// ignore-tidy-filelength //! MIR datatypes and passes. See the [rustc guide] for more info. //! //! [rustc guide]: https://rust-lang.github.io/rustc-guide/mir/index.html use crate::hir::def::{CtorKind, Namespace}; use crate::hir::def_id::DefId; use crate::hir::{self, GeneratorKind}; use crate::mir::interpret::{GlobalAlloc, PanicInfo, Scalar}; use crate::mir::visit::MirVisitable; use crate::ty::adjustment::PointerCast; use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor}; use crate::ty::layout::VariantIdx; use crate::ty::print::{FmtPrinter, Printer}; use crate::ty::subst::{Subst, SubstsRef}; use crate::ty::{ self, AdtDef, CanonicalUserTypeAnnotations, List, Region, Ty, TyCtxt, UserTypeAnnotationIndex, }; use polonius_engine::Atom; use rustc_index::bit_set::BitMatrix; use rustc_data_structures::fx::FxHashSet; use rustc_data_structures::graph::dominators::{dominators, Dominators}; use rustc_data_structures::graph::{self, GraphPredecessors, GraphSuccessors}; use rustc_index::vec::{Idx, IndexVec}; use rustc_data_structures::sync::Lrc; use rustc_data_structures::sync::MappedReadGuard; use rustc_macros::HashStable; use rustc_serialize::{Encodable, Decodable}; use smallvec::SmallVec; use std::borrow::Cow; use std::fmt::{self, Debug, Display, Formatter, Write}; use std::ops::{Index, IndexMut}; use std::slice; use std::vec::IntoIter; use std::{iter, mem, option, u32}; use syntax::ast::Name; use syntax::symbol::Symbol; use syntax_pos::{Span, DUMMY_SP}; pub use crate::mir::interpret::AssertMessage; mod cache; pub mod interpret; pub mod mono; pub mod tcx; pub mod traversal; pub mod visit; /// Types for locals type LocalDecls<'tcx> = IndexVec>; pub trait HasLocalDecls<'tcx> { fn local_decls(&self) -> &LocalDecls<'tcx>; } impl<'tcx> HasLocalDecls<'tcx> for LocalDecls<'tcx> { fn local_decls(&self) -> &LocalDecls<'tcx> { self } } impl<'tcx> HasLocalDecls<'tcx> for Body<'tcx> { fn local_decls(&self) -> &LocalDecls<'tcx> { &self.local_decls } } /// The various "big phases" that MIR goes through. /// /// Warning: ordering of variants is significant. #[derive(Copy, Clone, RustcEncodable, RustcDecodable, HashStable, Debug, PartialEq, Eq, PartialOrd, Ord)] pub enum MirPhase { Build = 0, Const = 1, Validated = 2, Optimized = 3, } impl MirPhase { /// Gets the index of the current MirPhase within the set of all `MirPhase`s. pub fn phase_index(&self) -> usize { *self as usize } } /// The lowered representation of a single function. #[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable, TypeFoldable)] pub struct Body<'tcx> { /// A list of basic blocks. References to basic block use a newtyped index type `BasicBlock` /// that indexes into this vector. basic_blocks: IndexVec>, /// Records how far through the "desugaring and optimization" process this particular /// MIR has traversed. This is particularly useful when inlining, since in that context /// we instantiate the promoted constants and add them to our promoted vector -- but those /// promoted items have already been optimized, whereas ours have not. This field allows /// us to see the difference and forego optimization on the inlined promoted items. pub phase: MirPhase, /// A list of source scopes; these are referenced by statements /// and used for debuginfo. Indexed by a `SourceScope`. pub source_scopes: IndexVec, /// Crate-local information for each source scope, that can't (and /// needn't) be tracked across crates. pub source_scope_local_data: ClearCrossCrate>, /// The yield type of the function, if it is a generator. pub yield_ty: Option>, /// Generator drop glue. pub generator_drop: Option>>, /// The layout of a generator. Produced by the state transformation. pub generator_layout: Option>, /// If this is a generator then record the type of source expression that caused this generator /// to be created. pub generator_kind: Option, /// Declarations of locals. /// /// The first local is the return value pointer, followed by `arg_count` /// locals for the function arguments, followed by any user-declared /// variables and temporaries. pub local_decls: LocalDecls<'tcx>, /// User type annotations. pub user_type_annotations: CanonicalUserTypeAnnotations<'tcx>, /// The number of arguments this function takes. /// /// Starting at local 1, `arg_count` locals will be provided by the caller /// and can be assumed to be initialized. /// /// If this MIR was built for a constant, this will be 0. pub arg_count: usize, /// Mark an argument local (which must be a tuple) as getting passed as /// its individual components at the LLVM level. /// /// This is used for the "rust-call" ABI. pub spread_arg: Option, /// Debug information pertaining to user variables, including captures. pub var_debug_info: Vec>, /// Mark this MIR of a const context other than const functions as having converted a `&&` or /// `||` expression into `&` or `|` respectively. This is problematic because if we ever stop /// this conversion from happening and use short circuiting, we will cause the following code /// to change the value of `x`: `let mut x = 42; false && { x = 55; true };` /// /// List of places where control flow was destroyed. Used for error reporting. pub control_flow_destroyed: Vec<(Span, String)>, /// A span representing this MIR, for error reporting. pub span: Span, /// A cache for various calculations. cache: cache::Cache, } impl<'tcx> Body<'tcx> { pub fn new( basic_blocks: IndexVec>, source_scopes: IndexVec, source_scope_local_data: ClearCrossCrate>, local_decls: LocalDecls<'tcx>, user_type_annotations: CanonicalUserTypeAnnotations<'tcx>, arg_count: usize, var_debug_info: Vec>, span: Span, control_flow_destroyed: Vec<(Span, String)>, generator_kind : Option, ) -> Self { // We need `arg_count` locals, and one for the return place. assert!( local_decls.len() >= arg_count + 1, "expected at least {} locals, got {}", arg_count + 1, local_decls.len() ); Body { phase: MirPhase::Build, basic_blocks, source_scopes, source_scope_local_data, yield_ty: None, generator_drop: None, generator_layout: None, generator_kind, local_decls, user_type_annotations, arg_count, spread_arg: None, var_debug_info, span, cache: cache::Cache::new(), control_flow_destroyed, } } #[inline] pub fn basic_blocks(&self) -> &IndexVec> { &self.basic_blocks } #[inline] pub fn basic_blocks_mut(&mut self) -> &mut IndexVec> { self.cache.invalidate(); &mut self.basic_blocks } #[inline] pub fn basic_blocks_and_local_decls_mut( &mut self, ) -> (&mut IndexVec>, &mut LocalDecls<'tcx>) { self.cache.invalidate(); (&mut self.basic_blocks, &mut self.local_decls) } #[inline] pub fn predecessors(&self) -> MappedReadGuard<'_, IndexVec>> { self.cache.predecessors(self) } #[inline] pub fn predecessors_for(&self, bb: BasicBlock) -> MappedReadGuard<'_, Vec> { MappedReadGuard::map(self.predecessors(), |p| &p[bb]) } #[inline] pub fn predecessor_locations(&self, loc: Location) -> impl Iterator + '_ { let if_zero_locations = if loc.statement_index == 0 { let predecessor_blocks = self.predecessors_for(loc.block); let num_predecessor_blocks = predecessor_blocks.len(); Some( (0..num_predecessor_blocks) .map(move |i| predecessor_blocks[i]) .map(move |bb| self.terminator_loc(bb)), ) } else { None }; let if_not_zero_locations = if loc.statement_index == 0 { None } else { Some(Location { block: loc.block, statement_index: loc.statement_index - 1 }) }; if_zero_locations.into_iter().flatten().chain(if_not_zero_locations) } #[inline] pub fn dominators(&self) -> Dominators { dominators(self) } /// Returns `true` if a cycle exists in the control-flow graph that is reachable from the /// `START_BLOCK`. pub fn is_cfg_cyclic(&self) -> bool { graph::is_cyclic(self) } #[inline] pub fn local_kind(&self, local: Local) -> LocalKind { let index = local.as_usize(); if index == 0 { debug_assert!( self.local_decls[local].mutability == Mutability::Mut, "return place should be mutable" ); LocalKind::ReturnPointer } else if index < self.arg_count + 1 { LocalKind::Arg } else if self.local_decls[local].is_user_variable() { LocalKind::Var } else { LocalKind::Temp } } /// Returns an iterator over all temporaries. #[inline] pub fn temps_iter<'a>(&'a self) -> impl Iterator + 'a { (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { let local = Local::new(index); if self.local_decls[local].is_user_variable() { None } else { Some(local) } }) } /// Returns an iterator over all user-declared locals. #[inline] pub fn vars_iter<'a>(&'a self) -> impl Iterator + 'a { (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { let local = Local::new(index); if self.local_decls[local].is_user_variable() { Some(local) } else { None } }) } /// Returns an iterator over all user-declared mutable locals. #[inline] pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator + 'a { (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| { let local = Local::new(index); let decl = &self.local_decls[local]; if decl.is_user_variable() && decl.mutability == Mutability::Mut { Some(local) } else { None } }) } /// Returns an iterator over all user-declared mutable arguments and locals. #[inline] pub fn mut_vars_and_args_iter<'a>(&'a self) -> impl Iterator + 'a { (1..self.local_decls.len()).filter_map(move |index| { let local = Local::new(index); let decl = &self.local_decls[local]; if (decl.is_user_variable() || index < self.arg_count + 1) && decl.mutability == Mutability::Mut { Some(local) } else { None } }) } /// Returns an iterator over all function arguments. #[inline] pub fn args_iter(&self) -> impl Iterator { let arg_count = self.arg_count; (1..=arg_count).map(Local::new) } /// Returns an iterator over all user-defined variables and compiler-generated temporaries (all /// locals that are neither arguments nor the return place). #[inline] pub fn vars_and_temps_iter(&self) -> impl Iterator { let arg_count = self.arg_count; let local_count = self.local_decls.len(); (arg_count + 1..local_count).map(Local::new) } /// Changes a statement to a nop. This is both faster than deleting instructions and avoids /// invalidating statement indices in `Location`s. pub fn make_statement_nop(&mut self, location: Location) { let block = &mut self[location.block]; debug_assert!(location.statement_index < block.statements.len()); block.statements[location.statement_index].make_nop() } /// Returns the source info associated with `location`. pub fn source_info(&self, location: Location) -> &SourceInfo { let block = &self[location.block]; let stmts = &block.statements; let idx = location.statement_index; if idx < stmts.len() { &stmts[idx].source_info } else { assert_eq!(idx, stmts.len()); &block.terminator().source_info } } /// Checks if `sub` is a sub scope of `sup` pub fn is_sub_scope(&self, mut sub: SourceScope, sup: SourceScope) -> bool { while sub != sup { match self.source_scopes[sub].parent_scope { None => return false, Some(p) => sub = p, } } true } /// Returns the return type; it always return first element from `local_decls` array. pub fn return_ty(&self) -> Ty<'tcx> { self.local_decls[RETURN_PLACE].ty } /// Gets the location of the terminator for the given block. pub fn terminator_loc(&self, bb: BasicBlock) -> Location { Location { block: bb, statement_index: self[bb].statements.len() } } } #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub enum Safety { Safe, /// Unsafe because of a PushUnsafeBlock BuiltinUnsafe, /// Unsafe because of an unsafe fn FnUnsafe, /// Unsafe because of an `unsafe` block ExplicitUnsafe(hir::HirId), } impl<'tcx> Index for Body<'tcx> { type Output = BasicBlockData<'tcx>; #[inline] fn index(&self, index: BasicBlock) -> &BasicBlockData<'tcx> { &self.basic_blocks()[index] } } impl<'tcx> IndexMut for Body<'tcx> { #[inline] fn index_mut(&mut self, index: BasicBlock) -> &mut BasicBlockData<'tcx> { &mut self.basic_blocks_mut()[index] } } #[derive(Copy, Clone, Debug, HashStable, TypeFoldable)] pub enum ClearCrossCrate { Clear, Set(T), } impl ClearCrossCrate { pub fn assert_crate_local(self) -> T { match self { ClearCrossCrate::Clear => bug!