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chromium / external / github.com / rust-lang / rust / e85a0d70b86491752eb501f73b9d2025c5991e8e / . / src / librustc / ty / mod.rs
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// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
pub use self::Variance::*;
pub use self::DtorKind::*;
pub use self::AssociatedItemContainer::*;
pub use self::BorrowKind::*;
pub use self::IntVarValue::*;
pub use self::LvaluePreference::*;
pub use self::fold::TypeFoldable;
use dep_graph::{self, DepNode};
use hir::map as ast_map;
use middle;
use hir::def::{Def, CtorKind, PathResolution, ExportMap};
use hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
use middle::region::{CodeExtent, ROOT_CODE_EXTENT};
use mir::Mir;
use traits;
use ty;
use ty::subst::{Subst, Substs};
use ty::walk::TypeWalker;
use util::common::MemoizationMap;
use util::nodemap::NodeSet;
use util::nodemap::FxHashMap;
use serialize::{self, Encodable, Encoder};
use std::borrow::Cow;
use std::cell::{Cell, RefCell, Ref};
use std::hash::{Hash, Hasher};
use std::iter;
use std::ops::Deref;
use std::rc::Rc;
use std::slice;
use std::vec::IntoIter;
use std::mem;
use syntax::ast::{self, Name, NodeId};
use syntax::attr;
use syntax::symbol::{Symbol, InternedString};
use syntax_pos::{DUMMY_SP, Span};
use rustc_const_math::ConstInt;
use hir;
use hir::itemlikevisit::ItemLikeVisitor;
pub use self::sty::{Binder, DebruijnIndex};
pub use self::sty::{BuiltinBound, BuiltinBounds};
pub use self::sty::{BareFnTy, FnSig, PolyFnSig};
pub use self::sty::{ClosureTy, InferTy, ParamTy, ProjectionTy, TraitObject};
pub use self::sty::{ClosureSubsts, TypeAndMut};
pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef};
pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
pub use self::sty::{ExistentialProjection, PolyExistentialProjection};
pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
pub use self::sty::Issue32330;
pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid, SkolemizedRegionVid};
pub use self::sty::BoundRegion::*;
pub use self::sty::InferTy::*;
pub use self::sty::Region::*;
pub use self::sty::TypeVariants::*;
pub use self::sty::BuiltinBound::Send as BoundSend;
pub use self::sty::BuiltinBound::Sized as BoundSized;
pub use self::sty::BuiltinBound::Copy as BoundCopy;
pub use self::sty::BuiltinBound::Sync as BoundSync;
pub use self::contents::TypeContents;
pub use self::context::{TyCtxt, tls};
pub use self::context::{CtxtArenas, Lift, Tables};
pub use self::trait_def::{TraitDef, TraitFlags};
pub mod adjustment;
pub mod cast;
pub mod error;
pub mod fast_reject;
pub mod fold;
pub mod item_path;
pub mod layout;
pub mod _match;
pub mod maps;
pub mod outlives;
pub mod relate;
pub mod subst;
pub mod trait_def;
pub mod walk;
pub mod wf;
pub mod util;
mod contents;
mod context;
mod flags;
mod ivar;
mod structural_impls;
mod sty;
pub type Disr = ConstInt;
// Data types
/// The complete set of all analyses described in this module. This is
/// produced by the driver and fed to trans and later passes.
#[derive(Clone)]
pub struct CrateAnalysis<'a> {
pub export_map: ExportMap,
pub access_levels: middle::privacy::AccessLevels,
pub reachable: NodeSet,
pub name: &'a str,
pub glob_map: Option<hir::GlobMap>,
}
#[derive(Copy, Clone)]
pub enum DtorKind {
NoDtor,
TraitDtor
}
impl DtorKind {
pub fn is_present(&self) -> bool {
match *self {
TraitDtor => true,
_ => false
}
}
}
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum AssociatedItemContainer {
TraitContainer(DefId),
ImplContainer(DefId),
}
impl AssociatedItemContainer {
pub fn id(&self) -> DefId {
match *self {
TraitContainer(id) => id,
ImplContainer(id) => id,
}
}
}
/// 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, PartialEq, Eq, Hash, Debug)]
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>>,
}
impl<'a, 'gcx, 'tcx> ImplHeader<'tcx> {
pub fn with_fresh_ty_vars(selcx: &mut traits::SelectionContext<'a, 'gcx, 'tcx>,
impl_def_id: DefId)
-> ImplHeader<'tcx>
{
let tcx = selcx.tcx();
let impl_substs = selcx.infcx().fresh_substs_for_item(DUMMY_SP, impl_def_id);
let header = ImplHeader {
impl_def_id: impl_def_id,
self_ty: tcx.item_type(impl_def_id),
trait_ref: tcx.impl_trait_ref(impl_def_id),
predicates: tcx.item_predicates(impl_def_id).predicates
}.subst(tcx, impl_substs);
let traits::Normalized { value: mut header, obligations } =
traits::normalize(selcx, traits::ObligationCause::dummy(), &header);
header.predicates.extend(obligations.into_iter().map(|o| o.predicate));
header
}
}
#[derive(Copy, Clone, Debug)]
pub struct AssociatedItem {
pub def_id: DefId,
pub name: Name,
pub kind: AssociatedKind,
pub vis: Visibility,
pub defaultness: hir::Defaultness,
pub container: AssociatedItemContainer,
/// Whether this is a method with an explicit self
/// as its first argument, allowing method calls.
pub method_has_self_argument: bool,
}
#[derive(Copy, Clone, PartialEq, Eq, Debug, RustcEncodable, RustcDecodable)]
pub enum AssociatedKind {
Const,
Method,
Type
}
impl AssociatedItem {
pub fn def(&self) -> Def {
match self.kind {
AssociatedKind::Const => Def::AssociatedConst(self.def_id),
AssociatedKind::Method => Def::Method(self.def_id),
AssociatedKind::Type => Def::AssociatedTy(self.def_id),
}
}
}
#[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)]
pub enum Visibility {
/// Visible everywhere (including in other crates).
Public,
/// Visible only in the given crate-local module.
Restricted(NodeId),
/// Not visible anywhere in the local crate. This is the visibility of private external items.
PrivateExternal,
}
pub trait NodeIdTree {
fn is_descendant_of(&self, node: NodeId, ancestor: NodeId) -> bool;
}
impl<'a> NodeIdTree for ast_map::Map<'a> {
fn is_descendant_of(&self, node: NodeId, ancestor: NodeId) -> bool {
let mut node_ancestor = node;
while node_ancestor != ancestor {
let node_ancestor_parent = self.get_module_parent(node_ancestor);
if node_ancestor_parent == node_ancestor {
return false;
}
node_ancestor = node_ancestor_parent;
}
true
}
}
impl Visibility {
pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self {
match *visibility {
hir::Public => Visibility::Public,
hir::Visibility::Crate => Visibility::Restricted(ast::CRATE_NODE_ID),
hir::Visibility::Restricted { id, .. } => match tcx.expect_def(id) {
// 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.
Def::Err => Visibility::Public,
def => Visibility::Restricted(tcx.map.as_local_node_id(def.def_id()).unwrap()),
},
hir::Inherited => Visibility::Restricted(tcx.map.get_module_parent(id)),
}
}
/// Returns true if an item with this visibility is accessible from the given block.
pub fn is_accessible_from<T: NodeIdTree>(self, block: NodeId, 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::PrivateExternal => return false,
// Restricted items are visible in an arbitrary local module.
Visibility::Restricted(module) => module,
};
tree.is_descendant_of(block, restriction)
}
/// Returns true if this visibility is at least as accessible as the given visibility
pub fn is_at_least<T: NodeIdTree>(self, vis: Visibility, tree: &T) -> bool {
let vis_restriction = match vis {
Visibility::Public => return self == Visibility::Public,
Visibility::PrivateExternal => return true,
Visibility::Restricted(module) => module,
};
self.is_accessible_from(vis_restriction, tree)
}
}
#[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)]
pub enum Variance {
Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
}
#[derive(Clone, Copy, Debug, RustcDecodable, RustcEncodable)]
pub struct MethodCallee<'tcx> {
/// Impl method ID, for inherent methods, or trait method ID, otherwise.
pub def_id: DefId,
pub ty: Ty<'tcx>,
pub substs: &'tcx Substs<'tcx>
}
/// With method calls, we store some extra information in
/// side tables (i.e method_map). We use
/// MethodCall as a key to index into these tables instead of
/// just directly using the expression's NodeId. The reason
/// for this being that we may apply adjustments (coercions)
/// with the resulting expression also needing to use the
/// side tables. The problem with this is that we don't
/// assign a separate NodeId to this new expression
/// and so it would clash with the base expression if both
/// needed to add to the side tables. Thus to disambiguate
/// we also keep track of whether there's an adjustment in
/// our key.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub struct MethodCall {
pub expr_id: NodeId,
pub autoderef: u32
}
impl MethodCall {
pub fn expr(id: NodeId) -> MethodCall {
MethodCall {
expr_id: id,
autoderef: 0
}
}
pub fn autoderef(expr_id: NodeId, autoderef: u32) -> MethodCall {
MethodCall {
expr_id: expr_id,
autoderef: 1 + autoderef
}
}
}
// maps from an expression id that corresponds to a method call to the details
// of the method to be invoked
pub type MethodMap<'tcx> = FxHashMap<MethodCall, MethodCallee<'tcx>>;
// 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: CrateNum,
pub pos: usize,
}
/// Describes the fragment-state associated with a NodeId.
///
/// Currently only unfragmented paths have entries in the table,
/// but longer-term this enum is expected to expand to also
/// include data for fragmented paths.
#[derive(Copy, Clone, Debug)]
pub enum FragmentInfo {
Moved { var: NodeId, move_expr: NodeId },
Assigned { var: NodeId, assign_expr: NodeId, assignee_id: NodeId },
}
// Flags that we track on types. These flags are propagated upwards
// through the type during type construction, so that we can quickly
// check whether the type has various kinds of types in it without
// recursing over the type itself.
bitflags! {
flags TypeFlags: u32 {
const HAS_PARAMS = 1 << 0,
const HAS_SELF = 1 << 1,
const HAS_TY_INFER = 1 << 2,
const HAS_RE_INFER = 1 << 3,
const HAS_RE_SKOL = 1 << 4,
const HAS_RE_EARLY_BOUND = 1 << 5,
const HAS_FREE_REGIONS = 1 << 6,
const HAS_TY_ERR = 1 << 7,
const HAS_PROJECTION = 1 << 8,
const HAS_TY_CLOSURE = 1 << 9,
// true if there are "names" of types and regions and so forth
// that are local to a particular fn
const HAS_LOCAL_NAMES = 1 << 10,
// Present if the type belongs in a local type context.
