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util.rs
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util.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.
//! misc. type-system utilities too small to deserve their own file
use hir::def_id::{DefId, LOCAL_CRATE};
use hir::map::DefPathData;
use infer::InferCtxt;
use ich::{StableHashingContext, NodeIdHashingMode};
use traits::{self, Reveal};
use ty::{self, Ty, TyCtxt, TypeAndMut, TypeFlags, TypeFoldable};
use ty::ParameterEnvironment;
use ty::fold::TypeVisitor;
use ty::layout::{Layout, LayoutError};
use ty::subst::{Subst, Kind};
use ty::TypeVariants::*;
use util::common::ErrorReported;
use util::nodemap::{FxHashMap, FxHashSet};
use middle::lang_items;
use rustc_const_math::{ConstInt, ConstIsize, ConstUsize};
use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
HashStable};
use std::cell::RefCell;
use std::cmp;
use std::hash::Hash;
use std::intrinsics;
use syntax::ast::{self, Name};
use syntax::attr::{self, SignedInt, UnsignedInt};
use syntax_pos::{Span, DUMMY_SP};
use hir;
type Disr = ConstInt;
pub trait IntTypeExt {
fn to_ty<'a, 'gcx, 'tcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx>;
fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>)
-> Option<Disr>;
fn assert_ty_matches(&self, val: Disr);
fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr;
}
macro_rules! typed_literal {
($tcx:expr, $ty:expr, $lit:expr) => {
match $ty {
SignedInt(ast::IntTy::I8) => ConstInt::I8($lit),
SignedInt(ast::IntTy::I16) => ConstInt::I16($lit),
SignedInt(ast::IntTy::I32) => ConstInt::I32($lit),
SignedInt(ast::IntTy::I64) => ConstInt::I64($lit),
SignedInt(ast::IntTy::I128) => ConstInt::I128($lit),
SignedInt(ast::IntTy::Is) => match $tcx.sess.target.int_type {
ast::IntTy::I16 => ConstInt::Isize(ConstIsize::Is16($lit)),
ast::IntTy::I32 => ConstInt::Isize(ConstIsize::Is32($lit)),
ast::IntTy::I64 => ConstInt::Isize(ConstIsize::Is64($lit)),
_ => bug!(),
},
UnsignedInt(ast::UintTy::U8) => ConstInt::U8($lit),
UnsignedInt(ast::UintTy::U16) => ConstInt::U16($lit),
UnsignedInt(ast::UintTy::U32) => ConstInt::U32($lit),
UnsignedInt(ast::UintTy::U64) => ConstInt::U64($lit),
UnsignedInt(ast::UintTy::U128) => ConstInt::U128($lit),
UnsignedInt(ast::UintTy::Us) => match $tcx.sess.target.uint_type {
ast::UintTy::U16 => ConstInt::Usize(ConstUsize::Us16($lit)),
ast::UintTy::U32 => ConstInt::Usize(ConstUsize::Us32($lit)),
ast::UintTy::U64 => ConstInt::Usize(ConstUsize::Us64($lit)),
_ => bug!(),
},
}
}
}
impl IntTypeExt for attr::IntType {
fn to_ty<'a, 'gcx, 'tcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
match *self {
SignedInt(ast::IntTy::I8) => tcx.types.i8,
SignedInt(ast::IntTy::I16) => tcx.types.i16,
SignedInt(ast::IntTy::I32) => tcx.types.i32,
SignedInt(ast::IntTy::I64) => tcx.types.i64,
SignedInt(ast::IntTy::I128) => tcx.types.i128,
SignedInt(ast::IntTy::Is) => tcx.types.isize,
UnsignedInt(ast::UintTy::U8) => tcx.types.u8,
UnsignedInt(ast::UintTy::U16) => tcx.types.u16,
UnsignedInt(ast::UintTy::U32) => tcx.types.u32,
UnsignedInt(ast::UintTy::U64) => tcx.types.u64,
UnsignedInt(ast::UintTy::U128) => tcx.types.u128,
UnsignedInt(ast::UintTy::Us) => tcx.types.usize,
}
}
fn initial_discriminant<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> Disr {
typed_literal!(tcx, *self, 0)
}
fn assert_ty_matches(&self, val: Disr) {
match (*self, val) {
(SignedInt(ast::IntTy::I8), ConstInt::I8(_)) => {},
(SignedInt(ast::IntTy::I16), ConstInt::I16(_)) => {},
