| //! Miscellaneous type-system utilities that are too small to deserve their own modules. |
| |
| use crate::ich::NodeIdHashingMode; |
| use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; |
| use crate::mir::interpret::{sign_extend, truncate}; |
| use crate::ty::layout::IntegerExt; |
| use crate::ty::query::TyCtxtAt; |
| use crate::ty::subst::{GenericArgKind, InternalSubsts, Subst, SubstsRef}; |
| use crate::ty::TyKind::*; |
| use crate::ty::{self, DefIdTree, GenericParamDefKind, Ty, TyCtxt, TypeFoldable}; |
| use rustc_apfloat::Float as _; |
| use rustc_ast::ast; |
| use rustc_attr::{self as attr, SignedInt, UnsignedInt}; |
| use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
| use rustc_errors::ErrorReported; |
| use rustc_hir as hir; |
| use rustc_hir::def::DefKind; |
| use rustc_hir::def_id::DefId; |
| use rustc_macros::HashStable; |
| use rustc_span::Span; |
| use rustc_target::abi::{Integer, Size, TargetDataLayout}; |
| use smallvec::SmallVec; |
| use std::{cmp, fmt}; |
| |
| #[derive(Copy, Clone, Debug)] |
| pub struct Discr<'tcx> { |
| /// Bit representation of the discriminant (e.g., `-128i8` is `0xFF_u128`). |
| pub val: u128, |
| pub ty: Ty<'tcx>, |
| } |
| |
| impl<'tcx> fmt::Display for Discr<'tcx> { |
| fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { |
| match self.ty.kind { |
| ty::Int(ity) => { |
| let size = ty::tls::with(|tcx| Integer::from_attr(&tcx, SignedInt(ity)).size()); |
| let x = self.val; |
| // sign extend the raw representation to be an i128 |
| let x = sign_extend(x, size) as i128; |
| write!(fmt, "{}", x) |
| } |
| _ => write!(fmt, "{}", self.val), |
| } |
| } |
| } |
| |
| fn signed_min(size: Size) -> i128 { |
| sign_extend(1_u128 << (size.bits() - 1), size) as i128 |
| } |
| |
| fn signed_max(size: Size) -> i128 { |
| i128::MAX >> (128 - size.bits()) |
| } |
| |
| fn unsigned_max(size: Size) -> u128 { |
| u128::MAX >> (128 - size.bits()) |
| } |
| |
| fn int_size_and_signed<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> (Size, bool) { |
| let (int, signed) = match ty.kind { |
| Int(ity) => (Integer::from_attr(&tcx, SignedInt(ity)), true), |
| Uint(uty) => (Integer::from_attr(&tcx, UnsignedInt(uty)), false), |
| _ => bug!("non integer discriminant"), |
| }; |
| (int.size(), signed) |
| } |
| |
| impl<'tcx> Discr<'tcx> { |
| /// Adds `1` to the value and wraps around if the maximum for the type is reached. |
| pub fn wrap_incr(self, tcx: TyCtxt<'tcx>) -> Self { |
| self.checked_add(tcx, 1).0 |
| } |
| pub fn checked_add(self, tcx: TyCtxt<'tcx>, n: u128) -> (Self, bool) { |
| let (size, signed) = int_size_and_signed(tcx, self.ty); |
| let (val, oflo) = if signed { |
| let min = signed_min(size); |
| let max = signed_max(size); |
| let val = sign_extend(self.val, size) as i128; |
| assert!(n < (i128::MAX as u128)); |
| let n = n as i128; |
| let oflo = val > max - n; |
| let val = if oflo { min + (n - (max - val) - 1) } else { val + n }; |
| // zero the upper bits |
| let val = val as u128; |
| let val = truncate(val, size); |
| (val, oflo) |
| } else { |
| let max = unsigned_max(size); |
| let val = self.val; |
| let oflo = val > max - n; |
| let val = if oflo { n - (max - val) - 1 } else { val + n }; |
| (val, oflo) |
| }; |
| (Self { val, ty: self.ty }, oflo) |
| } |
| } |
| |
| pub trait IntTypeExt { |
| fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx>; |
| fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>>; |
| fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx>; |
| } |
| |
| impl IntTypeExt for attr::IntType { |
| fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> { |
| match *self { |
| SignedInt(ast::IntTy::I8) => tcx.types.i8, |
| SignedInt(ast::IntTy::I16) => tcx.types.i16, |
| SignedInt(ast::IntTy::I32) => tcx.types.i32, |
| SignedInt(ast::IntTy::I64) => tcx.types.i64, |
| SignedInt(ast::IntTy::I128) => tcx.types.i128, |
| SignedInt(ast::IntTy::Isize) => tcx.types.isize, |
| UnsignedInt(ast::UintTy::U8) => tcx.types.u8, |
| UnsignedInt(ast::UintTy::U16) => tcx.types.u16, |
| UnsignedInt(ast::UintTy::U32) => tcx.types.u32, |
| UnsignedInt(ast::UintTy::U64) => tcx.types.u64, |
| UnsignedInt(ast::UintTy::U128) => tcx.types.u128, |
| UnsignedInt(ast::UintTy::Usize) => tcx.types.usize, |
| } |
| } |
| |
| fn initial_discriminant<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Discr<'tcx> { |
| Discr { val: 0, ty: self.to_ty(tcx) } |
| } |
| |
| fn disr_incr<'tcx>(&self, tcx: TyCtxt<'tcx>, val: Option<Discr<'tcx>>) -> Option<Discr<'tcx>> { |
| if let Some(val) = val { |
| assert_eq!(self.to_ty(tcx), val.ty); |
| let (new, oflo) = val.checked_add(tcx, 1); |
| if oflo { None } else { Some(new) } |
| } else { |
| Some(self.initial_discriminant(tcx)) |
| } |
| } |
| } |
| |
| /// Describes whether a type is representable. For types that are not |
| /// representable, 'SelfRecursive' and 'ContainsRecursive' are used to |
| /// distinguish between types that are recursive with themselves and types that |
| /// contain a different recursive type. These cases can therefore be treated |