// Only set for TyInfer other than Fresh.
const KEEP_IN_LOCAL_TCX = 1 << 11,
// Is there a projection that does not involve a bound region?
// Currently we can't normalize projections w/ bound regions.
const HAS_NORMALIZABLE_PROJECTION = 1 << 12,
const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
TypeFlags::HAS_SELF.bits |
TypeFlags::HAS_RE_EARLY_BOUND.bits,
// Flags representing the nominal content of a type,
// computed by FlagsComputation. If you add a new nominal
// flag, it should be added here too.
const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
TypeFlags::HAS_SELF.bits |
TypeFlags::HAS_TY_INFER.bits |
TypeFlags::HAS_RE_INFER.bits |
TypeFlags::HAS_RE_SKOL.bits |
TypeFlags::HAS_RE_EARLY_BOUND.bits |
TypeFlags::HAS_FREE_REGIONS.bits |
TypeFlags::HAS_TY_ERR.bits |
TypeFlags::HAS_PROJECTION.bits |
TypeFlags::HAS_TY_CLOSURE.bits |
TypeFlags::HAS_LOCAL_NAMES.bits |
TypeFlags::KEEP_IN_LOCAL_TCX.bits,
// Caches for type_is_sized, type_moves_by_default
const SIZEDNESS_CACHED = 1 << 16,
const IS_SIZED = 1 << 17,
const MOVENESS_CACHED = 1 << 18,
const MOVES_BY_DEFAULT = 1 << 19,
}
}
pub struct TyS<'tcx> {
pub sty: TypeVariants<'tcx>,
pub flags: Cell<TypeFlags>,
// the maximal depth of any bound regions appearing in this type.
region_depth: u32,
}
impl<'tcx> PartialEq for TyS<'tcx> {
#[inline]
fn eq(&self, other: &TyS<'tcx>) -> bool {
// (self as *const _) == (other as *const _)
(self as *const TyS<'tcx>) == (other as *const TyS<'tcx>)
}
}
impl<'tcx> Eq for TyS<'tcx> {}
impl<'tcx> Hash for TyS<'tcx> {
fn hash<H: Hasher>(&self, s: &mut H) {
(self as *const TyS).hash(s)
}
}
pub type Ty<'tcx> = &'tcx TyS<'tcx>;
impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {}
impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {}
/// A wrapper for slices with the additional invariant
/// that the slice is interned and no other slice with
/// the same contents can exist in the same context.
/// This means we can use pointer + length for both
/// equality comparisons and hashing.
#[derive(Debug, RustcEncodable)]
pub struct Slice<T>([T]);
impl<T> PartialEq for Slice<T> {
#[inline]
fn eq(&self, other: &Slice<T>) -> bool {
(&self.0 as *const [T]) == (&other.0 as *const [T])
}
}
impl<T> Eq for Slice<T> {}
impl<T> Hash for Slice<T> {
fn hash<H: Hasher>(&self, s: &mut H) {
(self.as_ptr(), self.len()).hash(s)
}
}
impl<T> Deref for Slice<T> {
type Target = [T];
fn deref(&self) -> &[T] {
&self.0
}
}
impl<'a, T> IntoIterator for &'a Slice<T> {
type Item = &'a T;
type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
fn into_iter(self) -> Self::IntoIter {
self[..].iter()
}
}
impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<Ty<'tcx>> {}
impl<T> Slice<T> {
pub fn empty<'a>() -> &'a Slice<T> {
unsafe {
mem::transmute(slice::from_raw_parts(0x1 as *const T, 0))
}
}
}
/// Upvars do not get their own node-id. Instead, we use the pair of
/// the original var id (that is, the root variable that is referenced
/// by the upvar) and the id of the closure expression.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct UpvarId {
pub var_id: NodeId,
pub closure_expr_id: NodeId,
}
#[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)]
pub enum BorrowKind {
/// Data must be immutable and is aliasable.
ImmBorrow,
/// Data must be immutable but not aliasable. This kind of borrow
/// cannot currently be expressed by the user and is used only in
/// implicit closure bindings. It is needed when you the closure
/// is borrowing or mutating a mutable referent, e.g.:
///
/// let x: &mut isize = ...;
/// let y = || *x += 5;
///
/// If we were to try to translate this closure into a more explicit
/// form, we'd encounter an error with the code as written:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
///
/// This is then illegal because you cannot mutate a `&mut` found
/// in an aliasable location. To solve, you'd have to translate with
/// an `&mut` borrow:
///
/// struct Env { x: & &mut isize }
/// let x: &mut isize = ...;
/// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
/// fn fn_ptr(env: &mut Env) { **env.x += 5; }
///
/// Now the assignment to `**env.x` is legal, but creating a
/// mutable pointer to `x` is not because `x` is not mutable. We
/// could fix this by declaring `x` as `let mut x`. This is ok in
/// user code, if awkward, but extra weird for closures, since the
/// borrow is hidden.
///
/// So we introduce a "unique imm" borrow -- the referent is
/// immutable, but not aliasable. This solves the problem. For
/// simplicity, we don't give users the way to express this
/// borrow, it's just used when translating closures.
UniqueImmBorrow,
/// Data is mutable and not aliasable.
MutBorrow
}
/// Information describing the capture of an upvar. This is computed
/// during `typeck`, specifically by `regionck`.
#[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable)]
pub enum UpvarCapture<'tcx> {
/// Upvar is captured by value. This is always true when the
/// closure is labeled `move`, but can also be true in other cases
/// depending on inference.
ByValue,
/// Upvar is captured by reference.
ByRef(UpvarBorrow<'tcx>),
}
#[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)]
pub struct UpvarBorrow<'tcx> {
/// The kind of borrow: by-ref upvars have access to shared
/// immutable borrows, which are not part of the normal language
/// syntax.
pub kind: BorrowKind,
/// Region of the resulting reference.
pub region: &'tcx ty::Region,
}
pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
#[derive(Copy, Clone)]
pub struct ClosureUpvar<'tcx> {
pub def: Def,
pub span: Span,
pub ty: Ty<'tcx>,
}
#[derive(Clone, Copy, PartialEq)]
pub enum IntVarValue {
IntType(ast::IntTy),
UintType(ast::UintTy),
}
/// Default region to use for the bound of objects that are
/// supplied as the value for this type parameter. This is derived
/// from `T:'a` annotations appearing in the type definition. If
/// this is `None`, then the default is inherited from the
/// surrounding context. See RFC #599 for details.
#[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
pub enum ObjectLifetimeDefault<'tcx> {
/// Require an explicit annotation. Occurs when multiple
/// `T:'a` constraints are found.
Ambiguous,
/// Use the base default, typically 'static, but in a fn body it is a fresh variable
BaseDefault,
/// Use the given region as the default.
Specific(&'tcx Region),
}
#[derive(Clone, RustcEncodable, RustcDecodable)]
pub struct TypeParameterDef<'tcx> {
pub name: Name,
pub def_id: DefId,
pub index: u32,
pub default_def_id: DefId, // for use in error reporing about defaults
pub default: Option<Ty<'tcx>>,
pub object_lifetime_default: ObjectLifetimeDefault<'tcx>,
/// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
/// on generic parameter `T`, asserts data behind the parameter
/// `T` won't be accessed during the parent type's `Drop` impl.
pub pure_wrt_drop: bool,
}
#[derive(Clone, RustcEncodable, RustcDecodable)]
pub struct RegionParameterDef<'tcx> {
pub name: Name,
pub def_id: DefId,
pub index: u32,
pub bounds: Vec<&'tcx ty::Region>,
/// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
/// on generic parameter `'a`, asserts data of lifetime `'a`
/// won't be accessed during the parent type's `Drop` impl.
pub pure_wrt_drop: bool,
}
impl<'tcx> RegionParameterDef<'tcx> {
pub fn to_early_bound_region(&self) -> ty::Region {
ty::ReEarlyBound(self.to_early_bound_region_data())
}
pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
ty::EarlyBoundRegion {
index: self.index,
name: self.name,
}
}
pub fn to_bound_region(&self) -> ty::BoundRegion {
// this is an early bound region, so unaffected by #32330
ty::BoundRegion::BrNamed(self.def_id, self.name, Issue32330::WontChange)
}
}
/// Information about the formal type/lifetime parameters associated
/// with an item or method. Analogous to hir::Generics.
#[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
pub struct Generics<'tcx> {
pub parent: Option<DefId>,
pub parent_regions: u32,
pub parent_types: u32,
pub regions: Vec<RegionParameterDef<'tcx>>,
pub types: Vec<TypeParameterDef<'tcx>>,
pub has_self: bool,
}
impl<'tcx> Generics<'tcx> {
pub fn parent_count(&self) -> usize {
self.parent_regions as usize + self.parent_types as usize
}
pub fn own_count(&self) -> usize {
self.regions.len() + self.types.len()
}
pub fn count(&self) -> usize {
self.parent_count() + self.own_count()
}
pub fn region_param(&self, param: &EarlyBoundRegion) -> &RegionParameterDef<'tcx> {
&self.regions[param.index as usize - self.has_self as usize]
}
pub fn type_param(&self, param: &ParamTy) -> &TypeParameterDef<'tcx> {
&self.types[param.idx as usize - self.has_self as usize - self.regions.len()]
}
}
/// Bounds on generics.
#[derive(Clone)]
pub struct GenericPredicates<'tcx> {
pub parent: Option<DefId>,
pub predicates: Vec<Predicate<'tcx>>,
}
impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {}
impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {}
impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> {
pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
-> InstantiatedPredicates<'tcx> {
let mut instantiated = InstantiatedPredicates::empty();
self.instantiate_into(tcx, &mut instantiated, substs);
instantiated
}
pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>)
-> InstantiatedPredicates<'tcx> {
InstantiatedPredicates {
predicates: self.predicates.subst(tcx, substs)
}
}
fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
instantiated: &mut InstantiatedPredicates<'tcx>,
substs: &Substs<'tcx>) {
if let Some(def_id) = self.parent {
tcx.item_predicates(def_id).instantiate_into(tcx, instantiated, substs);
}
instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs)))
}
pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
poly_trait_ref: &ty::PolyTraitRef<'tcx>)
-> InstantiatedPredicates<'tcx>
{
assert_eq!(self.parent, None);
InstantiatedPredicates {
predicates: self.predicates.iter().map(|pred| {
pred.subst_supertrait(tcx, poly_trait_ref)
}).collect()
}
}
}
#[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub enum Predicate<'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(PolyTraitPredicate<'tcx>),
/// where `T1 == T2`.
