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fuchsia / third_party / rust / de56c295c394349a68f293039481c3aa6402f9c6 / . / compiler / rustc_middle / src / ty / mod.rs
blob: c2accea11ba2aee2bb6604ba30d8b7e7e2f768ee [file] [log] [blame]
//! Defines how the compiler represents types internally.
//!
//! Two important entities in this module are:
//!
//! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
//! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
//!
//! For more information, see ["The `ty` module: representing types"] in the rustc-dev-guide.
//!
//! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeVisitor};
pub use self::AssocItemContainer::*;
pub use self::BorrowKind::*;
pub use self::IntVarValue::*;
pub use self::Variance::*;
pub use adt::*;
pub use assoc::*;
pub use generics::*;
use rustc_data_structures::fingerprint::Fingerprint;
pub use vtable::*;
use crate::metadata::ModChild;
use crate::middle::privacy::AccessLevels;
use crate::mir::{Body, GeneratorLayout};
use crate::traits::{self, Reveal};
use crate::ty;
use crate::ty::fast_reject::SimplifiedType;
use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
use crate::ty::util::Discr;
use rustc_ast as ast;
use rustc_attr as attr;
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
use rustc_data_structures::intern::{Interned, WithStableHash};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX};
use rustc_hir::Node;
use rustc_macros::HashStable;
use rustc_query_system::ich::StableHashingContext;
use rustc_session::cstore::CrateStoreDyn;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::Span;
use rustc_target::abi::Align;
use std::fmt::Debug;
use std::hash::Hash;
use std::ops::ControlFlow;
use std::{fmt, str};
pub use crate::ty::diagnostics::*;
pub use rustc_type_ir::InferTy::*;
pub use rustc_type_ir::*;
pub use self::binding::BindingMode;
pub use self::binding::BindingMode::*;
pub use self::closure::{
is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
CAPTURE_STRUCT_LOCAL,
};
pub use self::consts::{
Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
};
pub use self::context::{
tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
};
pub use self::instance::{Instance, InstanceDef};
pub use self::list::List;
pub use self::sty::BoundRegionKind::*;
pub use self::sty::RegionKind::*;
pub use self::sty::TyKind::*;
pub use self::sty::{
Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
UpvarSubsts, VarianceDiagInfo,
};
pub use self::trait_def::TraitDef;
pub mod _match;
pub mod adjustment;
pub mod binding;
pub mod cast;
pub mod codec;
pub mod error;
pub mod fast_reject;
pub mod flags;
pub mod fold;
pub mod inhabitedness;
pub mod layout;
pub mod normalize_erasing_regions;
pub mod print;
pub mod query;
pub mod relate;
pub mod subst;
pub mod trait_def;
pub mod util;
pub mod vtable;
pub mod walk;
mod adt;
mod assoc;
mod closure;
mod consts;
mod context;
mod diagnostics;
mod erase_regions;
mod generics;
mod impls_ty;
mod instance;
mod list;
mod structural_impls;
mod sty;
// Data types
pub type RegisteredTools = FxHashSet<Ident>;
#[derive(Debug)]
pub struct ResolverOutputs {
pub definitions: rustc_hir::definitions::Definitions,
pub cstore: Box<CrateStoreDyn>,
pub visibilities: FxHashMap<LocalDefId, Visibility>,
pub access_levels: AccessLevels,
pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
/// Extern prelude entries. The value is `true` if the entry was introduced
/// via `extern crate` item and not `--extern` option or compiler built-in.
pub extern_prelude: FxHashMap<Symbol, bool>,
pub main_def: Option<MainDefinition>,
pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
/// A list of proc macro LocalDefIds, written out in the order in which
/// they are declared in the static array generated by proc_macro_harness.
pub proc_macros: Vec<LocalDefId>,
/// Mapping from ident span to path span for paths that don't exist as written, but that
/// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
pub confused_type_with_std_module: FxHashMap<Span, Span>,
pub registered_tools: RegisteredTools,
}
#[derive(Clone, Copy, Debug)]
pub struct MainDefinition {
pub res: Res<ast::NodeId>,
pub is_import: bool,
pub span: Span,
}
impl MainDefinition {
pub fn opt_fn_def_id(self) -> Option<DefId> {
if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
}
}
/// The "header" of an impl is everything outside the body: a Self type, a trait
/// ref (in the case of a trait impl), and a set of predicates (from the
/// bounds / where-clauses).
#[derive(Clone, Debug, TypeFoldable)]
pub struct ImplHeader<'tcx> {
pub impl_def_id: DefId,
pub self_ty: Ty<'tcx>,
pub trait_ref: Option<TraitRef<'tcx>>,
pub predicates: Vec<Predicate<'tcx>>,
}
#[derive(Copy, Clone, Debug, TypeFoldable)]
pub enum ImplSubject<'tcx> {
Trait(TraitRef<'tcx>),
Inherent(Ty<'tcx>),
}
#[derive(
Copy,
Clone,
PartialEq,
Eq,
Hash,
TyEncodable,
TyDecodable,
HashStable,
Debug,
TypeFoldable
)]
pub enum ImplPolarity {
/// `impl Trait for Type`
Positive,
/// `impl !Trait for Type`
Negative,
/// `#[rustc_reservation_impl] impl Trait for Type`
///
/// This is a "stability hack", not a real Rust feature.
/// See #64631 for details.
Reservation,
}
impl ImplPolarity {
/// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
pub fn flip(&self) -> Option<ImplPolarity> {
match self {
ImplPolarity::Positive => Some(ImplPolarity::Negative),
ImplPolarity::Negative => Some(ImplPolarity::Positive),
ImplPolarity::Reservation => None,
}
}
}
impl fmt::Display for ImplPolarity {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Positive => f.write_str("positive"),
Self::Negative => f.write_str("negative"),
Self::Reservation => f.write_str("reservation"),
}
}
}
#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
pub enum Visibility {
/// Visible everywhere (including in other crates).
Public,
/// Visible only in the given crate-local module.
Restricted(DefId),
/// Not visible anywhere in the local crate. This is the visibility of private external items.
Invisible,
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
pub enum BoundConstness {
/// `T: Trait`
NotConst,
/// `T: ~const Trait`
///
/// Requires resolving to const only when we are in a const context.
ConstIfConst,
}
impl BoundConstness {
/// Reduce `self` and `constness` to two possible combined states instead of four.
pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
match (constness, self) {
(hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
(_, this) => {
*this = BoundConstness::NotConst;
hir::Constness::NotConst
}
}
}
}
impl fmt::Display for BoundConstness {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::NotConst => f.write_str("normal"),
Self::ConstIfConst => f.write_str("`~const`"),
}
}
}
#[derive(
Clone,
Debug,
PartialEq,
Eq,
Copy,
Hash,
TyEncodable,
TyDecodable,
HashStable,
TypeFoldable
)]
pub struct ClosureSizeProfileData<'tcx> {
/// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
pub before_feature_tys: Ty<'tcx>,
/// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
pub after_feature_tys: Ty<'tcx>,
}
pub trait DefIdTree: Copy {
fn parent(self, id: DefId) -> Option<DefId>;
#[inline]
fn local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
Some(self.parent(id.to_def_id())?.expect_local())
}
fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
if descendant.krate != ancestor.krate {
return false;
}
while descendant != ancestor {
match self.parent(descendant) {
Some(parent) => descendant = parent,
None => return false,
}
}
true
}
}
impl<'tcx> DefIdTree for TyCtxt<'tcx> {
fn parent(self, id: DefId) -> Option<DefId> {
self.def_key(id).parent.map(|index| DefId { index, ..id })
}
}
impl Visibility {
pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
match visibility.node {
hir::VisibilityKind::Public => Visibility::Public,
hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
// If there is no resolution, `resolve` will have already reported an error, so
// assume that the visibility is public to avoid reporting more privacy errors.