("unwrapping cross-crate data"), ClearCrossCrate::Set(v) => v, } } } impl rustc_serialize::UseSpecializedEncodable for ClearCrossCrate {} impl rustc_serialize::UseSpecializedDecodable for ClearCrossCrate {} /// Grouped information about the source code origin of a MIR entity. /// Intended to be inspected by diagnostics and debuginfo. /// Most passes can work with it as a whole, within a single function. // The unofficial Cranelift backend, at least as of #65828, needs `SourceInfo` to implement `Eq` and // `Hash`. Please ping @bjorn3 if removing them. #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Hash, HashStable)] pub struct SourceInfo { /// The source span for the AST pertaining to this MIR entity. pub span: Span, /// The source scope, keeping track of which bindings can be /// seen by debuginfo, active lint levels, `unsafe {...}`, etc. pub scope: SourceScope, } /////////////////////////////////////////////////////////////////////////// // Mutability and borrow kinds #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum Mutability { Mut, Not, } impl From for hir::Mutability { fn from(m: Mutability) -> Self { match m { Mutability::Mut => hir::Mutability::Mutable, Mutability::Not => hir::Mutability::Immutable, } } } #[derive( Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, HashStable, )] pub enum BorrowKind { /// Data must be immutable and is aliasable. Shared, /// The immediately borrowed place must be immutable, but projections from /// it don't need to be. For example, a shallow borrow of `a.b` doesn't /// conflict with a mutable borrow of `a.b.c`. /// /// This is used when lowering matches: when matching on a place we want to /// ensure that place have the same value from the start of the match until /// an arm is selected. This prevents this code from compiling: /// /// let mut x = &Some(0); /// match *x { /// None => (), /// Some(_) if { x = &None; false } => (), /// Some(_) => (), /// } /// /// This can't be a shared borrow because mutably borrowing (*x as Some).0 /// should not prevent `if let None = x { ... }`, for example, because the /// mutating `(*x as Some).0` can't affect the discriminant of `x`. /// We can also report errors with this kind of borrow differently. Shallow, /// Data must be immutable but not aliasable. This kind of borrow /// cannot currently be expressed by the user and is used only in /// implicit closure bindings. It is needed when the closure is /// borrowing or mutating a mutable referent, e.g.: /// /// let x: &mut isize = ...; /// let y = || *x += 5; /// /// If we were to try to translate this closure into a more explicit /// form, we'd encounter an error with the code as written: /// /// struct Env { x: & &mut isize } /// let x: &mut isize = ...; /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn /// fn fn_ptr(env: &mut Env) { **env.x += 5; } /// /// This is then illegal because you cannot mutate an `&mut` found /// in an aliasable location. To solve, you'd have to translate with /// an `&mut` borrow: /// /// struct Env { x: & &mut isize } /// let x: &mut isize = ...; /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x /// fn fn_ptr(env: &mut Env) { **env.x += 5; } /// /// Now the assignment to `**env.x` is legal, but creating a /// mutable pointer to `x` is not because `x` is not mutable. We /// could fix this by declaring `x` as `let mut x`. This is ok in /// user code, if awkward, but extra weird for closures, since the /// borrow is hidden. /// /// So we introduce a "unique imm" borrow -- the referent is /// immutable, but not aliasable. This solves the problem. For /// simplicity, we don't give users the way to express this /// borrow, it's just used when translating closures. Unique, /// Data is mutable and not aliasable. Mut { /// `true` if this borrow arose from method-call auto-ref /// (i.e., `adjustment::Adjust::Borrow`). allow_two_phase_borrow: bool, }, } impl BorrowKind { pub fn allows_two_phase_borrow(&self) -> bool { match *self { BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => false, BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow, } } } /////////////////////////////////////////////////////////////////////////// // Variables and temps rustc_index::newtype_index! { pub struct Local { derive [HashStable] DEBUG_FORMAT = "_{}", const RETURN_PLACE = 0, } } impl Atom for Local { fn index(self) -> usize { Idx::index(self) } } /// Classifies locals into categories. See `Body::local_kind`. #[derive(PartialEq, Eq, Debug, HashStable)] pub enum LocalKind { /// User-declared variable binding. Var, /// Compiler-introduced temporary. Temp, /// Function argument. Arg, /// Location of function's return value. ReturnPointer, } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct VarBindingForm<'tcx> { /// Is variable bound via `x`, `mut x`, `ref x`, or `ref mut x`? pub binding_mode: ty::BindingMode, /// If an explicit type was provided for this variable binding, /// this holds the source Span of that type. /// /// NOTE: if you want to change this to a `HirId`, be wary that /// doing so breaks incremental compilation (as of this writing), /// while a `Span` does not cause our tests to fail. pub opt_ty_info: Option, /// Place of the RHS of the =, or the subject of the `match` where this /// variable is initialized. None in the case of `let PATTERN;`. /// Some((None, ..)) in the case of and `let [mut] x = ...` because /// (a) the right-hand side isn't evaluated as a place expression. /// (b) it gives a way to separate this case from the remaining cases /// for diagnostics. pub opt_match_place: Option<(Option>, Span)>, /// The span of the pattern in which this variable was bound. pub pat_span: Span, } #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] pub enum BindingForm<'tcx> { /// This is a binding for a non-`self` binding, or a `self` that has an explicit type. Var(VarBindingForm<'tcx>), /// Binding for a `self`/`&self`/`&mut self` binding where the type is implicit. ImplicitSelf(ImplicitSelfKind), /// Reference used in a guard expression to ensure immutability. RefForGuard, } /// Represents what type of implicit self a function has, if any. #[derive(Clone, Copy, PartialEq, Debug, RustcEncodable, RustcDecodable, HashStable)] pub enum ImplicitSelfKind { /// Represents a `fn x(self);`. Imm, /// Represents a `fn x(mut self);`. Mut, /// Represents a `fn x(&self);`. ImmRef, /// Represents a `fn x(&mut self);`. MutRef, /// Represents when a function does not have a self argument or /// when a function has a `self: X` argument. None, } CloneTypeFoldableAndLiftImpls! { BindingForm<'tcx>, } mod binding_form_impl { use crate::ich::StableHashingContext; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; impl<'a, 'tcx> HashStable> for super::BindingForm<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { use super::BindingForm::*; ::std::mem::discriminant(self).hash_stable(hcx, hasher); match self { Var(binding) => binding.hash_stable(hcx, hasher), ImplicitSelf(kind) => kind.hash_stable(hcx, hasher), RefForGuard => (), } } } } /// `BlockTailInfo` is attached to the `LocalDecl` for temporaries /// created during evaluation of expressions in a block tail /// expression; that is, a block like `{ STMT_1; STMT_2; EXPR }`. /// /// It is used to improve diagnostics when such temporaries are /// involved in borrow_check errors, e.g., explanations of where the /// temporaries come from, when their destructors are run, and/or how /// one might revise the code to satisfy the borrow checker's rules. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct BlockTailInfo { /// If `true`, then the value resulting from evaluating this tail /// expression is ignored by the block's expression context. /// /// Examples include `{ ...; tail };` and `let _ = { ...; tail };` /// but not e.g., `let _x = { ...; tail };` pub tail_result_is_ignored: bool, } /// A MIR local. /// /// This can be a binding declared by the user, a temporary inserted by the compiler, a function /// argument, or the return place. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct LocalDecl<'tcx> { /// Whether this is a mutable minding (i.e., `let x` or `let mut x`). /// /// Temporaries and the return place are always mutable. pub mutability: Mutability, // FIXME(matthewjasper) Don't store in this in `Body` pub local_info: LocalInfo<'tcx>, /// `true` if this is an internal local. /// /// These locals are not based on types in the source code and are only used /// for a few desugarings at the moment. /// /// The generator transformation will sanity check the locals which are live /// across a suspension point against the type components of the generator /// which type checking knows are live across a suspension point. We need to /// flag drop flags to avoid triggering this check as they are introduced /// after typeck. /// /// Unsafety checking will also ignore dereferences of these locals, /// so they can be used for raw pointers only used in a desugaring. /// /// This should be sound because the drop flags are fully algebraic, and /// therefore don't affect the OIBIT or outlives properties of the /// generator. pub internal: bool, /// If this local is a temporary and `is_block_tail` is `Some`, /// then it is a temporary created for evaluation of some /// subexpression of some block's tail expression (with no /// intervening statement context). // FIXME(matthewjasper) Don't store in this in `Body` pub is_block_tail: Option, /// The type of this local. pub ty: Ty<'tcx>, /// If the user manually ascribed a type to this variable, /// e.g., via `let x: T`, then we carry that type here. The MIR /// borrow checker needs this information since it can affect /// region inference. // FIXME(matthewjasper) Don't store in this in `Body` pub user_ty: UserTypeProjections, /// The *syntactic* (i.e., not visibility) source scope the local is defined /// in. If the local was defined in a let-statement, this /// is *within* the let-statement, rather than outside /// of it. /// /// This is needed because the visibility source scope of locals within /// a let-statement is weird. /// /// The reason is that we want the local to be *within* the let-statement /// for lint purposes, but we want the local to be *after* the let-statement /// for names-in-scope purposes. /// /// That's it, if we have a let-statement like the one in this /// function: /// /// ``` /// fn foo(x: &str) { /// #[allow(unused_mut)] /// let mut x: u32 = { // <- one unused mut /// let mut y: u32 = x.parse().unwrap(); /// y + 2 /// }; /// drop(x); /// } /// ``` /// /// Then, from a lint point of view, the declaration of `x: u32` /// (and `y: u32`) are within the `#[allow(unused_mut)]` scope - the /// lint scopes are the same as the AST/HIR nesting. /// /// However, from a name lookup point of view, the scopes look more like /// as if the let-statements were `match` expressions: /// /// ``` /// fn foo(x: &str) { /// match { /// match x.parse().unwrap() { /// y => y + 2 /// } /// } { /// x => drop(x) /// }; /// } /// ``` /// /// We care about the name-lookup scopes for debuginfo - if the /// debuginfo instruction pointer is at the call to `x.parse()`, we /// want `x` to refer to `x: &str`, but if it is at the call to /// `drop(x)`, we want it to refer to `x: u32`. /// /// To allow both uses to work, we need to have more than a single scope /// for a local. We have the `source_info.scope` represent the "syntactic" /// lint scope (with a variable being under its let block) while the /// `var_debug_info.source_info.scope` represents the "local variable" /// scope (where the "rest" of a block is under all prior let-statements). /// /// The end result looks like this: /// /// ```text /// ROOT SCOPE /// │{ argument x: &str } /// │ /// │ │{ #[allow(unused_mut)] } // This is actually split into 2 scopes /// │ │ // in practice because I'm lazy. /// │ │ /// │ │← x.source_info.scope /// │ │← `x.parse().unwrap()` /// │ │ /// │ │ │← y.source_info.scope /// │ │ /// │ │ │{ let y: u32 } /// │ │ │ /// │ │ │← y.var_debug_info.source_info.scope /// │ │ │← `y + 2` /// │ /// │ │{ let x: u32 } /// │ │← x.var_debug_info.source_info.scope /// │ │← `drop(x)` // This accesses `x: u32`. /// ``` pub source_info: SourceInfo, } /// Extra information about a local that's used for diagnostics. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub enum LocalInfo<'tcx> { /// A user-defined local variable or function parameter /// /// The `BindingForm` is solely used for local diagnostics when generating /// warnings/errors when compiling the current crate, and therefore it need /// not be visible across crates. User(ClearCrossCrate>), /// A temporary created that references the static with the given `DefId`. StaticRef { def_id: DefId, is_thread_local: bool }, /// Any other temporary, the return place, or an anonymous function parameter. Other, } impl<'tcx> LocalDecl<'tcx> { /// Returns `true` only if local is a binding that can itself be /// made mutable via the addition of the `mut` keyword, namely /// something like the occurrences of `x` in: /// - `fn foo(x: Type) { ... }`, /// - `let x = ...`, /// - or `match ... { C(x) => ... }` pub fn can_be_made_mutable(&self) -> bool { match self.local_info { LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm { binding_mode: ty::BindingMode::BindByValue(_), opt_ty_info: _, opt_match_place: _, pat_span: _, }))) => true, LocalInfo::User( ClearCrossCrate::Set(BindingForm::ImplicitSelf(ImplicitSelfKind::Imm)), ) => true, _ => false, } } /// Returns `true` if local is definitely not a `ref ident` or /// `ref mut ident` binding. (Such bindings cannot be made into /// mutable bindings, but the inverse does not necessarily hold). pub fn is_nonref_binding(&self) -> bool { match self.local_info { LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm { binding_mode: ty::BindingMode::BindByValue(_), opt_ty_info: _, opt_match_place: _, pat_span: _, }))) => true, LocalInfo::User(ClearCrossCrate::Set(BindingForm::ImplicitSelf(_))) => true, _ => false, } } /// Returns `true` if this variable is a named variable or function /// parameter declared by the user. #[inline] pub fn is_user_variable(&self) -> bool { match self.local_info { LocalInfo::User(_) => true, _ => false, } } /// Returns `true` if this is a reference to a variable bound in a `match` /// expression that is used to access said variable for the guard of the /// match arm. pub fn is_ref_for_guard(&self) -> bool { match self.local_info { LocalInfo::User(ClearCrossCrate::Set(BindingForm::RefForGuard)) => true, _ => false, } } /// Returns `Some` if this is a reference to a static item that is used to /// access that static pub fn is_ref_to_static(&self) -> bool { match self.local_info { LocalInfo::StaticRef { .. } => true, _ => false, } } /// Returns `Some` if this is a reference to a static item that is used to /// access that static pub fn is_ref_to_thread_local(&self) -> bool { match self.local_info { LocalInfo::StaticRef { is_thread_local, .. } => is_thread_local, _ => false, } } /// Returns `true` is the local is from a compiler desugaring, e.g., /// `__next` from a `for` loop. #[inline] pub fn from_compiler_desugaring(&self) -> bool { self.source_info.span.desugaring_kind().is_some() } /// Creates a new `LocalDecl` for a temporary. #[inline] pub fn new_temp(ty: Ty<'tcx>, span: Span) -> Self { Self::new_local(ty, Mutability::Mut, false, span) } /// Converts `self` into same `LocalDecl` except tagged as immutable. #[inline] pub fn immutable(mut self) -> Self { self.mutability = Mutability::Not; self } /// Converts `self` into same `LocalDecl` except tagged as internal temporary. #[inline] pub fn block_tail(mut self, info: BlockTailInfo) -> Self { assert!(self.is_block_tail.is_none()); self.is_block_tail = Some(info); self } /// Creates a new `LocalDecl` for a internal temporary. #[inline] pub fn new_internal(ty: Ty<'tcx>, span: Span) -> Self { Self::new_local(ty, Mutability::Mut, true, span) } #[inline] fn new_local(ty: Ty<'tcx>, mutability: Mutability, internal: bool, span: Span) -> Self { LocalDecl { mutability, ty, user_ty: UserTypeProjections::none(), source_info: SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE }, internal, local_info: LocalInfo::Other, is_block_tail: None, } } /// Builds a `LocalDecl` for the return place. /// /// This must be inserted into the `local_decls` list as the first local. #[inline] pub fn new_return_place(return_ty: Ty<'_>, span: Span) -> LocalDecl<'_> { LocalDecl { mutability: Mutability::Mut, ty: return_ty, user_ty: UserTypeProjections::none(), source_info: SourceInfo { span, scope: OUTERMOST_SOURCE_SCOPE }, internal: false, is_block_tail: None, local_info: LocalInfo::Other, } } } /// Debug information pertaining to a user variable. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct VarDebugInfo<'tcx> { pub name: Name, /// Source info of the user variable, including the scope /// within which the variable is visible (to debuginfo) /// (see `LocalDecl`'s `source_info` field for more details). pub source_info: SourceInfo, /// Where the data for this user variable is to be found. /// NOTE(eddyb) There's an unenforced invariant that this `Place` is /// based on a `Local`, not a `Static`, and contains no indexing. pub place: Place<'tcx>, } /////////////////////////////////////////////////////////////////////////// // BasicBlock rustc_index::newtype_index! { pub struct BasicBlock { derive [HashStable] DEBUG_FORMAT = "bb{}", const START_BLOCK = 0, } } impl BasicBlock { pub fn start_location(self) -> Location { Location { block: self, statement_index: 0 } } } /////////////////////////////////////////////////////////////////////////// // BasicBlockData and Terminator #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct BasicBlockData<'tcx> { /// List of statements in this block. pub statements: Vec>, /// Terminator for this block. /// /// N.B., this should generally ONLY be `None` during construction. /// Therefore, you should generally access it via the /// `terminator()` or `terminator_mut()` methods. The only /// exception is that certain passes, such as `simplify_cfg`, swap /// out the terminator temporarily with `None` while they continue /// to recurse over the set of basic blocks. pub terminator: Option>, /// If true, this block lies on an unwind path. This is used /// during codegen where distinct kinds of basic blocks may be /// generated (particularly for MSVC cleanup). Unwind blocks must /// only branch to other unwind blocks. pub is_cleanup: bool, } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct Terminator<'tcx> { pub source_info: SourceInfo, pub kind: TerminatorKind<'tcx>, } #[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)] pub enum TerminatorKind<'tcx> { /// Block should have one successor in the graph; we jump there. Goto { target: BasicBlock }, /// Operand evaluates to an integer; jump depending on its value /// to one of the targets, and otherwise fallback to `otherwise`. SwitchInt { /// The discriminant value being tested. discr: Operand<'tcx>, /// The type of value being tested. switch_ty: Ty<'tcx>, /// Possible values. The locations to branch to in each case /// are found in the corresponding indices from the `targets` vector. values: Cow<'tcx, [u128]>, /// Possible branch sites. The last element of this vector is used /// for the otherwise branch, so targets.len() == values.len() + 1 /// should hold. // // This invariant is quite non-obvious and also could be improved. // One way to make this invariant is to have something like this instead: // // branches: Vec<(ConstInt, BasicBlock)>, // otherwise: Option // exhaustive if None // // However we’ve decided to keep this as-is until we figure a case // where some other approach seems to be strictly better than other. targets: Vec, }, /// Indicates that the landing pad is finished and unwinding should /// continue. Emitted by `build::scope::diverge_cleanup`. Resume, /// Indicates that the landing pad is finished and that the process /// should abort. Used to prevent unwinding for foreign items. Abort, /// Indicates a normal return. The return place should have /// been filled in by now. This should occur at most once. Return, /// Indicates a terminator that can never be reached. Unreachable, /// Drop the `Place`. Drop { location: Place<'tcx>, target: BasicBlock, unwind: Option }, /// Drop the `Place` and assign the new value over it. This ensures /// that the assignment to `P` occurs *even if* the destructor for /// place unwinds. Its semantics are best explained by the /// elaboration: /// /// ``` /// BB0 { /// DropAndReplace(P <- V, goto BB1, unwind BB2) /// } /// ``` /// /// becomes /// /// ``` /// BB0 { /// Drop(P, goto BB1, unwind BB2) /// } /// BB1 { /// // P is now uninitialized /// P <- V /// } /// BB2 { /// // P is now uninitialized -- its dtor panicked /// P <- V /// } /// ``` DropAndReplace { location: Place<'tcx>, value: Operand<'tcx>, target: BasicBlock, unwind: Option, }, /// Block ends with a call of a converging function. Call { /// The function that’s being called. func: Operand<'tcx>, /// Arguments the function is called with. /// These are owned by the callee, which is free to modify them. /// This allows the memory occupied by "by-value" arguments to be /// reused across function calls without duplicating the contents. args: Vec>, /// Destination for the return value. If some, the call is converging. destination: Option<(Place<'tcx>, BasicBlock)>, /// Cleanups to be done if the call unwinds. cleanup: Option, /// `true` if this is from a call in HIR rather than from an overloaded /// operator. True for overloaded function call. from_hir_call: bool, }, /// Jump to the target if the condition has the expected value, /// otherwise panic with a message and a cleanup target. Assert { cond: Operand<'tcx>, expected: bool, msg: AssertMessage<'tcx>, target: BasicBlock, cleanup: Option, }, /// A suspend point. Yield { /// The value to return. value: Operand<'tcx>, /// Where to resume to. resume: BasicBlock, /// Cleanup to be done if the generator is dropped at this suspend point. drop: Option, }, /// Indicates the end of the dropping of a generator. GeneratorDrop, /// A block where control flow only ever takes one real path, but borrowck /// needs to be more conservative. FalseEdges { /// The target normal control flow will take. real_target: BasicBlock, /// A block control flow could conceptually jump to, but won't in /// practice. imaginary_target: BasicBlock, }, /// A terminator for blocks that only take one path in reality, but where we /// reserve the right to unwind in borrowck, even if it won't happen in practice. /// This can arise in infinite loops with no function calls for example. FalseUnwind { /// The target normal control flow will take. real_target: BasicBlock, /// The imaginary cleanup block link. This particular path will never be taken /// in practice, but in order to avoid fragility we want to always /// consider it in borrowck. We don't want to accept programs which /// pass borrowck only when `panic=abort` or some assertions are disabled /// due to release vs. debug mode builds. This needs to be an `Option` because /// of the `remove_noop_landing_pads` and `no_landing_pads` passes. unwind: Option, }, } pub type Successors<'a> = iter::Chain, slice::Iter<'a, BasicBlock>>; pub type SuccessorsMut<'a> = iter::Chain, slice::IterMut<'a, BasicBlock>>; impl<'tcx> Terminator<'tcx> { pub fn successors(&self) -> Successors<'_> { self.kind.successors() } pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { self.kind.successors_mut() } pub fn