Equate(PolyEquatePredicate<'tcx>),
/// where 'a : 'b
RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
/// where T : 'a
TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
/// where <T as TraitRef>::Name == X, approximately.
/// See `ProjectionPredicate` struct for details.
Projection(PolyProjectionPredicate<'tcx>),
/// no syntax: T WF
WellFormed(Ty<'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, ClosureKind),
}
impl<'a, 'gcx, '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<'a, 'gcx, 'tcx>,
trait_ref: &ty::PolyTraitRef<'tcx>)
-> ty::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 super-trait-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).
let substs = &trait_ref.0.substs;
match *self {
Predicate::Trait(ty::Binder(ref data)) =>
Predicate::Trait(ty::Binder(data.subst(tcx, substs))),
Predicate::Equate(ty::Binder(ref data)) =>
Predicate::Equate(ty::Binder(data.subst(tcx, substs))),
Predicate::RegionOutlives(ty::Binder(ref data)) =>
Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))),
Predicate::TypeOutlives(ty::Binder(ref data)) =>
Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))),
Predicate::Projection(ty::Binder(ref data)) =>
Predicate::Projection(ty::Binder(data.subst(tcx, substs))),
Predicate::WellFormed(data) =>
Predicate::WellFormed(data.subst(tcx, substs)),
Predicate::ObjectSafe(trait_def_id) =>
Predicate::ObjectSafe(trait_def_id),
Predicate::ClosureKind(closure_def_id, kind) =>
Predicate::ClosureKind(closure_def_id, kind),
}
}
}
#[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
pub struct TraitPredicate<'tcx> {
pub trait_ref: TraitRef<'tcx>
}
pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
impl<'tcx> TraitPredicate<'tcx> {
pub fn def_id(&self) -> DefId {
self.trait_ref.def_id
}
/// Creates the dep-node for selecting/evaluating this trait reference.
fn dep_node(&self) -> DepNode<DefId> {
// Ideally, the dep-node would just have all the input types
// in it. But they are limited to including def-ids. So as an
// approximation we include the def-ids for all nominal types
// found somewhere. This means that we will e.g. conflate the
// dep-nodes for `u32: SomeTrait` and `u64: SomeTrait`, but we
// would have distinct dep-nodes for `Vec<u32>: SomeTrait`,
// `Rc<u32>: SomeTrait`, and `(Vec<u32>, Rc<u32>): SomeTrait`.
// Note that it's always sound to conflate dep-nodes, it just
// leads to more recompilation.
let def_ids: Vec<_> =
self.input_types()
.flat_map(|t| t.walk())
.filter_map(|t| match t.sty {
ty::TyAdt(adt_def, _) =>
Some(adt_def.did),
_ =>
None
})
.chain(iter::once(self.def_id()))
.collect();
DepNode::TraitSelect(def_ids)
}
pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
self.trait_ref.input_types()
}
pub fn self_ty(&self) -> Ty<'tcx> {
self.trait_ref.self_ty()
}
}
impl<'tcx> PolyTraitPredicate<'tcx> {
pub fn def_id(&self) -> DefId {
// ok to skip binder since trait def-id does not care about regions
self.0.def_id()
}
pub fn dep_node(&self) -> DepNode<DefId> {
// ok to skip binder since depnode does not care about regions
self.0.dep_node()
}
}
#[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct EquatePredicate<'tcx>(pub Ty<'tcx>, pub Ty<'tcx>); // `0 == 1`
pub type PolyEquatePredicate<'tcx> = ty::Binder<EquatePredicate<'tcx>>;
#[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub struct OutlivesPredicate<A,B>(pub A, pub B); // `A : B`
pub type PolyOutlivesPredicate<A,B> = ty::Binder<OutlivesPredicate<A,B>>;
pub type PolyRegionOutlivesPredicate<'tcx> = PolyOutlivesPredicate<&'tcx ty::Region,
&'tcx ty::Region>;
pub type PolyTypeOutlivesPredicate<'tcx> = PolyOutlivesPredicate<Ty<'tcx>, &'tcx ty::Region>;
/// 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, RustcEncodable, RustcDecodable)]
pub struct ProjectionPredicate<'tcx> {
pub projection_ty: ProjectionTy<'tcx>,
pub ty: Ty<'tcx>,
}
pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
impl<'tcx> PolyProjectionPredicate<'tcx> {
pub fn item_name(&self) -> Name {
self.0.projection_ty.item_name // safe to skip the binder to access a name
}
}
pub trait ToPolyTraitRef<'tcx> {
fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
}
impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
assert!(!self.has_escaping_regions());
ty::Binder(self.clone())
}
}
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)
}
}
impl<'tcx> ToPolyTraitRef<'tcx> for PolyProjectionPredicate<'tcx> {
fn to_poly_trait_ref(&self) -> 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.
ty::Binder(self.0.projection_ty.trait_ref)
}
}
pub trait ToPredicate<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx>;
}
impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
// we're about to add a binder, so let's check that we don't
// accidentally capture anything, or else that might be some
// weird debruijn accounting.
assert!(!self.has_escaping_regions());
ty::Predicate::Trait(ty::Binder(ty::TraitPredicate {
trait_ref: self.clone()
}))
}
}
impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
ty::Predicate::Trait(self.to_poly_trait_predicate())
}
}
impl<'tcx> ToPredicate<'tcx> for PolyEquatePredicate<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
Predicate::Equate(self.clone())
}
}
impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
Predicate::RegionOutlives(self.clone())
}
}
impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
Predicate::TypeOutlives(self.clone())
}
}
impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
fn to_predicate(&self) -> Predicate<'tcx> {
Predicate::Projection(self.clone())
}
}
impl<'tcx> Predicate<'tcx> {
/// Iterates over the types in this predicate. Note that in all
/// cases this is skipping over a binder, so late-bound regions
/// with depth 0 are bound by the predicate.
pub fn walk_tys(&self) -> IntoIter<Ty<'tcx>> {
let vec: Vec<_> = match *self {
ty::Predicate::Trait(ref data) => {
data.skip_binder().input_types().collect()
}
ty::Predicate::Equate(ty::Binder(ref data)) => {
vec![data.0, data.1]
}
ty::Predicate::TypeOutlives(ty::Binder(ref data)) => {
vec![data.0]
}
ty::Predicate::RegionOutlives(..) => {
vec![]
}
ty::Predicate::Projection(ref data) => {
let trait_inputs = data.0.projection_ty.trait_ref.input_types();
trait_inputs.chain(Some(data.0.ty)).collect()
}
ty::Predicate::WellFormed(data) => {
vec![data]
}
ty::Predicate::ObjectSafe(_trait_def_id) => {
vec![]
}
ty::Predicate::ClosureKind(_closure_def_id, _kind) => {
vec![]
}
};
// The only reason to collect into a vector here is that I was
// too lazy to make the full (somewhat complicated) iterator
// type that would be needed here. But I wanted this fn to
// return an iterator conceptually, rather than a `Vec`, so as
// to be closer to `Ty::walk`.
vec.into_iter()
}
pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
match *self {
Predicate::Trait(ref t) => {
Some(t.to_poly_trait_ref())
}
Predicate::Projection(..) |
Predicate::Equate(..) |
Predicate::RegionOutlives(..) |
Predicate::WellFormed(..) |
Predicate::ObjectSafe(..) |
Predicate::ClosureKind(..) |
Predicate::TypeOutlives(..) => {
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 a `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)]
pub struct InstantiatedPredicates<'tcx> {
pub predicates: Vec<Predicate<'tcx>>,
}
impl<'tcx> InstantiatedPredicates<'tcx> {
pub fn empty() -> InstantiatedPredicates<'tcx> {
InstantiatedPredicates { predicates: vec![] }
}
pub fn is_empty(&self) -> bool {
self.predicates.is_empty()
}
}
impl<'tcx> TraitRef<'tcx> {
pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
TraitRef { def_id: def_id, substs: substs }
}
pub fn self_ty(&self) -> Ty<'tcx> {
self.substs.type_at(0)
}
pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
// Select only the "input types" from a trait-reference. For
// now this is all the types that appear in the
// trait-reference, but it should eventually exclude
// associated types.
self.substs.types()
}
}
/// When type checking, we use the `ParameterEnvironment` to track
/// details about the type/lifetime parameters that are in scope.
/// It primarily stores the bounds information.
///
/// Note: This information might seem to be redundant with the data in
/// `tcx.ty_param_defs`, but it is not. That table contains the
/// parameter definitions from an "outside" perspective, but this
/// struct will contain the bounds for a parameter as seen from inside
/// the function body. Currently the only real distinction is that
/// bound lifetime parameters are replaced with free ones, but in the
/// future I hope to refine the representation of types so as to make
/// more distinctions clearer.
#[derive(Clone)]
pub struct ParameterEnvironment<'tcx> {
/// See `construct_free_substs` for details.
pub free_substs: &'tcx Substs<'tcx>,
/// Each type parameter has an implicit region bound that
/// indicates it must outlive at least the function body (the user
/// may specify stronger requirements). This field indicates the
/// region of the callee.
pub implicit_region_bound: &'tcx ty::Region,
/// Obligations that the caller must satisfy. This is basically
/// the set of bounds on the in-scope type parameters, translated
/// into Obligations, and elaborated and normalized.
pub caller_bounds: Vec<ty::Predicate<'tcx>>,
/// Scope that is attached to free regions for this scope. This
/// is usually the id of the fn body, but for more abstract scopes
/// like structs we often use the node-id of the struct.