| /// differently when reporting errors. |
| /// |
| /// The ordering of the cases is significant. They are sorted so that cmp::max |
| /// will keep the "more erroneous" of two values. |
| #[derive(Clone, PartialOrd, Ord, Eq, PartialEq, Debug)] |
| pub enum Representability { |
| Representable, |
| ContainsRecursive, |
| SelfRecursive(Vec<Span>), |
| } |
| |
| impl<'tcx> TyCtxt<'tcx> { |
| /// Creates a hash of the type `Ty` which will be the same no matter what crate |
| /// context it's calculated within. This is used by the `type_id` intrinsic. |
| pub fn type_id_hash(self, ty: Ty<'tcx>) -> u64 { |
| let mut hasher = StableHasher::new(); |
| let mut hcx = self.create_stable_hashing_context(); |
| |
| // We want the type_id be independent of the types free regions, so we |
| // erase them. The erase_regions() call will also anonymize bound |
| // regions, which is desirable too. |
| let ty = self.erase_regions(&ty); |
| |
| hcx.while_hashing_spans(false, |hcx| { |
| hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| { |
| ty.hash_stable(hcx, &mut hasher); |
| }); |
| }); |
| hasher.finish() |
| } |
| } |
| |
| impl<'tcx> TyCtxt<'tcx> { |
| pub fn has_error_field(self, ty: Ty<'tcx>) -> bool { |
| if let ty::Adt(def, substs) = ty.kind { |
| for field in def.all_fields() { |
| let field_ty = field.ty(self, substs); |
| if let Error(_) = field_ty.kind { |
| return true; |
| } |
| } |
| } |
| false |
| } |
| |
| /// Attempts to returns the deeply last field of nested structures, but |
| /// does not apply any normalization in its search. Returns the same type |
| /// if input `ty` is not a structure at all. |
| pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx> { |
| let tcx = self; |
| tcx.struct_tail_with_normalize(ty, |ty| ty) |
| } |
| |
| /// Returns the deeply last field of nested structures, or the same type if |
| /// not a structure at all. Corresponds to the only possible unsized field, |
| /// and its type can be used to determine unsizing strategy. |
| /// |
| /// Should only be called if `ty` has no inference variables and does not |
| /// need its lifetimes preserved (e.g. as part of codegen); otherwise |
| /// normalization attempt may cause compiler bugs. |
| pub fn struct_tail_erasing_lifetimes( |
| self, |
| ty: Ty<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> Ty<'tcx> { |
| let tcx = self; |
| tcx.struct_tail_with_normalize(ty, |ty| tcx.normalize_erasing_regions(param_env, ty)) |
| } |
| |
| /// Returns the deeply last field of nested structures, or the same type if |
| /// not a structure at all. Corresponds to the only possible unsized field, |
| /// and its type can be used to determine unsizing strategy. |
| /// |
| /// This is parameterized over the normalization strategy (i.e. how to |
| /// handle `<T as Trait>::Assoc` and `impl Trait`); pass the identity |
| /// function to indicate no normalization should take place. |
| /// |
| /// See also `struct_tail_erasing_lifetimes`, which is suitable for use |
| /// during codegen. |
| pub fn struct_tail_with_normalize( |
| self, |
| mut ty: Ty<'tcx>, |
| normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, |
| ) -> Ty<'tcx> { |
| loop { |
| match ty.kind { |
| ty::Adt(def, substs) => { |
| if !def.is_struct() { |
| break; |
| } |
| match def.non_enum_variant().fields.last() { |
| Some(f) => ty = f.ty(self, substs), |
| None => break, |
| } |
| } |
| |
| ty::Tuple(tys) => { |
| if let Some((&last_ty, _)) = tys.split_last() { |
| ty = last_ty.expect_ty(); |
| } else { |
| break; |
| } |
| } |
| |
| ty::Projection(_) | ty::Opaque(..) => { |
| let normalized = normalize(ty); |
| if ty == normalized { |
| return ty; |
| } else { |
| ty = normalized; |
| } |
| } |
| |
| _ => { |
| break; |
| } |
| } |
| } |
| ty |
| } |
| |
| /// Same as applying `struct_tail` on `source` and `target`, but only |
| /// keeps going as long as the two types are instances of the same |
| /// structure definitions. |
| /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, |
| /// whereas struct_tail produces `T`, and `Trait`, respectively. |
| /// |
| /// Should only be called if the types have no inference variables and do |
| /// not need their lifetimes preserved (e.g., as part of codegen); otherwise, |
| /// normalization attempt may cause compiler bugs. |
| pub fn struct_lockstep_tails_erasing_lifetimes( |
| self, |
| source: Ty<'tcx>, |
| target: Ty<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> (Ty<'tcx>, Ty<'tcx>) { |
| let tcx = self; |
| tcx.struct_lockstep_tails_with_normalize(source, target, |ty| { |
| tcx.normalize_erasing_regions(param_env, ty) |
| }) |
| } |
| |
| /// Same as applying `struct_tail` on `source` and `target`, but only |
| /// keeps going as long as the two types are instances of the same |
| /// structure definitions. |
| /// For `(Foo<Foo<T>>, Foo<dyn Trait>)`, the result will be `(Foo<T>, Trait)`, |
| /// whereas struct_tail produces `T`, and `Trait`, respectively. |
| /// |
