Index(ref v) => Index(v.fold_with(folder)),
3324 ref elem => elem.clone(),
3327 Projection { base, elem }
3330 fn super_visit_with<Vs: TypeVisitor<'tcx>>(&self, visitor: &mut Vs) -> bool {
3331 use mir::ProjectionElem::*;
3333 self.base.visit_with(visitor) || match self.elem {
3334 Field(_, ref ty) => ty.visit_with(visitor),
3335 Index(ref v) => v.visit_with(visitor),
3341 impl<'tcx> TypeFoldable<'tcx> for Field {
3342 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> Self {
3345 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> bool {
3350 impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
3351 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
3353 span: self.span.clone(),
3354 ty: self.ty.fold_with(folder),
3355 user_ty: self.user_ty.fold_with(folder),
3356 literal: self.literal.fold_with(folder),
3359 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
3360 self.ty.visit_with(visitor) || self.literal.visit_with(visitor)