///
/// FIXME(#3696). It would be nice to refactor so that free
/// regions don't have this implicit scope and instead introduce
/// relationships in the environment.
pub free_id_outlive: CodeExtent,
/// A cache for `moves_by_default`.
pub is_copy_cache: RefCell<FxHashMap<Ty<'tcx>, bool>>,
/// A cache for `type_is_sized`
pub is_sized_cache: RefCell<FxHashMap<Ty<'tcx>, bool>>,
}
impl<'a, 'tcx> ParameterEnvironment<'tcx> {
pub fn with_caller_bounds(&self,
caller_bounds: Vec<ty::Predicate<'tcx>>)
-> ParameterEnvironment<'tcx>
{
ParameterEnvironment {
free_substs: self.free_substs,
implicit_region_bound: self.implicit_region_bound,
caller_bounds: caller_bounds,
free_id_outlive: self.free_id_outlive,
is_copy_cache: RefCell::new(FxHashMap()),
is_sized_cache: RefCell::new(FxHashMap()),
}
}
/// Construct a parameter environment given an item, impl item, or trait item
pub fn for_item(tcx: TyCtxt<'a, 'tcx, 'tcx>, id: NodeId)
-> ParameterEnvironment<'tcx> {
match tcx.map.find(id) {
Some(ast_map::NodeImplItem(ref impl_item)) => {
match impl_item.node {
hir::ImplItemKind::Type(_) | hir::ImplItemKind::Const(..) => {
// associated types don't have their own entry (for some reason),
// so for now just grab environment for the impl
let impl_id = tcx.map.get_parent(id);
let impl_def_id = tcx.map.local_def_id(impl_id);
tcx.construct_parameter_environment(impl_item.span,
impl_def_id,
tcx.region_maps.item_extent(id))
}
hir::ImplItemKind::Method(_, ref body) => {
tcx.construct_parameter_environment(
impl_item.span,
tcx.map.local_def_id(id),
tcx.region_maps.call_site_extent(id, body.id))
}
}
}
Some(ast_map::NodeTraitItem(trait_item)) => {
match trait_item.node {
hir::TypeTraitItem(..) | hir::ConstTraitItem(..) => {
// associated types don't have their own entry (for some reason),
// so for now just grab environment for the trait
let trait_id = tcx.map.get_parent(id);
let trait_def_id = tcx.map.local_def_id(trait_id);
tcx.construct_parameter_environment(trait_item.span,
trait_def_id,
tcx.region_maps.item_extent(id))
}
hir::MethodTraitItem(_, ref body) => {
// Use call-site for extent (unless this is a
// trait method with no default; then fallback
// to the method id).
let extent = if let Some(ref body) = *body {
// default impl: use call_site extent as free_id_outlive bound.
tcx.region_maps.call_site_extent(id, body.id)
} else {
// no default impl: use item extent as free_id_outlive bound.
tcx.region_maps.item_extent(id)
};
tcx.construct_parameter_environment(
trait_item.span,
tcx.map.local_def_id(id),
extent)
}
}
}
Some(ast_map::NodeItem(item)) => {
match item.node {
hir::ItemFn(.., ref body) => {
// We assume this is a function.
let fn_def_id = tcx.map.local_def_id(id);
tcx.construct_parameter_environment(
item.span,
fn_def_id,
tcx.region_maps.call_site_extent(id, body.id))
}
hir::ItemEnum(..) |
hir::ItemStruct(..) |
hir::ItemUnion(..) |
hir::ItemTy(..) |
hir::ItemImpl(..) |
hir::ItemConst(..) |
hir::ItemStatic(..) => {
let def_id = tcx.map.local_def_id(id);
tcx.construct_parameter_environment(item.span,
def_id,
tcx.region_maps.item_extent(id))
}
hir::ItemTrait(..) => {
let def_id = tcx.map.local_def_id(id);
tcx.construct_parameter_environment(item.span,
def_id,
tcx.region_maps.item_extent(id))
}
_ => {
span_bug!(item.span,
"ParameterEnvironment::for_item():
can't create a parameter \
environment for this kind of item")
}
}
}
Some(ast_map::NodeExpr(expr)) => {
// This is a convenience to allow closures to work.
if let hir::ExprClosure(..) = expr.node {
ParameterEnvironment::for_item(tcx, tcx.map.get_parent(id))
} else {
tcx.empty_parameter_environment()
}
}
Some(ast_map::NodeForeignItem(item)) => {
let def_id = tcx.map.local_def_id(id);
tcx.construct_parameter_environment(item.span,
def_id,
ROOT_CODE_EXTENT)
}
_ => {
bug!("ParameterEnvironment::from_item(): \
`{}` is not an item",
tcx.map.node_to_string(id))
}
}
}
}
bitflags! {
flags AdtFlags: u32 {
const NO_ADT_FLAGS = 0,
const IS_ENUM = 1 << 0,
const IS_DTORCK = 1 << 1, // is this a dtorck type?
const IS_DTORCK_VALID = 1 << 2,
const IS_PHANTOM_DATA = 1 << 3,
const IS_SIMD = 1 << 4,
const IS_FUNDAMENTAL = 1 << 5,
const IS_UNION = 1 << 6,
}
}
pub type AdtDef<'tcx> = &'tcx AdtDefData<'tcx, 'static>;
pub type VariantDef<'tcx> = &'tcx VariantDefData<'tcx, 'static>;
pub type FieldDef<'tcx> = &'tcx FieldDefData<'tcx, 'static>;
// See comment on AdtDefData for explanation
pub type AdtDefMaster<'tcx> = &'tcx AdtDefData<'tcx, 'tcx>;
pub type VariantDefMaster<'tcx> = &'tcx VariantDefData<'tcx, 'tcx>;
pub type FieldDefMaster<'tcx> = &'tcx FieldDefData<'tcx, 'tcx>;
pub struct VariantDefData<'tcx, 'container: 'tcx> {
/// The variant's DefId. If this is a tuple-like struct,
/// this is the DefId of the struct's ctor.
pub did: DefId,
pub name: Name, // struct's name if this is a struct
pub disr_val: Disr,
pub fields: Vec<FieldDefData<'tcx, 'container>>,
pub ctor_kind: CtorKind,
}
pub struct FieldDefData<'tcx, 'container: 'tcx> {
pub did: DefId,
pub name: Name,
pub vis: Visibility,
/// TyIVar is used here to allow for variance (see the doc at
/// AdtDefData).
///
/// Note: direct accesses to `ty` must also add dep edges.
ty: ivar::TyIVar<'tcx, 'container>
}
/// The definition of an abstract data type - a struct or enum.
///
/// These are all interned (by intern_adt_def) into the adt_defs
/// table.
///
/// Because of the possibility of nested tcx-s, this type
/// needs 2 lifetimes: the traditional variant lifetime ('tcx)
/// bounding the lifetime of the inner types is of course necessary.
/// However, it is not sufficient - types from a child tcx must
/// not be leaked into the master tcx by being stored in an AdtDefData.
///
/// The 'container lifetime ensures that by outliving the container
/// tcx and preventing shorter-lived types from being inserted. When
/// write access is not needed, the 'container lifetime can be
/// erased to 'static, which can be done by the AdtDef wrapper.
pub struct AdtDefData<'tcx, 'container: 'tcx> {
pub did: DefId,
pub variants: Vec<VariantDefData<'tcx, 'container>>,
destructor: Cell<Option<DefId>>,
flags: Cell<AdtFlags>,
sized_constraint: ivar::TyIVar<'tcx, 'container>,
}
impl<'tcx, 'container> PartialEq for AdtDefData<'tcx, 'container> {
// AdtDefData are always interned and this is part of TyS equality
#[inline]
fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ }
}
impl<'tcx, 'container> Eq for AdtDefData<'tcx, 'container> {}
impl<'tcx, 'container> Hash for AdtDefData<'tcx, 'container> {
#[inline]
fn hash<H: Hasher>(&self, s: &mut H) {
(self as *const AdtDefData).hash(s)
}
}
impl<'tcx> serialize::UseSpecializedEncodable for AdtDef<'tcx> {
fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
self.did.encode(s)
}
}
impl<'tcx> serialize::UseSpecializedDecodable for AdtDef<'tcx> {}
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum AdtKind { Struct, Union, Enum }
impl<'a, 'gcx, 'tcx, 'container> AdtDefData<'gcx, 'container> {
fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>,
did: DefId,
kind: AdtKind,
variants: Vec<VariantDefData<'gcx, 'container>>) -> Self {
let mut flags = AdtFlags::NO_ADT_FLAGS;
let attrs = tcx.get_attrs(did);
if attr::contains_name(&attrs, "fundamental") {
flags = flags | AdtFlags::IS_FUNDAMENTAL;
}
if tcx.lookup_simd(did) {
flags = flags | AdtFlags::IS_SIMD;
}
if Some(did) == tcx.lang_items.phantom_data() {
flags = flags | AdtFlags::IS_PHANTOM_DATA;
}
match kind {
AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM,
AdtKind::Union => flags = flags | AdtFlags::IS_UNION,
AdtKind::Struct => {}
}
AdtDefData {
did: did,
variants: variants,
flags: Cell::new(flags),
destructor: Cell::new(None),
sized_constraint: ivar::TyIVar::new(),
}
}
fn calculate_dtorck(&'gcx self, tcx: TyCtxt) {
if tcx.is_adt_dtorck(self) {
self.flags.set(self.flags.get() | AdtFlags::IS_DTORCK);
}
self.flags.set(self.flags.get() | AdtFlags::IS_DTORCK_VALID)
}
#[inline]
pub fn is_struct(&self) -> bool {
!self.is_union() && !self.is_enum()
}
#[inline]
pub fn is_union(&self) -> bool {
self.flags.get().intersects(AdtFlags::IS_UNION)
}
#[inline]
pub fn is_enum(&self) -> bool {
self.flags.get().intersects(AdtFlags::IS_ENUM)
}
/// Returns the kind of the ADT - Struct or Enum.
#[inline]
pub fn adt_kind(&self) -> AdtKind {
if self.is_enum() {
AdtKind::Enum
} else if self.is_union() {
AdtKind::Union
} else {
AdtKind::Struct
}
}
pub fn descr(&self) -> &'static str {
match self.adt_kind() {
AdtKind::Struct => "struct",
AdtKind::Union => "union",
AdtKind::Enum => "enum",
}
}
pub fn variant_descr(&self) -> &'static str {
match self.adt_kind() {
AdtKind::Struct => "struct",
AdtKind::Union => "union",
AdtKind::Enum => "variant",
}
}
/// Returns whether this is a dtorck type. If this returns
/// true, this type being safe for destruction requires it to be
/// alive; Otherwise, only the contents are required to be.