| /// See also `struct_lockstep_tails_erasing_lifetimes`, which is suitable for use |
| /// during codegen. |
| pub fn struct_lockstep_tails_with_normalize( |
| self, |
| source: Ty<'tcx>, |
| target: Ty<'tcx>, |
| normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>, |
| ) -> (Ty<'tcx>, Ty<'tcx>) { |
| let (mut a, mut b) = (source, target); |
| loop { |
| match (&a.kind, &b.kind) { |
| (&Adt(a_def, a_substs), &Adt(b_def, b_substs)) |
| if a_def == b_def && a_def.is_struct() => |
| { |
| if let Some(f) = a_def.non_enum_variant().fields.last() { |
| a = f.ty(self, a_substs); |
| b = f.ty(self, b_substs); |
| } else { |
| break; |
| } |
| } |
| (&Tuple(a_tys), &Tuple(b_tys)) if a_tys.len() == b_tys.len() => { |
| if let Some(a_last) = a_tys.last() { |
| a = a_last.expect_ty(); |
| b = b_tys.last().unwrap().expect_ty(); |
| } else { |
| break; |
| } |
| } |
| (ty::Projection(_) | ty::Opaque(..), _) |
| | (_, ty::Projection(_) | ty::Opaque(..)) => { |
| // If either side is a projection, attempt to |
| // progress via normalization. (Should be safe to |
| // apply to both sides as normalization is |
| // idempotent.) |
| let a_norm = normalize(a); |
| let b_norm = normalize(b); |
| if a == a_norm && b == b_norm { |
| break; |
| } else { |
| a = a_norm; |
| b = b_norm; |
| } |
| } |
| |
| _ => break, |
| } |
| } |
| (a, b) |
| } |
| |
| /// Calculate the destructor of a given type. |
| pub fn calculate_dtor( |
| self, |
| adt_did: DefId, |
| validate: &mut dyn FnMut(Self, DefId) -> Result<(), ErrorReported>, |
| ) -> Option<ty::Destructor> { |
| let drop_trait = self.lang_items().drop_trait()?; |
| self.ensure().coherent_trait(drop_trait); |
| |
| let mut dtor_did = None; |
| let ty = self.type_of(adt_did); |
| self.for_each_relevant_impl(drop_trait, ty, |impl_did| { |
| if let Some(item) = self.associated_items(impl_did).in_definition_order().next() { |
| if validate(self, impl_did).is_ok() { |
| dtor_did = Some(item.def_id); |
| } |
| } |
| }); |
| |
| Some(ty::Destructor { did: dtor_did? }) |
| } |
| |
| /// Returns the set of types that are required to be alive in |
| /// order to run the destructor of `def` (see RFCs 769 and |
| /// 1238). |
| /// |
| /// Note that this returns only the constraints for the |
| /// destructor of `def` itself. For the destructors of the |
| /// contents, you need `adt_dtorck_constraint`. |
| pub fn destructor_constraints(self, def: &'tcx ty::AdtDef) -> Vec<ty::subst::GenericArg<'tcx>> { |
| let dtor = match def.destructor(self) { |
| None => { |
| debug!("destructor_constraints({:?}) - no dtor", def.did); |
| return vec![]; |
| } |
| Some(dtor) => dtor.did, |
| }; |
| |
| let impl_def_id = self.associated_item(dtor).container.id(); |
| let impl_generics = self.generics_of(impl_def_id); |
| |
| // We have a destructor - all the parameters that are not |
| // pure_wrt_drop (i.e, don't have a #[may_dangle] attribute) |
| // must be live. |
| |
| // We need to return the list of parameters from the ADTs |
| // generics/substs that correspond to impure parameters on the |
| // impl's generics. This is a bit ugly, but conceptually simple: |
| // |
| // Suppose our ADT looks like the following |
| // |
| // struct S<X, Y, Z>(X, Y, Z); |
| // |
| // and the impl is |
| // |
| // impl<#[may_dangle] P0, P1, P2> Drop for S<P1, P2, P0> |
| // |
| // We want to return the parameters (X, Y). For that, we match |
| // up the item-substs <X, Y, Z> with the substs on the impl ADT, |
| // <P1, P2, P0>, and then look up which of the impl substs refer to |
| // parameters marked as pure. |
| |
| let impl_substs = match self.type_of(impl_def_id).kind { |
| ty::Adt(def_, substs) if def_ == def => substs, |
| _ => bug!(), |
| }; |
| |
| let item_substs = match self.type_of(def.did).kind { |
| ty::Adt(def_, substs) if def_ == def => substs, |
| _ => bug!(), |
| }; |
| |
| let result = item_substs |
| .iter() |
| .zip(impl_substs.iter()) |
| .filter(|&(_, k)| { |
| match k.unpack() { |
| GenericArgKind::Lifetime(&ty::RegionKind::ReEarlyBound(ref ebr)) => { |
| !impl_generics.region_param(ebr, self).pure_wrt_drop |
| } |
| GenericArgKind::Type(&ty::TyS { kind: ty::Param(ref pt), .. }) => { |
| !impl_generics.type_param(pt, self).pure_wrt_drop |
| } |
| GenericArgKind::Const(&ty::Const { |
| val: ty::ConstKind::Param(ref pc), .. |
| }) => !impl_generics.const_param(pc, self).pure_wrt_drop, |
| GenericArgKind::Lifetime(_) |
| | GenericArgKind::Type(_) |
| | GenericArgKind::Const(_) => { |
| // Not a type, const or region param: this should be reported |
| // as an error. |
| false |
| } |
| } |
| }) |
| .map(|(item_param, _)| item_param) |
| .collect(); |
| debug!("destructor_constraint({:?}) = {:?}", def.did, result); |
| result |
| } |
| |
| /// Returns `true` if `def_id` refers to a closure (e.g., `|x| x * 2`). Note |
| /// that closures have a `DefId`, but the closure *expression* also |
| /// has a `HirId` that is located within the context where the |
| /// closure appears (and, sadly, a corresponding `NodeId`, since |
| /// those are not yet phased out). The parent of the closure's |
