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fuchsia / third_party / rust / 03534ac8b70de1134ce7e91b172cd629048a6c8b / . / compiler / rustc_middle / src / ty / sty.rs
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//! This module contains `TyKind` and its major components.
#![allow(rustc::usage_of_ty_tykind)]
use crate::infer::canonical::Canonical;
use crate::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
use crate::ty::visit::ValidateBoundVars;
use crate::ty::InferTy::*;
use crate::ty::{
self, AdtDef, Discr, Term, Ty, TyCtxt, TypeFlags, TypeSuperVisitable, TypeVisitable,
TypeVisitableExt, TypeVisitor,
};
use crate::ty::{List, ParamEnv};
use hir::def::DefKind;
use polonius_engine::Atom;
use rustc_data_structures::captures::Captures;
use rustc_data_structures::intern::Interned;
use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
use rustc_hir as hir;
use rustc_hir::def_id::DefId;
use rustc_hir::LangItem;
use rustc_index::Idx;
use rustc_macros::HashStable;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::Span;
use rustc_target::abi::{FieldIdx, VariantIdx, FIRST_VARIANT};
use rustc_target::spec::abi::{self, Abi};
use std::borrow::Cow;
use std::cmp::Ordering;
use std::fmt;
use std::marker::PhantomData;
use std::ops::{ControlFlow, Deref, Range};
use ty::util::IntTypeExt;
use rustc_type_ir::sty::TyKind::*;
use rustc_type_ir::RegionKind as IrRegionKind;
use rustc_type_ir::TyKind as IrTyKind;
// Re-export the `TyKind` from `rustc_type_ir` here for convenience
#[rustc_diagnostic_item = "TyKind"]
pub type TyKind<'tcx> = IrTyKind<TyCtxt<'tcx>>;
pub type RegionKind<'tcx> = IrRegionKind<TyCtxt<'tcx>>;
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct TypeAndMut<'tcx> {
pub ty: Ty<'tcx>,
pub mutbl: hir::Mutability,
}
#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
#[derive(HashStable)]
/// A "free" region `fr` can be interpreted as "some region
/// at least as big as the scope `fr.scope`".
pub struct FreeRegion {
pub scope: DefId,
pub bound_region: BoundRegionKind,
}
#[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
#[derive(HashStable)]
pub enum BoundRegionKind {
/// An anonymous region parameter for a given fn (&T)
BrAnon(Option<Span>),
/// Named region parameters for functions (a in &'a T)
///
/// The `DefId` is needed to distinguish free regions in
/// the event of shadowing.
BrNamed(DefId, Symbol),
/// Anonymous region for the implicit env pointer parameter
/// to a closure
BrEnv,
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
#[derive(HashStable)]
pub struct BoundRegion {
pub var: BoundVar,
pub kind: BoundRegionKind,
}
impl BoundRegionKind {
pub fn is_named(&self) -> bool {
match *self {
BoundRegionKind::BrNamed(_, name) => {
name != kw::UnderscoreLifetime && name != kw::Empty
}
_ => false,
}
}
pub fn get_name(&self) -> Option<Symbol> {
if self.is_named() {
match *self {
BoundRegionKind::BrNamed(_, name) => return Some(name),
_ => unreachable!(),
}
}
None
}
pub fn get_id(&self) -> Option<DefId> {
match *self {
BoundRegionKind::BrNamed(id, _) => return Some(id),
_ => None,
}
}
}
pub trait Article {
fn article(&self) -> &'static str;
}
impl<'tcx> Article for TyKind<'tcx> {
/// Get the article ("a" or "an") to use with this type.
fn article(&self) -> &'static str {
match self {
Int(_) | Float(_) | Array(_, _) => "an",
Adt(def, _) if def.is_enum() => "an",
// This should never happen, but ICEing and causing the user's code
// to not compile felt too harsh.
Error(_) => "a",
_ => "a",
}
}
}
/// A closure can be modeled as a struct that looks like:
/// ```ignore (illustrative)
/// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
/// ```
/// where:
///
/// - 'l0...'li and T0...Tj are the generic parameters
/// in scope on the function that defined the closure,
/// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
/// is rather hackily encoded via a scalar type. See
/// `Ty::to_opt_closure_kind` for details.
/// - CS represents the *closure signature*, representing as a `fn()`
/// type. For example, `fn(u32, u32) -> u32` would mean that the closure
/// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
/// specified above.
/// - U is a type parameter representing the types of its upvars, tupled up
/// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
/// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
///
/// So, for example, given this function:
/// ```ignore (illustrative)
/// fn foo<'a, T>(data: &'a mut T) {
/// do(|| data.count += 1)
/// }
/// ```
/// the type of the closure would be something like:
/// ```ignore (illustrative)
/// struct Closure<'a, T, U>(...U);
/// ```
/// Note that the type of the upvar is not specified in the struct.
/// You may wonder how the impl would then be able to use the upvar,
/// if it doesn't know it's type? The answer is that the impl is
/// (conceptually) not fully generic over Closure but rather tied to
/// instances with the expected upvar types:
/// ```ignore (illustrative)
/// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
/// ...
/// }
/// ```
/// You can see that the *impl* fully specified the type of the upvar
/// and thus knows full well that `data` has type `&'b mut &'a mut T`.
/// (Here, I am assuming that `data` is mut-borrowed.)
///
/// Now, the last question you may ask is: Why include the upvar types
/// in an extra type parameter? The reason for this design is that the
/// upvar types can reference lifetimes that are internal to the
/// creating function. In my example above, for example, the lifetime
/// `'b` represents the scope of the closure itself; this is some
/// subset of `foo`, probably just the scope of the call to the to
/// `do()`. If we just had the lifetime/type parameters from the
/// enclosing function, we couldn't name this lifetime `'b`. Note that
/// there can also be lifetimes in the types of the upvars themselves,
/// if one of them happens to be a reference to something that the
/// creating fn owns.