#[inline]
pub fn is_dtorck(&'gcx self, tcx: TyCtxt) -> bool {
if !self.flags.get().intersects(AdtFlags::IS_DTORCK_VALID) {
self.calculate_dtorck(tcx)
}
self.flags.get().intersects(AdtFlags::IS_DTORCK)
}
/// Returns whether this type is #[fundamental] for the purposes
/// of coherence checking.
#[inline]
pub fn is_fundamental(&self) -> bool {
self.flags.get().intersects(AdtFlags::IS_FUNDAMENTAL)
}
#[inline]
pub fn is_simd(&self) -> bool {
self.flags.get().intersects(AdtFlags::IS_SIMD)
}
/// Returns true if this is PhantomData<T>.
#[inline]
pub fn is_phantom_data(&self) -> bool {
self.flags.get().intersects(AdtFlags::IS_PHANTOM_DATA)
}
/// Returns whether this type has a destructor.
pub fn has_dtor(&self) -> bool {
self.dtor_kind().is_present()
}
/// Asserts this is a struct and returns the struct's unique
/// variant.
pub fn struct_variant(&self) -> &VariantDefData<'gcx, 'container> {
assert!(!self.is_enum());
&self.variants[0]
}
#[inline]
pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> {
tcx.item_predicates(self.did)
}
/// Returns an iterator over all fields contained
/// by this ADT.
#[inline]
pub fn all_fields(&self) ->
iter::FlatMap<
slice::Iter<VariantDefData<'gcx, 'container>>,
slice::Iter<FieldDefData<'gcx, 'container>>,
for<'s> fn(&'s VariantDefData<'gcx, 'container>)
-> slice::Iter<'s, FieldDefData<'gcx, 'container>>
> {
self.variants.iter().flat_map(VariantDefData::fields_iter)
}
#[inline]
pub fn is_empty(&self) -> bool {
self.variants.is_empty()
}
#[inline]
pub fn is_univariant(&self) -> bool {
self.variants.len() == 1
}
pub fn is_payloadfree(&self) -> bool {
!self.variants.is_empty() &&
self.variants.iter().all(|v| v.fields.is_empty())
}
pub fn variant_with_id(&self, vid: DefId) -> &VariantDefData<'gcx, 'container> {
self.variants
.iter()
.find(|v| v.did == vid)
.expect("variant_with_id: unknown variant")
}
pub fn variant_index_with_id(&self, vid: DefId) -> usize {
self.variants
.iter()
.position(|v| v.did == vid)
.expect("variant_index_with_id: unknown variant")
}
pub fn variant_of_def(&self, def: Def) -> &VariantDefData<'gcx, 'container> {
match def {
Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid),
Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) |
Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.struct_variant(),
_ => bug!("unexpected def {:?} in variant_of_def", def)
}
}
pub fn destructor(&self) -> Option<DefId> {
self.destructor.get()
}
pub fn set_destructor(&self, dtor: DefId) {
self.destructor.set(Some(dtor));
}
pub fn dtor_kind(&self) -> DtorKind {
match self.destructor.get() {
Some(_) => TraitDtor,
None => NoDtor,
}
}
}
impl<'a, 'gcx, 'tcx, 'container> AdtDefData<'tcx, 'container> {
/// Returns a simpler type such that `Self: Sized` if and only
/// if that type is Sized, or `TyErr` if this type is recursive.
///
/// HACK: instead of returning a list of types, this function can
/// return a tuple. In that case, the result is Sized only if
/// all elements of the tuple are Sized.
///
/// This is generally the `struct_tail` if this is a struct, or a
/// tuple of them if this is an enum.
///
/// Oddly enough, checking that the sized-constraint is Sized is
/// actually more expressive than checking all members:
/// the Sized trait is inductive, so an associated type that references
/// Self would prevent its containing ADT from being Sized.
///
/// Due to normalization being eager, this applies even if
/// the associated type is behind a pointer, e.g. issue #31299.
pub fn sized_constraint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
match self.sized_constraint.get(DepNode::SizedConstraint(self.did)) {
None => {
let global_tcx = tcx.global_tcx();
let this = global_tcx.lookup_adt_def_master(self.did);
this.calculate_sized_constraint_inner(global_tcx, &mut Vec::new());
self.sized_constraint(tcx)
}
Some(ty) => ty
}
}
}
impl<'a, 'tcx> AdtDefData<'tcx, 'tcx> {
/// Calculates the Sized-constraint.
///
/// As the Sized-constraint of enums can be a *set* of types,
/// the Sized-constraint may need to be a set also. Because introducing
/// a new type of IVar is currently a complex affair, the Sized-constraint
/// may be a tuple.
///
/// In fact, there are only a few options for the constraint:
/// - `bool`, if the type is always Sized
/// - an obviously-unsized type
/// - a type parameter or projection whose Sizedness can't be known
/// - a tuple of type parameters or projections, if there are multiple
/// such.
/// - a TyError, if a type contained itself. The representability
/// check should catch this case.
fn calculate_sized_constraint_inner(&'tcx self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
stack: &mut Vec<AdtDefMaster<'tcx>>)
{
let dep_node = || DepNode::SizedConstraint(self.did);
// Follow the memoization pattern: push the computation of
// DepNode::SizedConstraint as our current task.
let _task = tcx.dep_graph.in_task(dep_node());
if self.sized_constraint.untracked_get().is_some() {
// ---------------
// can skip the dep-graph read since we just pushed the task
return;
}
if stack.contains(&self) {
debug!("calculate_sized_constraint: {:?} is recursive", self);
// This should be reported as an error by `check_representable`.
//
// Consider the type as Sized in the meanwhile to avoid
// further errors.
self.sized_constraint.fulfill(dep_node(), tcx.types.err);
return;
}
stack.push(self);
let tys : Vec<_> =
self.variants.iter().flat_map(|v| {
v.fields.last()
}).flat_map(|f| {
self.sized_constraint_for_ty(tcx, stack, f.unsubst_ty())
}).collect();
let self_ = stack.pop().unwrap();
assert_eq!(self_, self);
let ty = match tys.len() {
_ if tys.references_error() => tcx.types.err,
0 => tcx.types.bool,
1 => tys[0],
_ => tcx.intern_tup(&tys[..])
};
match self.sized_constraint.get(dep_node()) {
Some(old_ty) => {
debug!("calculate_sized_constraint: {:?} recurred", self);
assert_eq!(old_ty, tcx.types.err)
}
None => {
debug!("calculate_sized_constraint: {:?} => {:?}", self, ty);
self.sized_constraint.fulfill(dep_node(), ty)
}
}
}
fn sized_constraint_for_ty(
&'tcx self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
stack: &mut Vec<AdtDefMaster<'tcx>>,
ty: Ty<'tcx>
) -> Vec<Ty<'tcx>> {
let result = match ty.sty {
TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
TyBox(..) | TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
TyArray(..) | TyClosure(..) | TyNever => {
vec![]
}
TyStr | TyTrait(..) | TySlice(_) | TyError => {
// these are never sized - return the target type
vec![ty]
}
TyTuple(ref tys) => {
match tys.last() {
None => vec![],
Some(ty) => self.sized_constraint_for_ty(tcx, stack, ty)
}
}
TyAdt(adt, substs) => {
// recursive case
let adt = tcx.lookup_adt_def_master(adt.did);
adt.calculate_sized_constraint_inner(tcx, stack);
let adt_ty =
adt.sized_constraint
.unwrap(DepNode::SizedConstraint(adt.did))
.subst(tcx, substs);
debug!("sized_constraint_for_ty({:?}) intermediate = {:?}",
ty, adt_ty);
if let ty::TyTuple(ref tys) = adt_ty.sty {
tys.iter().flat_map(|ty| {
self.sized_constraint_for_ty(tcx, stack, ty)
}).collect()
} else {
self.sized_constraint_for_ty(tcx, stack, adt_ty)
}
}
TyProjection(..) | TyAnon(..) => {
// must calculate explicitly.
// FIXME: consider special-casing always-Sized projections
vec![ty]
}
TyParam(..) => {
// perf hack: if there is a `T: Sized` bound, then
// we know that `T` is Sized and do not need to check
// it on the impl.
let sized_trait = match tcx.lang_items.sized_trait() {
Some(x) => x,
_ => return vec![ty]
};
let sized_predicate = Binder(TraitRef {
def_id: sized_trait,
substs: tcx.mk_substs_trait(ty, &[])
}).to_predicate();
let predicates = tcx.item_predicates(self.did).predicates;
if predicates.into_iter().any(|p| p == sized_predicate) {
vec![]
} else {
vec![ty]
}
}
TyInfer(..) => {
bug!("unexpected type `{:?}` in sized_constraint_for_ty",
ty)
}
};
debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result);
result
}
}
impl<'tcx, 'container> VariantDefData<'tcx, 'container> {
#[inline]
fn fields_iter(&self) -> slice::Iter<FieldDefData<'tcx, 'container>> {
self.fields.iter()
}
#[inline]
pub fn find_field_named(&self,
name: ast::Name)
-> Option<&FieldDefData<'tcx, 'container>> {
self.fields.iter().find(|f| f.name == name)
}
#[inline]
pub fn index_of_field_named(&self,
name: ast::Name)
-> Option<usize> {
self.fields.iter().position(|f| f.name == name)
}
#[inline]
pub fn field_named(&self, name: ast::Name) -> &FieldDefData<'tcx, 'container> {
self.find_field_named(name).unwrap()
}
}
impl<'a, 'gcx, 'tcx, 'container> FieldDefData<'tcx, 'container> {
pub fn new(did: DefId,
name: Name,
vis: Visibility) -> Self {
FieldDefData {
did: did,
name: name,
vis: vis,
ty: ivar::TyIVar::new()
}
}
pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> {
self.unsubst_ty().subst(tcx, subst)
}
pub fn unsubst_ty(&self) -> Ty<'tcx> {
self.ty.unwrap(DepNode::FieldTy(self.did))
}
pub fn fulfill_ty(&self, ty: Ty<'container>) {
self.ty.fulfill(DepNode::FieldTy(self.did), ty);
}
}
/// Records the substitutions used to translate the polytype for an
/// item into the monotype of an item reference.