(SignedInt(ast::IntTy::I32), ConstInt::I32(_)) => {},
(SignedInt(ast::IntTy::I64), ConstInt::I64(_)) => {},
(SignedInt(ast::IntTy::I128), ConstInt::I128(_)) => {},
(SignedInt(ast::IntTy::Is), ConstInt::Isize(_)) => {},
(UnsignedInt(ast::UintTy::U8), ConstInt::U8(_)) => {},
(UnsignedInt(ast::UintTy::U16), ConstInt::U16(_)) => {},
(UnsignedInt(ast::UintTy::U32), ConstInt::U32(_)) => {},
(UnsignedInt(ast::UintTy::U64), ConstInt::U64(_)) => {},
(UnsignedInt(ast::UintTy::U128), ConstInt::U128(_)) => {},
(UnsignedInt(ast::UintTy::Us), ConstInt::Usize(_)) => {},
_ => bug!("disr type mismatch: {:?} vs {:?}", self, val),
}
}
fn disr_incr<'a, 'tcx>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, val: Option<Disr>)
-> Option<Disr> {
if let Some(val) = val {
self.assert_ty_matches(val);
(val + typed_literal!(tcx, *self, 1)).ok()
} else {
Some(self.initial_discriminant(tcx))
}
}
}
#[derive(Copy, Clone)]
pub enum CopyImplementationError<'tcx> {
InfrigingField(&'tcx ty::FieldDef),
NotAnAdt,
HasDestructor,
}
/// Describes whether a type is representable. For types that are not
/// representable, 'SelfRecursive' and 'ContainsRecursive' are used to
/// distinguish between types that are recursive with themselves and types that
/// contain a different recursive type. These cases can therefore be treated
/// differently when reporting errors.
///
/// The ordering of the cases is significant. They are sorted so that cmp::max
/// will keep the "more erroneous" of two values.
#[derive(Copy, Clone, PartialOrd, Ord, Eq, PartialEq, Debug)]
pub enum Representability {
Representable,
ContainsRecursive,
SelfRecursive,
}
impl<'tcx> ParameterEnvironment<'tcx> {
pub fn can_type_implement_copy<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
self_type: Ty<'tcx>, span: Span)
-> Result<(), CopyImplementationError> {
// FIXME: (@jroesch) float this code up
tcx.infer_ctxt(self.clone(), Reveal::UserFacing).enter(|infcx| {
let (adt, substs) = match self_type.sty {
ty::TyAdt(adt, substs) => (adt, substs),
_ => return Err(CopyImplementationError::NotAnAdt),
};
let field_implements_copy = |field: &ty::FieldDef| {
let cause = traits::ObligationCause::dummy();
match traits::fully_normalize(&infcx, cause, &field.ty(tcx, substs)) {
Ok(ty) => !infcx.type_moves_by_default(ty, span),
Err(..) => false,
}
};
for variant in &adt.variants {
for field in &variant.fields {
if !field_implements_copy(field) {
return Err(CopyImplementationError::InfrigingField(field));
}
}
}
if adt.has_dtor(tcx) {
return Err(CopyImplementationError::HasDestructor);
}
Ok(())
})
}
}
impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
/// Creates a hash of the type `Ty` which will be the same no matter what crate
/// context it's calculated within. This is used by the `type_id` intrinsic.
pub fn type_id_hash(self, ty: Ty<'tcx>) -> u64 {
let mut hasher = StableHasher::new();
let mut hcx = StableHashingContext::new(self);
hcx.while_hashing_spans(false, |hcx| {
hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
ty.hash_stable(hcx, &mut hasher);
});
});
hasher.finish()
}
}
impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
pub fn has_error_field(self, ty: Ty<'tcx>) -> bool {
match ty.sty {
ty::TyAdt(def, substs) => {
for field in def.all_fields() {
let field_ty = field.ty(self, substs);
if let TyError = field_ty.sty {
return true;
}
}
}
_ => (),
}
false
}
/// Returns the type of element at index `i` in tuple or tuple-like type `t`.