///
/// OK, you say, so why not create a more minimal set of parameters
/// that just includes the extra lifetime parameters? The answer is
/// primarily that it would be hard --- we don't know at the time when
/// we create the closure type what the full types of the upvars are,
/// nor do we know which are borrowed and which are not. In this
/// design, we can just supply a fresh type parameter and figure that
/// out later.
///
/// All right, you say, but why include the type parameters from the
/// original function then? The answer is that codegen may need them
/// when monomorphizing, and they may not appear in the upvars. A
/// closure could capture no variables but still make use of some
/// in-scope type parameter with a bound (e.g., if our example above
/// had an extra `U: Default`, and the closure called `U::default()`).
///
/// There is another reason. This design (implicitly) prohibits
/// closures from capturing themselves (except via a trait
/// object). This simplifies closure inference considerably, since it
/// means that when we infer the kind of a closure or its upvars, we
/// don't have to handle cycles where the decisions we make for
/// closure C wind up influencing the decisions we ought to make for
/// closure C (which would then require fixed point iteration to
/// handle). Plus it fixes an ICE. :P
///
/// ## Generators
///
/// Generators are handled similarly in `GeneratorSubsts`. The set of
/// type parameters is similar, but `CK` and `CS` are replaced by the
/// following type parameters:
///
/// * `GS`: The generator's "resume type", which is the type of the
/// argument passed to `resume`, and the type of `yield` expressions
/// inside the generator.
/// * `GY`: The "yield type", which is the type of values passed to
/// `yield` inside the generator.
/// * `GR`: The "return type", which is the type of value returned upon
/// completion of the generator.
/// * `GW`: The "generator witness".
#[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)]
pub struct ClosureSubsts<'tcx> {
/// Lifetime and type parameters from the enclosing function,
/// concatenated with a tuple containing the types of the upvars.
///
/// These are separated out because codegen wants to pass them around
/// when monomorphizing.
pub substs: SubstsRef<'tcx>,
}
/// Struct returned by `split()`.
pub struct ClosureSubstsParts<'tcx, T> {
pub parent_substs: &'tcx [GenericArg<'tcx>],
pub closure_kind_ty: T,
pub closure_sig_as_fn_ptr_ty: T,
pub tupled_upvars_ty: T,
}
impl<'tcx> ClosureSubsts<'tcx> {
/// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
/// for the closure parent, alongside additional closure-specific components.
pub fn new(
tcx: TyCtxt<'tcx>,
parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
) -> ClosureSubsts<'tcx> {
ClosureSubsts {
substs: tcx.mk_substs_from_iter(
parts.parent_substs.iter().copied().chain(
[parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
.iter()
.map(|&ty| ty.into()),
),
),
}
}
/// Divides the closure substs into their respective components.
/// The ordering assumed here must match that used by `ClosureSubsts::new` above.
fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
match self.substs[..] {
[
ref parent_substs @ ..,
closure_kind_ty,
closure_sig_as_fn_ptr_ty,
tupled_upvars_ty,
] => ClosureSubstsParts {
parent_substs,
closure_kind_ty,
closure_sig_as_fn_ptr_ty,
tupled_upvars_ty,
},
_ => bug!("closure substs missing synthetics"),
}
}
/// Returns `true` only if enough of the synthetic types are known to
/// allow using all of the methods on `ClosureSubsts` without panicking.
///
/// Used primarily by `ty::print::pretty` to be able to handle closure
/// types that haven't had their synthetic types substituted in.
pub fn is_valid(self) -> bool {
self.substs.len() >= 3
&& matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
}
/// Returns the substitutions of the closure's parent.
pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
self.split().parent_substs
}
/// Returns an iterator over the list of types of captured paths by the closure.
/// In case there was a type error in figuring out the types of the captured path, an
/// empty iterator is returned.
#[inline]
pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
match self.tupled_upvars_ty().kind() {
TyKind::Error(_) => None,
TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
}
.into_iter()
.flatten()
}
/// Returns the tuple type representing the upvars for this closure.
#[inline]
pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
self.split().tupled_upvars_ty.expect_ty()
}
/// Returns the closure kind for this closure; may return a type
/// variable during inference. To get the closure kind during
/// inference, use `infcx.closure_kind(substs)`.
pub fn kind_ty(self) -> Ty<'tcx> {
self.split().closure_kind_ty.expect_ty()
}
/// Returns the `fn` pointer type representing the closure signature for this
/// closure.
// FIXME(eddyb) this should be unnecessary, as the shallowly resolved
// type is known at the time of the creation of `ClosureSubsts`,
// see `rustc_hir_analysis::check::closure`.
pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
self.split().closure_sig_as_fn_ptr_ty.expect_ty()
}
/// Returns the closure kind for this closure; only usable outside
/// of an inference context, because in that context we know that
/// there are no type variables.
///
/// If you have an inference context, use `infcx.closure_kind()`.
pub fn kind(self) -> ty::ClosureKind {
self.kind_ty().to_opt_closure_kind().unwrap()
}
/// Extracts the signature from the closure.
pub fn sig(self) -> ty::PolyFnSig<'tcx> {
let ty = self.sig_as_fn_ptr_ty();
match ty.kind() {
ty::FnPtr(sig) => *sig,
_ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
}
}
pub fn print_as_impl_trait(self) -> ty::print::PrintClosureAsImpl<'tcx> {
ty::print::PrintClosureAsImpl { closure: self }
}
}
/// Similar to `ClosureSubsts`; see the above documentation for more.