#[derive(Clone, RustcEncodable, RustcDecodable)]
pub struct ItemSubsts<'tcx> {
pub substs: &'tcx Substs<'tcx>,
}
#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
pub enum ClosureKind {
// Warning: Ordering is significant here! The ordering is chosen
// because the trait Fn is a subtrait of FnMut and so in turn, and
// hence we order it so that Fn < FnMut < FnOnce.
Fn,
FnMut,
FnOnce,
}
impl<'a, 'tcx> ClosureKind {
pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId {
let result = match *self {
ClosureKind::Fn => tcx.lang_items.require(FnTraitLangItem),
ClosureKind::FnMut => {
tcx.lang_items.require(FnMutTraitLangItem)
}
ClosureKind::FnOnce => {
tcx.lang_items.require(FnOnceTraitLangItem)
}
};
match result {
Ok(trait_did) => trait_did,
Err(err) => tcx.sess.fatal(&err[..]),
}
}
/// True if this a type that impls this closure kind
/// must also implement `other`.
pub fn extends(self, other: ty::ClosureKind) -> bool {
match (self, other) {
(ClosureKind::Fn, ClosureKind::Fn) => true,
(ClosureKind::Fn, ClosureKind::FnMut) => true,
(ClosureKind::Fn, ClosureKind::FnOnce) => true,
(ClosureKind::FnMut, ClosureKind::FnMut) => true,
(ClosureKind::FnMut, ClosureKind::FnOnce) => true,
(ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
_ => false,
}
}
}
impl<'tcx> TyS<'tcx> {
/// Iterator that walks `self` and any types reachable from
/// `self`, in depth-first order. Note that just walks the types
/// that appear in `self`, it does not descend into the fields of
/// structs or variants. For example:
///
/// ```notrust
/// isize => { isize }
/// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
/// [isize] => { [isize], isize }
/// ```
pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
TypeWalker::new(self)
}
/// Iterator that walks the immediate children of `self`. Hence
/// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
/// (but not `i32`, like `walk`).
pub fn walk_shallow(&'tcx self) -> IntoIter<Ty<'tcx>> {
walk::walk_shallow(self)
}
/// Walks `ty` and any types appearing within `ty`, invoking the
/// callback `f` on each type. If the callback returns false, then the
/// children of the current type are ignored.
///
/// Note: prefer `ty.walk()` where possible.
pub fn maybe_walk<F>(&'tcx self, mut f: F)
where F : FnMut(Ty<'tcx>) -> bool
{
let mut walker = self.walk();
while let Some(ty) = walker.next() {
if !f(ty) {
walker.skip_current_subtree();
}
}
}
}
impl<'tcx> ItemSubsts<'tcx> {
pub fn is_noop(&self) -> bool {
self.substs.is_noop()
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum LvaluePreference {
PreferMutLvalue,
NoPreference
}
impl LvaluePreference {
pub fn from_mutbl(m: hir::Mutability) -> Self {
match m {
hir::MutMutable => PreferMutLvalue,
hir::MutImmutable => NoPreference,
}
}
}
/// Helper for looking things up in the various maps that are populated during
/// typeck::collect (e.g., `tcx.associated_items`, `tcx.types`, etc). All of
/// these share the pattern that if the id is local, it should have been loaded
/// into the map by the `typeck::collect` phase. If the def-id is external,
/// then we have to go consult the crate loading code (and cache the result for
/// the future).
fn lookup_locally_or_in_crate_store<M, F>(descr: &str,
def_id: DefId,
map: &M,
load_external: F)
-> M::Value where
M: MemoizationMap<Key=DefId>,
F: FnOnce() -> M::Value,
{
map.memoize(def_id, || {
if def_id.is_local() {
bug!("No def'n found for {:?} in tcx.{}", def_id, descr);
}
load_external()
})
}
impl BorrowKind {
pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
match m {
hir::MutMutable => MutBorrow,
hir::MutImmutable => ImmBorrow,
}
}
/// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
/// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
/// mutability that is stronger than necessary so that it at least *would permit* the borrow in
/// question.
pub fn to_mutbl_lossy(self) -> hir::Mutability {
match self {
MutBorrow => hir::MutMutable,
ImmBorrow => hir::MutImmutable,
// We have no type corresponding to a unique imm borrow, so
// use `&mut`. It gives all the capabilities of an `&uniq`
// and hence is a safe "over approximation".
UniqueImmBorrow => hir::MutMutable,
}
}
pub fn to_user_str(&self) -> &'static str {
match *self {
MutBorrow => "mutable",
ImmBorrow => "immutable",
UniqueImmBorrow => "uniquely immutable",
}
}
}
impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
pub fn tables(self) -> Ref<'a, Tables<'gcx>> {
self.tables.borrow()
}
pub fn expr_span(self, id: NodeId) -> Span {
match self.map.find(id) {
Some(ast_map::NodeExpr(e)) => {
e.span
}
Some(f) => {
bug!("Node id {} is not an expr: {:?}", id, f);
}
None => {
bug!("Node id {} is not present in the node map", id);
}
}
}
pub fn local_var_name_str(self, id: NodeId) -> InternedString {
match self.map.find(id) {
Some(ast_map::NodeLocal(pat)) => {
match pat.node {
hir::PatKind::Binding(_, ref path1, _) => path1.node.as_str(),
_ => {
bug!("Variable id {} maps to {:?}, not local", id, pat);
},
}
},
r => bug!("Variable id {} maps to {:?}, not local", id, r),
}
}
pub fn expr_is_lval(self, expr: &hir::Expr) -> bool {
match expr.node {
hir::ExprPath(..) => {
// This function can be used during type checking when not all paths are
// fully resolved. Partially resolved paths in expressions can only legally
// refer to associated items which are always rvalues.
match self.expect_resolution(expr.id).base_def {
Def::Local(..) | Def::Upvar(..) | Def::Static(..) | Def::Err => true,
_ => false,
}
}
hir::ExprType(ref e, _) => {
self.expr_is_lval(e)
}
hir::ExprUnary(hir::UnDeref, _) |
hir::ExprField(..) |
hir::ExprTupField(..) |
hir::ExprIndex(..) => {
true
}
hir::ExprCall(..) |
hir::ExprMethodCall(..) |
hir::ExprStruct(..) |
hir::ExprTup(..) |
hir::ExprIf(..) |
hir::ExprMatch(..) |
hir::ExprClosure(..) |
hir::ExprBlock(..) |
hir::ExprRepeat(..) |
hir::ExprArray(..) |
hir::ExprBreak(..) |
hir::ExprAgain(..) |
hir::ExprRet(..) |
hir::ExprWhile(..) |
hir::ExprLoop(..) |
hir::ExprAssign(..) |
hir::ExprInlineAsm(..) |
hir::ExprAssignOp(..) |
hir::ExprLit(_) |
hir::ExprUnary(..) |
hir::ExprBox(..) |
hir::ExprAddrOf(..) |
hir::ExprBinary(..) |
hir::ExprCast(..) => {
false
}
}
}
pub fn provided_trait_methods(self, id: DefId) -> Vec<AssociatedItem> {
self.associated_items(id)
.filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value())
.collect()
}
pub fn trait_impl_polarity(self, id: DefId) -> hir::ImplPolarity {
if let Some(id) = self.map.as_local_node_id(id) {
match self.map.expect_item(id).node {
hir::ItemImpl(_, polarity, ..) => polarity,
ref item => bug!("trait_impl_polarity: {:?} not an impl", item)
}
} else {
self.sess.cstore.impl_polarity(id)
}
}
pub fn custom_coerce_unsized_kind(self, did: DefId) -> adjustment::CustomCoerceUnsized {
self.custom_coerce_unsized_kinds.memoize(did, || {
let (kind, src) = if did.krate != LOCAL_CRATE {
(self.sess.cstore.custom_coerce_unsized_kind(did), "external")
} else {
(None, "local")
};
match kind {
Some(kind) => kind,
None => {
bug!("custom_coerce_unsized_kind: \
{} impl `{}` is missing its kind",
src, self.item_path_str(did));
}
}
})
}
pub fn associated_item(self, def_id: DefId) -> AssociatedItem {
self.associated_items.memoize(def_id, || {
if !def_id.is_local() {
return self.sess.cstore.associated_item(self.global_tcx(), def_id)
.expect("missing AssociatedItem in metadata");
}
// When the user asks for a given associated item, we
// always go ahead and convert all the associated items in
// the container. Note that we are also careful only to
// ever register a read on the *container* of the assoc
// item, not the assoc item itself. This prevents changes
// in the details of an item (for example, the type to
// which an associated type is bound) from contaminating
// those tasks that just need to scan the names of items
// and so forth.
let id = self.map.as_local_node_id(def_id).unwrap();
let parent_id = self.map.get_parent(id);
let parent_def_id = self.map.local_def_id(parent_id);
let parent_item = self.map.expect_item(parent_id);
match parent_item.node {
hir::ItemImpl(.., ref impl_trait_ref, _, ref impl_item_refs) => {
for impl_item_ref in impl_item_refs {
let assoc_item =
self.associated_item_from_impl_item_ref(parent_def_id,
impl_trait_ref.is_some(),
impl_item_ref);
self.associated_items.borrow_mut().insert(assoc_item.def_id, assoc_item);
}
}
hir::ItemTrait(.., ref trait_items) => {
for trait_item in trait_items {
let assoc_item =
self.associated_item_from_trait_item_ref(parent_def_id, trait_item);
self.associated_items.borrow_mut().insert(assoc_item.def_id, assoc_item);
}
}
ref r => {
panic!("unexpected container of associated items: {:?}", r)
}
}
// memoize wants us to return something, so return
// the one we generated for this def-id
*self.associated_items.borrow().get(&def_id).unwrap()
})
}
fn associated_item_from_trait_item_ref(self,
parent_def_id: DefId,
trait_item: &hir::TraitItem)
-> AssociatedItem {
let def_id = self.map.local_def_id(trait_item.id);
let (kind, has_self, has_value) = match trait_item.node {
hir::MethodTraitItem(ref sig, ref body) => {
(AssociatedKind::Method, sig.decl.get_self().is_some(),
body.is_some())
}
hir::ConstTraitItem(_, ref value) => {
(AssociatedKind::Const, false, value.is_some())
}
hir::TypeTraitItem(_, ref ty) => {
(AssociatedKind::Type, false, ty.is_some())
}
};
AssociatedItem {
name: trait_item.name,
kind: kind,
vis: Visibility::from_hir(&hir::Inherited, trait_item.id, self),
defaultness: hir::Defaultness::Default { has_value: has_value },
def_id: def_id,
container: TraitContainer(parent_def_id),
method_has_self_argument: has_self
}
}
fn associated_item_from_impl_item_ref(self,
parent_def_id: DefId,
from_trait_impl: bool,
impl_item_ref: &hir::ImplItemRef)
-> AssociatedItem {
let def_id = self.map.local_def_id(impl_item_ref.id.node_id);
let (kind, has_self) = match impl_item_ref.kind {
hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false),
hir::AssociatedItemKind::Method { has_self } => {
(ty::AssociatedKind::Method, has_self)
}
hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false),
};
// Trait impl items are always public.