/// For an enum `t`, `variant` is None only if `t` is a univariant enum.
pub fn positional_element_ty(self,
ty: Ty<'tcx>,
i: usize,
variant: Option<DefId>) -> Option<Ty<'tcx>> {
match (&ty.sty, variant) {
(&TyAdt(adt, substs), Some(vid)) => {
adt.variant_with_id(vid).fields.get(i).map(|f| f.ty(self, substs))
}
(&TyAdt(adt, substs), None) => {
// Don't use `struct_variant`, this may be a univariant enum.
adt.variants[0].fields.get(i).map(|f| f.ty(self, substs))
}
(&TyTuple(ref v, _), None) => v.get(i).cloned(),
_ => None,
}
}
/// Returns the type of element at field `n` in struct or struct-like type `t`.
/// For an enum `t`, `variant` must be some def id.
pub fn named_element_ty(self,
ty: Ty<'tcx>,
n: Name,
variant: Option<DefId>) -> Option<Ty<'tcx>> {
match (&ty.sty, variant) {
(&TyAdt(adt, substs), Some(vid)) => {
adt.variant_with_id(vid).find_field_named(n).map(|f| f.ty(self, substs))
}
(&TyAdt(adt, substs), None) => {
adt.struct_variant().find_field_named(n).map(|f| f.ty(self, substs))
}
_ => return None
}
}
/// Returns the deeply last field of nested structures, or the same type,
/// if not a structure at all. Corresponds to the only possible unsized
/// field, and its type can be used to determine unsizing strategy.
pub fn struct_tail(self, mut ty: Ty<'tcx>) -> Ty<'tcx> {
while let TyAdt(def, substs) = ty.sty {
if !def.is_struct() {
break;
}
match def.struct_variant().fields.last() {
Some(f) => ty = f.ty(self, substs),
None => break,
}
}
ty
}
/// Same as applying struct_tail on `source` and `target`, but only
/// keeps going as long as the two types are instances of the same
/// structure definitions.
/// For `(Foo<Foo<T>>, Foo<Trait>)`, the result will be `(Foo<T>, Trait)`,
/// whereas struct_tail produces `T`, and `Trait`, respectively.
pub fn struct_lockstep_tails(self,
source: Ty<'tcx>,
target: Ty<'tcx>)
-> (Ty<'tcx>, Ty<'tcx>) {
let (mut a, mut b) = (source, target);
while let (&TyAdt(a_def, a_substs), &TyAdt(b_def, b_substs)) = (&a.sty, &b.sty) {
if a_def != b_def || !a_def.is_struct() {
break;
}
match a_def.struct_variant().fields.last() {
Some(f) => {
a = f.ty(self, a_substs);
b = f.ty(self, b_substs);
}
_ => break,
}
}
(a, b)
}
/// Given a set of predicates that apply to an object type, returns
/// the region bounds that the (erased) `Self` type must
/// outlive. Precisely *because* the `Self` type is erased, the
/// parameter `erased_self_ty` must be supplied to indicate what type
/// has been used to represent `Self` in the predicates
/// themselves. This should really be a unique type; `FreshTy(0)` is a
/// popular choice.
///
/// NB: in some cases, particularly around higher-ranked bounds,
/// this function returns a kind of conservative approximation.
/// That is, all regions returned by this function are definitely
/// required, but there may be other region bounds that are not
/// returned, as well as requirements like `for<'a> T: 'a`.
///
/// Requires that trait definitions have been processed so that we can
/// elaborate predicates and walk supertraits.
pub fn required_region_bounds(self,
erased_self_ty: Ty<'tcx>,
predicates: Vec<ty::Predicate<'tcx>>)
-> Vec<&'tcx ty::Region> {
debug!("required_region_bounds(erased_self_ty={:?}, predicates={:?})",
erased_self_ty,
predicates);
assert!(!erased_self_ty.has_escaping_regions());
traits::elaborate_predicates(self, predicates)
.filter_map(|predicate| {
match predicate {
ty::Predicate::Projection(..) |
ty::Predicate::Trait(..) |
ty::Predicate::Equate(..) |
ty::Predicate::Subtype(..) |
ty::Predicate::WellFormed(..) |
ty::Predicate::ObjectSafe(..) |
ty::Predicate::ClosureKind(..) |
ty::Predicate::RegionOutlives(..) => {
None
}
ty::Predicate::TypeOutlives(ty::Binder(ty::OutlivesPredicate(t, r))) => {
// Search for a bound of the form `erased_self_ty
// : 'a`, but be wary of something like `for<'a>
// erased_self_ty : 'a` (we interpret a
// higher-ranked bound like that as 'static,
// though at present the code in `fulfill.rs`
// considers such bounds to be unsatisfiable, so
// it's kind of a moot point since you could never
// construct such an object, but this seems
// correct even if that code changes).