#[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable, Lift)]
pub struct GeneratorSubsts<'tcx> {
pub substs: SubstsRef<'tcx>,
}
pub struct GeneratorSubstsParts<'tcx, T> {
pub parent_substs: &'tcx [GenericArg<'tcx>],
pub resume_ty: T,
pub yield_ty: T,
pub return_ty: T,
pub witness: T,
pub tupled_upvars_ty: T,
}
impl<'tcx> GeneratorSubsts<'tcx> {
/// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
/// for the generator parent, alongside additional generator-specific components.
pub fn new(
tcx: TyCtxt<'tcx>,
parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
) -> GeneratorSubsts<'tcx> {
GeneratorSubsts {
substs: tcx.mk_substs_from_iter(
parts.parent_substs.iter().copied().chain(
[
parts.resume_ty,
parts.yield_ty,
parts.return_ty,
parts.witness,
parts.tupled_upvars_ty,
]
.iter()
.map(|&ty| ty.into()),
),
),
}
}
/// Divides the generator substs into their respective components.
/// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
match self.substs[..] {
[ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
GeneratorSubstsParts {
parent_substs,
resume_ty,
yield_ty,
return_ty,
witness,
tupled_upvars_ty,
}
}
_ => bug!("generator substs missing synthetics"),
}
}
/// Returns `true` only if enough of the synthetic types are known to
/// allow using all of the methods on `GeneratorSubsts` without panicking.
///
/// Used primarily by `ty::print::pretty` to be able to handle generator
/// types that haven't had their synthetic types substituted in.
pub fn is_valid(self) -> bool {
self.substs.len() >= 5
&& matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
}
/// Returns the substitutions of the generator's parent.
pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
self.split().parent_substs
}
/// This describes the types that can be contained in a generator.
/// It will be a type variable initially and unified in the last stages of typeck of a body.
/// It contains a tuple of all the types that could end up on a generator frame.
/// The state transformation MIR pass may only produce layouts which mention types
/// in this tuple. Upvars are not counted here.
pub fn witness(self) -> Ty<'tcx> {
self.split().witness.expect_ty()
}
/// Returns an iterator over the list of types of captured paths by the generator.
/// In case there was a type error in figuring out the types of the captured path, an
/// empty iterator is returned.
#[inline]
pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
match self.tupled_upvars_ty().kind() {
TyKind::Error(_) => None,
TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
}
.into_iter()
.flatten()
}
/// Returns the tuple type representing the upvars for this generator.
#[inline]
pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
self.split().tupled_upvars_ty.expect_ty()
}
/// Returns the type representing the resume type of the generator.
pub fn resume_ty(self) -> Ty<'tcx> {
self.split().resume_ty.expect_ty()
}
/// Returns the type representing the yield type of the generator.
pub fn yield_ty(self) -> Ty<'tcx> {
self.split().yield_ty.expect_ty()
}
/// Returns the type representing the return type of the generator.
pub fn return_ty(self) -> Ty<'tcx> {
self.split().return_ty.expect_ty()
}
/// Returns the "generator signature", which consists of its yield
/// and return types.
///
/// N.B., some bits of the code prefers to see this wrapped in a
/// binder, but it never contains bound regions. Probably this
/// function should be removed.
pub fn poly_sig(self) -> PolyGenSig<'tcx> {
ty::Binder::dummy(self.sig())
}
/// Returns the "generator signature", which consists of its resume, yield
/// and return types.
pub fn sig(self) -> GenSig<'tcx> {
ty::GenSig {
resume_ty: self.resume_ty(),
yield_ty: self.yield_ty(),
return_ty: self.return_ty(),
}
}
}
impl<'tcx> GeneratorSubsts<'tcx> {
/// Generator has not been resumed yet.
pub const UNRESUMED: usize = 0;
/// Generator has returned or is completed.
pub const RETURNED: usize = 1;
/// Generator has been poisoned.
pub const POISONED: usize = 2;
const UNRESUMED_NAME: &'static str = "Unresumed";
const RETURNED_NAME: &'static str = "Returned";
const POISONED_NAME: &'static str = "Panicked";
/// The valid variant indices of this generator.
#[inline]
pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
// FIXME requires optimized MIR
FIRST_VARIANT..tcx.generator_layout(def_id).unwrap().variant_fields.next_index()
}
/// The discriminant for the given variant. Panics if the `variant_index` is
/// out of range.
#[inline]
pub fn discriminant_for_variant(
&self,
def_id: DefId,
tcx: TyCtxt<'tcx>,
variant_index: VariantIdx,
) -> Discr<'tcx> {
// Generators don't support explicit discriminant values, so they are
// the same as the variant index.
assert!(self.variant_range(def_id, tcx).contains(&variant_index));
Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
}
/// The set of all discriminants for the generator, enumerated with their
/// variant indices.
#[inline]
pub fn discriminants(
self,
def_id: DefId,
tcx: TyCtxt<'tcx>,
) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
self.variant_range(def_id, tcx).map(move |index| {
(index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
})
}
/// Calls `f` with a reference to the name of the enumerator for the given
/// variant `v`.
pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
match v.as_usize() {
Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
Self::RETURNED => Cow::from(Self::RETURNED_NAME),
Self::POISONED => Cow::from(Self::POISONED_NAME),
_ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
}
}
/// The type of the state discriminant used in the generator type.
#[inline]
pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
tcx.types.u32
}
/// This returns the types of the MIR locals which had to be stored across suspension points.
/// It is calculated in rustc_mir_transform::generator::StateTransform.
/// All the types here must be in the tuple in GeneratorInterior.
///
/// The locals are grouped by their variant number. Note that some locals may
/// be repeated in multiple variants.