let public = hir::Public;
let vis = if from_trait_impl { &public } else { &impl_item_ref.vis };
ty::AssociatedItem {
name: impl_item_ref.name,
kind: kind,
vis: ty::Visibility::from_hir(vis, impl_item_ref.id.node_id, self),
defaultness: impl_item_ref.defaultness,
def_id: def_id,
container: ImplContainer(parent_def_id),
method_has_self_argument: has_self
}
}
pub fn associated_item_def_ids(self, def_id: DefId) -> Rc<Vec<DefId>> {
self.associated_item_def_ids.memoize(def_id, || {
if !def_id.is_local() {
return Rc::new(self.sess.cstore.associated_item_def_ids(def_id));
}
let id = self.map.as_local_node_id(def_id).unwrap();
let item = self.map.expect_item(id);
let vec: Vec<_> = match item.node {
hir::ItemTrait(.., ref trait_items) => {
trait_items.iter()
.map(|trait_item| trait_item.id)
.map(|id| self.map.local_def_id(id))
.collect()
}
hir::ItemImpl(.., ref impl_item_refs) => {
impl_item_refs.iter()
.map(|impl_item_ref| impl_item_ref.id)
.map(|id| self.map.local_def_id(id.node_id))
.collect()
}
_ => span_bug!(item.span, "associated_item_def_ids: not impl or trait")
};
Rc::new(vec)
})
}
#[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait.
pub fn associated_items(self, def_id: DefId)
-> impl Iterator<Item = ty::AssociatedItem> + 'a {
let def_ids = self.associated_item_def_ids(def_id);
(0..def_ids.len()).map(move |i| self.associated_item(def_ids[i]))
}
/// Returns the trait-ref corresponding to a given impl, or None if it is
/// an inherent impl.
pub fn impl_trait_ref(self, id: DefId) -> Option<TraitRef<'gcx>> {
lookup_locally_or_in_crate_store(
"impl_trait_refs", id, &self.impl_trait_refs,
|| self.sess.cstore.impl_trait_ref(self.global_tcx(), id))
}
/// Returns a path resolution for node id if it exists, panics otherwise.
pub fn expect_resolution(self, id: NodeId) -> PathResolution {
*self.def_map.borrow().get(&id).expect("no def-map entry for node id")
}
/// Returns a fully resolved definition for node id if it exists, panics otherwise.
pub fn expect_def(self, id: NodeId) -> Def {
self.expect_resolution(id).full_def()
}
/// Returns a fully resolved definition for node id if it exists, or none if no
/// definition exists, panics on partial resolutions to catch errors.
pub fn expect_def_or_none(self, id: NodeId) -> Option<Def> {
self.def_map.borrow().get(&id).map(|resolution| resolution.full_def())
}
// Returns `ty::VariantDef` if `def` refers to a struct,
// or variant or their constructors, panics otherwise.
pub fn expect_variant_def(self, def: Def) -> VariantDef<'tcx> {
match def {
Def::Variant(did) | Def::VariantCtor(did, ..) => {
let enum_did = self.parent_def_id(did).unwrap();
self.lookup_adt_def(enum_did).variant_with_id(did)
}
Def::Struct(did) | Def::Union(did) => {
self.lookup_adt_def(did).struct_variant()
}
Def::StructCtor(ctor_did, ..) => {
let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent");
self.lookup_adt_def(did).struct_variant()
}
_ => bug!("expect_variant_def used with unexpected def {:?}", def)
}
}
pub fn def_key(self, id: DefId) -> ast_map::DefKey {
if id.is_local() {
self.map.def_key(id)
} else {
self.sess.cstore.def_key(id)
}
}
/// Convert a `DefId` into its fully expanded `DefPath` (every
/// `DefId` is really just an interned def-path).
///
/// Note that if `id` is not local to this crate -- or is
/// inlined into this crate -- the result will be a non-local
/// `DefPath`.
///
/// This function is only safe to use when you are sure that the
/// full def-path is accessible. Examples that are known to be
/// safe are local def-ids or items; see `opt_def_path` for more
/// details.
pub fn def_path(self, id: DefId) -> ast_map::DefPath {
self.opt_def_path(id).unwrap_or_else(|| {
bug!("could not load def-path for {:?}", id)
})
}
/// Convert a `DefId` into its fully expanded `DefPath` (every
/// `DefId` is really just an interned def-path).
///
/// When going across crates, we do not save the full info for
/// every cross-crate def-id, and hence we may not always be able
/// to create a def-path. Therefore, this returns
/// `Option<DefPath>` to cover that possibility. It will always
/// return `Some` for local def-ids, however, as well as for
/// items. The problems arise with "minor" def-ids like those
/// associated with a pattern, `impl Trait`, or other internal
/// detail to a fn.
///
/// Note that if `id` is not local to this crate -- or is
/// inlined into this crate -- the result will be a non-local
/// `DefPath`.
pub fn opt_def_path(self, id: DefId) -> Option<ast_map::DefPath> {
if id.is_local() {
Some(self.map.def_path(id))
} else {
self.sess.cstore.relative_def_path(id)
}
}
pub fn item_name(self, id: DefId) -> ast::Name {
if let Some(id) = self.map.as_local_node_id(id) {
self.map.name(id)
} else if id.index == CRATE_DEF_INDEX {
self.sess.cstore.original_crate_name(id.krate)
} else {
let def_key = self.sess.cstore.def_key(id);
// The name of a StructCtor is that of its struct parent.
if let ast_map::DefPathData::StructCtor = def_key.disambiguated_data.data {
self.item_name(DefId {
krate: id.krate,
index: def_key.parent.unwrap()
})
} else {
def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
bug!("item_name: no name for {:?}", self.def_path(id));
})
}
}
}
// If the given item is in an external crate, looks up its type and adds it to
// the type cache. Returns the type parameters and type.
pub fn item_type(self, did: DefId) -> Ty<'gcx> {
lookup_locally_or_in_crate_store(
"item_types", did, &self.item_types,
|| self.sess.cstore.item_type(self.global_tcx(), did))
}
/// Given the did of a trait, returns its canonical trait ref.
pub fn lookup_trait_def(self, did: DefId) -> &'gcx TraitDef<'gcx> {
lookup_locally_or_in_crate_store(
"trait_defs", did, &self.trait_defs,
|| self.alloc_trait_def(self.sess.cstore.trait_def(self.global_tcx(), did))
)
}
/// Given the did of an ADT, return a master reference to its
/// definition. Unless you are planning on fulfilling the ADT's fields,
/// use lookup_adt_def instead.
pub fn lookup_adt_def_master(self, did: DefId) -> AdtDefMaster<'gcx> {
lookup_locally_or_in_crate_store(
"adt_defs", did, &self.adt_defs,
|| self.sess.cstore.adt_def(self.global_tcx(), did)
)
}
/// Given the did of an ADT, return a reference to its definition.
pub fn lookup_adt_def(self, did: DefId) -> AdtDef<'gcx> {
// when reverse-variance goes away, a transmute::<AdtDefMaster,AdtDef>
// would be needed here.
self.lookup_adt_def_master(did)
}
/// Given the did of an item, returns its generics.
pub fn item_generics(self, did: DefId) -> &'gcx Generics<'gcx> {
lookup_locally_or_in_crate_store(
"generics", did, &self.generics,
|| self.alloc_generics(self.sess.cstore.item_generics(self.global_tcx(), did)))
}
/// Given the did of an item, returns its full set of predicates.
pub fn item_predicates(self, did: DefId) -> GenericPredicates<'gcx> {
lookup_locally_or_in_crate_store(
"predicates", did, &self.predicates,
|| self.sess.cstore.item_predicates(self.global_tcx(), did))
}
/// Given the did of a trait, returns its superpredicates.
pub fn item_super_predicates(self, did: DefId) -> GenericPredicates<'gcx> {
lookup_locally_or_in_crate_store(
"super_predicates", did, &self.super_predicates,
|| self.sess.cstore.item_super_predicates(self.global_tcx(), did))
}
/// Given the did of an item, returns its MIR, borrowed immutably.
pub fn item_mir(self, did: DefId) -> Ref<'gcx, Mir<'gcx>> {
lookup_locally_or_in_crate_store("mir_map", did, &self.mir_map, || {
let mir = self.sess.cstore.get_item_mir(self.global_tcx(), did);
let mir = self.alloc_mir(mir);
// Perma-borrow MIR from extern crates to prevent mutation.
mem::forget(mir.borrow());
mir
}).borrow()
}
/// If `type_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 `type_needs_drop` will definitely return `true` for `ty`.)
pub fn type_needs_drop_given_env(self,
ty: Ty<'gcx>,
param_env: &ty::ParameterEnvironment<'gcx>) -> bool {
// Issue #22536: We first query type_moves_by_default. It sees a
// normalized version of the type, and therefore will definitely
// know whether the type implements Copy (and thus needs no
// cleanup/drop/zeroing) ...
let tcx = self.global_tcx();
let implements_copy = !ty.moves_by_default(tcx, param_env, DUMMY_SP);
if implements_copy { return false; }
// ... (issue #22536 continued) but as an optimization, still use
// prior logic of asking if the `needs_drop` bit is set; we need
// not zero non-Copy types if they have no destructor.