if t == erased_self_ty && !r.has_escaping_regions() {
Some(r)
} else {
None
}
}
}
})
.collect()
}
/// Calculate the destructor of a given type.
pub fn calculate_dtor(
self,
adt_did: DefId,
validate: &mut FnMut(Self, DefId) -> Result<(), ErrorReported>
) -> Option<ty::Destructor> {
let drop_trait = if let Some(def_id) = self.lang_items.drop_trait() {
def_id
} else {
return None;
};
self.coherent_trait((LOCAL_CRATE, drop_trait));
let mut dtor_did = None;
let ty = self.type_of(adt_did);
self.trait_def(drop_trait).for_each_relevant_impl(self, ty, |impl_did| {
if let Some(item) = self.associated_items(impl_did).next() {
if let Ok(()) = validate(self, impl_did) {
dtor_did = Some(item.def_id);
}
}
});
let dtor_did = match dtor_did {
Some(dtor) => dtor,
None => return None,
};
Some(ty::Destructor { did: dtor_did })
}
/// Return the set of types that are required to be alive in
/// order to run the destructor of `def` (see RFCs 769 and
/// 1238).
///
/// Note that this returns only the constraints for the
/// destructor of `def` itself. For the destructors of the
/// contents, you need `adt_dtorck_constraint`.
pub fn destructor_constraints(self, def: &'tcx ty::AdtDef)
-> Vec<ty::subst::Kind<'tcx>>
{
let dtor = match def.destructor(self) {
None => {
debug!("destructor_constraints({:?}) - no dtor", def.did);
return vec![]
}
Some(dtor) => dtor.did
};
// RFC 1238: if the destructor method is tagged with the
// attribute `unsafe_destructor_blind_to_params`, then the
// compiler is being instructed to *assume* that the
// destructor will not access borrowed data,
// even if such data is otherwise reachable.
//
// Such access can be in plain sight (e.g. dereferencing
// `*foo.0` of `Foo<'a>(&'a u32)`) or indirectly hidden
// (e.g. calling `foo.0.clone()` of `Foo<T:Clone>`).
if self.has_attr(dtor, "unsafe_destructor_blind_to_params") {
debug!("destructor_constraint({:?}) - blind", def.did);
return vec![];
}
let impl_def_id = self.associated_item(dtor).container.id();
let impl_generics = self.generics_of(impl_def_id);
// We have a destructor - all the parameters that are not
// pure_wrt_drop (i.e, don't have a #[may_dangle] attribute)
// must be live.
// We need to return the list of parameters from the ADTs
// generics/substs that correspond to impure parameters on the
// impl's generics. This is a bit ugly, but conceptually simple:
//
// Suppose our ADT looks like the following
//
// struct S<X, Y, Z>(X, Y, Z);
//
// and the impl is
//
// impl<#[may_dangle] P0, P1, P2> Drop for S<P1, P2, P0>
//
// We want to return the parameters (X, Y). For that, we match
// up the item-substs <X, Y, Z> with the substs on the impl ADT,
// <P1, P2, P0>, and then look up which of the impl substs refer to
// parameters marked as pure.
let impl_substs = match self.type_of(impl_def_id).sty {
ty::TyAdt(def_, substs) if def_ == def => substs,
_ => bug!()
};
let item_substs = match self.type_of(def.did).sty {
ty::TyAdt(def_, substs) if def_ == def => substs,
_ => bug!()
};
let result = item_substs.iter().zip(impl_substs.iter())
.filter(|&(_, &k)| {
if let Some(&ty::Region::ReEarlyBound(ref ebr)) = k.as_region() {
!impl_generics.region_param(ebr).pure_wrt_drop
} else if let Some(&ty::TyS {
sty: ty::TypeVariants::TyParam(ref pt), ..