Res::Err => Visibility::Public,
def => Visibility::Restricted(def.def_id()),
},
hir::VisibilityKind::Inherited => {
Visibility::Restricted(tcx.parent_module(id).to_def_id())
}
}
}
/// Returns `true` if an item with this visibility is accessible from the given block.
pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
let restriction = match self {
// Public items are visible everywhere.
Visibility::Public => return true,
// Private items from other crates are visible nowhere.
Visibility::Invisible => return false,
// Restricted items are visible in an arbitrary local module.
Visibility::Restricted(other) if other.krate != module.krate => return false,
Visibility::Restricted(module) => module,
};
tree.is_descendant_of(module, restriction)
}
/// Returns `true` if this visibility is at least as accessible as the given visibility
pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
let vis_restriction = match vis {
Visibility::Public => return self == Visibility::Public,
Visibility::Invisible => return true,
Visibility::Restricted(module) => module,
};
self.is_accessible_from(vis_restriction, tree)
}
// Returns `true` if this item is visible anywhere in the local crate.
pub fn is_visible_locally(self) -> bool {
match self {
Visibility::Public => true,
Visibility::Restricted(def_id) => def_id.is_local(),
Visibility::Invisible => false,
}
}
pub fn is_public(self) -> bool {
matches!(self, Visibility::Public)
}
}
/// The crate variances map is computed during typeck and contains the
/// variance of every item in the local crate. You should not use it
/// directly, because to do so will make your pass dependent on the
/// HIR of every item in the local crate. Instead, use
/// `tcx.variances_of()` to get the variance for a *particular*
/// item.
#[derive(HashStable, Debug)]
pub struct CrateVariancesMap<'tcx> {
/// For each item with generics, maps to a vector of the variance
/// of its generics. If an item has no generics, it will have no
/// entry.
pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
}
// Contains information needed to resolve types and (in the future) look up
// the types of AST nodes.
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
pub struct CReaderCacheKey {
pub cnum: Option<CrateNum>,
pub pos: usize,
}
/// Represents a type.
///
/// IMPORTANT:
/// - This is a very "dumb" struct (with no derives and no `impls`).
/// - Values of this type are always interned and thus unique, and are stored
/// as an `Interned<TyS>`.
/// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
/// should be used everywhere instead of `TyS`. In particular, `Ty` has most
/// of the relevant methods.
#[derive(PartialEq, Eq, PartialOrd, Ord)]
#[allow(rustc::usage_of_ty_tykind)]
crate struct TyS<'tcx> {
/// This field shouldn't be used directly and may be removed in the future.
/// Use `Ty::kind()` instead.
kind: TyKind<'tcx>,
/// This field provides fast access to information that is also contained
/// in `kind`.
///
/// This field shouldn't be used directly and may be removed in the future.
/// Use `Ty::flags()` instead.
flags: TypeFlags,
/// This field provides fast access to information that is also contained
/// in `kind`.
///
/// This is a kind of confusing thing: it stores the smallest
/// binder such that
///
/// (a) the binder itself captures nothing but
/// (b) all the late-bound things within the type are captured
/// by some sub-binder.
///
/// So, for a type without any late-bound things, like `u32`, this
/// will be *innermost*, because that is the innermost binder that
/// captures nothing. But for a type `&'D u32`, where `'D` is a
/// late-bound region with De Bruijn index `D`, this would be `D + 1`
/// -- the binder itself does not capture `D`, but `D` is captured
/// by an inner binder.
///
/// We call this concept an "exclusive" binder `D` because all
/// De Bruijn indices within the type are contained within `0..D`
/// (exclusive).
outer_exclusive_binder: ty::DebruijnIndex,
}
// `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
static_assert_size!(TyS<'_>, 40);
// We are actually storing a stable hash cache next to the type, so let's
// also check the full size
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
static_assert_size!(WithStableHash<TyS<'_>>, 56);
/// Use this rather than `TyS`, whenever possible.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
#[rustc_diagnostic_item = "Ty"]
#[rustc_pass_by_value]
pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
// Statics only used for internal testing.
pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&WithStableHash {
internee: BOOL_TYS,
stable_hash: Fingerprint::ZERO,
}));
const BOOL_TYS: TyS<'static> = TyS {
kind: ty::Bool,
flags: TypeFlags::empty(),
outer_exclusive_binder: DebruijnIndex::from_usize(0),
};
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
#[inline]
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
let TyS {
kind,
// The other fields just provide fast access to information that is
// also contained in `kind`, so no need to hash them.
flags: _,
outer_exclusive_binder: _,
} = self;
kind.hash_stable(hcx, hasher)
}
}
impl ty::EarlyBoundRegion {
/// Does this early bound region have a name? Early bound regions normally
/// always have names except when using anonymous lifetimes (`'_`).
pub fn has_name(&self) -> bool {
self.name != kw::UnderscoreLifetime
}
}
/// Represents a predicate.
///
/// See comments on `TyS`, which apply here too (albeit for
/// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
#[derive(Debug)]
crate struct PredicateS<'tcx> {
kind: Binder<'tcx, PredicateKind<'tcx>>,
flags: TypeFlags,
/// See the comment for the corresponding field of [TyS].
outer_exclusive_binder: ty::DebruijnIndex,
}
// This type is used a lot. Make sure it doesn't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
static_assert_size!(PredicateS<'_>, 56);
/// Use this rather than `PredicateS`, whenever possible.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
#[rustc_pass_by_value]
pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
impl<'tcx> Predicate<'tcx> {
/// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
#[inline]
pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
self.0.kind
}
#[inline(always)]
pub fn flags(self) -> TypeFlags {
self.0.flags
}
#[inline(always)]
pub fn outer_exclusive_binder(self) -> DebruijnIndex {
self.0.outer_exclusive_binder
}
/// Flips the polarity of a Predicate.
///
/// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
let kind = self
.kind()
.map_bound(|kind| match kind {
PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
Some(PredicateKind::Trait(TraitPredicate {
trait_ref,
constness,
polarity: polarity.flip()?,
}))
}
_ => None,
})
.transpose()?;
Some(tcx.mk_predicate(kind))
}
}
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
let PredicateS {
ref kind,
// The other fields just provide fast access to information that is
// also contained in `kind`, so no need to hash them.
flags: _,
outer_exclusive_binder: _,
} = self.0.0;
kind.hash_stable(hcx, hasher);
}
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub enum PredicateKind<'tcx> {
/// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
/// the `Self` type of the trait reference and `A`, `B`, and `C`
/// would be the type parameters.
Trait(TraitPredicate<'tcx>),
/// `where 'a: 'b`
RegionOutlives(RegionOutlivesPredicate<'tcx>),
/// `where T: 'a`
TypeOutlives(TypeOutlivesPredicate<'tcx>),
/// `where <T as TraitRef>::Name == X`, approximately.
/// See the `ProjectionPredicate` struct for details.
Projection(ProjectionPredicate<'tcx>),
/// No syntax: `T` well-formed.
WellFormed(GenericArg<'tcx>),
/// Trait must be object-safe.
ObjectSafe(DefId),
/// No direct syntax. May be thought of as `where T: FnFoo<...>`
/// for some substitutions `...` and `T` being a closure type.
/// Satisfied (or refuted) once we know the closure's kind.
ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
/// `T1 <: T2`
///
/// This obligation is created most often when we have two
/// unresolved type variables and hence don't have enough
/// information to process the subtyping obligation yet.
Subtype(SubtypePredicate<'tcx>),
/// `T1` coerced to `T2`
///
/// Like a subtyping obligation, this is created most often
/// when we have two unresolved type variables and hence
/// don't have enough information to process the coercion
/// obligation yet. At the moment, we actually process coercions
/// very much like subtyping and don't handle the full coercion
/// logic.