| /// `DefId` will also be the context where it appears. |
| pub fn is_closure(self, def_id: DefId) -> bool { |
| matches!(self.def_kind(def_id), DefKind::Closure | DefKind::Generator) |
| } |
| |
| /// Returns `true` if `def_id` refers to a trait (i.e., `trait Foo { ... }`). |
| pub fn is_trait(self, def_id: DefId) -> bool { |
| self.def_kind(def_id) == DefKind::Trait |
| } |
| |
| /// Returns `true` if `def_id` refers to a trait alias (i.e., `trait Foo = ...;`), |
| /// and `false` otherwise. |
| pub fn is_trait_alias(self, def_id: DefId) -> bool { |
| self.def_kind(def_id) == DefKind::TraitAlias |
| } |
| |
| /// Returns `true` if this `DefId` refers to the implicit constructor for |
| /// a tuple struct like `struct Foo(u32)`, and `false` otherwise. |
| pub fn is_constructor(self, def_id: DefId) -> bool { |
| matches!(self.def_kind(def_id), DefKind::Ctor(..)) |
| } |
| |
| /// Given the def-ID of a fn or closure, returns the def-ID of |
| /// the innermost fn item that the closure is contained within. |
| /// This is a significant `DefId` because, when we do |
| /// type-checking, we type-check this fn item and all of its |
| /// (transitive) closures together. Therefore, when we fetch the |
| /// `typeck_tables_of` the closure, for example, we really wind up |
| /// fetching the `typeck_tables_of` the enclosing fn item. |
| pub fn closure_base_def_id(self, def_id: DefId) -> DefId { |
| let mut def_id = def_id; |
| while self.is_closure(def_id) { |
| def_id = self.parent(def_id).unwrap_or_else(|| { |
| bug!("closure {:?} has no parent", def_id); |
| }); |
| } |
| def_id |
| } |
| |
| /// Given the `DefId` and substs a closure, creates the type of |
| /// `self` argument that the closure expects. For example, for a |
| /// `Fn` closure, this would return a reference type `&T` where |
| /// `T = closure_ty`. |
| /// |
| /// Returns `None` if this closure's kind has not yet been inferred. |
| /// This should only be possible during type checking. |
| /// |
| /// Note that the return value is a late-bound region and hence |
| /// wrapped in a binder. |
| pub fn closure_env_ty( |
| self, |
| closure_def_id: DefId, |
| closure_substs: SubstsRef<'tcx>, |
| ) -> Option<ty::Binder<Ty<'tcx>>> { |
| let closure_ty = self.mk_closure(closure_def_id, closure_substs); |
| let env_region = ty::ReLateBound(ty::INNERMOST, ty::BrEnv); |
| let closure_kind_ty = closure_substs.as_closure().kind_ty(); |
| let closure_kind = closure_kind_ty.to_opt_closure_kind()?; |
| let env_ty = match closure_kind { |
| ty::ClosureKind::Fn => self.mk_imm_ref(self.mk_region(env_region), closure_ty), |
| ty::ClosureKind::FnMut => self.mk_mut_ref(self.mk_region(env_region), closure_ty), |
| ty::ClosureKind::FnOnce => closure_ty, |
| }; |
| Some(ty::Binder::bind(env_ty)) |
| } |
| |
| /// Given the `DefId` of some item that has no type or const parameters, make |
| /// a suitable "empty substs" for it. |
| pub fn empty_substs_for_def_id(self, item_def_id: DefId) -> SubstsRef<'tcx> { |
| InternalSubsts::for_item(self, item_def_id, |param, _| match param.kind { |
| GenericParamDefKind::Lifetime => self.lifetimes.re_erased.into(), |
| GenericParamDefKind::Type { .. } => { |
| bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id) |
| } |
| GenericParamDefKind::Const { .. } => { |
| bug!("empty_substs_for_def_id: {:?} has const parameters", item_def_id) |
| } |
| }) |
| } |
| |
| /// Returns `true` if the node pointed to by `def_id` is a `static` item. |
| pub fn is_static(&self, def_id: DefId) -> bool { |
| self.static_mutability(def_id).is_some() |
| } |
| |
| /// Returns `true` if this is a `static` item with the `#[thread_local]` attribute. |
| pub fn is_thread_local_static(&self, def_id: DefId) -> bool { |
| self.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) |
| } |
| |
| /// Returns `true` if the node pointed to by `def_id` is a mutable `static` item. |
| pub fn is_mutable_static(&self, def_id: DefId) -> bool { |
| self.static_mutability(def_id) == Some(hir::Mutability::Mut) |
| } |
| |
| /// Get the type of the pointer to the static that we use in MIR. |
| pub fn static_ptr_ty(&self, def_id: DefId) -> Ty<'tcx> { |
| // Make sure that any constants in the static's type are evaluated. |
| let static_ty = self.normalize_erasing_regions(ty::ParamEnv::empty(), self.type_of(def_id)); |
| |
| if self.is_mutable_static(def_id) { |
| self.mk_mut_ptr(static_ty) |
| } else { |
| self.mk_imm_ref(self.lifetimes.re_erased, static_ty) |
| } |
| } |
| |
| /// Expands the given impl trait type, stopping if the type is recursive. |
| pub fn try_expand_impl_trait_type( |
| self, |
| def_id: DefId, |
| substs: SubstsRef<'tcx>, |
| ) -> Result<Ty<'tcx>, Ty<'tcx>> { |
| use crate::ty::fold::TypeFolder; |
| |
| struct OpaqueTypeExpander<'tcx> { |
| // Contains the DefIds of the opaque types that are currently being |
| // expanded. When we expand an opaque type we insert the DefId of |
| // that type, and when we finish expanding that type we remove the |
| // its DefId. |