}) = k.as_type() {
!impl_generics.type_param(pt).pure_wrt_drop
} else {
// not a type or region param - this should be reported
// as an error.
false
}
}).map(|(&item_param, _)| item_param).collect();
debug!("destructor_constraint({:?}) = {:?}", def.did, result);
result
}
/// Return a set of constraints that needs to be satisfied in
/// order for `ty` to be valid for destruction.
pub fn dtorck_constraint_for_ty(self,
span: Span,
for_ty: Ty<'tcx>,
depth: usize,
ty: Ty<'tcx>)
-> Result<ty::DtorckConstraint<'tcx>, ErrorReported>
{
debug!("dtorck_constraint_for_ty({:?}, {:?}, {:?}, {:?})",
span, for_ty, depth, ty);
if depth >= self.sess.recursion_limit.get() {
let mut err = struct_span_err!(
self.sess, span, E0320,
"overflow while adding drop-check rules for {}", for_ty);
err.note(&format!("overflowed on {}", ty));
err.emit();
return Err(ErrorReported);
}
let result = match ty.sty {
ty::TyBool | ty::TyChar | ty::TyInt(_) | ty::TyUint(_) |
ty::TyFloat(_) | ty::TyStr | ty::TyNever |
ty::TyRawPtr(..) | ty::TyRef(..) | ty::TyFnDef(..) | ty::TyFnPtr(_) => {
// these types never have a destructor
Ok(ty::DtorckConstraint::empty())
}
ty::TyArray(ety, _) | ty::TySlice(ety) => {
// single-element containers, behave like their element
self.dtorck_constraint_for_ty(span, for_ty, depth+1, ety)
}
ty::TyTuple(tys, _) => {
tys.iter().map(|ty| {
self.dtorck_constraint_for_ty(span, for_ty, depth+1, ty)
}).collect()
}
ty::TyClosure(def_id, substs) => {
substs.upvar_tys(def_id, self).map(|ty| {
self.dtorck_constraint_for_ty(span, for_ty, depth+1, ty)
}).collect()
}
ty::TyAdt(def, substs) => {
let ty::DtorckConstraint {
dtorck_types, outlives
} = ty::queries::adt_dtorck_constraint::get(self, span, def.did);
Ok(ty::DtorckConstraint {
// FIXME: we can try to recursively `dtorck_constraint_on_ty`
// there, but that needs some way to handle cycles.
dtorck_types: dtorck_types.subst(self, substs),
outlives: outlives.subst(self, substs)
})
}
// Objects must be alive in order for their destructor
// to be called.
ty::TyDynamic(..) => Ok(ty::DtorckConstraint {
outlives: vec![Kind::from(ty)],
dtorck_types: vec![],
}),
// Types that can't be resolved. Pass them forward.
ty::TyProjection(..) | ty::TyAnon(..) | ty::TyParam(..) => {
Ok(ty::DtorckConstraint {
outlives: vec![],
dtorck_types: vec![ty],
})
}
ty::TyInfer(..) | ty::TyError => {
self.sess.delay_span_bug(span, "unresolved type in dtorck");
Err(ErrorReported)
}
};
debug!("dtorck_constraint_for_ty({:?}) = {:?}", ty, result);
result
}
pub fn closure_base_def_id(self, def_id: DefId) -> DefId {
let mut def_id = def_id;
while self.def_key(def_id).disambiguated_data.data == DefPathData::ClosureExpr {
def_id = self.parent_def_id(def_id).unwrap_or_else(|| {
bug!("closure {:?} has no parent", def_id);
});
}
def_id
}
/// Given the def-id of some item that has no type parameters, make
/// a suitable "empty substs" for it.
pub fn empty_substs_for_def_id(self, item_def_id: DefId) -> &'tcx ty::Substs<'tcx> {
ty::Substs::for_item(self, item_def_id,
|_, _| self.types.re_erased,
|_, _| {
bug!("empty_substs_for_def_id: {:?} has type parameters", item_def_id)
})
}
}
pub struct TypeIdHasher<'a, 'gcx: 'a+'tcx, 'tcx: 'a, W> {
tcx: TyCtxt<'a, 'gcx, 'tcx>,
state: StableHasher<W>,
}
impl<'a, 'gcx, 'tcx, W> TypeIdHasher<'a, 'gcx, 'tcx, W>
where W: StableHasherResult
{
pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Self {
TypeIdHasher { tcx: tcx, state: StableHasher::new() }
}
pub fn finish(self) -> W {
self.state.finish()
}
pub fn hash<T: Hash>(&mut self, x: T) {
x.hash(&mut self.state);
}
fn hash_discriminant_u8<T>(&mut self, x: &T) {
let v = unsafe {
intrinsics::discriminant_value(x)
};
let b = v as u8;
assert_eq!(v, b as u64);
self.hash(b)
}
fn def_id(&mut self, did: DefId) {
// Hash the DefPath corresponding to the DefId, which is independent
// of compiler internal state. We already have a stable hash value of
// all DefPaths available via tcx.def_path_hash(), so we just feed that
// into the hasher.