#[inline]
pub fn state_tys(
self,
def_id: DefId,
tcx: TyCtxt<'tcx>,
) -> impl Iterator<Item: Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
let layout = tcx.generator_layout(def_id).unwrap();
layout.variant_fields.iter().map(move |variant| {
variant.iter().map(move |field| {
ty::EarlyBinder::new(layout.field_tys[*field].ty).subst(tcx, self.substs)
})
})
}
/// This is the types of the fields of a generator which are not stored in a
/// variant.
#[inline]
pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
self.upvar_tys()
}
}
#[derive(Debug, Copy, Clone, HashStable)]
pub enum UpvarSubsts<'tcx> {
Closure(SubstsRef<'tcx>),
Generator(SubstsRef<'tcx>),
}
impl<'tcx> UpvarSubsts<'tcx> {
/// Returns an iterator over the list of types of captured paths by the closure/generator.
/// In case there was a type error in figuring out the types of the captured path, an
/// empty iterator is returned.
#[inline]
pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
let tupled_tys = match self {
UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
};
match tupled_tys.kind() {
TyKind::Error(_) => None,
TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
}
.into_iter()
.flatten()
}
#[inline]
pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
match self {
UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
}
}
}
/// An inline const is modeled like
/// ```ignore (illustrative)
/// const InlineConst<'l0...'li, T0...Tj, R>: R;
/// ```
/// where:
///
/// - 'l0...'li and T0...Tj are the generic parameters
/// inherited from the item that defined the inline const,
/// - R represents the type of the constant.
///
/// When the inline const is instantiated, `R` is substituted as the actual inferred
/// type of the constant. The reason that `R` is represented as an extra type parameter
/// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
/// inline const can reference lifetimes that are internal to the creating function.
#[derive(Copy, Clone, Debug)]
pub struct InlineConstSubsts<'tcx> {
/// Generic parameters from the enclosing item,
/// concatenated with the inferred type of the constant.
pub substs: SubstsRef<'tcx>,
}
/// Struct returned by `split()`.
pub struct InlineConstSubstsParts<'tcx, T> {
pub parent_substs: &'tcx [GenericArg<'tcx>],
pub ty: T,
}
impl<'tcx> InlineConstSubsts<'tcx> {
/// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
pub fn new(
tcx: TyCtxt<'tcx>,
parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
) -> InlineConstSubsts<'tcx> {
InlineConstSubsts {
substs: tcx.mk_substs_from_iter(
parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
),
}
}
/// Divides the inline const substs into their respective components.
/// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
match self.substs[..] {
[ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
_ => bug!("inline const substs missing synthetics"),
}
}
/// Returns the substitutions of the inline const's parent.
pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
self.split().parent_substs
}
/// Returns the type of this inline const.
pub fn ty(self) -> Ty<'tcx> {
self.split().ty.expect_ty()
}
}
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub enum ExistentialPredicate<'tcx> {
/// E.g., `Iterator`.
Trait(ExistentialTraitRef<'tcx>),
/// E.g., `Iterator::Item = T`.
Projection(ExistentialProjection<'tcx>),
/// E.g., `Send`.
AutoTrait(DefId),
}
impl<'tcx> ExistentialPredicate<'tcx> {
/// Compares via an ordering that will not change if modules are reordered or other changes are
/// made to the tree. In particular, this ordering is preserved across incremental compilations.
pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
use self::ExistentialPredicate::*;
match (*self, *other) {
(Trait(_), Trait(_)) => Ordering::Equal,
(Projection(ref a), Projection(ref b)) => {
tcx.def_path_hash(a.def_id).cmp(&tcx.def_path_hash(b.def_id))
}
(AutoTrait(ref a), AutoTrait(ref b)) => {
tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
}
(Trait(_), _) => Ordering::Less,
(Projection(_), Trait(_)) => Ordering::Greater,
(Projection(_), _) => Ordering::Less,
(AutoTrait(_), _) => Ordering::Greater,
}
}
}
pub type PolyExistentialPredicate<'tcx> = Binder<'tcx, ExistentialPredicate<'tcx>>;
impl<'tcx> PolyExistentialPredicate<'tcx> {
/// Given an existential predicate like `?Self: PartialEq<u32>` (e.g., derived from `dyn PartialEq<u32>`),
/// and a concrete type `self_ty`, returns a full predicate where the existentially quantified variable `?Self`
/// has been replaced with `self_ty` (e.g., `self_ty: PartialEq<u32>`, in our example).
pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
use crate::ty::ToPredicate;
match self.skip_binder() {
ExistentialPredicate::Trait(tr) => {
self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
}
ExistentialPredicate::Projection(p) => {
self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
}
ExistentialPredicate::AutoTrait(did) => {
let generics = tcx.generics_of(did);
let trait_ref = if generics.params.len() == 1 {
ty::TraitRef::new(tcx, did, [self_ty])
} else {
// If this is an ill-formed auto trait, then synthesize
// new error substs for the missing generics.
let err_substs =
ty::InternalSubsts::extend_with_error(tcx, did, &[self_ty.into()]);
ty::TraitRef::new(tcx, did, err_substs)
};
self.rebind(trait_ref).without_const().to_predicate(tcx)
}
}
}
}
impl<'tcx> List<ty::PolyExistentialPredicate<'tcx>> {
/// Returns the "principal `DefId`" of this set of existential predicates.
///
/// A Rust trait object type consists (in addition to a lifetime bound)
/// of a set of trait bounds, which are separated into any number
/// of auto-trait bounds, and at most one non-auto-trait bound. The
/// non-auto-trait bound is called the "principal" of the trait
/// object.
///
/// Only the principal can have methods or type parameters (because
/// auto traits can have neither of them). This is important, because
/// it means the auto traits can be treated as an unordered set (methods
/// would force an order for the vtable, while relating traits with
/// type parameters without knowing the order to relate them in is
/// a rather non-trivial task).
