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Diffstat (limited to 'compiler/rustc_middle/src/ty/util.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/util.rs | 1294 |
1 files changed, 1294 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs new file mode 100644 index 000000000..591bb7831 --- /dev/null +++ b/compiler/rustc_middle/src/ty/util.rs @@ -0,0 +1,1294 @@ +//! Miscellaneous type-system utilities that are too small to deserve their own modules. + +use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags; +use crate::ty::layout::IntegerExt; +use crate::ty::query::TyCtxtAt; +use crate::ty::subst::{GenericArgKind, Subst, SubstsRef}; +use crate::ty::{ + self, DefIdTree, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, + TypeVisitable, +}; +use rustc_apfloat::Float as _; +use rustc_ast as 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::ErrorGuaranteed; +use rustc_hir as hir; +use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_index::bit_set::GrowableBitSet; +use rustc_macros::HashStable; +use rustc_span::{sym, DUMMY_SP}; +use rustc_target::abi::{Integer, Size, TargetDataLayout}; +use rustc_target::spec::abi::Abi; +use smallvec::SmallVec; +use std::{fmt, iter}; + +#[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>, +} + +/// Used as an input to [`TyCtxt::uses_unique_generic_params`]. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum IgnoreRegions { + Yes, + No, +} + +#[derive(Copy, Clone, Debug)] +pub enum NotUniqueParam<'tcx> { + DuplicateParam(ty::GenericArg<'tcx>), + NotParam(ty::GenericArg<'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_int_ty(&tcx, ity).size()); + let x = self.val; + // sign extend the raw representation to be an i128 + let x = size.sign_extend(x) as i128; + write!(fmt, "{}", x) + } + _ => write!(fmt, "{}", self.val), + } + } +} + +fn int_size_and_signed<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> (Size, bool) { + let (int, signed) = match *ty.kind() { + ty::Int(ity) => (Integer::from_int_ty(&tcx, ity), true), + ty::Uint(uty) => (Integer::from_uint_ty(&tcx, 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 = size.signed_int_min(); + let max = size.signed_int_max(); + let val = size.sign_extend(self.val) 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 = size.truncate(val); + (val, oflo) + } else { + let max = size.unsigned_int_max(); + 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)) + } + } +} + +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 { + // 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); + + self.with_stable_hashing_context(|mut hcx| { + let mut hasher = StableHasher::new(); + hcx.while_hashing_spans(false, |hcx| ty.hash_stable(hcx, &mut hasher)); + hasher.finish() + }) + } + + pub fn res_generics_def_id(self, res: Res) -> Option<DefId> { + match res { + Res::Def(DefKind::Ctor(CtorOf::Variant, _), def_id) => { + Some(self.parent(self.parent(def_id))) + } + Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Struct, _), def_id) => { + Some(self.parent(def_id)) + } + // Other `DefKind`s don't have generics and would ICE when calling + // `generics_of`. + Res::Def( + DefKind::Struct + | DefKind::Union + | DefKind::Enum + | DefKind::Trait + | DefKind::OpaqueTy + | DefKind::TyAlias + | DefKind::ForeignTy + | DefKind::TraitAlias + | DefKind::AssocTy + | DefKind::Fn + | DefKind::AssocFn + | DefKind::AssocConst + | DefKind::Impl, + def_id, + ) => Some(def_id), + Res::Err => None, + _ => None, + } + } + + 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 ty::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>, + mut normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>, + // This is currently used to allow us to walk a ValTree + // in lockstep with the type in order to get the ValTree branch that + // corresponds to an unsized field. + mut f: impl FnMut() -> (), + ) -> Ty<'tcx> { + let recursion_limit = self.recursion_limit(); + for iteration in 0.. { + if !recursion_limit.value_within_limit(iteration) { + return self.ty_error_with_message( + DUMMY_SP, + &format!