| seen_opaque_tys: FxHashSet<DefId>, |
| // Cache of all expansions we've seen so far. This is a critical |
| // optimization for some large types produced by async fn trees. |
| expanded_cache: FxHashMap<(DefId, SubstsRef<'tcx>), Ty<'tcx>>, |
| primary_def_id: DefId, |
| found_recursion: bool, |
| tcx: TyCtxt<'tcx>, |
| } |
| |
| impl<'tcx> OpaqueTypeExpander<'tcx> { |
| fn expand_opaque_ty( |
| &mut self, |
| def_id: DefId, |
| substs: SubstsRef<'tcx>, |
| ) -> Option<Ty<'tcx>> { |
| if self.found_recursion { |
| return None; |
| } |
| let substs = substs.fold_with(self); |
| if self.seen_opaque_tys.insert(def_id) { |
| let expanded_ty = match self.expanded_cache.get(&(def_id, substs)) { |
| Some(expanded_ty) => expanded_ty, |
| None => { |
| let generic_ty = self.tcx.type_of(def_id); |
| let concrete_ty = generic_ty.subst(self.tcx, substs); |
| let expanded_ty = self.fold_ty(concrete_ty); |
| self.expanded_cache.insert((def_id, substs), expanded_ty); |
| expanded_ty |
| } |
| }; |
| self.seen_opaque_tys.remove(&def_id); |
| Some(expanded_ty) |
| } else { |
| // If another opaque type that we contain is recursive, then it |
| // will report the error, so we don't have to. |
| self.found_recursion = def_id == self.primary_def_id; |
| None |
| } |
| } |
| } |
| |
| impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> { |
| fn tcx(&self) -> TyCtxt<'tcx> { |
| self.tcx |
| } |
| |
| fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { |
| if let ty::Opaque(def_id, substs) = t.kind { |
| self.expand_opaque_ty(def_id, substs).unwrap_or(t) |
| } else if t.has_opaque_types() { |
| t.super_fold_with(self) |
| } else { |
| t |
| } |
| } |
| } |
| |
| let mut visitor = OpaqueTypeExpander { |
| seen_opaque_tys: FxHashSet::default(), |
| expanded_cache: FxHashMap::default(), |
| primary_def_id: def_id, |
| found_recursion: false, |
| tcx: self, |
| }; |
| let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap(); |
| if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) } |
| } |
| } |
| |
| impl<'tcx> ty::TyS<'tcx> { |
| /// Returns the maximum value for the given numeric type (including `char`s) |
| /// or returns `None` if the type is not numeric. |
| pub fn numeric_max_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { |
| let val = match self.kind { |
| ty::Int(_) | ty::Uint(_) => { |
| let (size, signed) = int_size_and_signed(tcx, self); |
| let val = if signed { signed_max(size) as u128 } else { unsigned_max(size) }; |
| Some(val) |
| } |
| ty::Char => Some(std::char::MAX as u128), |
| ty::Float(fty) => Some(match fty { |
| ast::FloatTy::F32 => ::rustc_apfloat::ieee::Single::INFINITY.to_bits(), |
| ast::FloatTy::F64 => ::rustc_apfloat::ieee::Double::INFINITY.to_bits(), |
| }), |
| _ => None, |
| }; |
| val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) |
| } |
| |
| /// Returns the minimum value for the given numeric type (including `char`s) |
| /// or returns `None` if the type is not numeric. |
| pub fn numeric_min_val(&'tcx self, tcx: TyCtxt<'tcx>) -> Option<&'tcx ty::Const<'tcx>> { |
| let val = match self.kind { |
| ty::Int(_) | ty::Uint(_) => { |
| let (size, signed) = int_size_and_signed(tcx, self); |
| let val = if signed { truncate(signed_min(size) as u128, size) } else { 0 }; |
| Some(val) |
| } |
| ty::Char => Some(0), |
| ty::Float(fty) => Some(match fty { |
| ast::FloatTy::F32 => (-::rustc_apfloat::ieee::Single::INFINITY).to_bits(), |
| ast::FloatTy::F64 => (-::rustc_apfloat::ieee::Double::INFINITY).to_bits(), |
| }), |
| _ => None, |
| }; |
| val.map(|v| ty::Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self))) |
| } |
| |
| /// Checks whether values of this type `T` are *moved* or *copied* |
| /// when referenced -- this amounts to a check for whether `T: |
| /// Copy`, but note that we **don't** consider lifetimes when |
| /// doing this check. This means that we may generate MIR which |
| /// does copies even when the type actually doesn't satisfy the |
| /// full requirements for the `Copy` trait (cc #29149) -- this |
| /// winds up being reported as an error during NLL borrow check. |
| pub fn is_copy_modulo_regions( |
| &'tcx self, |
| tcx_at: TyCtxtAt<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| ) -> bool { |
| tcx_at.is_copy_raw(param_env.and(self)) |
| } |
| |
| /// Checks whether values of this type `T` have a size known at |
| /// compile time (i.e., whether `T: Sized`). Lifetimes are ignored |
| /// for the purposes of this check, so it can be an |
| /// over-approximation in generic contexts, where one can have |
| /// strange rules like `<T as Foo<'static>>::Bar: Sized` that |
| /// actually carry lifetime requirements. |
| pub fn is_sized(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
| self.is_trivially_sized(tcx_at.tcx) || tcx_at.is_sized_raw(param_env.and(self)) |
| } |
| |
| /// Checks whether values of this type `T` implement the `Freeze` |
| /// trait -- frozen types are those that do not contain a |
| /// `UnsafeCell` anywhere. This is a language concept used to |