///
/// For example, in the trait object `dyn fmt::Debug + Sync`, the
/// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
/// are the set `{Sync}`.
///
/// It is also possible to have a "trivial" trait object that
/// consists only of auto traits, with no principal - for example,
/// `dyn Send + Sync`. In that case, the set of auto-trait bounds
/// is `{Send, Sync}`, while there is no principal. These trait objects
/// have a "trivial" vtable consisting of just the size, alignment,
/// and destructor.
pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
self[0]
.map_bound(|this| match this {
ExistentialPredicate::Trait(tr) => Some(tr),
_ => None,
})
.transpose()
}
pub fn principal_def_id(&self) -> Option<DefId> {
self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
}
#[inline]
pub fn projection_bounds<'a>(
&'a self,
) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
self.iter().filter_map(|predicate| {
predicate
.map_bound(|pred| match pred {
ExistentialPredicate::Projection(projection) => Some(projection),
_ => None,
})
.transpose()
})
}
#[inline]
pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'a {
self.iter().filter_map(|predicate| match predicate.skip_binder() {
ExistentialPredicate::AutoTrait(did) => Some(did),
_ => None,
})
}
}
/// A complete reference to a trait. These take numerous guises in syntax,
/// but perhaps the most recognizable form is in a where-clause:
/// ```ignore (illustrative)
/// T: Foo<U>
/// ```
/// This would be represented by a trait-reference where the `DefId` is the
/// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
/// and `U` as parameter 1.
///
/// Trait references also appear in object types like `Foo<U>`, but in
/// that case the `Self` parameter is absent from the substitutions.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct TraitRef<'tcx> {
pub def_id: DefId,
pub substs: SubstsRef<'tcx>,
/// This field exists to prevent the creation of `TraitRef` without
/// calling [`TraitRef::new`].
pub(super) _use_trait_ref_new_instead: (),
}
impl<'tcx> TraitRef<'tcx> {
pub fn new(
tcx: TyCtxt<'tcx>,
trait_def_id: DefId,
substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
) -> Self {
let substs = tcx.check_and_mk_substs(trait_def_id, substs);
Self { def_id: trait_def_id, substs, _use_trait_ref_new_instead: () }
}
pub fn from_lang_item(
tcx: TyCtxt<'tcx>,
trait_lang_item: LangItem,
span: Span,
substs: impl IntoIterator<Item: Into<ty::GenericArg<'tcx>>>,
) -> Self {
let trait_def_id = tcx.require_lang_item(trait_lang_item, Some(span));
Self::new(tcx, trait_def_id, substs)
}
pub fn from_method(
tcx: TyCtxt<'tcx>,
trait_id: DefId,
substs: SubstsRef<'tcx>,
) -> ty::TraitRef<'tcx> {
let defs = tcx.generics_of(trait_id);
ty::TraitRef::new(tcx, trait_id, tcx.mk_substs(&substs[..defs.params.len()]))
}
/// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
/// are the parameters defined on trait.
pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> {
ty::TraitRef::new(tcx, def_id, InternalSubsts::identity_for_item(tcx, def_id))
}
pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
ty::TraitRef::new(
tcx,
self.def_id,
[self_ty.into()].into_iter().chain(self.substs.iter().skip(1)),
)
}
/// Converts this trait ref to a trait predicate with a given `constness` and a positive polarity.
#[inline]
pub fn with_constness(self, constness: ty::BoundConstness) -> ty::TraitPredicate<'tcx> {
ty::TraitPredicate { trait_ref: self, constness, polarity: ty::ImplPolarity::Positive }
}
/// Converts this trait ref to a trait predicate without `const` and a positive polarity.
#[inline]
pub fn without_const(self) -> ty::TraitPredicate<'tcx> {
self.with_constness(ty::BoundConstness::NotConst)
}
#[inline]
pub fn self_ty(&self) -> Ty<'tcx> {
self.substs.type_at(0)
}
}
pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
impl<'tcx> PolyTraitRef<'tcx> {
pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
self.map_bound_ref(|tr| tr.self_ty())
}
pub fn def_id(&self) -> DefId {
self.skip_binder().def_id
}
}
impl<'tcx> IntoDiagnosticArg for TraitRef<'tcx> {
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
self.to_string().into_diagnostic_arg()
}
}
/// An existential reference to a trait, where `Self` is erased.
/// For example, the trait object `Trait<'a, 'b, X, Y>` is:
/// ```ignore (illustrative)
/// exists T. T: Trait<'a, 'b, X, Y>
/// ```
/// The substitutions don't include the erased `Self`, only trait
/// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct ExistentialTraitRef<'tcx> {
pub def_id: DefId,
pub substs: SubstsRef<'tcx>,
}
impl<'tcx> ExistentialTraitRef<'tcx> {
pub fn erase_self_ty(
tcx: TyCtxt<'tcx>,
trait_ref: ty::TraitRef<'tcx>,
) -> ty::ExistentialTraitRef<'tcx> {
// Assert there is a Self.
trait_ref.substs.type_at(0);
ty::ExistentialTraitRef {
def_id: trait_ref.def_id,
substs: tcx.mk_substs(&trait_ref.substs[1..]),
}
}
/// Object types don't have a self type specified. Therefore, when
/// we convert the principal trait-ref into a normal trait-ref,
/// you must give *some* self type. A common choice is `mk_err()`
/// or some placeholder type.
pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
// otherwise the escaping vars would be captured by the binder
// debug_assert!(!self_ty.has_escaping_bound_vars());
ty::TraitRef::new(tcx, self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter()))
}
}
impl<'tcx> IntoDiagnosticArg for ExistentialTraitRef<'tcx> {
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
self.to_string().into_diagnostic_arg()
}
}
pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
impl<'tcx> PolyExistentialTraitRef<'tcx> {
pub fn def_id(&self) -> DefId {
self.skip_binder().def_id
}
/// Object types don't have a self type specified. Therefore, when
/// we convert the principal trait-ref into a normal trait-ref,
/// you must give *some* self type. A common choice is `mk_err()`
/// or some placeholder type.
pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
}
}
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable)]
pub enum BoundVariableKind {
Ty(BoundTyKind),
Region(BoundRegionKind),
Const,
}
impl BoundVariableKind {
pub fn expect_region(self) -> BoundRegionKind {
match self {
BoundVariableKind::Region(lt) => lt,
_ => bug!("expected a region, but found another kind"),
}
}
pub fn expect_ty(self) -> BoundTyKind {
match self {
BoundVariableKind::Ty(ty) => ty,
_ => bug!("expected a type, but found another kind"),
}
}
pub fn expect_const(self) {
match self {
BoundVariableKind::Const => (),
_ => bug!("expected a const, but found another kind"),
}
}
}
/// Binder is a binder for higher-ranked lifetimes or types. It is part of the
/// compiler's representation for things like `for<'a> Fn(&'a isize)`
/// (which would be represented by the type `PolyTraitRef ==
/// Binder<'tcx, TraitRef>`). Note that when we instantiate,
/// erase, or otherwise "discharge" these bound vars, we change the
/// type from `Binder<'tcx, T>` to just `T` (see
/// e.g., `liberate_late_bound_regions`).
///
/// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[derive(HashStable, Lift)]
pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
impl<'tcx, T> Binder<'tcx, T>
where
T: TypeVisitable<TyCtxt<'tcx>>,
{
/// Wraps `value` in a binder, asserting that `value` does not
/// contain any bound vars that would be bound by the
/// binder. This is commonly used to 'inject' a value T into a
/// different binding level.
#[track_caller]
pub fn dummy(value: T) -> Binder<'tcx, T> {
assert!(
!value.has_escaping_bound_vars(),
"`{value:?}` has escaping bound vars, so it cannot be wrapped in a dummy binder."
);
Binder(value, ty::List::empty())
}
pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
if cfg!(debug_assertions) {
let mut validator = ValidateBoundVars::new(vars);
value.visit_with(&mut validator);
}
Binder(value, vars)
}
}
impl<'tcx, T> Binder<'tcx, T> {
/// Skips the binder and returns the "bound" value. This is a
/// risky thing to do because it's easy to get confused about
/// De Bruijn indices and the like. It is usually better to
/// discharge the binder using `no_bound_vars` or
/// `replace_late_bound_regions` or something like
/// that. `skip_binder` is only valid when you are either
/// extracting data that has nothing to do with bound vars, you
/// are doing some sort of test that does not involve bound
/// regions, or you are being very careful about your depth
/// accounting.
///
/// Some examples where `skip_binder` is reasonable:
///
/// - extracting the `DefId` from a PolyTraitRef;
/// - comparing the self type of a PolyTraitRef to see if it is equal to
/// a type parameter `X`, since the type `X` does not reference any regions
pub fn skip_binder(self) -> T {
self.0
}
pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
self.1
}
pub fn as_ref(&self) -> Binder<'tcx, &T> {
Binder(&self.0, self.1)
}
pub fn as_deref(&self) -> Binder<'tcx, &T::Target>
where
T: Deref,
{
Binder(&self.0, self.1)
}
pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
where
F: FnOnce(&T) -> U,
{
let value = f(&self.0);
Binder(value, self.1)
}
pub fn map_bound_ref<F, U: TypeVisitable<TyCtxt<'tcx>>>(&self, f: F) -> Binder<'tcx, U>
where
F: FnOnce(&T) -> U,
{
self.as_ref().map_bound(f)
}
pub fn map_bound<F, U: TypeVisitable<TyCtxt<'tcx>>>(self, f: F) -> Binder<'tcx, U>
where
F: FnOnce(T) -> U,
{
let value = f(self.0);
if cfg!(debug_assertions) {
let mut validator = ValidateBoundVars::new(self.1);
value.visit_with(&mut validator);
}
Binder(value, self.1)
}
pub fn try_map_bound<F, U: TypeVisitable<TyCtxt<'tcx>>, E>(
self,
f: F,
) -> Result<Binder<'tcx, U>, E>
where
F: FnOnce(T) -> Result<U, E>,
{
let value = f(self.0)?;
if cfg!(debug_assertions) {
let mut validator = ValidateBoundVars::new(self.1);
value.visit_with(&mut validator);
}
Ok(Binder(value, self.1))
}
/// Wraps a `value` in a binder, using the same bound variables as the
/// current `Binder`. This should not be used if the new value *changes*
/// the bound variables. Note: the (old or new) value itself does not
/// necessarily need to *name* all the bound variables.
///
/// This currently doesn't do anything different than `bind`, because we
/// don't actually track bound vars. However, semantically, it is different
/// because bound vars aren't allowed to change here, whereas they are
/// in `bind`. This may be (debug) asserted in the future.
pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
where
U: TypeVisitable<TyCtxt<'tcx>>,
{
if cfg!(debug_assertions) {
let mut validator = ValidateBoundVars::new(self.bound_vars());
value.visit_with(&mut validator);
}
Binder(value, self.1)
}
/// Unwraps and returns the value within, but only if it contains
/// no bound vars at all. (In other words, if this binder --
/// and indeed any enclosing binder -- doesn't bind anything at
/// all.) Otherwise, returns `None`.