Coerce(CoercePredicate<'tcx>),
/// Constant initializer must evaluate successfully.
ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
/// Constants must be equal. The first component is the const that is expected.
ConstEquate(Const<'tcx>, Const<'tcx>),
/// Represents a type found in the environment that we can use for implied bounds.
///
/// Only used for Chalk.
TypeWellFormedFromEnv(Ty<'tcx>),
}
/// The crate outlives map is computed during typeck and contains the
/// outlives of every item in the local crate. You should not use it
/// directly, because to do so will make your pass dependent on the
/// HIR of every item in the local crate. Instead, use
/// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
/// item.
#[derive(HashStable, Debug)]
pub struct CratePredicatesMap<'tcx> {
/// For each struct with outlive bounds, maps to a vector of the
/// predicate of its outlive bounds. If an item has no outlives
/// bounds, it will have no entry.
pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
}
impl<'tcx> Predicate<'tcx> {
/// Performs a substitution suitable for going from a
/// poly-trait-ref to supertraits that must hold if that
/// poly-trait-ref holds. This is slightly different from a normal
/// substitution in terms of what happens with bound regions. See
/// lengthy comment below for details.
pub fn subst_supertrait(
self,
tcx: TyCtxt<'tcx>,
trait_ref: &ty::PolyTraitRef<'tcx>,
) -> Predicate<'tcx> {
// The interaction between HRTB and supertraits is not entirely
// obvious. Let me walk you (and myself) through an example.
//
// Let's start with an easy case. Consider two traits:
//
// trait Foo<'a>: Bar<'a,'a> { }
// trait Bar<'b,'c> { }
//
// Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
// we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
// knew that `Foo<'x>` (for any 'x) then we also know that
// `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
// normal substitution.
//
// In terms of why this is sound, the idea is that whenever there
// is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
// holds. So if there is an impl of `T:Foo<'a>` that applies to
// all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
// `'a`.
//
// Another example to be careful of is this:
//
// trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
// trait Bar1<'b,'c> { }
//
// Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
// The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
// reason is similar to the previous example: any impl of
// `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
// basically we would want to collapse the bound lifetimes from
// the input (`trait_ref`) and the supertraits.
//
// To achieve this in practice is fairly straightforward. Let's
// consider the more complicated scenario:
//
// - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
// has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
// where both `'x` and `'b` would have a DB index of 1.
// The substitution from the input trait-ref is therefore going to be
// `'a => 'x` (where `'x` has a DB index of 1).
// - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
// early-bound parameter and `'b' is a late-bound parameter with a
// DB index of 1.
// - If we replace `'a` with `'x` from the input, it too will have
// a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
// just as we wanted.
//
// There is only one catch. If we just apply the substitution `'a
// => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
// adjust the DB index because we substituting into a binder (it
// tries to be so smart...) resulting in `for<'x> for<'b>
// Bar1<'x,'b>` (we have no syntax for this, so use your
// imagination). Basically the 'x will have DB index of 2 and 'b
// will have DB index of 1. Not quite what we want. So we apply
// the substitution to the *contents* of the trait reference,
// rather than the trait reference itself (put another way, the
// substitution code expects equal binding levels in the values
// from the substitution and the value being substituted into, and
// this trick achieves that).
// Working through the second example:
// trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
// predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
// We want to end up with:
// for<'x, 'b> T: Bar1<'^0.0, '^0.1>
// To do this:
// 1) We must shift all bound vars in predicate by the length
// of trait ref's bound vars. So, we would end up with predicate like
// Self: Bar1<'a, '^0.1>
// 2) We can then apply the trait substs to this, ending up with
// T: Bar1<'^0.0, '^0.1>
// 3) Finally, to create the final bound vars, we concatenate the bound
// vars of the trait ref with those of the predicate:
// ['x, 'b]
let bound_pred = self.kind();
let pred_bound_vars = bound_pred.bound_vars();
let trait_bound_vars = trait_ref.bound_vars();
// 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
let shifted_pred =
tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
// 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
// 3) ['x] + ['b] -> ['x, 'b]
let bound_vars =
tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
}
}
#[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub struct TraitPredicate<'tcx> {
pub trait_ref: TraitRef<'tcx>,
pub constness: BoundConstness,
/// If polarity is Positive: we are proving that the trait is implemented.
///
/// If polarity is Negative: we are proving that a negative impl of this trait
/// exists. (Note that coherence also checks whether negative impls of supertraits
/// exist via a series of predicates.)
///
/// If polarity is Reserved: that's a bug.
pub polarity: ImplPolarity,
}
pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
impl<'tcx> TraitPredicate<'tcx> {
pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
// remap without changing constness of this predicate.
// this is because `T: ~const Drop` has a different meaning to `T: Drop`
// FIXME(fee1-dead): remove this logic after beta bump
param_env.remap_constness_with(self.constness)
} else {
*param_env = param_env.with_constness(self.constness.and(param_env.constness()))
}
}
/// Remap the constness of this predicate before emitting it for diagnostics.
pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
// this is different to `remap_constness` that callees want to print this predicate
// in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
// param_env is not const because we it is always satisfied in non-const contexts.
if let hir::Constness::NotConst = param_env.constness() {
self.constness = ty::BoundConstness::NotConst;
}
}
pub fn def_id(self) -> DefId {
self.trait_ref.def_id
}
pub fn self_ty(self) -> Ty<'tcx> {
self.trait_ref.self_ty()
}
#[inline]
pub fn is_const_if_const(self) -> bool {
self.constness == BoundConstness::ConstIfConst
}
}
impl<'tcx> PolyTraitPredicate<'tcx> {
pub fn def_id(self) -> DefId {
// Ok to skip binder since trait `DefId` does not care about regions.
self.skip_binder().def_id()
}
pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
self.map_bound(|trait_ref| trait_ref.self_ty())
}
/// Remap the constness of this predicate before emitting it for diagnostics.
pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
*self = self.map_bound(|mut p| {
p.remap_constness_diag(param_env);
p
});
}
#[inline]
pub fn is_const_if_const(self) -> bool {
self.skip_binder().is_const_if_const()
}
}
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
/// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
/// whether the `a` type is the type that we should label as "expected" when
/// presenting user diagnostics.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub struct SubtypePredicate<'tcx> {
pub a_is_expected: bool,
pub a: Ty<'tcx>,
pub b: Ty<'tcx>,
}
pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
/// Encodes that we have to coerce *from* the `a` type to the `b` type.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub struct CoercePredicate<'tcx> {
pub a: Ty<'tcx>,
pub b: Ty<'tcx>,
}
pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub enum Term<'tcx> {
Ty(Ty<'tcx>),
Const(Const<'tcx>),
}
impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
fn from(ty: Ty<'tcx>) -> Self {
Term::Ty(ty)
}
}
impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
fn from(c: Const<'tcx>) -> Self {
Term::Const(c)
}
}
impl<'tcx> Term<'tcx> {
pub fn ty(&self) -> Option<Ty<'tcx>> {
if let Term::Ty(ty) = self { Some(*ty) } else { None }
}
pub fn ct(&self) -> Option<Const<'tcx>> {
if let Term::Const(c) = self { Some(*c) } else { None }
}
}
/// This kind of predicate has no *direct* correspondent in the
/// syntax, but it roughly corresponds to the syntactic forms:
///
/// 1. `T: TraitRef<..., Item = Type>`
/// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
///
/// In particular, form #1 is "desugared" to the combination of a
/// normal trait predicate (`T: TraitRef<...>`) and one of these
/// predicates. Form #2 is a broader form in that it also permits
/// equality between arbitrary types. Processing an instance of
/// Form #2 eventually yields one of these `ProjectionPredicate`
/// instances to normalize the LHS.