| /// distinguish "true immutability", which is relevant to |
| /// optimization as well as the rules around static values. Note |
| /// that the `Freeze` trait is not exposed to end users and is |
| /// effectively an implementation detail. |
| // FIXME: use `TyCtxtAt` instead of separate `Span`. |
| pub fn is_freeze(&'tcx self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
| self.is_trivially_freeze() || tcx_at.is_freeze_raw(param_env.and(self)) |
| } |
| |
| /// Fast path helper for testing if a type is `Freeze`. |
| /// |
| /// Returning true means the type is known to be `Freeze`. Returning |
| /// `false` means nothing -- could be `Freeze`, might not be. |
| fn is_trivially_freeze(&self) -> bool { |
| match self.kind { |
| ty::Int(_) |
| | ty::Uint(_) |
| | ty::Float(_) |
| | ty::Bool |
| | ty::Char |
| | ty::Str |
| | ty::Never |
| | ty::Ref(..) |
| | ty::RawPtr(_) |
| | ty::FnDef(..) |
| | ty::Error(_) |
| | ty::FnPtr(_) => true, |
| ty::Tuple(_) => self.tuple_fields().all(Self::is_trivially_freeze), |
| ty::Slice(elem_ty) | ty::Array(elem_ty, _) => elem_ty.is_trivially_freeze(), |
| ty::Adt(..) |
| | ty::Bound(..) |
| | ty::Closure(..) |
| | ty::Dynamic(..) |
| | ty::Foreign(_) |
| | ty::Generator(..) |
| | ty::GeneratorWitness(_) |
| | ty::Infer(_) |
| | ty::Opaque(..) |
| | ty::Param(_) |
| | ty::Placeholder(_) |
| | ty::Projection(_) => false, |
| } |
| } |
| |
| /// If `ty.needs_drop(...)` returns `true`, then `ty` is definitely |
| /// non-copy and *might* have a destructor attached; if it returns |
| /// `false`, then `ty` definitely has no destructor (i.e., no drop glue). |
| /// |
| /// (Note that this implies that if `ty` has a destructor attached, |
| /// then `needs_drop` will definitely return `true` for `ty`.) |
| /// |
| /// Note that this method is used to check eligible types in unions. |
| #[inline] |
| pub fn needs_drop(&'tcx self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { |
| // Avoid querying in simple cases. |
| match needs_drop_components(self, &tcx.data_layout) { |
| Err(AlwaysRequiresDrop) => true, |
| Ok(components) => { |
| let query_ty = match *components { |
| [] => return false, |
| // If we've got a single component, call the query with that |
| // to increase the chance that we hit the query cache. |
| [component_ty] => component_ty, |
| _ => self, |
| }; |
| // This doesn't depend on regions, so try to minimize distinct |
| // query keys used. |
| let erased = tcx.normalize_erasing_regions(param_env, query_ty); |
| tcx.needs_drop_raw(param_env.and(erased)) |
| } |
| } |
| } |
| |
| /// Returns `true` if equality for this type is both reflexive and structural. |
| /// |
| /// Reflexive equality for a type is indicated by an `Eq` impl for that type. |
| /// |
| /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data |
| /// types, equality for the type as a whole is structural when it is the same as equality |
| /// between all components (fields, array elements, etc.) of that type. For ADTs, structural |
| /// equality is indicated by an implementation of `PartialStructuralEq` and `StructuralEq` for |
| /// that type. |
| /// |
| /// This function is "shallow" because it may return `true` for a composite type whose fields |
| /// are not `StructuralEq`. For example, `[T; 4]` has structural equality regardless of `T` |
| /// because equality for arrays is determined by the equality of each array element. If you |
| /// want to know whether a given call to `PartialEq::eq` will proceed structurally all the way |
| /// down, you will need to use a type visitor. |
| #[inline] |
| pub fn is_structural_eq_shallow(&'tcx self, tcx: TyCtxt<'tcx>) -> bool { |
| match self.kind { |
| // Look for an impl of both `PartialStructuralEq` and `StructuralEq`. |
| Adt(..) => tcx.has_structural_eq_impls(self), |
| |
| // Primitive types that satisfy `Eq`. |
| Bool | Char | Int(_) | Uint(_) | Str | Never => true, |
| |
| // Composite types that satisfy `Eq` when all of their fields do. |
| // |
| // Because this function is "shallow", we return `true` for these composites regardless |
| // of the type(s) contained within. |
| Ref(..) | Array(..) | Slice(_) | Tuple(..) => true, |
| |
| // Raw pointers use bitwise comparison. |
| RawPtr(_) | FnPtr(_) => true, |
| |
| // Floating point numbers are not `Eq`. |
| Float(_) => false, |
| |
| // Conservatively return `false` for all others... |
| |
| // Anonymous function types |
| FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false, |
| |
| // Generic or inferred types |
| // |
| // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be |
| // called for known, fully-monomorphized types. |
| Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false, |
| |
| Foreign(_) | GeneratorWitness(..) | Error(_) => false, |
| } |
| } |
| |
| pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool { |
| match (&a.kind, &b.kind) { |
| (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => { |
| if did_a != did_b { |
| return false; |
| } |
| |