///
/// (One could imagine having a method that just unwraps a single
/// binder, but permits late-bound vars bound by enclosing
/// binders, but that would require adjusting the debruijn
/// indices, and given the shallow binding structure we often use,
/// would not be that useful.)
pub fn no_bound_vars(self) -> Option<T>
where
T: TypeVisitable<TyCtxt<'tcx>>,
{
if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
}
/// Splits the contents into two things that share the same binder
/// level as the original, returning two distinct binders.
///
/// `f` should consider bound regions at depth 1 to be free, and
/// anything it produces with bound regions at depth 1 will be
/// bound in the resulting return values.
pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
where
F: FnOnce(T) -> (U, V),
{
let (u, v) = f(self.0);
(Binder(u, self.1), Binder(v, self.1))
}
}
impl<'tcx, T> Binder<'tcx, Option<T>> {
pub fn transpose(self) -> Option<Binder<'tcx, T>> {
let bound_vars = self.1;
self.0.map(|v| Binder(v, bound_vars))
}
}
impl<'tcx, T: IntoIterator> Binder<'tcx, T> {
pub fn iter(self) -> impl Iterator<Item = ty::Binder<'tcx, T::Item>> {
let bound_vars = self.1;
self.0.into_iter().map(|v| Binder(v, bound_vars))
}
}
impl<'tcx, T> IntoDiagnosticArg for Binder<'tcx, T>
where
T: IntoDiagnosticArg,
{
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
self.0.into_diagnostic_arg()
}
}
/// Represents the projection of an associated type.
///
/// * For a projection, this would be `<Ty as Trait<...>>::N<...>`.
/// * For an inherent projection, this would be `Ty::N<...>`.
/// * For an opaque type, there is no explicit syntax.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct AliasTy<'tcx> {
/// The parameters of the associated or opaque item.
///
/// For a projection, these are the substitutions for the trait and the
/// GAT substitutions, if there are any.
///
/// For an inherent projection, they consist of the self type and the GAT substitutions,
/// if there are any.
///
/// For RPIT the substitutions are for the generics of the function,
/// while for TAIT it is used for the generic parameters of the alias.
pub substs: SubstsRef<'tcx>,
/// The `DefId` of the `TraitItem` or `ImplItem` for the associated type `N` depending on whether
/// this is a projection or an inherent projection or the `DefId` of the `OpaqueType` item if
/// this is an opaque.
///
/// During codegen, `tcx.type_of(def_id)` can be used to get the type of the
/// underlying type if the type is an opaque.
///
/// Note that if this is an associated type, this is not the `DefId` of the
/// `TraitRef` containing this associated type, which is in `tcx.associated_item(def_id).container`,
/// aka. `tcx.parent(def_id)`.
pub def_id: DefId,
/// This field exists to prevent the creation of `AliasTy` without using
/// [TyCtxt::mk_alias_ty].
pub(super) _use_mk_alias_ty_instead: (),
}
impl<'tcx> AliasTy<'tcx> {
pub fn kind(self, tcx: TyCtxt<'tcx>) -> ty::AliasKind {
match tcx.def_kind(self.def_id) {
DefKind::AssocTy if let DefKind::Impl { of_trait: false } = tcx.def_kind(tcx.parent(self.def_id)) => ty::Inherent,
DefKind::AssocTy | DefKind::ImplTraitPlaceholder => ty::Projection,
DefKind::OpaqueTy => ty::Opaque,
kind => bug!("unexpected DefKind in AliasTy: {kind:?}"),
}
}
pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
tcx.mk_alias(self.kind(tcx), self)
}
}
/// The following methods work only with associated type projections.
impl<'tcx> AliasTy<'tcx> {
pub fn self_ty(self) -> Ty<'tcx> {
self.substs.type_at(0)
}
pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
tcx.mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs.iter().skip(1)))
}
}
/// The following methods work only with trait associated type projections.
impl<'tcx> AliasTy<'tcx> {
pub fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId {
match tcx.def_kind(self.def_id) {
DefKind::AssocTy | DefKind::AssocConst => tcx.parent(self.def_id),
DefKind::ImplTraitPlaceholder => {
tcx.parent(tcx.impl_trait_in_trait_parent_fn(self.def_id))
}
kind => bug!("expected a projection AliasTy; found {kind:?}"),
}
}
/// Extracts the underlying trait reference and own substs from this projection.
/// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
/// then this function would return a `T: StreamingIterator` trait reference and `['a]` as the own substs
pub fn trait_ref_and_own_substs(
self,
tcx: TyCtxt<'tcx>,
) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
debug_assert!(matches!(tcx.def_kind(self.def_id), DefKind::AssocTy | DefKind::AssocConst));
let trait_def_id = self.trait_def_id(tcx);
let trait_generics = tcx.generics_of(trait_def_id);
(
ty::TraitRef::new(tcx, trait_def_id, self.substs.truncate_to(tcx, trait_generics)),
&self.substs[trait_generics.count()..],
)
}
/// Extracts the underlying trait reference from this projection.
/// For example, if this is a projection of `<T as Iterator>::Item`,
/// then this function would return a `T: Iterator` trait reference.
///
/// WARNING: This will drop the substs for generic associated types
/// consider calling [Self::trait_ref_and_own_substs] to get those
/// as well.
pub fn trait_ref(self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
let def_id = self.trait_def_id(tcx);
ty::TraitRef::new(tcx, def_id, self.substs.truncate_to(tcx, tcx.generics_of(def_id)))
}
}
/// The following methods work only with inherent associated type projections.
impl<'tcx> AliasTy<'tcx> {
/// Transform the substitutions to have the given `impl` substs as the base and the GAT substs on top of that.