#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable)]
pub struct ProjectionPredicate<'tcx> {
pub projection_ty: ProjectionTy<'tcx>,
pub term: Term<'tcx>,
}
pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
impl<'tcx> PolyProjectionPredicate<'tcx> {
/// Returns the `DefId` of the trait of the associated item being projected.
#[inline]
pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
self.skip_binder().projection_ty.trait_def_id(tcx)
}
/// Get the [PolyTraitRef] required for this projection to be well formed.
/// Note that for generic associated types the predicates of the associated
/// type also need to be checked.
#[inline]
pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
// Note: unlike with `TraitRef::to_poly_trait_ref()`,
// `self.0.trait_ref` is permitted to have escaping regions.
// This is because here `self` has a `Binder` and so does our
// return value, so we are preserving the number of binding
// levels.
self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
}
pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
self.map_bound(|predicate| predicate.term)
}
/// The `DefId` of the `TraitItem` for the associated type.
///
/// Note that this is not the `DefId` of the `TraitRef` containing this
/// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
pub fn projection_def_id(&self) -> DefId {
// Ok to skip binder since trait `DefId` does not care about regions.
self.skip_binder().projection_ty.item_def_id
}
}
pub trait ToPolyTraitRef<'tcx> {
fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
}
impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
}
}
pub trait ToPredicate<'tcx> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
}
impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
#[inline(always)]
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
tcx.mk_predicate(self)
}
}
impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
self.map_bound(PredicateKind::Trait).to_predicate(tcx)
}
}
impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
}
}
impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
}
}
impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
self.map_bound(PredicateKind::Projection).to_predicate(tcx)
}
}
impl<'tcx> Predicate<'tcx> {
pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
let predicate = self.kind();
match predicate.skip_binder() {
PredicateKind::Trait(t) => Some(predicate.rebind(t)),
PredicateKind::Projection(..)
| PredicateKind::Subtype(..)
| PredicateKind::Coerce(..)
| PredicateKind::RegionOutlives(..)
| PredicateKind::WellFormed(..)
| PredicateKind::ObjectSafe(..)
| PredicateKind::ClosureKind(..)
| PredicateKind::TypeOutlives(..)
| PredicateKind::ConstEvaluatable(..)
| PredicateKind::ConstEquate(..)
| PredicateKind::TypeWellFormedFromEnv(..) => None,
}
}
pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
let predicate = self.kind();
match predicate.skip_binder() {
PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
PredicateKind::Trait(..)
| PredicateKind::Projection(..)
| PredicateKind::Subtype(..)
| PredicateKind::Coerce(..)
| PredicateKind::RegionOutlives(..)
| PredicateKind::WellFormed(..)
| PredicateKind::ObjectSafe(..)
| PredicateKind::ClosureKind(..)
| PredicateKind::ConstEvaluatable(..)
| PredicateKind::ConstEquate(..)
| PredicateKind::TypeWellFormedFromEnv(..) => None,
}
}
}
/// Represents the bounds declared on a particular set of type
/// parameters. Should eventually be generalized into a flag list of
/// where-clauses. You can obtain an `InstantiatedPredicates` list from a
/// `GenericPredicates` by using the `instantiate` method. Note that this method
/// reflects an important semantic invariant of `InstantiatedPredicates`: while
/// the `GenericPredicates` are expressed in terms of the bound type
/// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
/// represented a set of bounds for some particular instantiation,
/// meaning that the generic parameters have been substituted with
/// their values.
///
/// Example:
///
/// struct Foo<T, U: Bar<T>> { ... }
///
/// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
/// `[[], [U:Bar<T>]]`. Now if there were some particular reference
/// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
/// [usize:Bar<isize>]]`.
#[derive(Clone, Debug, TypeFoldable)]
pub struct InstantiatedPredicates<'tcx> {
pub predicates: Vec<Predicate<'tcx>>,
pub spans: Vec<Span>,
}
impl<'tcx> InstantiatedPredicates<'tcx> {
pub fn empty() -> InstantiatedPredicates<'tcx> {
InstantiatedPredicates { predicates: vec![], spans: vec![] }
}
pub fn is_empty(&self) -> bool {
self.predicates.is_empty()
}
}
#[derive(
Copy,
Clone,
Debug,
PartialEq,
Eq,
HashStable,
TyEncodable,
TyDecodable,
TypeFoldable,
Lift
)]
pub struct OpaqueTypeKey<'tcx> {
pub def_id: DefId,
pub substs: SubstsRef<'tcx>,
}
#[derive(Copy, Clone, Debug, TypeFoldable, HashStable, TyEncodable, TyDecodable)]
pub struct OpaqueHiddenType<'tcx> {
/// The span of this particular definition of the opaque type. So
/// for example:
///
/// ```ignore (incomplete snippet)
/// type Foo = impl Baz;
/// fn bar() -> Foo {
/// // ^^^ This is the span we are looking for!
/// }
/// ```
///
/// In cases where the fn returns `(impl Trait, impl Trait)` or
/// other such combinations, the result is currently
/// over-approximated, but better than nothing.
pub span: Span,
/// The type variable that represents the value of the opaque type
/// that we require. In other words, after we compile this function,
/// we will be created a constraint like:
///
/// Foo<'a, T> = ?C
///
/// where `?C` is the value of this type variable. =) It may
/// naturally refer to the type and lifetime parameters in scope
/// in this function, though ultimately it should only reference
/// those that are arguments to `Foo` in the constraint above. (In
/// other words, `?C` should not include `'b`, even though it's a
/// lifetime parameter on `foo`.)
pub ty: Ty<'tcx>,
}
impl<'tcx> OpaqueHiddenType<'tcx> {
pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) {
// Found different concrete types for the opaque type.
let mut err = tcx.sess.struct_span_err(
other.span,
"concrete type differs from previous defining opaque type use",
);
err.span_label(other.span, format!("expected `{}`, got `{}`", self.ty, other.ty));
if self.span == other.span {
err.span_label(
self.span,
"this expression supplies two conflicting concrete types for the same opaque type",
);
} else {
err.span_note(self.span, "previous use here");
}
err.emit();
}
}
rustc_index::newtype_index! {
/// "Universes" are used during type- and trait-checking in the
/// presence of `for<..>` binders to control what sets of names are
/// visible. Universes are arranged into a tree: the root universe
/// contains names that are always visible. Each child then adds a new
/// set of names that are visible, in addition to those of its parent.
/// We say that the child universe "extends" the parent universe with
/// new names.
///
/// To make this more concrete, consider this program:
///
/// ```
/// struct Foo { }
/// fn bar<T>(x: T) {
/// let y: for<'a> fn(&'a u8, Foo) = ...;
/// }
/// ```
///
/// The struct name `Foo` is in the root universe U0. But the type
/// parameter `T`, introduced on `bar`, is in an extended universe U1
/// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
/// of `bar`, we cannot name `T`. Then, within the type of `y`, the
/// region `'a` is in a universe U2 that extends U1, because we can
/// name it inside the fn type but not outside.