| substs_a.types().zip(substs_b.types()).all(|(a, b)| Self::same_type(a, b)) |
| } |
| _ => a == b, |
| } |
| } |
| |
| /// Check whether a type is representable. This means it cannot contain unboxed |
| /// structural recursion. This check is needed for structs and enums. |
| pub fn is_representable(&'tcx self, tcx: TyCtxt<'tcx>, sp: Span) -> Representability { |
| // Iterate until something non-representable is found |
| fn fold_repr<It: Iterator<Item = Representability>>(iter: It) -> Representability { |
| iter.fold(Representability::Representable, |r1, r2| match (r1, r2) { |
| (Representability::SelfRecursive(v1), Representability::SelfRecursive(v2)) => { |
| Representability::SelfRecursive(v1.into_iter().chain(v2).collect()) |
| } |
| (r1, r2) => cmp::max(r1, r2), |
| }) |
| } |
| |
| fn are_inner_types_recursive<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, |
| representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, |
| ty: Ty<'tcx>, |
| ) -> Representability { |
| match ty.kind { |
| Tuple(..) => { |
| // Find non representable |
| fold_repr(ty.tuple_fields().map(|ty| { |
| is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty) |
| })) |
| } |
| // Fixed-length vectors. |
| // FIXME(#11924) Behavior undecided for zero-length vectors. |
| Array(ty, _) => { |
| is_type_structurally_recursive(tcx, sp, seen, representable_cache, ty) |
| } |
| Adt(def, substs) => { |
| // Find non representable fields with their spans |
| fold_repr(def.all_fields().map(|field| { |
| let ty = field.ty(tcx, substs); |
| let span = match field |
| .did |
| .as_local() |
| .map(|id| tcx.hir().as_local_hir_id(id)) |
| .and_then(|id| tcx.hir().find(id)) |
| { |
| Some(hir::Node::Field(field)) => field.ty.span, |
| _ => sp, |
| }; |
| match is_type_structurally_recursive( |
| tcx, |
| span, |
| seen, |
| representable_cache, |
| ty, |
| ) { |
| Representability::SelfRecursive(_) => { |
| Representability::SelfRecursive(vec![span]) |
| } |
| x => x, |
| } |
| })) |
| } |
| Closure(..) => { |
| // this check is run on type definitions, so we don't expect |
| // to see closure types |
| bug!("requires check invoked on inapplicable type: {:?}", ty) |
| } |
| _ => Representability::Representable, |
| } |
| } |
| |
| fn same_struct_or_enum<'tcx>(ty: Ty<'tcx>, def: &'tcx ty::AdtDef) -> bool { |
| match ty.kind { |
| Adt(ty_def, _) => ty_def == def, |
| _ => false, |
| } |
| } |
| |
| // Does the type `ty` directly (without indirection through a pointer) |
| // contain any types on stack `seen`? |
| fn is_type_structurally_recursive<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, |
| representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, |
| ty: Ty<'tcx>, |
| ) -> Representability { |
| debug!("is_type_structurally_recursive: {:?} {:?}", ty, sp); |
| if let Some(representability) = representable_cache.get(ty) { |
| debug!( |
| "is_type_structurally_recursive: {:?} {:?} - (cached) {:?}", |
| ty, sp, representability |
| ); |
| return representability.clone(); |
| } |
| |
| let representability = |
| is_type_structurally_recursive_inner(tcx, sp, seen, representable_cache, ty); |
| |
| representable_cache.insert(ty, representability.clone()); |
| representability |
| } |
| |
| fn is_type_structurally_recursive_inner<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| sp: Span, |
| seen: &mut Vec<Ty<'tcx>>, |
| representable_cache: &mut FxHashMap<Ty<'tcx>, Representability>, |
| ty: Ty<'tcx>, |
| ) -> Representability { |
| match ty.kind { |
| Adt(def, _) => { |
| { |
| // Iterate through stack of previously seen types. |
| let mut iter = seen.iter(); |
| |
| // The first item in `seen` is the type we are actually curious about. |
| // We want to return SelfRecursive if this type contains itself. |
| // It is important that we DON'T take generic parameters into account |
| // for this check, so that Bar<T> in this example counts as SelfRecursive: |
| // |
| // struct Foo; |
| // struct Bar<T> { x: Bar<Foo> } |
| |
| if let Some(&seen_type) = iter.next() { |
| if same_struct_or_enum(seen_type, def) { |
| debug!("SelfRecursive: {:?} contains {:?}", seen_type, ty); |
| return Representability::SelfRecursive(vec![sp]); |
| } |
| } |
| |
| // We also need to know whether the first item contains other types |
| // that are structurally recursive. If we don't catch this case, we |
| // will recurse infinitely for some inputs. |
| // |
| // It is important that we DO take generic parameters into account |
| // here, so that code like this is considered SelfRecursive, not |
| // ContainsRecursive: |
| // |
| // struct Foo { Option<Option<Foo>> } |
| |
| for &seen_type in iter { |
| if ty::TyS::same_type(ty, seen_type) { |
| debug!("ContainsRecursive: {:?} contains {:?}", seen_type, ty); |
| return Representability::ContainsRecursive; |
| } |
| } |
| } |
| |
| // For structs and enums, track all previously seen types by pushing them |
| // onto the 'seen' stack. |
| seen.push(ty); |
| let out = are_inner_types_recursive(tcx, sp, seen, representable_cache, ty); |
| seen.pop(); |