unwind(&self) -> Option<&Option> { self.kind.unwind() } pub fn unwind_mut(&mut self) -> Option<&mut Option> { self.kind.unwind_mut() } } impl<'tcx> TerminatorKind<'tcx> { pub fn if_( tcx: TyCtxt<'tcx>, cond: Operand<'tcx>, t: BasicBlock, f: BasicBlock, ) -> TerminatorKind<'tcx> { static BOOL_SWITCH_FALSE: &'static [u128] = &[0]; TerminatorKind::SwitchInt { discr: cond, switch_ty: tcx.types.bool, values: From::from(BOOL_SWITCH_FALSE), targets: vec![f, t], } } pub fn successors(&self) -> Successors<'_> { use self::TerminatorKind::*; match *self { Resume | Abort | GeneratorDrop | Return | Unreachable | Call { destination: None, cleanup: None, .. } => None.into_iter().chain(&[]), Goto { target: ref t } | Call { destination: None, cleanup: Some(ref t), .. } | Call { destination: Some((_, ref t)), cleanup: None, .. } | Yield { resume: ref t, drop: None, .. } | DropAndReplace { target: ref t, unwind: None, .. } | Drop { target: ref t, unwind: None, .. } | Assert { target: ref t, cleanup: None, .. } | FalseUnwind { real_target: ref t, unwind: None } => Some(t).into_iter().chain(&[]), Call { destination: Some((_, ref t)), cleanup: Some(ref u), .. } | Yield { resume: ref t, drop: Some(ref u), .. } | DropAndReplace { target: ref t, unwind: Some(ref u), .. } | Drop { target: ref t, unwind: Some(ref u), .. } | Assert { target: ref t, cleanup: Some(ref u), .. } | FalseUnwind { real_target: ref t, unwind: Some(ref u) } => { Some(t).into_iter().chain(slice::from_ref(u)) } SwitchInt { ref targets, .. } => None.into_iter().chain(&targets[..]), FalseEdges { ref real_target, ref imaginary_target } => { Some(real_target).into_iter().chain(slice::from_ref(imaginary_target)) } } } pub fn successors_mut(&mut self) -> SuccessorsMut<'_> { use self::TerminatorKind::*; match *self { Resume | Abort | GeneratorDrop | Return | Unreachable | Call { destination: None, cleanup: None, .. } => None.into_iter().chain(&mut []), Goto { target: ref mut t } | Call { destination: None, cleanup: Some(ref mut t), .. } | Call { destination: Some((_, ref mut t)), cleanup: None, .. } | Yield { resume: ref mut t, drop: None, .. } | DropAndReplace { target: ref mut t, unwind: None, .. } | Drop { target: ref mut t, unwind: None, .. } | Assert { target: ref mut t, cleanup: None, .. } | FalseUnwind { real_target: ref mut t, unwind: None } => { Some(t).into_iter().chain(&mut []) } Call { destination: Some((_, ref mut t)), cleanup: Some(ref mut u), .. } | Yield { resume: ref mut t, drop: Some(ref mut u), .. } | DropAndReplace { target: ref mut t, unwind: Some(ref mut u), .. } | Drop { target: ref mut t, unwind: Some(ref mut u), .. } | Assert { target: ref mut t, cleanup: Some(ref mut u), .. } | FalseUnwind { real_target: ref mut t, unwind: Some(ref mut u) } => { Some(t).into_iter().chain(slice::from_mut(u)) } SwitchInt { ref mut targets, .. } => None.into_iter().chain(&mut targets[..]), FalseEdges { ref mut real_target, ref mut imaginary_target } => { Some(real_target).into_iter().chain(slice::from_mut(imaginary_target)) } } } pub fn unwind(&self) -> Option<&Option> { match *self { TerminatorKind::Goto { .. } | TerminatorKind::Resume | TerminatorKind::Abort | TerminatorKind::Return | TerminatorKind::Unreachable | TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } | TerminatorKind::SwitchInt { .. } | TerminatorKind::FalseEdges { .. } => None, TerminatorKind::Call { cleanup: ref unwind, .. } | TerminatorKind::Assert { cleanup: ref unwind, .. } | TerminatorKind::DropAndReplace { ref unwind, .. } | TerminatorKind::Drop { ref unwind, .. } | TerminatorKind::FalseUnwind { ref unwind, .. } => Some(unwind), } } pub fn unwind_mut(&mut self) -> Option<&mut Option> { match *self { TerminatorKind::Goto { .. } | TerminatorKind::Resume | TerminatorKind::Abort | TerminatorKind::Return | TerminatorKind::Unreachable | TerminatorKind::GeneratorDrop | TerminatorKind::Yield { .. } | TerminatorKind::SwitchInt { .. } | TerminatorKind::FalseEdges { .. } => None, TerminatorKind::Call { cleanup: ref mut unwind, .. } | TerminatorKind::Assert { cleanup: ref mut unwind, .. } | TerminatorKind::DropAndReplace { ref mut unwind, .. } | TerminatorKind::Drop { ref mut unwind, .. } | TerminatorKind::FalseUnwind { ref mut unwind, .. } => Some(unwind), } } } impl<'tcx> BasicBlockData<'tcx> { pub fn new(terminator: Option>) -> BasicBlockData<'tcx> { BasicBlockData { statements: vec![], terminator, is_cleanup: false } } /// Accessor for terminator. /// /// Terminator may not be None after construction of the basic block is complete. This accessor /// provides a convenience way to reach the terminator. pub fn terminator(&self) -> &Terminator<'tcx> { self.terminator.as_ref().expect("invalid terminator state") } pub fn terminator_mut(&mut self) -> &mut Terminator<'tcx> { self.terminator.as_mut().expect("invalid terminator state") } pub fn retain_statements(&mut self, mut f: F) where F: FnMut(&mut Statement<'_>) -> bool, { for s in &mut self.statements { if !f(s) { s.make_nop(); } } } pub fn expand_statements(&mut self, mut f: F) where F: FnMut(&mut Statement<'tcx>) -> Option, I: iter::TrustedLen>, { // Gather all the iterators we'll need to splice in, and their positions. let mut splices: Vec<(usize, I)> = vec![]; let mut extra_stmts = 0; for (i, s) in self.statements.iter_mut().enumerate() { if let Some(mut new_stmts) = f(s) { if let Some(first) = new_stmts.next() { // We can already store the first new statement. *s = first; // Save the other statements for optimized splicing. let remaining = new_stmts.size_hint().0; if remaining > 0 { splices.push((i + 1 + extra_stmts, new_stmts)); extra_stmts += remaining; } } else { s.make_nop(); } } } // Splice in the new statements, from the end of the block. // FIXME(eddyb) This could be more efficient with a "gap buffer" // where a range of elements ("gap") is left uninitialized, with // splicing adding new elements to the end of that gap and moving // existing elements from before the gap to the end of the gap. // For now, this is safe code, emulating a gap but initializing it. let mut gap = self.statements.len()..self.statements.len() + extra_stmts; self.statements.resize( gap.end, Statement { source_info: SourceInfo { span: DUMMY_SP, scope: OUTERMOST_SOURCE_SCOPE }, kind: StatementKind::Nop, }, ); for (splice_start, new_stmts) in splices.into_iter().rev() { let splice_end = splice_start + new_stmts.size_hint().0; while gap.end > splice_end { gap.start -= 1; gap.end -= 1; self.statements.swap(gap.start, gap.end); } self.statements.splice(splice_start..splice_end, new_stmts); gap.end = splice_start; } } pub fn visitable(&self, index: usize) -> &dyn MirVisitable<'tcx> { if index < self.statements.len() { &self.statements[index] } else { &self.terminator } } } impl<'tcx> Debug for TerminatorKind<'tcx> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { self.fmt_head(fmt)?; let successor_count = self.successors().count(); let labels = self.fmt_successor_labels(); assert_eq!(successor_count, labels.len()); match successor_count { 0 => Ok(()), 1 => write!(fmt, " -> {:?}", self.successors().nth(0).unwrap()), _ => { write!(fmt, " -> [")?; for (i, target) in self.successors().enumerate() { if i > 0 { write!(fmt, ", ")?; } write!(fmt, "{}: {:?}", labels[i], target)?; } write!(fmt, "]") } } } } impl<'tcx> TerminatorKind<'tcx> { /// Writes the "head" part of the terminator; that is, its name and the data it uses to pick the /// successor basic block, if any. The only information not included is the list of possible /// successors, which may be rendered differently between the text and the graphviz format. pub fn fmt_head(&self, fmt: &mut W) -> fmt::Result { use self::TerminatorKind::*; match *self { Goto { .. } => write!(fmt, "goto"), SwitchInt { discr: ref place, .. } => write!(fmt, "switchInt({:?})", place), Return => write!(fmt, "return"), GeneratorDrop => write!(fmt, "generator_drop"), Resume => write!(fmt, "resume"), Abort => write!(fmt, "abort"), Yield { ref value, .. } => write!(fmt, "_1 = suspend({:?})", value), Unreachable => write!(fmt, "unreachable"), Drop { ref location, .. } => write!(fmt, "drop({:?})", location), DropAndReplace { ref location, ref value, .. } => { write!(fmt, "replace({:?} <- {:?})", location, value) } Call { ref func, ref args, ref destination, .. } => { if let Some((ref destination, _)) = *destination { write!(fmt, "{:?} = ", destination)?; } write!(fmt, "{:?}(", func)?; for (index, arg) in args.iter().enumerate() { if index > 0 { write!(fmt, ", ")?; } write!(fmt, "{:?}", arg)?; } write!(fmt, ")") } Assert { ref cond, expected, ref msg, .. } => { write!(fmt, "assert(")?; if !expected { write!(fmt, "!")?; } write!(fmt, "{:?}, \"{:?}\")", cond, msg) } FalseEdges { .. } => write!(fmt, "falseEdges"), FalseUnwind { .. } => write!(fmt, "falseUnwind"), } } /// Returns the list of labels for the edges to the successor basic blocks. pub fn fmt_successor_labels(&self) -> Vec> { use self::TerminatorKind::*; match *self { Return | Resume | Abort | Unreachable | GeneratorDrop => vec![], Goto { .. } => vec!["".into()], SwitchInt { ref values, switch_ty, .. } => ty::tls::with(|tcx| { let param_env = ty::ParamEnv::empty(); let switch_ty = tcx.lift(&switch_ty).unwrap(); let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size; values .iter() .map(|&u| { ty::Const::from_scalar( tcx, Scalar::from_uint(u, size).into(), switch_ty, ) .to_string() .into() }) .chain(iter::once("otherwise".into())) .collect() }), Call { destination: Some(_), cleanup: Some(_), .. } => { vec!["return".into(), "unwind".into()] } Call { destination: Some(_), cleanup: None, .. } => vec!["return".into()], Call { destination: None, cleanup: Some(_), .. } => vec!["unwind".into()], Call { destination: None, cleanup: None, .. } => vec![], Yield { drop: Some(_), .. } => vec!["resume".into(), "drop".into()], Yield { drop: None, .. } => vec!["resume".into()], DropAndReplace { unwind: None, .. } | Drop { unwind: None, .. } => { vec!["return".into()] } DropAndReplace { unwind: Some(_), .. } | Drop { unwind: Some(_), .. } => { vec!["return".into(), "unwind".into()] } Assert { cleanup: None, .. } => vec!["".into()], Assert { .. } => vec!["success".into(), "unwind".into()], FalseEdges { .. } => vec!["real".into(), "imaginary".into()], FalseUnwind { unwind: Some(_), .. } => vec!["real".into(), "cleanup".into()], FalseUnwind { unwind: None, .. } => vec!["real".into()], } } } /////////////////////////////////////////////////////////////////////////// // Statements #[derive(Clone, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct Statement<'tcx> { pub source_info: SourceInfo, pub kind: StatementKind<'tcx>, } // `Statement` is used a lot. Make sure it doesn't unintentionally get bigger. #[cfg(target_arch = "x86_64")] static_assert_size!