("reached the recursion limit finding the struct tail for {}", ty), + ); + } + match *ty.kind() { + ty::Adt(def, substs) => { + if !def.is_struct() { + break; + } + match def.non_enum_variant().fields.last() { + Some(field) => { + f(); + ty = field.ty(self, substs); + } + None => break, + } + } + + ty::Tuple(tys) if let Some((&last_ty, _)) = tys.split_last() => { + f(); + ty = last_ty; + } + + ty::Tuple(_) => 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()) { + (&ty::Adt(a_def, a_substs), &ty::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; + } + } + (&ty::Tuple(a_tys), &ty::Tuple(b_tys)) if a_tys.len() == b_tys.len() => { + if let Some(&a_last) = a_tys.last() { + a = a_last; + b = *b_tys.last().unwrap(); + } 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: impl Fn(Self, DefId) -> Result<(), ErrorGuaranteed>, + ) -> Option<ty::Destructor> { + let drop_trait = self.lang_items().drop_trait()?; + self.ensure().coherent_trait(drop_trait); + + let ty = self.type_of(adt_did); + let (did, constness) = self.find_map_relevant_impl(drop_trait, ty, |impl_did| { + if let Some(item_id) = self.associated_item_def_ids(impl_did).first() { + if validate(self, impl_did).is_ok() { + return Some((*item_id, self.constness(impl_did))); + } + } + None + })?; + + Some(ty::Destructor { did, constness }) + } + + /// 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: ty::AdtDef<'tcx>) -> 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.parent(dtor); + 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 = iter::zip(item_substs, impl_substs) + .filter(|&(_, k)| { + match k.unpack() { + GenericArgKind::Lifetime(region) => match region.kind() { + ty::ReEarlyBound(ref ebr) => { + !impl_generics.region_param(ebr, self).pure_wrt_drop + } + // Error: not a region param + _ => false, + }, + GenericArgKind::Type(ty) => match ty.kind() { + ty::Param(ref pt) => !impl_generics.type_param(pt, self).pure_wrt_drop, + // Error: not a type param + _ => false, + }, + GenericArgKind::Const(ct) => match ct.kind() { + ty::ConstKind::Param(ref pc) => { + !impl_generics.const_param(pc, self).pure_wrt_drop + } + // Error: not a const param + _ => false, + }, + } + }) + .map(|(item_param, _)| item_param) + .collect(); + debug!("destructor_constraint({:?}) = {:?}", def.did(), result); + result + } + + /// Checks whether each generic argument is simply a unique generic parameter. + pub fn uses_unique_generic_params( + self, + substs: SubstsRef<'tcx>, + ignore_regions: IgnoreRegions, + ) -> Result<(), NotUniqueParam<'tcx>> { + let mut seen = GrowableBitSet::default(); + for arg in substs { + match arg.unpack() { + GenericArgKind::Lifetime(lt) => { + if ignore_regions == IgnoreRegions::No { + let ty::ReEarlyBound(p) = lt.kind() else { + return Err(NotUniqueParam::NotParam(lt.into())) + }; + if !seen.insert(p.index) { + return Err(NotUniqueParam::DuplicateParam(lt.into())); + } + } + } + GenericArgKind::Type(t) => match t.kind() { + ty::Param(p) => { + if !seen.insert(p.index) { + return Err(NotUniqueParam::DuplicateParam(t.into())); + } + } + _ => return Err(NotUniqueParam::NotParam(t.into())), + }, + GenericArgKind::Const(c) => match c.kind() { + ty::ConstKind::Param(p) => { + if !seen.insert(p.index) { + return Err(NotUniqueParam::DuplicateParam(c.into())); + } + } + _ => return Err(NotUniqueParam::NotParam(c.into())), + }, + } + } + + Ok(()) + } + + /// 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 definition that does not have its own + /// type-checking context, i.e. closure, generator or inline const. + pub fn is_typeck_child(self, def_id: DefId) -> bool { + matches!( + self.def_kind(def_id), + DefKind::Closure | DefKind::Generator | DefKind::InlineConst + ) + } + + /// 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 `DefId`, returns the `DefId` of the innermost item that + /// has its own type-checking context or "inference environment". + /// + /// For example, a closure has its own `DefId`, but it is type-checked + /// with the containing item. Similarly, an inline const block has its + /// own `DefId` but it is type-checked together with the containing item. + /// + /// Therefore, when we fetch the + /// `typeck` the closure, for example, we really wind up + /// fetching the `typeck` the enclosing fn item. + pub fn typeck_root_def_id(self, def_id: DefId) -> DefId { + let mut def_id = def_id; + while self.is_typeck_child(def_id) { + def_id = self.