| out |
| } |
| _ => { |
| // No need to push in other cases. |
| are_inner_types_recursive(tcx, sp, seen, representable_cache, ty) |
| } |
| } |
| } |
| |
| debug!("is_type_representable: {:?}", self); |
| |
| // To avoid a stack overflow when checking an enum variant or struct that |
| // contains a different, structurally recursive type, maintain a stack |
| // of seen types and check recursion for each of them (issues #3008, #3779). |
| let mut seen: Vec<Ty<'_>> = Vec::new(); |
| let mut representable_cache = FxHashMap::default(); |
| let r = is_type_structurally_recursive(tcx, sp, &mut seen, &mut representable_cache, self); |
| debug!("is_type_representable: {:?} is {:?}", self, r); |
| r |
| } |
| |
| /// Peel off all reference types in this type until there are none left. |
| /// |
| /// This method is idempotent, i.e. `ty.peel_refs().peel_refs() == ty.peel_refs()`. |
| /// |
| /// # Examples |
| /// |
| /// - `u8` -> `u8` |
| /// - `&'a mut u8` -> `u8` |
| /// - `&'a &'b u8` -> `u8` |
| /// - `&'a *const &'b u8 -> *const &'b u8` |
| pub fn peel_refs(&'tcx self) -> Ty<'tcx> { |
| let mut ty = self; |
| while let Ref(_, inner_ty, _) = ty.kind { |
| ty = inner_ty; |
| } |
| ty |
| } |
| } |
| |
| pub enum ExplicitSelf<'tcx> { |
| ByValue, |
| ByReference(ty::Region<'tcx>, hir::Mutability), |
| ByRawPointer(hir::Mutability), |
| ByBox, |
| Other, |
| } |
| |
| impl<'tcx> ExplicitSelf<'tcx> { |
| /// Categorizes an explicit self declaration like `self: SomeType` |
| /// into either `self`, `&self`, `&mut self`, `Box<self>`, or |
| /// `Other`. |
| /// This is mainly used to require the arbitrary_self_types feature |
| /// in the case of `Other`, to improve error messages in the common cases, |
| /// and to make `Other` non-object-safe. |
| /// |
| /// Examples: |
| /// |
| /// ``` |
| /// impl<'a> Foo for &'a T { |
| /// // Legal declarations: |
| /// fn method1(self: &&'a T); // ExplicitSelf::ByReference |
| /// fn method2(self: &'a T); // ExplicitSelf::ByValue |
| /// fn method3(self: Box<&'a T>); // ExplicitSelf::ByBox |
| /// fn method4(self: Rc<&'a T>); // ExplicitSelf::Other |
| /// |
| /// // Invalid cases will be caught by `check_method_receiver`: |
| /// fn method_err1(self: &'a mut T); // ExplicitSelf::Other |
| /// fn method_err2(self: &'static T) // ExplicitSelf::ByValue |
| /// fn method_err3(self: &&T) // ExplicitSelf::ByReference |
| /// } |
| /// ``` |
| /// |
| pub fn determine<P>(self_arg_ty: Ty<'tcx>, is_self_ty: P) -> ExplicitSelf<'tcx> |
| where |
| P: Fn(Ty<'tcx>) -> bool, |
| { |
| use self::ExplicitSelf::*; |
| |
| match self_arg_ty.kind { |
| _ if is_self_ty(self_arg_ty) => ByValue, |
| ty::Ref(region, ty, mutbl) if is_self_ty(ty) => ByReference(region, mutbl), |
| ty::RawPtr(ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => ByRawPointer(mutbl), |
| ty::Adt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => ByBox, |
| _ => Other, |
| } |
| } |
| } |
| |
| /// Returns a list of types such that the given type needs drop if and only if |
| /// *any* of the returned types need drop. Returns `Err(AlwaysRequiresDrop)` if |
| /// this type always needs drop. |
| pub fn needs_drop_components( |
| ty: Ty<'tcx>, |
| target_layout: &TargetDataLayout, |
| ) -> Result<SmallVec<[Ty<'tcx>; 2]>, AlwaysRequiresDrop> { |
| match ty.kind { |
| ty::Infer(ty::FreshIntTy(_)) |
| | ty::Infer(ty::FreshFloatTy(_)) |
| | ty::Bool |
| | ty::Int(_) |
| | ty::Uint(_) |
| | ty::Float(_) |
| | ty::Never |
| | ty::FnDef(..) |
| | ty::FnPtr(_) |
| | ty::Char |
| | ty::GeneratorWitness(..) |
| | ty::RawPtr(_) |
| | ty::Ref(..) |
| | ty::Str => Ok(SmallVec::new()), |
| |
| // Foreign types can never have destructors. |
| ty::Foreign(..) => Ok(SmallVec::new()), |
| |
| ty::Dynamic(..) | ty::Error(_) => Err(AlwaysRequiresDrop), |
| |
| ty::Slice(ty) => needs_drop_components(ty, target_layout), |
| ty::Array(elem_ty, size) => { |
| match needs_drop_components(elem_ty, target_layout) { |
| Ok(v) if v.is_empty() => Ok(v), |
| res => match size.val.try_to_bits(target_layout.pointer_size) { |
| // Arrays of size zero don't need drop, even if their element |
| // type does. |
| Some(0) => Ok(SmallVec::new()), |
| Some(_) => res, |
| // We don't know which of the cases above we are in, so |
| // return the whole type and let the caller decide what to |
| // do. |
| None => Ok(smallvec![ty]), |
| }, |
| } |
| } |
| // If any field needs drop, then the whole tuple does. |
| ty::Tuple(..) => ty.tuple_fields().try_fold(SmallVec::new(), move |mut acc, elem| { |
| acc.extend(needs_drop_components(elem, target_layout)?); |
| Ok(acc) |
| }), |
| |
| // These require checking for `Copy` bounds or `Adt` destructors. |
| ty::Adt(..) |
| | ty::Projection(..) |
| | ty::Param(_) |
| | ty::Bound(..) |
| | ty::Placeholder(..) |
| | ty::Opaque(..) |
| | ty::Infer(_) |
| | ty::Closure(..) |
| | ty::Generator(..) => Ok(smallvec![ty]), |
| } |
| } |
| |
| #[derive(Copy, Clone, Debug, HashStable, RustcEncodable, RustcDecodable)] |
| pub struct AlwaysRequiresDrop; |