(Statement<'_>, 32); impl Statement<'_> { /// Changes a statement to a nop. This is both faster than deleting instructions and avoids /// invalidating statement indices in `Location`s. pub fn make_nop(&mut self) { self.kind = StatementKind::Nop } /// Changes a statement to a nop and returns the original statement. pub fn replace_nop(&mut self) -> Self { Statement { source_info: self.source_info, kind: mem::replace(&mut self.kind, StatementKind::Nop), } } } #[derive(Clone, Debug, PartialEq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub enum StatementKind<'tcx> { /// Write the RHS Rvalue to the LHS Place. Assign(Box<(Place<'tcx>, Rvalue<'tcx>)>), /// This represents all the reading that a pattern match may do /// (e.g., inspecting constants and discriminant values), and the /// kind of pattern it comes from. This is in order to adapt potential /// error messages to these specific patterns. /// /// Note that this also is emitted for regular `let` bindings to ensure that locals that are /// never accessed still get some sanity checks for, e.g., `let x: ! = ..;` FakeRead(FakeReadCause, Box>), /// Write the discriminant for a variant to the enum Place. SetDiscriminant { place: Box>, variant_index: VariantIdx }, /// Start a live range for the storage of the local. StorageLive(Local), /// End the current live range for the storage of the local. StorageDead(Local), /// Executes a piece of inline Assembly. Stored in a Box to keep the size /// of `StatementKind` low. InlineAsm(Box>), /// Retag references in the given place, ensuring they got fresh tags. This is /// part of the Stacked Borrows model. These statements are currently only interpreted /// by miri and only generated when "-Z mir-emit-retag" is passed. /// See /// for more details. Retag(RetagKind, Box>), /// Encodes a user's type ascription. These need to be preserved /// intact so that NLL can respect them. For example: /// /// let a: T = y; /// /// The effect of this annotation is to relate the type `T_y` of the place `y` /// to the user-given type `T`. The effect depends on the specified variance: /// /// - `Covariant` -- requires that `T_y <: T` /// - `Contravariant` -- requires that `T_y :> T` /// - `Invariant` -- requires that `T_y == T` /// - `Bivariant` -- no effect AscribeUserType(Box<(Place<'tcx>, UserTypeProjection)>, ty::Variance), /// No-op. Useful for deleting instructions without affecting statement indices. Nop, } /// Describes what kind of retag is to be performed. #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, PartialEq, Eq, HashStable)] pub enum RetagKind { /// The initial retag when entering a function. FnEntry, /// Retag preparing for a two-phase borrow. TwoPhase, /// Retagging raw pointers. Raw, /// A "normal" retag. Default, } /// The `FakeReadCause` describes the type of pattern why a FakeRead statement exists. #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable, PartialEq)] pub enum FakeReadCause { /// Inject a fake read of the borrowed input at the end of each guards /// code. /// /// This should ensure that you cannot change the variant for an enum while /// you are in the midst of matching on it. ForMatchGuard, /// `let x: !; match x {}` doesn't generate any read of x so we need to /// generate a read of x to check that it is initialized and safe. ForMatchedPlace, /// A fake read of the RefWithinGuard version of a bind-by-value variable /// in a match guard to ensure that it's value hasn't change by the time /// we create the OutsideGuard version. ForGuardBinding, /// Officially, the semantics of /// /// `let pattern = ;` /// /// is that `` is evaluated into a temporary and then this temporary is /// into the pattern. /// /// However, if we see the simple pattern `let var = `, we optimize this to /// evaluate `` directly into the variable `var`. This is mostly unobservable, /// but in some cases it can affect the borrow checker, as in #53695. /// Therefore, we insert a "fake read" here to ensure that we get /// appropriate errors. ForLet, /// If we have an index expression like /// /// (*x)[1][{ x = y; 4}] /// /// then the first bounds check is invalidated when we evaluate the second /// index expression. Thus we create a fake borrow of `x` across the second /// indexer, which will cause a borrow check error. ForIndex, } #[derive(Clone, Debug, PartialEq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct InlineAsm<'tcx> { pub asm: hir::InlineAsmInner, pub outputs: Box<[Place<'tcx>]>, pub inputs: Box<[(Span, Operand<'tcx>)]>, } impl Debug for Statement<'_> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { use self::StatementKind::*; match self.kind { Assign(box(ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv), FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place), Retag(ref kind, ref place) => write!( fmt, "Retag({}{:?})", match kind { RetagKind::FnEntry => "[fn entry] ", RetagKind::TwoPhase => "[2phase] ", RetagKind::Raw => "[raw] ", RetagKind::Default => "", }, place, ), StorageLive(ref place) => write!(fmt, "StorageLive({:?})", place), StorageDead(ref place) => write!(fmt, "StorageDead({:?})", place), SetDiscriminant { ref place, variant_index } => { write!(fmt, "discriminant({:?}) = {:?}", place, variant_index) } InlineAsm(ref asm) => { write!(fmt, "asm!({:?} : {:?} : {:?})", asm.asm, asm.outputs, asm.inputs) } AscribeUserType(box(ref place, ref c_ty), ref variance) => { write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty) } Nop => write!(fmt, "nop"), } } } /////////////////////////////////////////////////////////////////////////// // Places /// A path to a value; something that can be evaluated without /// changing or disturbing program state. #[derive( Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, HashStable, )] pub struct Place<'tcx> { pub base: PlaceBase<'tcx>, /// projection out of a place (access a field, deref a pointer, etc) pub projection: &'tcx List>, } impl<'tcx> rustc_serialize::UseSpecializedDecodable for Place<'tcx> {} #[derive( Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable, )] pub enum PlaceBase<'tcx> { /// local variable Local(Local), /// static or static mut variable Static(Box>), } /// We store the normalized type to avoid requiring normalization when reading MIR #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable)] pub struct Static<'tcx> { pub ty: Ty<'tcx>, pub kind: StaticKind<'tcx>, /// The `DefId` of the item this static was declared in. For promoted values, usually, this is /// the same as the `DefId` of the `mir::Body` containing the `Place` this promoted appears in. /// However, after inlining, that might no longer be the case as inlined `Place`s are copied /// into the calling frame. pub def_id: DefId, } #[derive( Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable, RustcEncodable, RustcDecodable, )] pub enum StaticKind<'tcx> { /// Promoted references consist of an id (`Promoted`) and the substs necessary to monomorphize /// it. Usually, these substs are just the identity substs for the item. However, the inliner /// will adjust these substs when it inlines a function based on the substs at the callsite. Promoted(Promoted, SubstsRef<'tcx>), Static, } #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] #[derive(RustcEncodable, RustcDecodable, HashStable)] pub enum ProjectionElem { Deref, Field(Field, T), Index(V), /// These indices are generated by slice patterns. Easiest to explain /// by example: /// /// ``` /// [X, _, .._, _, _] => { offset: 0, min_length: 4, from_end: false }, /// [_, X, .._, _, _] => { offset: 1, min_length: 4, from_end: false }, /// [_, _, .._, X, _] => { offset: 2, min_length: 4, from_end: true }, /// [_, _, .._, _, X] => { offset: 1, min_length: 4, from_end: true }, /// ``` ConstantIndex { /// index or -index (in Python terms), depending on from_end offset: u32, /// thing being indexed must be at least this long min_length: u32, /// counting backwards from end? from_end: bool, }, /// These indices are generated by slice patterns. /// /// slice[from:-to] in Python terms. Subslice { from: u32, to: u32, }, /// "Downcast" to a variant of an ADT. Currently, we only introduce /// this for ADTs with more than one variant. It may be better to /// just introduce it always, or always for enums. /// /// The included Symbol is the name of the variant, used for printing MIR. Downcast(Option, VariantIdx), } impl ProjectionElem { /// Returns `true` if the target of this projection may refer to a different region of memory /// than the base. fn is_indirect(&self) -> bool { match self { Self::Deref => true, | Self::Field(_, _) | Self::Index(_) | Self::ConstantIndex { .. } | Self::Subslice { .. } | Self::Downcast(_, _) => false } } } /// Alias for projections as they appear in places, where the base is a place /// and the index is a local. pub type PlaceElem<'tcx> = ProjectionElem>; impl<'tcx> Copy for PlaceElem<'tcx> { } // At least on 64 bit systems, `PlaceElem` should not be larger than two pointers. #[cfg(target_arch = "x86_64")] static_assert_size!(PlaceElem<'_>, 16); /// Alias for projections as they appear in `UserTypeProjection`, where we /// need neither the `V` parameter for `Index` nor the `T` for `Field`. pub type ProjectionKind = ProjectionElem<(), ()>; rustc_index::newtype_index! { pub struct Field { derive [HashStable] DEBUG_FORMAT = "field[{}]" } } #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] pub struct PlaceRef<'a, 'tcx> { pub base: &'a PlaceBase<'tcx>, pub projection: &'a [PlaceElem<'tcx>], } impl<'tcx> Place<'tcx> { // FIXME change this to a const fn by also making List::empty a const fn. pub fn return_place() -> Place<'tcx> { Place { base: PlaceBase::Local(RETURN_PLACE), projection: List::empty(), } } /// Returns `true` if this `Place` contains a `Deref` projection. /// /// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the /// same region of memory as its base. pub fn is_indirect(&self) -> bool { self.projection.iter().any(|elem| elem.is_indirect()) } /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or /// a single deref of a local. // // FIXME: can we safely swap the semantics of `fn base_local` below in here instead? pub fn local_or_deref_local(&self) -> Option { match self.as_ref() { PlaceRef { base: &PlaceBase::Local(local), projection: &[], } | PlaceRef { base: &PlaceBase::Local(local), projection: &[ProjectionElem::Deref], } => Some(local), _ => None, } } /// If this place represents a local variable like `_X` with no /// projections, return `Some(_X)`. pub fn as_local(&self) -> Option { self.as_ref().as_local() } pub fn as_ref(&self) -> PlaceRef<'_, 'tcx> { PlaceRef { base: &self.base, projection: &self.projection, } } } impl From for Place<'_> { fn from(local: Local) -> Self { Place { base: local.into(), projection: List::empty(), } } } impl From for PlaceBase<'_> { fn from(local: Local) -> Self { PlaceBase::Local(local) } } impl<'a, 'tcx> PlaceRef<'a, 'tcx> { /// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or /// a single deref of a local. // // FIXME: can we safely swap the semantics of `fn base_local` below in here instead? pub fn local_or_deref_local(&self) -> Option { match self { PlaceRef { base: PlaceBase::Local(local), projection: [], } | PlaceRef { base: PlaceBase::Local(local), projection: [ProjectionElem::Deref], } => Some(*local), _ => None, } } /// If this place represents a local variable like `_X` with no /// projections, return `Some(_X)`. pub fn as_local(&self) -> Option { match self { PlaceRef { base: PlaceBase::Local(l), projection: [] } => Some(*l), _ => None, } } } impl Debug for Place<'_> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { for elem in self.projection.iter().rev() { match elem { ProjectionElem::Downcast(_, _) | ProjectionElem::Field(_, _) => { write!(fmt, "(").unwrap(); } ProjectionElem::Deref => { write!(fmt, "(*").unwrap(); } ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {} } } write!(fmt, "{:?}", self.base)?; for elem in self.projection.iter() { match elem { ProjectionElem::Downcast(Some(name), _index) => { write!(fmt, " as {})", name)?; } ProjectionElem::Downcast(None, index) => { write!(fmt, " as variant#{:?})", index)?; } ProjectionElem::Deref => { write!(fmt, ")")?; } ProjectionElem::Field(field, ty) => { write!(fmt, ".{:?}: {:?})", field.index(), ty)?; } ProjectionElem::Index(ref index) => { write!(fmt, "[{:?}]", index)?; } ProjectionElem::ConstantIndex { offset, min_length, from_end: false } => { write!(fmt, "[{:?} of {:?}]", offset, min_length)?; } ProjectionElem::ConstantIndex { offset, min_length, from_end: true } => { write!(fmt, "[-{:?} of {:?}]", offset, min_length)?; } ProjectionElem::Subslice { from, to } if *to == 0 => { write!(fmt, "[{:?}:]", from)?; } ProjectionElem::Subslice { from, to } if *from == 0 => { write!(fmt, "[:-{:?}]", to)?; } ProjectionElem::Subslice { from, to } => { write!(fmt, "[{:?}:-{:?}]", from, to)?; } } } Ok(()) } } impl Debug for PlaceBase<'_> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { match *self { PlaceBase::Local(id) => write!