///
/// Universes are used to do type- and trait-checking around these
/// "forall" binders (also called **universal quantification**). The
/// idea is that when, in the body of `bar`, we refer to `T` as a
/// type, we aren't referring to any type in particular, but rather a
/// kind of "fresh" type that is distinct from all other types we have
/// actually declared. This is called a **placeholder** type, and we
/// use universes to talk about this. In other words, a type name in
/// universe 0 always corresponds to some "ground" type that the user
/// declared, but a type name in a non-zero universe is a placeholder
/// type -- an idealized representative of "types in general" that we
/// use for checking generic functions.
pub struct UniverseIndex {
derive [HashStable]
DEBUG_FORMAT = "U{}",
}
}
impl UniverseIndex {
pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
/// Returns the "next" universe index in order -- this new index
/// is considered to extend all previous universes. This
/// corresponds to entering a `forall` quantifier. So, for
/// example, suppose we have this type in universe `U`:
///
/// ```
/// for<'a> fn(&'a u32)
/// ```
///
/// Once we "enter" into this `for<'a>` quantifier, we are in a
/// new universe that extends `U` -- in this new universe, we can
/// name the region `'a`, but that region was not nameable from
/// `U` because it was not in scope there.
pub fn next_universe(self) -> UniverseIndex {
UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
}
/// Returns `true` if `self` can name a name from `other` -- in other words,
/// if the set of names in `self` is a superset of those in
/// `other` (`self >= other`).
pub fn can_name(self, other: UniverseIndex) -> bool {
self.private >= other.private
}
/// Returns `true` if `self` cannot name some names from `other` -- in other
/// words, if the set of names in `self` is a strict subset of
/// those in `other` (`self < other`).
pub fn cannot_name(self, other: UniverseIndex) -> bool {
self.private < other.private
}
}
/// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
/// identified by both a universe, as well as a name residing within that universe. Distinct bound
/// regions/types/consts within the same universe simply have an unknown relationship to one
/// another.
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
pub struct Placeholder<T> {
pub universe: UniverseIndex,
pub name: T,
}
impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
where
T: HashStable<StableHashingContext<'a>>,
{
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
self.universe.hash_stable(hcx, hasher);
self.name.hash_stable(hcx, hasher);
}
}
pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
pub type PlaceholderType = Placeholder<BoundVar>;
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
#[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
pub struct BoundConst<'tcx> {
pub var: BoundVar,
pub ty: Ty<'tcx>,
}
pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
/// A `DefId` which, in case it is a const argument, is potentially bundled with
/// the `DefId` of the generic parameter it instantiates.
///
/// This is used to avoid calls to `type_of` for const arguments during typeck
/// which cause cycle errors.
///
/// ```rust
/// struct A;
/// impl A {
/// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
/// // ^ const parameter
/// }
/// struct B;
/// impl B {
/// fn foo<const M: u8>(&self) -> usize { 42 }
/// // ^ const parameter
/// }
///
/// fn main() {
/// let a = A;
/// let _b = a.foo::<{ 3 + 7 }>();
/// // ^^^^^^^^^ const argument
/// }
/// ```
///
/// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
/// which `foo` is used until we know the type of `a`.
///
/// We only know the type of `a` once we are inside of `typeck(main)`.
/// We also end up normalizing the type of `_b` during `typeck(main)` which
/// requires us to evaluate the const argument.
///
/// To evaluate that const argument we need to know its type,
/// which we would get using `type_of(const_arg)`. This requires us to
/// resolve `foo` as it can be either `usize` or `u8` in this example.
/// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
/// which results in a cycle.
///
/// In short we must not call `type_of(const_arg)` during `typeck(main)`.
///
/// When first creating the `ty::Const` of the const argument inside of `typeck` we have
/// already resolved `foo` so we know which const parameter this argument instantiates.
/// This means that we also know the expected result of `type_of(const_arg)` even if we
/// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
/// trivial to compute.
///
/// If we now want to use that constant in a place which potentially needs its type
/// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
/// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
/// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
/// to get the type of `did`.
#[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
#[derive(PartialEq, Eq, PartialOrd, Ord)]
#[derive(Hash, HashStable)]
pub struct WithOptConstParam<T> {
pub did: T,
/// The `DefId` of the corresponding generic parameter in case `did` is
/// a const argument.
///
/// Note that even if `did` is a const argument, this may still be `None`.
/// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
/// to potentially update `param_did` in the case it is `None`.
pub const_param_did: Option<DefId>,
}
impl<T> WithOptConstParam<T> {
/// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
#[inline(always)]
pub fn unknown(did: T) -> WithOptConstParam<T> {
WithOptConstParam { did, const_param_did: None }
}
}
impl WithOptConstParam<LocalDefId> {
/// Returns `Some((did, param_did))` if `def_id` is a const argument,
/// `None` otherwise.
#[inline(always)]
pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
}
/// In case `self` is unknown but `self.did` is a const argument, this returns
/// a `WithOptConstParam` with the correct `const_param_did`.
#[inline(always)]
pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
if self.const_param_did.is_none() {
if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
return Some(WithOptConstParam { did: self.did, const_param_did });
}
}
None
}
pub fn to_global(self) -> WithOptConstParam<DefId> {
WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
}
pub fn def_id_for_type_of(self) -> DefId {
if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
}
}
impl WithOptConstParam<DefId> {
pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
self.did
.as_local()
.map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
}
pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
if let Some(param_did) = self.const_param_did {
if let Some(did) = self.did.as_local() {
return Some((did, param_did));
}
}
None
}
pub fn is_local(self) -> bool {
self.did.is_local()
}
pub fn def_id_for_type_of(self) -> DefId {
self.const_param_did.unwrap_or(self.did)
}
}
/// When type checking, we use the `ParamEnv` to track
/// details about the set of where-clauses that are in scope at this
/// particular point.
#[derive(Copy, Clone, Hash, PartialEq, Eq)]
pub struct ParamEnv<'tcx> {
/// This packs both caller bounds and the reveal enum into one pointer.
///
/// Caller bounds are `Obligation`s that the caller must satisfy. This is
/// basically the set of bounds on the in-scope type parameters, translated
/// into `Obligation`s, and elaborated and normalized.
///
/// Use the `caller_bounds()` method to access.
///
/// Typically, this is `Reveal::UserFacing`, but during codegen we
/// want `Reveal::All`.
///
/// Note: This is packed, use the reveal() method to access it.
packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
}
#[derive(Copy, Clone)]
struct ParamTag {
reveal: traits::Reveal,
constness: hir::Constness,
}
unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
const BITS: usize = 2;
#[inline]
fn into_usize(self) -> usize {
match self {
Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
}
}
#[inline]
unsafe fn from_usize(ptr: usize) -> Self {
match ptr {
0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
_ => std::hint::unreachable_unchecked(),
}
}
}
impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("ParamEnv")
.field("caller_bounds", &self.caller_bounds())
.field("reveal", &self.reveal())
.field("constness", &self.constness())
.finish()
}
}
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
self.caller_bounds().hash_stable(hcx, hasher);
self.reveal().hash_stable(hcx, hasher);
self.constness().hash_stable(hcx, hasher);
}
}
impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
Ok(ParamEnv::new(
self.caller_bounds().try_fold_with(folder)?,
self.reveal().try_fold_with(folder)?,
self.constness().try_fold_with(folder)?,
))
}
fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
self.caller_bounds().visit_with(visitor)?;
self.reveal().visit_with(visitor)?;
self.constness().visit_with(visitor)
}
}
impl<'tcx> ParamEnv<'tcx> {
/// Construct a trait environment suitable for contexts where
/// there are no where-clauses in scope. Hidden types (like `impl
/// Trait`) are left hidden, so this is suitable for ordinary
/// type-checking.
#[inline]
pub fn empty() -> Self {
Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
}
#[inline]
pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
self.packed.pointer()
}
#[inline]
pub fn reveal(self) -> traits::Reveal {
self.packed.tag().reveal
}
#[inline]
pub fn constness(self) -> hir::Constness {
self.packed.tag().constness
}
#[inline]
pub fn is_const(self) -> bool {
self.packed.tag().constness == hir::Constness::Const
}
/// Construct a trait environment with no where-clauses in scope
/// where the values of all `impl Trait` and other hidden types
/// are revealed. This is suitable for monomorphized, post-typeck
/// environments like codegen or doing optimizations.
///
/// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
/// or invoke `param_env.with_reveal_all()`.
#[inline]
pub fn reveal_all() -> Self {
Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
}
/// Construct a trait environment with the given set of predicates.