let hash = self.tcx.def_path_hash(did);
self.hash(hash);
}
}
impl<'a, 'gcx, 'tcx, W> TypeVisitor<'tcx> for TypeIdHasher<'a, 'gcx, 'tcx, W>
where W: StableHasherResult
{
fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
// Distinguish between the Ty variants uniformly.
self.hash_discriminant_u8(&ty.sty);
match ty.sty {
TyInt(i) => self.hash(i),
TyUint(u) => self.hash(u),
TyFloat(f) => self.hash(f),
TyArray(_, n) => self.hash(n),
TyRawPtr(m) |
TyRef(_, m) => self.hash(m.mutbl),
TyClosure(def_id, _) |
TyAnon(def_id, _) |
TyFnDef(def_id, ..) => self.def_id(def_id),
TyAdt(d, _) => self.def_id(d.did),
TyFnPtr(f) => {
self.hash(f.unsafety());
self.hash(f.abi());
self.hash(f.variadic());
self.hash(f.inputs().skip_binder().len());
}
TyDynamic(ref data, ..) => {
if let Some(p) = data.principal() {
self.def_id(p.def_id());
}
for d in data.auto_traits() {
self.def_id(d);
}
}
TyTuple(tys, defaulted) => {
self.hash(tys.len());
self.hash(defaulted);
}
TyParam(p) => {
self.hash(p.idx);
self.hash(p.name.as_str());
}
TyProjection(ref data) => {
self.def_id(data.trait_ref.def_id);
self.hash(data.item_name.as_str());
}
TyNever |
TyBool |
TyChar |
TyStr |
TySlice(_) => {}
TyError |
TyInfer(_) => bug!("TypeIdHasher: unexpected type {}", ty)
}
ty.super_visit_with(self)
}
fn visit_region(&mut self, r: &'tcx ty::Region) -> bool {
self.hash_discriminant_u8(r);
match *r {
ty::ReErased |
ty::ReStatic |
ty::ReEmpty => {
// No variant fields to hash for these ...
}
ty::ReLateBound(db, ty::BrAnon(i)) => {
self.hash(db.depth);
self.hash(i);
}
ty::ReEarlyBound(ty::EarlyBoundRegion { index, name }) => {
self.hash(index);
self.hash(name.as_str());
}
ty::ReLateBound(..) |
ty::ReFree(..) |
ty::ReScope(..) |
ty::ReVar(..) |
ty::ReSkolemized(..) => {
bug!("TypeIdHasher: unexpected region {:?}", r)
}
}
false
}
fn visit_binder<T: TypeFoldable<'tcx>>(&mut self, x: &ty::Binder<T>) -> bool {
// Anonymize late-bound regions so that, for example:
// `for<'a, b> fn(&'a &'b T)` and `for<'a, b> fn(&'b &'a T)`
// result in the same TypeId (the two types are equivalent).
self.tcx.anonymize_late_bound_regions(x).super_visit_with(self)
}
}
impl<'a, 'tcx> ty::TyS<'tcx> {
fn impls_bound(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
def_id: DefId,
cache: &RefCell<FxHashMap<Ty<'tcx>, bool>>,
span: Span) -> bool
{
if self.has_param_types() || self.has_self_ty() {
if let Some(result) = cache.borrow().get(self) {
return *result;
}
}
let result =
tcx.infer_ctxt(param_env.clone(), Reveal::UserFacing)
.enter(|infcx| {
traits::type_known_to_meet_bound(&infcx, self, def_id, span)
});
if self.has_param_types() || self.has_self_ty() {
cache.borrow_mut().insert(self, result);
}
return result;
}
// FIXME (@jroesch): I made this public to use it, not sure if should be private
pub fn moves_by_default(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
span: Span) -> bool {
if self.flags.get().intersects(TypeFlags::MOVENESS_CACHED) {
return self.flags.get().intersects(TypeFlags::MOVES_BY_DEFAULT);
}
assert!(!self.needs_infer());
// Fast-path for primitive types
let result = match self.sty {
TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) | TyNever |
TyRawPtr(..) | TyFnDef(..) | TyFnPtr(_) | TyRef(_, TypeAndMut {
mutbl: hir::MutImmutable, ..