(fmt, "{:?}", id), PlaceBase::Static(box self::Static { ty, kind: StaticKind::Static, def_id }) => { write!(fmt, "({}: {:?})", ty::tls::with(|tcx| tcx.def_path_str(def_id)), ty) } PlaceBase::Static(box self::Static { ty, kind: StaticKind::Promoted(promoted, _), def_id: _ }) => { write!(fmt, "({:?}: {:?})", promoted, ty) } } } } /////////////////////////////////////////////////////////////////////////// // Scopes rustc_index::newtype_index! { pub struct SourceScope { derive [HashStable] DEBUG_FORMAT = "scope[{}]", const OUTERMOST_SOURCE_SCOPE = 0, } } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct SourceScopeData { pub span: Span, pub parent_scope: Option, } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct SourceScopeLocalData { /// An `HirId` with lint levels equivalent to this scope's lint levels. pub lint_root: hir::HirId, /// The unsafe block that contains this node. pub safety: Safety, } /////////////////////////////////////////////////////////////////////////// // Operands /// These are values that can appear inside an rvalue. They are intentionally /// limited to prevent rvalues from being nested in one another. #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)] pub enum Operand<'tcx> { /// Copy: The value must be available for use afterwards. /// /// This implies that the type of the place must be `Copy`; this is true /// by construction during build, but also checked by the MIR type checker. Copy(Place<'tcx>), /// Move: The value (including old borrows of it) will not be used again. /// /// Safe for values of all types (modulo future developments towards `?Move`). /// Correct usage patterns are enforced by the borrow checker for safe code. /// `Copy` may be converted to `Move` to enable "last-use" optimizations. Move(Place<'tcx>), /// Synthesizes a constant value. Constant(Box>), } impl<'tcx> Debug for Operand<'tcx> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { use self::Operand::*; match *self { Constant(ref a) => write!(fmt, "{:?}", a), Copy(ref place) => write!(fmt, "{:?}", place), Move(ref place) => write!(fmt, "move {:?}", place), } } } impl<'tcx> Operand<'tcx> { /// Convenience helper to make a constant that refers to the fn /// with given `DefId` and substs. Since this is used to synthesize /// MIR, assumes `user_ty` is None. pub fn function_handle( tcx: TyCtxt<'tcx>, def_id: DefId, substs: SubstsRef<'tcx>, span: Span, ) -> Self { let ty = tcx.type_of(def_id).subst(tcx, substs); Operand::Constant(box Constant { span, user_ty: None, literal: ty::Const::zero_sized(tcx, ty), }) } pub fn to_copy(&self) -> Self { match *self { Operand::Copy(_) | Operand::Constant(_) => self.clone(), Operand::Move(ref place) => Operand::Copy(place.clone()), } } } /////////////////////////////////////////////////////////////////////////// /// Rvalues #[derive(Clone, RustcEncodable, RustcDecodable, HashStable, PartialEq)] pub enum Rvalue<'tcx> { /// x (either a move or copy, depending on type of x) Use(Operand<'tcx>), /// [x; 32] Repeat(Operand<'tcx>, u64), /// &x or &mut x Ref(Region<'tcx>, BorrowKind, Place<'tcx>), /// length of a [X] or [X;n] value Len(Place<'tcx>), Cast(CastKind, Operand<'tcx>, Ty<'tcx>), BinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>), CheckedBinaryOp(BinOp, Operand<'tcx>, Operand<'tcx>), NullaryOp(NullOp, Ty<'tcx>), UnaryOp(UnOp, Operand<'tcx>), /// Read the discriminant of an ADT. /// /// Undefined (i.e., no effort is made to make it defined, but there’s no reason why it cannot /// be defined to return, say, a 0) if ADT is not an enum. Discriminant(Place<'tcx>), /// Creates an aggregate value, like a tuple or struct. This is /// only needed because we want to distinguish `dest = Foo { x: /// ..., y: ... }` from `dest.x = ...; dest.y = ...;` in the case /// that `Foo` has a destructor. These rvalues can be optimized /// away after type-checking and before lowering. Aggregate(Box>, Vec>), } #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum CastKind { Misc, Pointer(PointerCast), } #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum AggregateKind<'tcx> { /// The type is of the element Array(Ty<'tcx>), Tuple, /// The second field is the variant index. It's equal to 0 for struct /// and union expressions. The fourth field is /// active field number and is present only for union expressions /// -- e.g., for a union expression `SomeUnion { c: .. }`, the /// active field index would identity the field `c` Adt(&'tcx AdtDef, VariantIdx, SubstsRef<'tcx>, Option, Option), Closure(DefId, SubstsRef<'tcx>), Generator(DefId, SubstsRef<'tcx>, hir::Movability), } #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum BinOp { /// The `+` operator (addition) Add, /// The `-` operator (subtraction) Sub, /// The `*` operator (multiplication) Mul, /// The `/` operator (division) Div, /// The `%` operator (modulus) Rem, /// The `^` operator (bitwise xor) BitXor, /// The `&` operator (bitwise and) BitAnd, /// The `|` operator (bitwise or) BitOr, /// The `<<` operator (shift left) Shl, /// The `>>` operator (shift right) Shr, /// The `==` operator (equality) Eq, /// The `<` operator (less than) Lt, /// The `<=` operator (less than or equal to) Le, /// The `!=` operator (not equal to) Ne, /// The `>=` operator (greater than or equal to) Ge, /// The `>` operator (greater than) Gt, /// The `ptr.offset` operator Offset, } impl BinOp { pub fn is_checkable(self) -> bool { use self::BinOp::*; match self { Add | Sub | Mul | Shl | Shr => true, _ => false, } } } #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum NullOp { /// Returns the size of a value of that type SizeOf, /// Creates a new uninitialized box for a value of that type Box, } #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum UnOp { /// The `!` operator for logical inversion Not, /// The `-` operator for negation Neg, } impl<'tcx> Debug for Rvalue<'tcx> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { use self::Rvalue::*; match *self { Use(ref place) => write!(fmt, "{:?}", place), Repeat(ref a, ref b) => write!(fmt, "[{:?}; {:?}]", a, b), Len(ref a) => write!(fmt, "Len({:?})", a), Cast(ref kind, ref place, ref ty) => { write!(fmt, "{:?} as {:?} ({:?})", place, ty, kind) } BinaryOp(ref op, ref a, ref b) => write!(fmt, "{:?}({:?}, {:?})", op, a, b), CheckedBinaryOp(ref op, ref a, ref b) => { write!(fmt, "Checked{:?}({:?}, {:?})", op, a, b) } UnaryOp(ref op, ref a) => write!(fmt, "{:?}({:?})", op, a), Discriminant(ref place) => write!(fmt, "discriminant({:?})", place), NullaryOp(ref op, ref t) => write!(fmt, "{:?}({:?})", op, t), Ref(region, borrow_kind, ref place) => { let kind_str = match borrow_kind { BorrowKind::Shared => "", BorrowKind::Shallow => "shallow ", BorrowKind::Mut { .. } | BorrowKind::Unique => "mut ", }; // When printing regions, add trailing space if necessary. let print_region = ty::tls::with(|tcx| { tcx.sess.verbose() || tcx.sess.opts.debugging_opts.identify_regions }); let region = if print_region { let mut region = region.to_string(); if region.len() > 0 { region.push(' '); } region } else { // Do not even print 'static String::new() }; write!(fmt, "&{}{}{:?}", region, kind_str, place) } Aggregate(ref kind, ref places) => { fn fmt_tuple(fmt: &mut Formatter<'_>, places: &[Operand<'_>]) -> fmt::Result { let mut tuple_fmt = fmt.debug_tuple(""); for place in places { tuple_fmt.field(place); } tuple_fmt.finish() } match **kind { AggregateKind::Array(_) => write!(fmt, "{:?}", places), AggregateKind::Tuple => match places.len() { 0 => write!(fmt, "()"), 1 => write!(fmt, "({:?},)", places[0]), _ => fmt_tuple(fmt, places), }, AggregateKind::Adt(adt_def, variant, substs, _user_ty, _) => { let variant_def = &adt_def.variants[variant]; let f = &mut *fmt; ty::tls::with(|tcx| { let substs = tcx.lift(&substs).expect("could not lift for printing"); FmtPrinter::new(tcx, f, Namespace::ValueNS) .print_def_path(variant_def.def_id, substs)?; Ok(()) })?; match variant_def.ctor_kind { CtorKind::Const => Ok(()), CtorKind::Fn => fmt_tuple(fmt, places), CtorKind::Fictive => { let mut struct_fmt = fmt.debug_struct(""); for (field, place) in variant_def.fields.iter().zip(places) { struct_fmt.field(&field.ident.as_str(), place); } struct_fmt.finish() } } } AggregateKind::Closure(def_id, _) => ty::tls::with(|tcx| { if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) { let name = if tcx.sess.opts.debugging_opts.span_free_formats { format!("[closure@{:?}]", hir_id) } else { format!("[closure@{:?}]", tcx.hir().span(hir_id)) }; let mut struct_fmt = fmt.debug_struct(&name); if let Some(upvars) = tcx.upvars(def_id) { for (&var_id, place) in upvars.keys().zip(places) { let var_name = tcx.hir().name(var_id); struct_fmt.field(&var_name.as_str(), place); } } struct_fmt.finish() } else { write!(fmt, "[closure]") } }), AggregateKind::Generator(def_id, _, _) => ty::tls::with(|tcx| { if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) { let name = format!("[generator@{:?}]", tcx.hir().span(hir_id)); let mut struct_fmt = fmt.debug_struct(&name); if let Some(upvars) = tcx.upvars(def_id) { for (&var_id, place) in upvars.keys().zip(places) { let var_name = tcx.hir().name(var_id); struct_fmt.field(&var_name.as_str(), place); } } struct_fmt.finish() } else { write!(fmt, "[generator]") } }), } } } } } /////////////////////////////////////////////////////////////////////////// /// Constants /// /// Two constants are equal if they are the same constant. Note that /// this does not necessarily mean that they are "==" in Rust -- in /// particular one must be wary of `NaN`! #[derive(Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)] pub struct Constant<'tcx> { pub span: Span, /// Optional user-given type: for something like /// `collect::>`, this would be present and would /// indicate that `Vec<_>` was explicitly specified. /// /// Needed for NLL to impose user-given type constraints. pub user_ty: Option, pub literal: &'tcx ty::Const<'tcx>, } impl Constant<'tcx> { pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option { match self.literal.val.try_to_scalar() { Some(Scalar::Ptr(ptr)) => match tcx.alloc_map.lock().get(ptr.alloc_id) { Some(GlobalAlloc::Static(def_id)) => Some(def_id), Some(_) => None, None => { tcx.sess.delay_span_bug( DUMMY_SP, "MIR cannot contain dangling const pointers", ); None }, }, _ => None, } } } /// A collection of projections into user types. /// /// They are projections because a binding can occur a part of a /// parent pattern that has been ascribed a type. /// /// Its a collection because there can be multiple type ascriptions on /// the path from the root of the pattern down to the binding itself. /// /// An example: /// /// ```rust /// struct S<'a>((i32, &'a str), String); /// let S((_, w): (i32, &'static str), _): S = ...; /// // ------ ^^^^^^^^^^^^^^^^^^^ (1) /// // --------------------------------- ^ (2) /// ``` /// /// The highlights labelled `(1)` show the subpattern `(_, w)` being /// ascribed the type `(i32, &'static str)`. /// /// The highlights labelled `(2)` show the whole pattern being /// ascribed the type `S`. /// /// In this example, when we descend to `w`, we will have built up the /// following two projected types: /// /// * base: `S`, projection: `(base.0).1` /// * base: `(i32, &'static str)`, projection: `base.1` /// /// The first will lead to the constraint `w: &'1 str` (for some /// inferred region `'1`). The second will lead to the constraint `w: /// &'static str`. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct UserTypeProjections { pub(crate) contents: Vec<(UserTypeProjection, Span)>, } impl<'tcx> UserTypeProjections { pub fn none() -> Self { UserTypeProjections { contents: vec![] } } pub fn from_projections(projs: impl Iterator) -> Self { UserTypeProjections { contents: projs.collect() } } pub fn projections_and_spans(&self) -> impl Iterator { self.contents.iter() } pub fn projections(&self) -> impl Iterator { self.contents.iter().map(|&(ref user_type, _span)| user_type) } pub fn push_projection(mut self, user_ty: &UserTypeProjection, span: Span) -> Self { self.contents.push((user_ty.clone(), span)); self } fn map_projections( mut self, mut f: impl FnMut(UserTypeProjection) -> UserTypeProjection, ) -> Self { self.contents = self.contents.drain(..).map(|(proj, span)| (f(proj), span)).collect(); self } pub fn index(self) -> Self { self.map_projections(|pat_ty_proj| pat_ty_proj.index()) } pub fn subslice(self, from: u32, to: u32) -> Self { self.map_projections(|pat_ty_proj| pat_ty_proj.subslice(from, to)) } pub fn deref(self) -> Self { self.map_projections(|pat_ty_proj| pat_ty_proj.deref()) } pub fn leaf(self, field: Field) -> Self { self.map_projections(|pat_ty_proj| pat_ty_proj.leaf(field)) } pub fn variant(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx, field: Field) -> Self { self.map_projections(|pat_ty_proj| pat_ty_proj.variant(adt_def, variant_index, field)) } } /// Encodes the effect of a user-supplied type annotation on the /// subcomponents of a pattern. The effect is determined by applying the /// given list of proejctions to some underlying base type. Often, /// the projection element list `projs` is empty, in which case this /// directly encodes a type in `base`. But in the case of complex patterns with /// subpatterns and bindings, we want to apply only a *part* of the type to a variable, /// in which case the `projs` vector is used. /// /// Examples: /// /// * `let x: T = ...` -- here, the `projs` vector is empty. /// /// * `let (x, _): T = ...` -- here, the `projs` vector would contain /// `field[0]` (aka `.0`), indicating that the type of `s` is /// determined by finding the type of the `.0` field from `T`. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, PartialEq)] pub struct UserTypeProjection { pub base: UserTypeAnnotationIndex, pub projs: Vec, } impl Copy for ProjectionKind {} impl UserTypeProjection { pub(crate) fn index(mut self) -> Self { self.projs.push(ProjectionElem::Index(())); self } pub(crate) fn subslice(mut self, from: u32, to: u32) -> Self { self.projs.push(ProjectionElem::Subslice { from, to }); self } pub(crate) fn deref(mut self) -> Self { self.projs.push(ProjectionElem::Deref); self } pub(crate) fn leaf(mut self, field: Field) -> Self { self.projs.push(ProjectionElem::Field(field, ())); self } pub(crate) fn variant( mut self, adt_def: &'tcx AdtDef, variant_index: VariantIdx, field: Field, ) -> Self { self.projs.push(ProjectionElem::Downcast( Some(adt_def.variants[variant_index].ident.name), variant_index, )); self.projs.push(ProjectionElem::Field(field, ())); self } } CloneTypeFoldableAndLiftImpls! { ProjectionKind, } impl<'tcx> TypeFoldable<'tcx> for UserTypeProjection { fn super_fold_with>(&self, folder: &mut F) -> Self { use crate::mir::ProjectionElem::*; let base = self.base.fold_with(folder); let projs: Vec<_> = self .projs .iter() .map(|elem| match elem { Deref => Deref, Field(f, ()) => Field(f.clone(), ()), Index(()) => Index(()), elem => elem.clone(), }) .collect(); UserTypeProjection { base, projs } } fn super_visit_with>(&self, visitor: &mut Vs) -> bool { self.base.visit_with(visitor) // Note: there's nothing in `self.proj` to visit. } } rustc_index::newtype_index! { pub struct Promoted { derive [HashStable] DEBUG_FORMAT = "promoted[{}]" } } impl<'tcx> Debug for Constant<'tcx> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { write!(fmt, "{}", self) } } impl<'tcx> Display for Constant<'tcx> { fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { write!(fmt, "const ")?; // FIXME make the default pretty printing of raw pointers more detailed. Here we output the // debug representation of raw pointers, so that the raw pointers in the mir dump output are // detailed and just not '{pointer}'. if let ty::RawPtr(_) = self.literal.ty.kind { write!(fmt, "{:?} : {}", self.literal.val, self.literal.ty) } else { write!(fmt, "{}", self.literal) } } } impl<'tcx> graph::DirectedGraph for Body<'tcx> { type Node = BasicBlock; } impl<'tcx> graph::WithNumNodes for Body<'tcx> { fn num_nodes(&self) -> usize { self.basic_blocks.len() } } impl<'tcx> graph::WithStartNode for Body<'tcx> { fn start_node(&self) -> Self::Node { START_BLOCK } } impl<'tcx> graph::WithPredecessors for Body<'tcx> { fn predecessors( &self, node: Self::Node, ) -> >::Iter { self.predecessors_for(node).clone().into_iter() } } impl<'tcx> graph::WithSuccessors for Body<'tcx> { fn successors( &self, node: Self::Node, ) -> >::Iter { self.basic_blocks[node].terminator().successors().cloned() } } impl<'a, 'b> graph::GraphPredecessors<'b> for Body<'a> { type Item = BasicBlock; type Iter = IntoIter; } impl<'a, 'b> graph::GraphSuccessors<'b> for Body<'a> { type Item = BasicBlock; type Iter = iter::Cloned>; } #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)] pub struct Location { /// The block that the location is within. pub block: BasicBlock, /// The location is the position of the start of the statement; or, if /// `statement_index` equals the number of statements, then the start of the /// terminator. pub statement_index: usize, } impl fmt::Debug for Location { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { write!(fmt, "{:?}[{}]", self.block, self.statement_index) } } impl Location { pub const START: Location = Location { block: START_BLOCK, statement_index: 0 }; /// Returns the location immediately after this one within the enclosing block. /// /// Note that if this location represents a terminator, then the /// resulting location would be out of bounds and invalid. pub fn successor_within_block(&self) -> Location { Location { block: self.block, statement_index: self.statement_index + 1 } } /// Returns `true` if `other` is earlier in the control flow graph than `self`. pub fn is_predecessor_of<'tcx>(&self, other: Location, body: &Body<'tcx>) -> bool { // If we are in the same block as the other location and are an earlier statement // then we are a predecessor of `other`. if self.block == other.block && self.statement_index < other.statement_index { return true; } // If we're in another block, then we want to check that block is a predecessor of `other`. let mut queue: Vec = body.predecessors_for(other.block).clone(); let mut visited = FxHashSet::default(); while let Some(block) = queue.pop() { // If we haven't visited this block before, then make sure we visit it's predecessors. if visited.insert(block) { queue.append(&mut body.predecessors_for(block).clone()); } else { continue; } // If we found the block that `self` is in, then we are a predecessor of `other` (since // we found that block by looking at the predecessors of `other`). if self.block == block { return true; } } false } pub fn dominates(&self, other: Location, dominators: &Dominators) -> bool { if self.block == other.block { self.statement_index <= other.statement_index } else { dominators.is_dominated_by(other.block, self.block) } } } #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)] pub enum UnsafetyViolationKind { General, /// Permitted both in `const fn`s and regular `fn`s. GeneralAndConstFn, BorrowPacked(hir::HirId), } #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)] pub struct UnsafetyViolation { pub source_info: SourceInfo, pub description: Symbol, pub details: Symbol, pub kind: UnsafetyViolationKind, } #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)] pub struct UnsafetyCheckResult { /// Violations that are propagated *upwards* from this function. pub violations: Lrc<[UnsafetyViolation]>, /// `unsafe` blocks in this function, along with whether they are used. This is /// used for the "unused_unsafe" lint. pub unsafe_blocks: Lrc<[(hir::HirId, bool)]>, } rustc_index::newtype_index! { pub struct GeneratorSavedLocal { derive [HashStable] DEBUG_FORMAT = "_{}", } } /// The layout of generator state. #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)] pub struct GeneratorLayout<'tcx> { /// The type of every local stored inside the generator. pub field_tys: IndexVec>, /// Which of the above fields are in each variant. Note that one field may /// be stored in multiple variants. pub variant_fields: IndexVec>, /// Which saved locals are storage-live at the same time. Locals that do not /// have conflicts with each other are allowed to overlap in the computed /// layout. pub storage_conflicts: BitMatrix, } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct BorrowCheckResult<'tcx> { pub closure_requirements: Option>, pub used_mut_upvars: SmallVec<[Field; 8]>, } /// The result of the `mir_const_qualif` query. /// /// Each field corresponds to an implementer of the `Qualif` trait in /// `librustc_mir/transform/check_consts/qualifs.rs`. See that file for more information on each /// `Qualif`. #[derive(Clone, Copy, Debug, Default, RustcEncodable, RustcDecodable, HashStable)] pub struct ConstQualifs { pub has_mut_interior: bool, pub needs_drop: bool, } /// After we borrow check a closure, we are left with various /// requirements that we have inferred between the free regions that /// appear in the closure's signature or on its field types. These /// requirements are then verified and proved by the closure's /// creating function. This struct encodes those requirements. /// /// The requirements are listed as being between various /// `RegionVid`. The 0th region refers to `'static`; subsequent region /// vids refer to the free regions that appear in the closure (or /// generator's) type, in order of appearance. (This numbering is /// actually defined by the `UniversalRegions` struct in the NLL /// region checker. See for example /// `UniversalRegions::closure_mapping`.) Note that we treat the free /// regions in the closure's type "as if" they were erased, so their /// precise identity is not important, only their position. /// /// Example: If type check produces a closure with the closure substs: /// /// ```text /// ClosureSubsts = [ /// i8, // the "closure kind" /// for<'x> fn(&'a &'x u32) -> &'x u32, // the "closure signature" /// &'a String, // some upvar /// ] /// ``` /// /// here, there is one unique free region (`'a`) but it appears /// twice. We would "renumber" each occurrence to a unique vid, as follows: /// /// ```text /// ClosureSubsts = [ /// i8, // the "closure kind" /// for<'x> fn(&'1 &'x u32) -> &'x u32, // the "closure signature" /// &'2 String, // some upvar /// ] /// ``` /// /// Now the code might impose a requirement like `'1: '2`. When an /// instance of the closure is created, the corresponding free regions /// can be extracted from its type and constrained to have the given /// outlives relationship. /// /// In some cases, we have to record outlives requirements between /// types and regions as well. In that case, if those types include /// any regions, those regions are recorded as `ReClosureBound` /// instances assigned one of these same indices. Those regions will /// be substituted away by the creator. We use `ReClosureBound` in /// that case because the regions must be allocated in the global /// `TyCtxt`, and hence we cannot use `ReVar` (which is what we use /// internally within the rest of the NLL code). #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct ClosureRegionRequirements<'tcx> { /// The number of external regions defined on the closure. In our /// example above, it would be 3 -- one for `'static`, then `'1` /// and `'2`. This is just used for a sanity check later on, to /// make sure that the number of regions we see at the callsite /// matches. pub num_external_vids: usize, /// Requirements between the various free regions defined in /// indices. pub outlives_requirements: Vec>, } /// Indicates an outlives-constraint between a type or between two /// free regions declared on the closure. #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct ClosureOutlivesRequirement<'tcx> { // This region or type ... pub subject: ClosureOutlivesSubject<'tcx>, // ... must outlive this one. pub outlived_free_region: ty::RegionVid, // If not, report an error here ... pub blame_span: Span, // ... due to this reason. pub category: ConstraintCategory, } /// Outlives-constraints can be categorized to determine whether and why they /// are interesting (for error reporting). Order of variants indicates sort /// order of the category, thereby influencing diagnostic output. /// /// See also [rustc_mir::borrow_check::nll::constraints]. #[derive( Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable, )] pub enum ConstraintCategory { Return, Yield, UseAsConst, UseAsStatic, TypeAnnotation, Cast, /// A constraint that came from checking the body of a closure. /// /// We try to get the category that the closure used when reporting this. ClosureBounds, CallArgument, CopyBound, SizedBound, Assignment, OpaqueType, /// A "boring" constraint (caused by the given location) is one that /// the user probably doesn't want to see described in diagnostics, /// because it is kind of an artifact of the type system setup. /// Example: `x = Foo { field: y }` technically creates /// intermediate regions representing the "type of `Foo { field: y /// }`", and data flows from `y` into those variables, but they /// are not very interesting. The assignment into `x` on the other /// hand might be. Boring, // Boring and applicable everywhere. BoringNoLocation, /// A constraint that doesn't correspond to anything the user sees. Internal, } /// The subject of a `ClosureOutlivesRequirement` -- that is, the thing /// that must outlive some region. #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub enum ClosureOutlivesSubject<'tcx> { /// Subject is a type, typically a type parameter, but could also /// be a projection. Indicates a requirement like `T: 'a` being /// passed to the caller, where the type here is `T`. /// /// The type here is guaranteed not to contain any free regions at /// present. Ty(Ty<'tcx>), /// Subject is a free region from the closure. Indicates a requirement /// like `'a: 'b` being passed to the caller; the region here is `'a`. Region(ty::RegionVid), } /* * `TypeFoldable` implementations for MIR types */ CloneTypeFoldableAndLiftImpls! { BlockTailInfo, MirPhase, Mutability, SourceInfo, FakeReadCause, RetagKind, SourceScope, SourceScopeData, SourceScopeLocalData, UserTypeAnnotationIndex, } impl<'tcx> TypeFoldable<'tcx> for Terminator<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { use crate::mir::TerminatorKind::*; let kind = match self.kind { Goto { target } => Goto { target }, SwitchInt { ref discr, switch_ty, ref values, ref targets } => SwitchInt { discr: discr.fold_with(folder), switch_ty: switch_ty.fold_with(folder), values: values.clone(), targets: targets.clone(), }, Drop { ref location, target, unwind } => { Drop { location: location.fold_with(folder), target, unwind } } DropAndReplace { ref location, ref value, target, unwind } => DropAndReplace { location: location.fold_with(folder), value: value.fold_with(folder), target, unwind, }, Yield { ref value, resume, drop } => { Yield { value: value.fold_with(folder), resume: resume, drop: drop } } Call { ref func, ref args, ref destination, cleanup, from_hir_call } => { let dest = destination.as_ref().map(|&(ref loc, dest)| (loc.fold_with(folder), dest)); Call { func: func.fold_with(folder), args: args.fold_with(folder), destination: dest, cleanup, from_hir_call, } } Assert { ref cond, expected, ref msg, target, cleanup } => { use PanicInfo::*; let msg = match msg { BoundsCheck { ref len, ref index } => BoundsCheck { len: len.fold_with(folder), index: index.fold_with(folder), }, Panic { .. } | Overflow(_) | OverflowNeg | DivisionByZero | RemainderByZero | ResumedAfterReturn(_) | ResumedAfterPanic(_) => msg.clone(), }; Assert { cond: cond.fold_with(folder), expected, msg, target, cleanup } } GeneratorDrop => GeneratorDrop, Resume => Resume, Abort => Abort, Return => Return, Unreachable => Unreachable, FalseEdges { real_target, imaginary_target } => { FalseEdges { real_target, imaginary_target } } FalseUnwind { real_target, unwind } => FalseUnwind { real_target, unwind }, }; Terminator { source_info: self.source_info, kind } } fn super_visit_with>(&self, visitor: &mut V) -> bool { use crate::mir::TerminatorKind::*; match self.kind { SwitchInt { ref discr, switch_ty, .. } => { discr.visit_with(visitor) || switch_ty.visit_with(visitor) } Drop { ref location, .. } => location.visit_with(visitor), DropAndReplace { ref location, ref value, .. } => { location.visit_with(visitor) || value.visit_with(visitor) } Yield { ref value, .. } => value.visit_with(visitor), Call { ref func, ref args, ref destination, .. } => { let dest = if let Some((ref loc, _)) = *destination { loc.visit_with(visitor) } else { false }; dest || func.visit_with(visitor) || args.visit_with(visitor) } Assert { ref cond, ref msg, .. } => { if cond.visit_with(visitor) { use PanicInfo::*; match msg { BoundsCheck { ref len, ref index } => len.visit_with(visitor) || index.visit_with(visitor), Panic { .. } | Overflow(_) | OverflowNeg | DivisionByZero | RemainderByZero | ResumedAfterReturn(_) | ResumedAfterPanic(_) => false } } else { false } } Goto { .. } | Resume | Abort | Return | GeneratorDrop | Unreachable | FalseEdges { .. } | FalseUnwind { .. } => false, } } } impl<'tcx> TypeFoldable<'tcx> for GeneratorKind { fn super_fold_with>(&self, _: &mut F) -> Self { *self } fn super_visit_with>(&self, _: &mut V) -> bool { false } } impl<'tcx> TypeFoldable<'tcx> for Place<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { Place { base: self.base.fold_with(folder), projection: self.projection.fold_with(folder), } } fn super_visit_with>(&self, visitor: &mut V) -> bool { self.base.visit_with(visitor) || self.projection.visit_with(visitor) } } impl<'tcx> TypeFoldable<'tcx> for PlaceBase<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { match self { PlaceBase::Local(local) => PlaceBase::Local(local.fold_with(folder)), PlaceBase::Static(static_) => PlaceBase::Static(static_.fold_with(folder)), } } fn super_visit_with>(&self, visitor: &mut V) -> bool { match self { PlaceBase::Local(local) => local.visit_with(visitor), PlaceBase::Static(static_) => (**static_).visit_with(visitor), } } } impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List> { fn super_fold_with>(&self, folder: &mut F) -> Self { let v = self.iter().map(|t| t.fold_with(folder)).collect::>(); folder.tcx().intern_place_elems(&v) } fn super_visit_with>(&self, visitor: &mut V) -> bool { self.iter().any(|t| t.visit_with(visitor)) } } impl<'tcx> TypeFoldable<'tcx> for Static<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { Static { ty: self.ty.fold_with(folder), kind: self.kind.fold_with(folder), def_id: self.def_id, } } fn super_visit_with>(&self, visitor: &mut V) -> bool { let Static { ty, kind, def_id: _ } = self; ty.visit_with(visitor) || kind.visit_with(visitor) } } impl<'tcx> TypeFoldable<'tcx> for StaticKind<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { match self { StaticKind::Promoted(promoted, substs) => StaticKind::Promoted(promoted.fold_with(folder), substs.fold_with(folder)), StaticKind::Static => StaticKind::Static } } fn super_visit_with>(&self, visitor: &mut V) -> bool { match self { StaticKind::Promoted(promoted, substs) => promoted.visit_with(visitor) || substs.visit_with(visitor), StaticKind::Static => { false } } } } impl<'tcx> TypeFoldable<'tcx> for Rvalue<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { use crate::mir::Rvalue::*; match *self { Use(ref op) => Use(op.fold_with(folder)), Repeat(ref op, len) => Repeat(op.fold_with(folder), len), Ref(region, bk, ref place) => { Ref(region.fold_with(folder), bk, place.fold_with(folder)) } Len(ref place) => Len(place.fold_with(folder)), Cast(kind, ref op, ty) => Cast(kind, op.fold_with(folder), ty.fold_with(folder)), BinaryOp(op, ref rhs, ref lhs) => { BinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder)) } CheckedBinaryOp(op, ref rhs, ref lhs) => { CheckedBinaryOp(op, rhs.fold_with(folder), lhs.fold_with(folder)) } UnaryOp(op, ref val) => UnaryOp(op, val.fold_with(folder)), Discriminant(ref place) => Discriminant(place.fold_with(folder)), NullaryOp(op, ty) => NullaryOp(op, ty.fold_with(folder)), Aggregate(ref kind, ref fields) => { let kind = box match **kind { AggregateKind::Array(ty) => AggregateKind::Array(ty.fold_with(folder)), AggregateKind::Tuple => AggregateKind::Tuple, AggregateKind::Adt(def, v, substs, user_ty, n) => AggregateKind::Adt( def, v, substs.fold_with(folder), user_ty.fold_with(folder), n, ), AggregateKind::Closure(id, substs) => { AggregateKind::Closure(id, substs.fold_with(folder)) } AggregateKind::Generator(id, substs, movablity) => { AggregateKind::Generator(id, substs.fold_with(folder), movablity) } }; Aggregate(kind, fields.fold_with(folder)) } } } fn super_visit_with>(&self, visitor: &mut V) -> bool { use crate::mir::Rvalue::*; match *self { Use(ref op) => op.visit_with(visitor), Repeat(ref op, _) => op.visit_with(visitor), Ref(region, _, ref place) => region.visit_with(visitor) || place.visit_with(visitor), Len(ref place) => place.visit_with(visitor), Cast(_, ref op, ty) => op.visit_with(visitor) || ty.visit_with(visitor), BinaryOp(_, ref rhs, ref lhs) | CheckedBinaryOp(_, ref rhs, ref lhs) => { rhs.visit_with(visitor) || lhs.visit_with(visitor) } UnaryOp(_, ref val) => val.visit_with(visitor), Discriminant(ref place) => place.visit_with(visitor), NullaryOp(_, ty) => ty.visit_with(visitor), Aggregate(ref kind, ref fields) => { (match **kind { AggregateKind::Array(ty) => ty.visit_with(visitor), AggregateKind::Tuple => false, AggregateKind::Adt(_, _, substs, user_ty, _) => { substs.visit_with(visitor) || user_ty.visit_with(visitor) } AggregateKind::Closure(_, substs) => substs.visit_with(visitor), AggregateKind::Generator(_, substs, _) => substs.visit_with(visitor), }) || fields.visit_with(visitor) } } } } impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { match *self { Operand::Copy(ref place) => Operand::Copy(place.fold_with(folder)), Operand::Move(ref place) => Operand::Move(place.fold_with(folder)), Operand::Constant(ref c) => Operand::Constant(c.fold_with(folder)), } } fn super_visit_with>(&self, visitor: &mut V) -> bool { match *self { Operand::Copy(ref place) | Operand::Move(ref place) => place.visit_with(visitor), Operand::Constant(ref c) => c.visit_with(visitor), } } } impl<'tcx> TypeFoldable<'tcx> for PlaceElem<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { use crate::mir::ProjectionElem::*; match self { Deref => Deref, Field(f, ty) => Field(*f, ty.fold_with(folder)), Index(v) => Index(v.fold_with(folder)), elem => elem.clone(), } } fn super_visit_with>(&self, visitor: &mut Vs) -> bool { use crate::mir::ProjectionElem::*; match self { Field(_, ty) => ty.visit_with(visitor), Index(v) => v.visit_with(visitor), _ => false, } } } impl<'tcx> TypeFoldable<'tcx> for Field { fn super_fold_with>(&self, _: &mut F) -> Self { *self } fn super_visit_with>(&self, _: &mut V) -> bool { false } } impl<'tcx> TypeFoldable<'tcx> for GeneratorSavedLocal { fn super_fold_with>(&self, _: &mut F) -> Self { *self } fn super_visit_with>(&self, _: &mut V) -> bool { false } } impl<'tcx, R: Idx, C: Idx> TypeFoldable<'tcx> for BitMatrix { fn super_fold_with>(&self, _: &mut F) -> Self { self.clone() } fn super_visit_with>(&self, _: &mut V) -> bool { false } } impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> { fn super_fold_with>(&self, folder: &mut F) -> Self { Constant { span: self.span.clone(), user_ty: self.user_ty.fold_with(folder), literal: self.literal.fold_with(folder), } } fn super_visit_with>(&self, visitor: &mut V) -> bool { self.literal.visit_with(visitor) } }