#[inline]
pub fn new(
caller_bounds: &'tcx List<Predicate<'tcx>>,
reveal: Reveal,
constness: hir::Constness,
) -> Self {
ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
}
pub fn with_user_facing(mut self) -> Self {
self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
self
}
#[inline]
pub fn with_constness(mut self, constness: hir::Constness) -> Self {
self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
self
}
#[inline]
pub fn with_const(mut self) -> Self {
self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
self
}
#[inline]
pub fn without_const(mut self) -> Self {
self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
self
}
#[inline]
pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
*self = self.with_constness(constness.and(self.constness()))
}
/// Returns a new parameter environment with the same clauses, but
/// which "reveals" the true results of projections in all cases
/// (even for associated types that are specializable). This is
/// the desired behavior during codegen and certain other special
/// contexts; normally though we want to use `Reveal::UserFacing`,
/// which is the default.
/// All opaque types in the caller_bounds of the `ParamEnv`
/// will be normalized to their underlying types.
/// See PR #65989 and issue #65918 for more details
pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
if self.packed.tag().reveal == traits::Reveal::All {
return self;
}
ParamEnv::new(
tcx.normalize_opaque_types(self.caller_bounds()),
Reveal::All,
self.constness(),
)
}
/// Returns this same environment but with no caller bounds.
#[inline]
pub fn without_caller_bounds(self) -> Self {
Self::new(List::empty(), self.reveal(), self.constness())
}
/// Creates a suitable environment in which to perform trait
/// queries on the given value. When type-checking, this is simply
/// the pair of the environment plus value. But when reveal is set to
/// All, then if `value` does not reference any type parameters, we will
/// pair it with the empty environment. This improves caching and is generally
/// invisible.
///
/// N.B., we preserve the environment when type-checking because it
/// is possible for the user to have wacky where-clauses like
/// `where Box<u32>: Copy`, which are clearly never
/// satisfiable. We generally want to behave as if they were true,
/// although the surrounding function is never reachable.
pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
match self.reveal() {
Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
Reveal::All => {
if value.is_global() {
ParamEnvAnd { param_env: self.without_caller_bounds(), value }
} else {
ParamEnvAnd { param_env: self, value }
}
}
}
}
}
// FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
// the constness of trait bounds is being propagated correctly.
impl<'tcx> PolyTraitRef<'tcx> {
#[inline]
pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
self.map_bound(|trait_ref| ty::TraitPredicate {
trait_ref,
constness,
polarity: ty::ImplPolarity::Positive,
})
}
#[inline]
pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
self.with_constness(BoundConstness::NotConst)
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
pub struct ParamEnvAnd<'tcx, T> {
pub param_env: ParamEnv<'tcx>,
pub value: T,
}
impl<'tcx, T> ParamEnvAnd<'tcx, T> {
pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
(self.param_env, self.value)
}
#[inline]
pub fn without_const(mut self) -> Self {
self.param_env = self.param_env.without_const();
self
}
}
impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
where
T: HashStable<StableHashingContext<'a>>,
{
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
let ParamEnvAnd { ref param_env, ref value } = *self;
param_env.hash_stable(hcx, hasher);
value.hash_stable(hcx, hasher);
}
}
#[derive(Copy, Clone, Debug, HashStable)]
pub struct Destructor {
/// The `DefId` of the destructor method
pub did: DefId,
/// The constness of the destructor method
pub constness: hir::Constness,
}
bitflags! {
#[derive(HashStable, TyEncodable, TyDecodable)]
pub struct VariantFlags: u32 {
const NO_VARIANT_FLAGS = 0;
/// Indicates whether the field list of this variant is `#[non_exhaustive]`.
const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
/// Indicates whether this variant was obtained as part of recovering from
/// a syntactic error. May be incomplete or bogus.
const IS_RECOVERED = 1 << 1;
}
}
/// Definition of a variant -- a struct's fields or an enum variant.
#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
pub struct VariantDef {
/// `DefId` that identifies the variant itself.
/// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
pub def_id: DefId,
/// `DefId` that identifies the variant's constructor.
/// If this variant is a struct variant, then this is `None`.
pub ctor_def_id: Option<DefId>,
/// Variant or struct name.
pub name: Symbol,
/// Discriminant of this variant.
pub discr: VariantDiscr,
/// Fields of this variant.
pub fields: Vec<FieldDef>,
/// Type of constructor of variant.
pub ctor_kind: CtorKind,
/// Flags of the variant (e.g. is field list non-exhaustive)?
flags: VariantFlags,
}
impl VariantDef {
/// Creates a new `VariantDef`.
///
/// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
/// represents an enum variant).
///
/// `ctor_did` is the `DefId` that identifies the constructor of unit or
/// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
///
/// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
/// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
/// to go through the redirect of checking the ctor's attributes - but compiling a small crate
/// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
/// built-in trait), and we do not want to load attributes twice.
///
/// If someone speeds up attribute loading to not be a performance concern, they can
/// remove this hack and use the constructor `DefId` everywhere.
pub fn new(
name: Symbol,
variant_did: Option<DefId>,
ctor_def_id: Option<DefId>,
discr: VariantDiscr,
fields: Vec<FieldDef>,
ctor_kind: CtorKind,
adt_kind: AdtKind,
parent_did: DefId,
recovered: bool,
is_field_list_non_exhaustive: bool,
) -> Self {
debug!(
"VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
);
let mut flags = VariantFlags::NO_VARIANT_FLAGS;
if is_field_list_non_exhaustive {
flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
}
if recovered {
flags |= VariantFlags::IS_RECOVERED;
}
VariantDef {
def_id: variant_did.unwrap_or(parent_did),
ctor_def_id,
name,
discr,
fields,
ctor_kind,
flags,
}
}
/// Is this field list non-exhaustive?
#[inline]
pub fn is_field_list_non_exhaustive(&self) -> bool {
self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
}
/// Was this variant obtained as part of recovering from a syntactic error?
#[inline]
pub fn is_recovered(&self) -> bool {
self.flags.intersects(VariantFlags::IS_RECOVERED)
}
/// Computes the `Ident` of this variant by looking up the `Span`
pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
pub enum VariantDiscr {
/// Explicit value for this variant, i.e., `X = 123`.
/// The `DefId` corresponds to the embedded constant.
Explicit(DefId),
/// The previous variant's discriminant plus one.
/// For efficiency reasons, the distance from the
/// last `Explicit` discriminant is being stored,
/// or `0` for the first variant, if it has none.
Relative(u32),
}
#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
pub struct FieldDef {
pub did: DefId,
pub name: Symbol,
pub vis: Visibility,
}
bitflags! {
#[derive(TyEncodable, TyDecodable, Default, HashStable)]
pub struct ReprFlags: u8 {
const IS_C = 1 << 0;
const IS_SIMD = 1 << 1;
const IS_TRANSPARENT = 1 << 2;
// Internal only for now. If true, don't reorder fields.
const IS_LINEAR = 1 << 3;
// If true, don't expose any niche to type's context.
const HIDE_NICHE = 1 << 4;
// If true, the type's layout can be randomized using
// the seed stored in `ReprOptions.layout_seed`
const RANDOMIZE_LAYOUT = 1 << 5;
// Any of these flags being set prevent field reordering optimisation.
const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
| ReprFlags::IS_SIMD.bits
| ReprFlags::IS_LINEAR.bits;
}
}
/// Represents the repr options provided by the user,
#[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
pub struct ReprOptions {
pub int: Option<attr::IntType>,
pub align: Option<Align>,
pub pack: Option<Align>,
pub flags: ReprFlags,
/// The seed to be used for randomizing a type's layout
///
/// Note: This could technically be a `[u8; 16]` (a `u128`) which would
/// be the "most accurate" hash as it'd encompass the item and crate
/// hash without loss, but it does pay the price of being larger.