// FIXME(#22815): Note that calling `ty::type_contents` is a
// conservative heuristic; it may report that `needs_drop` is set
// when actual type does not actually have a destructor associated
// with it. But since `ty` absolutely did not have the `Copy`
// bound attached (see above), it is sound to treat it as having a
// destructor (e.g. zero its memory on move).
let contents = ty.type_contents(tcx);
debug!("type_needs_drop ty={:?} contents={:?}", ty, contents);
contents.needs_drop(tcx)
}
/// Get the attributes of a definition.
pub fn get_attrs(self, did: DefId) -> Cow<'gcx, [ast::Attribute]> {
if let Some(id) = self.map.as_local_node_id(did) {
Cow::Borrowed(self.map.attrs(id))
} else {
Cow::Owned(self.sess.cstore.item_attrs(did))
}
}
/// Determine whether an item is annotated with an attribute
pub fn has_attr(self, did: DefId, attr: &str) -> bool {
self.get_attrs(did).iter().any(|item| item.check_name(attr))
}
/// Determine whether an item is annotated with `#[repr(packed)]`
pub fn lookup_packed(self, did: DefId) -> bool {
self.lookup_repr_hints(did).contains(&attr::ReprPacked)
}
/// Determine whether an item is annotated with `#[simd]`
pub fn lookup_simd(self, did: DefId) -> bool {
self.has_attr(did, "simd")
|| self.lookup_repr_hints(did).contains(&attr::ReprSimd)
}
pub fn item_variances(self, item_id: DefId) -> Rc<Vec<ty::Variance>> {
lookup_locally_or_in_crate_store(
"item_variance_map", item_id, &self.item_variance_map,
|| Rc::new(self.sess.cstore.item_variances(item_id)))
}
pub fn trait_has_default_impl(self, trait_def_id: DefId) -> bool {
self.populate_implementations_for_trait_if_necessary(trait_def_id);
let def = self.lookup_trait_def(trait_def_id);
def.flags.get().intersects(TraitFlags::HAS_DEFAULT_IMPL)
}
/// Records a trait-to-implementation mapping.
pub fn record_trait_has_default_impl(self, trait_def_id: DefId) {
let def = self.lookup_trait_def(trait_def_id);
def.flags.set(def.flags.get() | TraitFlags::HAS_DEFAULT_IMPL)
}
/// Populates the type context with all the inherent implementations for
/// the given type if necessary.
pub fn populate_inherent_implementations_for_type_if_necessary(self,
type_id: DefId) {
if type_id.is_local() {
return
}
// The type is not local, hence we are reading this out of
// metadata and don't need to track edges.
let _ignore = self.dep_graph.in_ignore();
if self.populated_external_types.borrow().contains(&type_id) {
return
}
debug!("populate_inherent_implementations_for_type_if_necessary: searching for {:?}",
type_id);
let inherent_impls = self.sess.cstore.inherent_implementations_for_type(type_id);
self.inherent_impls.borrow_mut().insert(type_id, inherent_impls);
self.populated_external_types.borrow_mut().insert(type_id);
}
/// Populates the type context with all the implementations for the given
/// trait if necessary.
pub fn populate_implementations_for_trait_if_necessary(self, trait_id: DefId) {
if trait_id.is_local() {
return
}
// The type is not local, hence we are reading this out of
// metadata and don't need to track edges.
let _ignore = self.dep_graph.in_ignore();
let def = self.lookup_trait_def(trait_id);
if def.flags.get().intersects(TraitFlags::IMPLS_VALID) {
return;
}
debug!("populate_implementations_for_trait_if_necessary: searching for {:?}", def);
if self.sess.cstore.is_defaulted_trait(trait_id) {
self.record_trait_has_default_impl(trait_id);
}
for impl_def_id in self.sess.cstore.implementations_of_trait(Some(trait_id)) {
let trait_ref = self.impl_trait_ref(impl_def_id).unwrap();
// Record the trait->implementation mapping.
let parent = self.sess.cstore.impl_parent(impl_def_id).unwrap_or(trait_id);
def.record_remote_impl(self, impl_def_id, trait_ref, parent);
}
def.flags.set(def.flags.get() | TraitFlags::IMPLS_VALID);
}
pub fn closure_kind(self, def_id: DefId) -> ty::ClosureKind {
// If this is a local def-id, it should be inserted into the
// tables by typeck; else, it will be retreived from
// the external crate metadata.
if let Some(&kind) = self.tables.borrow().closure_kinds.get(&def_id) {
return kind;
}
let kind = self.sess.cstore.closure_kind(def_id);
self.tables.borrow_mut().closure_kinds.insert(def_id, kind);
kind
}
pub fn closure_type(self,
def_id: DefId,
substs: ClosureSubsts<'tcx>)
-> ty::ClosureTy<'tcx>
{
// If this is a local def-id, it should be inserted into the
// tables by typeck; else, it will be retreived from
// the external crate metadata.
if let Some(ty) = self.tables.borrow().closure_tys.get(&def_id) {
return ty.subst(self, substs.substs);
}
let ty = self.sess.cstore.closure_ty(self.global_tcx(), def_id);
self.tables.borrow_mut().closure_tys.insert(def_id, ty.clone());
ty.subst(self, substs.substs)
}
/// Given the def_id of an impl, return the def_id of the trait it implements.
/// If it implements no trait, return `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 def ID describes a method belonging to an impl, return the
/// ID of the impl that the method belongs to. Otherwise, return `None`.
pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
if def_id.krate != LOCAL_CRATE {
return self.sess.cstore.associated_item(self.global_tcx(), def_id)
.and_then(|item| {
match item.container {
TraitContainer(_) => None,
ImplContainer(def_id) => Some(def_id),
}
});
}
match self.associated_items.borrow().get(&def_id).cloned() {
Some(trait_item) => {
match trait_item.container {
TraitContainer(_) => None,
ImplContainer(def_id) => Some(def_id),
}
}
None => None
}
}
/// If the given def ID describes an item belonging to a trait,
/// return the ID of the trait that the trait item belongs to.
/// Otherwise, return `None`.
pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
if def_id.krate != LOCAL_CRATE {
return self.sess.cstore.trait_of_item(def_id);
}
match self.associated_items.borrow().get(&def_id) {
Some(associated_item) => {
match associated_item.container {
TraitContainer(def_id) => Some(def_id),
ImplContainer(_) => None
}
}
None => None
}
}
/// Construct a parameter environment suitable for static contexts or other contexts where there
/// are no free type/lifetime parameters in scope.
pub fn empty_parameter_environment(self) -> ParameterEnvironment<'tcx> {
// for an empty parameter environment, there ARE no free
// regions, so it shouldn't matter what we use for the free id
let free_id_outlive = self.region_maps.node_extent(ast::DUMMY_NODE_ID);
ty::ParameterEnvironment {
free_substs: self.intern_substs(&[]),
caller_bounds: Vec::new(),
implicit_region_bound: self.mk_region(ty::ReEmpty),
free_id_outlive: free_id_outlive,
is_copy_cache: RefCell::new(FxHashMap()),
is_sized_cache: RefCell::new(FxHashMap()),
}
}
/// Constructs and returns a substitution that can be applied to move from
/// the "outer" view of a type or method to the "inner" view.
/// In general, this means converting from bound parameters to
/// free parameters. Since we currently represent bound/free type
/// parameters in the same way, this only has an effect on regions.
pub fn construct_free_substs(self, def_id: DefId,
free_id_outlive: CodeExtent)
-> &'gcx Substs<'gcx> {
let substs = Substs::for_item(self.global_tcx(), def_id, |def, _| {
// map bound 'a => free 'a
self.global_tcx().mk_region(ReFree(FreeRegion {
scope: free_id_outlive,
bound_region: def.to_bound_region()
}))
}, |def, _| {
// map T => T
self.global_tcx().mk_param_from_def(def)
});
debug!("construct_parameter_environment: {:?}", substs);
substs
}
/// See `ParameterEnvironment` struct def'n for details.
/// If you were using `free_id: NodeId`, you might try `self.region_maps.item_extent(free_id)`
/// for the `free_id_outlive` parameter. (But note that this is not always quite right.)
pub fn construct_parameter_environment(self,
span: Span,
def_id: DefId,
free_id_outlive: CodeExtent)
-> ParameterEnvironment<'gcx>
{
//
// Construct the free substs.
//
let free_substs = self.construct_free_substs(def_id, free_id_outlive);
//
// Compute the bounds on Self and the type parameters.
//
let tcx = self.global_tcx();
let generic_predicates = tcx.item_predicates(def_id);
let bounds = generic_predicates.instantiate(tcx, free_substs);
let bounds = tcx.liberate_late_bound_regions(free_id_outlive, &ty::Binder(bounds));
let predicates = bounds.predicates;
// Finally, we have to normalize the bounds in the environment, in
// case they contain any associated type projections. This process
// can yield errors if the put in illegal associated types, like
// `<i32 as Foo>::Bar` where `i32` does not implement `Foo`. We
// report these errors right here; this doesn't actually feel
// right to me, because constructing the environment feels like a
// kind of a "idempotent" action, but I'm not sure where would be
// a better place. In practice, we construct environments for
// every fn once during type checking, and we'll abort if there
// are any errors at that point, so after type checking you can be
// sure that this will succeed without errors anyway.
//
let unnormalized_env = ty::ParameterEnvironment {
free_substs: free_substs,
implicit_region_bound: tcx.mk_region(ty::ReScope(free_id_outlive)),
caller_bounds: predicates,
free_id_outlive: free_id_outlive,
is_copy_cache: RefCell::new(FxHashMap()),
is_sized_cache: RefCell::new(FxHashMap()),
};
let cause = traits::ObligationCause::misc(span, free_id_outlive.node_id(&self.region_maps));
traits::normalize_param_env_or_error(tcx, unnormalized_env, cause)
}
pub fn node_scope_region(self, id: NodeId) -> &'tcx Region {
self.mk_region(ty::ReScope(self.region_maps.node_extent(id)))
}
pub fn visit_all_item_likes_in_krate<V,F>(self,
dep_node_fn: F,
visitor: &mut V)
where F: FnMut(DefId) -> DepNode<DefId>, V: ItemLikeVisitor<'gcx>
{
dep_graph::visit_all_item_likes_in_krate(self.global_tcx(), dep_node_fn, visitor);
}
/// 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 impl_did.is_local() {
let node_id = self.map.as_local_node_id(impl_did).unwrap();
Ok(self.map.span(node_id))
} else {
Err(self.sess.cstore.crate_name(impl_did.krate))
}
}
}
impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
pub fn with_freevars<T, F>(self, fid: NodeId, f: F) -> T where
F: FnOnce(&[hir::Freevar]) -> T,
{
match self.freevars.borrow().get(&fid) {
None => f(&[]),
Some(d) => f(&d[..])
}
}
}