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>, + env_region: ty::RegionKind<'tcx>, + ) -> Option<Ty<'tcx>> { + let closure_ty = self.mk_closure(closure_def_id, closure_substs); + 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(env_ty) + } + + /// Returns `true` if the node pointed to by `def_id` is a `static` item. + #[inline] + pub fn is_static(self, def_id: DefId) -> bool { + matches!(self.def_kind(def_id), DefKind::Static(_)) + } + + #[inline] + pub fn static_mutability(self, def_id: DefId) -> Option<hir::Mutability> { + if let DefKind::Static(mt) = self.def_kind(def_id) { Some(mt) } else { None } + } + + /// 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. + #[inline] + 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)); + + // Make sure that accesses to unsafe statics end up using raw pointers. + // For thread-locals, this needs to be kept in sync with `Rvalue::ty`. + if self.is_mutable_static(def_id) { + self.mk_mut_ptr(static_ty) + } else if self.is_foreign_item(def_id) { + self.mk_imm_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. + #[instrument(skip(self), level = "debug")] + pub fn try_expand_impl_trait_type( + self, + def_id: DefId, + substs: SubstsRef<'tcx>, + ) -> Result<Ty<'tcx>, Ty<'tcx>> { + let mut visitor = OpaqueTypeExpander { + seen_opaque_tys: FxHashSet::default(), + expanded_cache: FxHashMap::default(), + primary_def_id: Some(def_id), + found_recursion: false, + found_any_recursion: false, + check_recursion: true, + tcx: self, + }; + + let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap(); + trace!(?expanded_type); + if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) } + } + + pub fn bound_type_of(self, def_id: DefId) -> ty::EarlyBinder<Ty<'tcx>> { + ty::EarlyBinder(self.type_of(def_id)) + } + + pub fn bound_fn_sig(self, def_id: DefId) -> ty::EarlyBinder<ty::PolyFnSig<'tcx>> { + ty::EarlyBinder(self.fn_sig(def_id)) + } + + pub fn bound_impl_trait_ref( + self, + def_id: DefId, + ) -> Option<ty::EarlyBinder<ty::TraitRef<'tcx>>> { + self.impl_trait_ref(def_id).map(|i| ty::EarlyBinder(i)) + } + + pub fn bound_explicit_item_bounds( + self, + def_id: DefId, + ) -> ty::EarlyBinder<&'tcx [(ty::Predicate<'tcx>, rustc_span::Span)]> { + ty::EarlyBinder(self.explicit_item_bounds(def_id)) + } + + pub fn bound_item_bounds( + self, + def_id: DefId, + ) -> ty::EarlyBinder<&'tcx ty::List<ty::Predicate<'tcx>>> { + ty::EarlyBinder(self.item_bounds(def_id)) + } + + pub fn bound_const_param_default(self, def_id: DefId) -> ty::EarlyBinder<ty::Const<'tcx>> { + ty::EarlyBinder(self.const_param_default(def_id)) + } + + pub fn bound_predicates_of( + self, + def_id: DefId, + ) -> ty::EarlyBinder<ty::generics::GenericPredicates<'tcx>> { + ty::EarlyBinder(self.predicates_of(def_id)) + } + + pub fn bound_explicit_predicates_of( + self, + def_id: DefId, + ) -> ty::EarlyBinder<ty::generics::GenericPredicates<'tcx>> { + ty::EarlyBinder(self.explicit_predicates_of(def_id)) + } + + pub fn bound_impl_subject(self, def_id: DefId) -> ty::EarlyBinder<ty::ImplSubject<'tcx>> { + ty::EarlyBinder(self.impl_subject(def_id)) + } +} + +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: Option<DefId>, + found_recursion: bool, + found_any_recursion: bool, + /// Whether or not to check for recursive opaque types. + /// This is `true` when we're explicitly checking for opaque type + /// recursion, and 'false' otherwise to avoid unnecessary work. + check_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_any_recursion { + return None; + } + let substs = substs.fold_with(self); + if !self.check_recursion || 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.bound_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 + } + }; + if self.check_recursion { + 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_any_recursion = true; + self.found_recursion = def_id == *self.primary_def_id.as_ref().unwrap(); + 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 + } + } +} + +impl<'tcx> Ty<'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(self, tcx: TyCtxt<'tcx>) -> Option<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 { size.signed_int_max() as u128 } else { size.unsigned_int_max() }; + Some(val) + } + ty::Char => Some(std::char::MAX as u128), + ty::Float(fty) => Some(match fty { + ty::FloatTy::F32 => rustc_apfloat::ieee::Single::INFINITY.to_bits(), + ty::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(self, tcx: TyCtxt<'tcx>) -> Option<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 { size.truncate(size.signed_int_min() as u128) } else { 0 }; + Some(val) + } + ty::Char => Some(0), + ty::Float(fty) => Some(match fty { + ty::FloatTy::F32 => (-::rustc_apfloat::ieee::Single::INFINITY).to_bits(), + ty::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( + self, + tcx_at: TyCtxtAt<'tcx>, + param_env: ty::ParamEnv<'tcx>, + ) -> bool { + self.is_trivially_pure_clone_copy() || 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(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 an + /// `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. + pub fn is_freeze(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(fields) => fields.iter().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, + } + } + + /// Checks whether values of this type `T` implement the `Unpin` trait. + pub fn is_unpin(self, tcx_at: TyCtxtAt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> bool { + self.is_trivially_unpin() || tcx_at.is_unpin_raw(param_env.and(self)) + } + + /// Fast path helper for testing if a type is `Unpin`. + /// + /// Returning true means the type is known to be `Unpin`. Returning + /// `false` means nothing -- could be `Unpin`, might not be. + fn is_trivially_unpin(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(fields) => fields.iter().all(Self::is_trivially_unpin), + ty::Slice(elem_ty) | ty::Array(elem_ty, _) => elem_ty.is_trivially_unpin(), + 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(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. + // If normalization fails, we just use `query_ty`. + let query_ty = + tcx.try_normalize_erasing_regions(param_env, query_ty).unwrap_or(query_ty); + + tcx.needs_drop_raw(param_env.and(query_ty)) + } + } + } + + /// Checks if `ty` has has a significant drop. + /// + /// Note that this method can return false even if `ty` has a destructor + /// attached; even if that is the case then the adt has been marked with + /// the attribute `rustc_insignificant_dtor`. + /// + /// Note that this method is used to check for change in drop order for + /// 2229 drop reorder migration analysis. + #[inline] + pub fn has_significant_drop(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, + }; + + // FIXME(#86868): We should be canonicalizing, or else moving this to a method of inference + // context, or *something* like that, but for now just avoid passing inference + // variables to queries that can't cope with them. Instead, conservatively + // return "true" (may change drop order). + if query_ty.needs_infer() { + return true; + } + + // 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.has_significant_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(self, tcx: TyCtxt<'tcx>) -> bool { + match self.kind() { + // Look for an impl of both `PartialStructuralEq` and `StructuralEq`. + ty::Adt(..) => tcx.has_structural_eq_impls(self), + + // Primitive types that satisfy `Eq`. + ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Str | ty::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. + ty::Ref(..) | ty::Array(..) | ty::Slice(_) | ty::Tuple(..) => true, + + // Raw pointers use bitwise comparison. + ty::RawPtr(_) | ty::FnPtr(_) => true, + + // Floating point numbers are not `Eq`. + ty::Float(_) => false, + + // Conservatively return `false` for all others... + + // Anonymous function types + ty::FnDef(..) | ty::Closure(..) | ty::Dynamic(..) | ty::Generator(..) => false, + + // Generic or inferred types + // + // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be + // called for known, fully-monomorphized types. + ty::Projection(_) + | ty::Opaque(..) + | ty::Param(_) + | ty::Bound(..) + | ty::Placeholder(_) + | ty::Infer(_) => false, + + ty::Foreign(_) | ty::GeneratorWitness(..) | ty::Error(_) => false, + } + } + + /// 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(self) -> Ty<'tcx> { + let mut ty = self; + while let ty::Ref(_, inner_ty, _) = ty.kind() { + ty = *inner_ty; + } + ty + } + + #[inline] + pub fn outer_exclusive_binder(self) -> ty::DebruijnIndex { + self.0.outer_exclusive_binder + } +} + +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: + /// + /// ```ignore (illustrative) + /// 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<'tcx>( + 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.kind().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(fields) => fields.iter().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]), + } +} + +pub fn is_trivially_const_drop<'tcx>(ty: Ty<'tcx>) -> bool { + match *ty.kind() { + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Float(_) + | ty::Infer(ty::IntVar(_)) + | ty::Infer(ty::FloatVar(_)) + | ty::Str + | ty::RawPtr(_) + | ty::Ref(..) + | ty::FnDef(..) + | ty::FnPtr(_) + | ty::Never + | ty::Foreign(_) => true, + + ty::Opaque(..) + | ty::Dynamic(..) + | ty::Error(_) + | ty::Bound(..) + | ty::Param(_) + | ty::Placeholder(_) + | ty::Projection(_) + | ty::Infer(_) => false, + + // Not trivial because they have components, and instead of looking inside, + // we'll just perform trait selection. + ty::Closure(..) | ty::Generator(..) | ty::GeneratorWitness(_) | ty::Adt(..) => false, + + ty::Array(ty, _) | ty::Slice(ty) => is_trivially_const_drop(ty), + + ty::Tuple(tys) => tys.iter().all(|ty| is_trivially_const_drop(ty)), + } +} + +// Does the equivalent of +// ``` +// let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>(); +// folder.tcx().intern_*(&v) +// ``` +pub fn fold_list<'tcx, F, T>( + list: &'tcx ty::List<T>, + folder: &mut F, + intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>, +) -> Result<&'tcx ty::List<T>, F::Error> +where + F: FallibleTypeFolder<'tcx>, + T: TypeFoldable<'tcx> + PartialEq + Copy, +{ + let mut iter = list.iter(); + // Look for the first element that changed + match iter.by_ref().enumerate().find_map(|(i, t)| match t.try_fold_with(folder) { + Ok(new_t) if new_t == t => None, + new_t => Some((i, new_t)), + }) { + Some((i, Ok(new_t))) => { + // An element changed, prepare to intern the resulting list + let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len()); + new_list.extend_from_slice(&list[..i]); + new_list.push(new_t); + for t in iter { + new_list.push(t.try_fold_with(folder)?) + } + Ok(intern(folder.tcx(), &new_list)) + } + Some((_, Err(err))) => { + return Err(err); + } + None => Ok(list), + } +} + +#[derive(Copy, Clone, Debug, HashStable, TyEncodable, TyDecodable)] +pub struct AlwaysRequiresDrop; + +/// Normalizes all opaque types in the given value, replacing them +/// with their underlying types. +pub fn normalize_opaque_types<'tcx>( + tcx: TyCtxt<'tcx>, + val: &'tcx ty::List<ty::Predicate<'tcx>>, +) -> &'tcx ty::List<ty::Predicate<'tcx>> { + let mut visitor = OpaqueTypeExpander { + seen_opaque_tys: FxHashSet::default(), + expanded_cache: FxHashMap::default(), + primary_def_id: None, + found_recursion: false, + found_any_recursion: false, + check_recursion: false, + tcx, + }; + val.fold_with(&mut visitor) +} + +/// Determines whether an item is annotated with `doc(hidden)`. +pub fn is_doc_hidden(tcx: TyCtxt<'_>, def_id: DefId) -> bool { + tcx.get_attrs(def_id, sym::doc) + .filter_map(|attr| attr.meta_item_list()) + .any(|items| items.iter().any(|item| item.has_name(sym::hidden))) +} + +/// Determines whether an item is an intrinsic by Abi. +pub fn is_intrinsic(tcx: TyCtxt<'_>, def_id: DefId) -> bool { + matches!(tcx.fn_sig(def_id).abi(), Abi::RustIntrinsic | Abi::PlatformIntrinsic) +} + +pub fn provide(providers: &mut ty::query::Providers) { + *providers = + ty::query::Providers { normalize_opaque_types, is_doc_hidden, is_intrinsic, ..*providers } +} |