/// Everything's a tradeoff, a `u64` seed should be sufficient for our
/// purposes (primarily `-Z randomize-layout`)
pub field_shuffle_seed: u64,
}
impl ReprOptions {
pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
let mut flags = ReprFlags::empty();
let mut size = None;
let mut max_align: Option<Align> = None;
let mut min_pack: Option<Align> = None;
// Generate a deterministically-derived seed from the item's path hash
// to allow for cross-crate compilation to actually work
let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
// If the user defined a custom seed for layout randomization, xor the item's
// path hash with the user defined seed, this will allowing determinism while
// still allowing users to further randomize layout generation for e.g. fuzzing
if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
field_shuffle_seed ^= user_seed;
}
for attr in tcx.get_attrs(did).iter() {
for r in attr::find_repr_attrs(&tcx.sess, attr) {
flags.insert(match r {
attr::ReprC => ReprFlags::IS_C,
attr::ReprPacked(pack) => {
let pack = Align::from_bytes(pack as u64).unwrap();
min_pack = Some(if let Some(min_pack) = min_pack {
min_pack.min(pack)
} else {
pack
});
ReprFlags::empty()
}
attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
attr::ReprSimd => ReprFlags::IS_SIMD,
attr::ReprInt(i) => {
size = Some(i);
ReprFlags::empty()
}
attr::ReprAlign(align) => {
max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
ReprFlags::empty()
}
});
}
}
// If `-Z randomize-layout` was enabled for the type definition then we can
// consider performing layout randomization
if tcx.sess.opts.debugging_opts.randomize_layout {
flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
}
// This is here instead of layout because the choice must make it into metadata.
if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
flags.insert(ReprFlags::IS_LINEAR);
}
Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
}
#[inline]
pub fn simd(&self) -> bool {
self.flags.contains(ReprFlags::IS_SIMD)
}
#[inline]
pub fn c(&self) -> bool {
self.flags.contains(ReprFlags::IS_C)
}
#[inline]
pub fn packed(&self) -> bool {
self.pack.is_some()
}
#[inline]
pub fn transparent(&self) -> bool {
self.flags.contains(ReprFlags::IS_TRANSPARENT)
}
#[inline]
pub fn linear(&self) -> bool {
self.flags.contains(ReprFlags::IS_LINEAR)
}
#[inline]
pub fn hide_niche(&self) -> bool {
self.flags.contains(ReprFlags::HIDE_NICHE)
}
/// Returns the discriminant type, given these `repr` options.
/// This must only be called on enums!
pub fn discr_type(&self) -> attr::IntType {
self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
}
/// Returns `true` if this `#[repr()]` should inhabit "smart enum
/// layout" optimizations, such as representing `Foo<&T>` as a
/// single pointer.
pub fn inhibit_enum_layout_opt(&self) -> bool {
self.c() || self.int.is_some()
}
/// Returns `true` if this `#[repr()]` should inhibit struct field reordering
/// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
if let Some(pack) = self.pack {
if pack.bytes() == 1 {
return true;
}
}
self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
}
/// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
/// was enabled for its declaration crate
pub fn can_randomize_type_layout(&self) -> bool {
!self.inhibit_struct_field_reordering_opt()
&& self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
}
/// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
pub fn inhibit_union_abi_opt(&self) -> bool {
self.c()
}
}
impl<'tcx> FieldDef {
/// Returns the type of this field. The resulting type is not normalized. The `subst` is
/// typically obtained via the second field of [`TyKind::Adt`].
pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
tcx.type_of(self.did).subst(tcx, subst)
}
/// Computes the `Ident` of this variant by looking up the `Span`
pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
}
}
pub type Attributes<'tcx> = &'tcx [ast::Attribute];
#[derive(Debug, PartialEq, Eq)]
pub enum ImplOverlapKind {
/// These impls are always allowed to overlap.
Permitted {
/// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
marker: bool,
},
/// These impls are allowed to overlap, but that raises
/// an issue #33140 future-compatibility warning.
///
/// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
/// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
///
/// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
/// that difference, making what reduces to the following set of impls:
///
/// ```
/// trait Trait {}
/// impl Trait for dyn Send + Sync {}
/// impl Trait for dyn Sync + Send {}
/// ```
///
/// Obviously, once we made these types be identical, that code causes a coherence
/// error and a fairly big headache for us. However, luckily for us, the trait
/// `Trait` used in this case is basically a marker trait, and therefore having
/// overlapping impls for it is sound.
///
/// To handle this, we basically regard the trait as a marker trait, with an additional
/// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
/// it has the following restrictions:
///
/// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
/// positive impls.
/// 2. The trait-ref of both impls must be equal.
/// 3. The trait-ref of both impls must be a trait object type consisting only of
/// marker traits.
/// 4. Neither of the impls can have any where-clauses.
///
/// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
Issue33140,
}
impl<'tcx> TyCtxt<'tcx> {
pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
self.typeck(self.hir().body_owner_def_id(body))
}
pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
self.associated_items(id)
.in_definition_order()
.filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
}
fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
if def_id.index == CRATE_DEF_INDEX {
Some(self.crate_name(def_id.krate))
} else {
let def_key = self.def_key(def_id);
match def_key.disambiguated_data.data {
// The name of a constructor is that of its parent.
rustc_hir::definitions::DefPathData::Ctor => self
.opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
// The name of opaque types only exists in HIR.
rustc_hir::definitions::DefPathData::ImplTrait
if let Some(def_id) = def_id.as_local() =>
self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
_ => def_key.get_opt_name(),
}
}
}
/// Look up the name of a definition across crates. This does not look at HIR.
///
/// When possible, this function should be used for cross-crate lookups over
/// [`opt_item_name`] to avoid invalidating the incremental cache. If you
/// need to handle items without a name, or HIR items that will not be
/// serialized cross-crate, or if you need the span of the item, use
/// [`opt_item_name`] instead.
///
/// [`opt_item_name`]: Self::opt_item_name
pub fn item_name(self, id: DefId) -> Symbol {
// Look at cross-crate items first to avoid invalidating the incremental cache
// unless we have to.
self.opt_item_name(id).unwrap_or_else(|| {
bug!("item_name: no name for {:?}", self.def_path(id));
})
}
/// Look up the name and span of a definition.
///
/// See [`item_name`][Self::item_name] for more information.
pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
let def = self.opt_item_name(def_id)?;
let span = def_id
.as_local()
.and_then(|id| self.def_ident_span(id))
.unwrap_or(rustc_span::DUMMY_SP);
Some(Ident::new(def, span))
}
pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
Some(self.associated_item(def_id))
} else {
None
}
}
pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
}
pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
variant
.fields
.iter()
.position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
}
/// Returns `true` if the impls are the same polarity and the trait either
/// has no items or is annotated `#[marker]` and prevents item overrides.
pub fn impls_are_allowed_to_overlap(
self,
def_id1: DefId,
def_id2: DefId,
) -> Option<ImplOverlapKind> {
// If either trait impl references an error, they're allowed to overlap,
// as one of them essentially doesn't exist.