}) => Some(false),
TyStr | TyRef(_, TypeAndMut {
mutbl: hir::MutMutable, ..
}) => Some(true),
TyArray(..) | TySlice(..) | TyDynamic(..) | TyTuple(..) |
TyClosure(..) | TyAdt(..) | TyAnon(..) |
TyProjection(..) | TyParam(..) | TyInfer(..) | TyError => None
}.unwrap_or_else(|| {
!self.impls_bound(tcx, param_env,
tcx.require_lang_item(lang_items::CopyTraitLangItem),
¶m_env.is_copy_cache, span) });
if !self.has_param_types() && !self.has_self_ty() {
self.flags.set(self.flags.get() | if result {
TypeFlags::MOVENESS_CACHED | TypeFlags::MOVES_BY_DEFAULT
} else {
TypeFlags::MOVENESS_CACHED
});
}
result
}
#[inline]
pub fn is_sized(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
span: Span) -> bool
{
if self.flags.get().intersects(TypeFlags::SIZEDNESS_CACHED) {
return self.flags.get().intersects(TypeFlags::IS_SIZED);
}
self.is_sized_uncached(tcx, param_env, span)
}
fn is_sized_uncached(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
span: Span) -> bool {
assert!(!self.needs_infer());
// Fast-path for primitive types
let result = match self.sty {
TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
TyArray(..) | TyTuple(..) | TyClosure(..) | TyNever => Some(true),
TyStr | TyDynamic(..) | TySlice(_) => Some(false),
TyAdt(..) | TyProjection(..) | TyParam(..) |
TyInfer(..) | TyAnon(..) | TyError => None
}.unwrap_or_else(|| {
self.impls_bound(tcx, param_env, tcx.require_lang_item(lang_items::SizedTraitLangItem),
¶m_env.is_sized_cache, span) });
if !self.has_param_types() && !self.has_self_ty() {
self.flags.set(self.flags.get() | if result {
TypeFlags::SIZEDNESS_CACHED | TypeFlags::IS_SIZED
} else {
TypeFlags::SIZEDNESS_CACHED
});
}
result
}
/// Returns `true` if and only if there are no `UnsafeCell`s
/// nested within the type (ignoring `PhantomData` or pointers).
#[inline]
pub fn is_freeze(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
span: Span) -> bool
{
if self.flags.get().intersects(TypeFlags::FREEZENESS_CACHED) {
return self.flags.get().intersects(TypeFlags::IS_FREEZE);
}
self.is_freeze_uncached(tcx, param_env, span)
}
fn is_freeze_uncached(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ParameterEnvironment<'tcx>,
span: Span) -> bool {
assert!(!self.needs_infer());
// Fast-path for primitive types
let result = match self.sty {
TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) |
TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) |
TyStr | TyNever => Some(true),
TyArray(..) | TySlice(_) |
TyTuple(..) | TyClosure(..) | TyAdt(..) |
TyDynamic(..) | TyProjection(..) | TyParam(..) |
TyInfer(..) | TyAnon(..) | TyError => None
}.unwrap_or_else(|| {
self.impls_bound(tcx, param_env, tcx.require_lang_item(lang_items::FreezeTraitLangItem),
¶m_env.is_freeze_cache, span) });
if !self.has_param_types() && !self.has_self_ty() {
self.flags.set(self.flags.get() | if result {
TypeFlags::FREEZENESS_CACHED | TypeFlags::IS_FREEZE
} else {
TypeFlags::FREEZENESS_CACHED
});
}
result
}
/// If `ty.needs_drop(...)` returns `true`, then `ty` is definitely
/// non-copy and *might* have a destructor attached; if it returns
/// `false`, then `ty` definitely has no destructor (i.e. no drop glue).
///
/// (Note that this implies that if `ty` has a destructor attached,
/// then `needs_drop` will definitely return `true` for `ty`.)
#[inline]
pub fn needs_drop(&'tcx self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ty::ParameterEnvironment<'tcx>) -> bool {
if self.flags.get().intersects(TypeFlags::NEEDS_DROP_CACHED) {
return self.flags.get().intersects(TypeFlags::NEEDS_DROP);
}
self.needs_drop_uncached(tcx, param_env, &mut FxHashSet())
}
fn needs_drop_inner(&'tcx self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ty::ParameterEnvironment<'tcx>,
stack: &mut FxHashSet<Ty<'tcx>>)
-> bool {
if self.flags.get().intersects(TypeFlags::NEEDS_DROP_CACHED) {
return self.flags.get().intersects(TypeFlags::NEEDS_DROP);
}
// This should be reported as an error by `check_representable`.
//
// Consider the type as not needing drop in the meanwhile to avoid
// further errors.
if let Some(_) = stack.replace(self) {
return false;
}
let needs_drop = self.needs_drop_uncached(tcx, param_env, stack);
// "Pop" the cycle detection "stack".
stack.remove(self);
needs_drop
}
fn needs_drop_uncached(&'tcx self,
tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: &ty::ParameterEnvironment<'tcx>,
stack: &mut FxHashSet<Ty<'tcx>>)
-> bool {
assert!(!self.needs_infer());
let result = match self.sty {
// Fast-path for primitive types
ty::TyInfer(ty::FreshIntTy(_)) | ty::TyInfer(ty::FreshFloatTy(_)) |
ty::TyBool | ty::TyInt(_) | ty::TyUint(_) | ty::TyFloat(_) | ty::TyNever |
ty::TyFnDef(..) | ty::TyFnPtr(_) | ty::TyChar |
ty::TyRawPtr(_) | ty::TyRef(..) | ty::TyStr => false,
// 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) ...
_ if !self.moves_by_default(tcx, param_env, DUMMY_SP) => false,
// ... (issue #22536 continued) but as an optimization, still use
// prior logic of asking for the structural "may drop".
// FIXME(#22815): Note that this is a conservative heuristic;
// it may report that the type "may drop" when actual type does
// not actually have a destructor associated with it. But since
// the type absolutely did not have the `Copy` bound attached
// (see above), it is sound to treat it as having a destructor.
// User destructors are the only way to have concrete drop types.
ty::TyAdt(def, _) if def.has_dtor(tcx) => true,
// Can refer to a type which may drop.
// FIXME(eddyb) check this against a ParameterEnvironment.
ty::TyDynamic(..) | ty::TyProjection(..) | ty::TyParam(_) |
ty::TyAnon(..) | ty::TyInfer(_) | ty::TyError => true,
// Structural recursion.
ty::TyArray(ty, _) | ty::TySlice(ty) => {
ty.needs_drop_inner(tcx, param_env, stack)
}
ty::TyClosure(def_id, ref substs) => {
substs.upvar_tys(def_id, tcx)
.any(|ty| ty.needs_drop_inner(tcx, param_env, stack))
}
ty::TyTuple(ref tys, _) => {
tys.iter().any(|ty| ty.needs_drop_inner(tcx, param_env, stack))
}
// unions don't have destructors regardless of the child types
ty::TyAdt(def, _) if def.is_union() => false,
ty::TyAdt(def, substs) => {
def.variants.iter().any(|v| {
v.fields.iter().any(|f| {
f.ty(tcx, substs).needs_drop_inner(tcx, param_env, stack)
})
})
}
};
if !self.has_param_types() && !self.has_self_ty() {
self.flags.set(self.flags.get() | if result {
TypeFlags::NEEDS_DROP_CACHED | TypeFlags::NEEDS_DROP
} else {
TypeFlags::NEEDS_DROP_CACHED
});
}
result
}
#[inline]
pub fn layout<'lcx>(&'tcx self, infcx: &InferCtxt<'a, 'tcx, 'lcx>)
-> Result<&'tcx Layout, LayoutError<'tcx>> {
let tcx = infcx.tcx.global_tcx();
let can_cache = !self.has_param_types() && !self.has_self_ty();
if can_cache {
if let Some(&cached) = tcx.layout_cache.borrow().get(&self) {
return Ok(cached);
}
}
let rec_limit = tcx.sess.recursion_limit.get();
let depth = tcx.layout_depth.get();
if depth > rec_limit {
tcx.sess.fatal(
&format!("overflow representing the type `{}`", self));
}
tcx.layout_depth.set(depth+1);
let layout = Layout::compute_uncached(self, infcx);
tcx.layout_depth.set(depth);
let layout = layout?;
if can_cache {
tcx.layout_cache.borrow_mut().insert(self, layout);
}
Ok(layout)