if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
|| self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
{
return Some(ImplOverlapKind::Permitted { marker: false });
}
match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
(ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
// `#[rustc_reservation_impl]` impls don't overlap with anything
debug!(
"impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
def_id1, def_id2
);
return Some(ImplOverlapKind::Permitted { marker: false });
}
(ImplPolarity::Positive, ImplPolarity::Negative)
| (ImplPolarity::Negative, ImplPolarity::Positive) => {
// `impl AutoTrait for Type` + `impl !AutoTrait for Type`
debug!(
"impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
def_id1, def_id2
);
return None;
}
(ImplPolarity::Positive, ImplPolarity::Positive)
| (ImplPolarity::Negative, ImplPolarity::Negative) => {}
};
let is_marker_overlap = {
let is_marker_impl = |def_id: DefId| -> bool {
let trait_ref = self.impl_trait_ref(def_id);
trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
};
is_marker_impl(def_id1) && is_marker_impl(def_id2)
};
if is_marker_overlap {
debug!(
"impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
def_id1, def_id2
);
Some(ImplOverlapKind::Permitted { marker: true })
} else {
if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
if self_ty1 == self_ty2 {
debug!(
"impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
def_id1, def_id2
);
return Some(ImplOverlapKind::Issue33140);
} else {
debug!(
"impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
def_id1, def_id2, self_ty1, self_ty2
);
}
}
}
debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
None
}
}
/// Returns `ty::VariantDef` if `res` refers to a struct,
/// or variant or their constructors, panics otherwise.
pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
match res {
Res::Def(DefKind::Variant, did) => {
let enum_did = self.parent(did).unwrap();
self.adt_def(enum_did).variant_with_id(did)
}
Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
let variant_did = self.parent(variant_ctor_did).unwrap();
let enum_did = self.parent(variant_did).unwrap();
self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
}
Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
self.adt_def(struct_did).non_enum_variant()
}
_ => bug!("expect_variant_res used with unexpected res {:?}", res),
}
}
/// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
match instance {
ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
DefKind::Const
| DefKind::Static(..)
| DefKind::AssocConst
| DefKind::Ctor(..)
| DefKind::AnonConst
| DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
// If the caller wants `mir_for_ctfe` of a function they should not be using
// `instance_mir`, so we'll assume const fn also wants the optimized version.
_ => {
assert_eq!(def.const_param_did, None);
self.optimized_mir(def.did)
}
},
ty::InstanceDef::VtableShim(..)
| ty::InstanceDef::ReifyShim(..)
| ty::InstanceDef::Intrinsic(..)
| ty::InstanceDef::FnPtrShim(..)
| ty::InstanceDef::Virtual(..)
| ty::InstanceDef::ClosureOnceShim { .. }
| ty::InstanceDef::DropGlue(..)
| ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
}
}
/// Gets the attributes of a definition.
pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
if let Some(did) = did.as_local() {
self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
} else {
self.item_attrs(did)
}
}
/// Determines whether an item is annotated with an attribute.
pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
self.sess.contains_name(&self.get_attrs(did), attr)
}
/// Returns `true` if this is an `auto trait`.
pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
self.trait_def(trait_def_id).has_auto_impl
}
/// Returns layout of a generator. Layout might be unavailable if the
/// generator is tainted by errors.
pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
self.optimized_mir(def_id).generator_layout()
}
/// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
/// If it implements no trait, returns `None`.
pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
self.impl_trait_ref(def_id).map(|tr| tr.def_id)
}
/// If the given `DefId` describes a method belonging to an impl, returns the
/// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
TraitContainer(_) => None,
ImplContainer(def_id) => Some(def_id),
})
}
/// If the given `DefId` belongs to a trait that was automatically derived, returns `true`.
pub fn is_builtin_derive(self, def_id: DefId) -> bool {
self.has_attr(def_id, sym::automatically_derived)
}
/// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
/// with the name of the crate containing the impl.
pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
if let Some(impl_did) = impl_did.as_local() {
Ok(self.def_span(impl_did))
} else {
Err(self.crate_name(impl_did.krate))
}
}
/// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
/// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
/// definition's parent/scope to perform comparison.
pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
// We could use `Ident::eq` here, but we deliberately don't. The name
// comparison fails frequently, and we want to avoid the expensive
// `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
use_name.name == def_name.name
&& use_name
.span
.ctxt()
.hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
}
pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
ident
}
pub fn adjust_ident_and_get_scope(
self,
mut ident: Ident,
scope: DefId,
block: hir::HirId,
) -> (Ident, DefId) {
let scope = ident
.span
.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
.and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
.unwrap_or_else(|| self.parent_module(block).to_def_id());
(ident, scope)
}
pub fn is_object_safe(self, key: DefId) -> bool {
self.object_safety_violations(key).is_empty()
}
#[inline]
pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
&& self.impl_constness(def_id) == hir::Constness::Const
}
}
/// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
let def_id = def_id.as_local()?;
if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
return match opaque_ty.origin {
hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
Some(parent)
}
hir::OpaqueTyOrigin::TyAlias => None,
};
}
}
None
}
pub fn int_ty(ity: ast::IntTy) -> IntTy {
match ity {
ast::IntTy::Isize => IntTy::Isize,
ast::IntTy::I8 => IntTy::I8,
ast::IntTy::I16 => IntTy::I16,
ast::IntTy::I32 => IntTy::I32,
ast::IntTy::I64 => IntTy::I64,
ast::IntTy::I128 => IntTy::I128,
}
}
pub fn uint_ty(uty: ast::UintTy) -> UintTy {
match uty {
ast::UintTy::Usize => UintTy::Usize,
ast::UintTy::U8 => UintTy::U8,
ast::UintTy::U16 => UintTy::U16,
ast::UintTy::U32 => UintTy::U32,
ast::UintTy::U64 => UintTy::U64,
ast::UintTy::U128 => UintTy::U128,
}
}
pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
match fty {
ast::FloatTy::F32 => FloatTy::F32,
ast::FloatTy::F64 => FloatTy::F64,
}
}
pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
match ity {
IntTy::Isize => ast::IntTy::Isize,
IntTy::I8 => ast::IntTy::I8,
IntTy::I16 => ast::IntTy::I16,
IntTy::I32 => ast::IntTy::I32,
IntTy::I64 => ast::IntTy::I64,
IntTy::I128 => ast::IntTy::I128,
}
}
pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
match uty {
UintTy::Usize => ast::UintTy::Usize,
UintTy::U8 => ast::UintTy::U8,
UintTy::U16 => ast::UintTy::U16,
UintTy::U32 => ast::UintTy::U32,
UintTy::U64 => ast::UintTy::U64,
UintTy::U128 => ast::UintTy::U128,
}
}
pub fn provide(providers: &mut ty::query::Providers) {
closure::provide(providers);
context::provide(providers);
erase_regions::provide(providers);
layout::provide(providers);
util::provide(providers);
print::provide(providers);
super::util::bug::provide(providers);
super::middle::provide(providers);
*providers = ty::query::Providers {
trait_impls_of: trait_def::trait_impls_of_provider,
incoherent_impls: trait_def::incoherent_impls_provider,
type_uninhabited_from: inhabitedness::type_uninhabited_from,
const_param_default: consts::const_param_default,
vtable_allocation: vtable::vtable_allocation_provider,
..*providers
};
}
/// A map for the local crate mapping each type to a vector of its
/// inherent impls. This is not meant to be used outside of coherence;
/// rather, you should request the vector for a specific type via
/// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
/// (constructing this map requires touching the entire crate).
#[derive(Clone, Debug, Default, HashStable)]
pub struct CrateInherentImpls {
pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
}
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
pub struct SymbolName<'tcx> {
/// `&str` gives a consistent ordering, which ensures reproducible builds.
pub name: &'tcx str,
}
impl<'tcx> SymbolName<'tcx> {
pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
SymbolName {
name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
}
}
}
impl<'tcx> fmt::Display for SymbolName<'tcx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.name, fmt)
}
}
impl<'tcx> fmt::Debug for SymbolName<'tcx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.name, fmt)
}
}
#[derive(Debug, Default, Copy, Clone)]
pub struct FoundRelationships {
/// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
/// obligation, where:
///
/// * `Foo` is not `Sized`
/// * `(): Foo` may be satisfied
pub self_in_trait: bool,
/// This is true if we identified that this Ty (`?T`) is found in a `<_ as
/// _>::AssocType = ?T`
pub output: bool,
}