///
/// Does the following transformation:
///
/// ```text
/// [Self, P_0...P_m] -> [I_0...I_n, P_0...P_m]
///
/// I_i impl subst
/// P_j GAT subst
/// ```
pub fn rebase_substs_onto_impl(
self,
impl_substs: ty::SubstsRef<'tcx>,
tcx: TyCtxt<'tcx>,
) -> ty::SubstsRef<'tcx> {
debug_assert_eq!(self.kind(tcx), ty::Inherent);
tcx.mk_substs_from_iter(impl_substs.into_iter().chain(self.substs.into_iter().skip(1)))
}
}
#[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift)]
pub struct GenSig<'tcx> {
pub resume_ty: Ty<'tcx>,
pub yield_ty: Ty<'tcx>,
pub return_ty: Ty<'tcx>,
}
pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
/// Signature of a function type, which we have arbitrarily
/// decided to use to refer to the input/output types.
///
/// - `inputs`: is the list of arguments and their modes.
/// - `output`: is the return type.
/// - `c_variadic`: indicates whether this is a C-variadic function.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct FnSig<'tcx> {
pub inputs_and_output: &'tcx List<Ty<'tcx>>,
pub c_variadic: bool,
pub unsafety: hir::Unsafety,
pub abi: abi::Abi,
}
impl<'tcx> FnSig<'tcx> {
pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
&self.inputs_and_output[..self.inputs_and_output.len() - 1]
}
pub fn output(&self) -> Ty<'tcx> {
self.inputs_and_output[self.inputs_and_output.len() - 1]
}
// Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
// method.
fn fake() -> FnSig<'tcx> {
FnSig {
inputs_and_output: List::empty(),
c_variadic: false,
unsafety: hir::Unsafety::Normal,
abi: abi::Abi::Rust,
}
}
}
impl<'tcx> IntoDiagnosticArg for FnSig<'tcx> {
fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
self.to_string().into_diagnostic_arg()
}
}
pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
impl<'tcx> PolyFnSig<'tcx> {
#[inline]
pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
}
#[inline]
pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
}
pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
}
#[inline]
pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
self.map_bound_ref(|fn_sig| fn_sig.output())
}
pub fn c_variadic(&self) -> bool {
self.skip_binder().c_variadic
}
pub fn unsafety(&self) -> hir::Unsafety {
self.skip_binder().unsafety
}
pub fn abi(&self) -> abi::Abi {
self.skip_binder().abi
}
pub fn is_fn_trait_compatible(&self) -> bool {
matches!(
self.skip_binder(),
ty::FnSig {
unsafety: rustc_hir::Unsafety::Normal,
abi: Abi::Rust,
c_variadic: false,
..
}
)
}
}
pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
#[derive(HashStable)]
pub struct ParamTy {
pub index: u32,
pub name: Symbol,
}
impl<'tcx> ParamTy {
pub fn new(index: u32, name: Symbol) -> ParamTy {
ParamTy { index, name }
}
pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
ParamTy::new(def.index, def.name)
}
#[inline]
pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
tcx.mk_ty_param(self.index, self.name)
}
pub fn span_from_generics(&self, tcx: TyCtxt<'tcx>, item_with_generics: DefId) -> Span {
let generics = tcx.generics_of(item_with_generics);
let type_param = generics.type_param(self, tcx);
tcx.def_span(type_param.def_id)
}
}
#[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
#[derive(HashStable)]
pub struct ParamConst {
pub index: u32,
pub name: Symbol,
}
impl ParamConst {
pub fn new(index: u32, name: Symbol) -> ParamConst {
ParamConst { index, name }
}
pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
ParamConst::new(def.index, def.name)
}
}
/// Use this rather than `RegionKind`, whenever possible.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
#[rustc_pass_by_value]
pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
impl<'tcx> Deref for Region<'tcx> {
type Target = RegionKind<'tcx>;
#[inline]
fn deref(&self) -> &RegionKind<'tcx> {
&self.0.0
}
}
impl<'tcx> fmt::Debug for Region<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{:?}", self.kind())
}
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
#[derive(HashStable)]
pub struct EarlyBoundRegion {
pub def_id: DefId,
pub index: u32,
pub name: Symbol,
}
impl fmt::Debug for EarlyBoundRegion {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}, {}", self.index, self.name)
}
}
/// A **`const`** **v**ariable **ID**.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[derive(HashStable, TyEncodable, TyDecodable)]
pub struct ConstVid<'tcx> {
pub index: u32,
pub phantom: PhantomData<&'tcx ()>,
}
rustc_index::newtype_index! {
/// A **region** (lifetime) **v**ariable **ID**.
#[derive(HashStable)]
#[debug_format = "'?{}"]
pub struct RegionVid {}
}
impl Atom for RegionVid {
fn index(self) -> usize {
Idx::index(self)
}
}
rustc_index::newtype_index! {
#[derive(HashStable)]
pub struct BoundVar {}
}
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable)]
pub struct BoundTy {
pub var: BoundVar,
pub kind: BoundTyKind,
}
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable)]
pub enum BoundTyKind {
Anon,
Param(DefId, Symbol),
}
impl From<BoundVar> for BoundTy {
fn from(var: BoundVar) -> Self {
BoundTy { var, kind: BoundTyKind::Anon }
}
}
/// A `ProjectionPredicate` for an `ExistentialTraitRef`.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
#[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
pub struct ExistentialProjection<'tcx> {
pub def_id: DefId,
pub substs: SubstsRef<'tcx>,
pub term: Term<'tcx>,
}
pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
impl<'tcx> ExistentialProjection<'tcx> {
/// Extracts the underlying existential trait reference from this projection.
/// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
/// then this function would return an `exists T. T: Iterator` existential trait
/// reference.
pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
let def_id = tcx.parent(self.def_id);
let subst_count = tcx.generics_of(def_id).count() - 1;
let substs = tcx.mk_substs(&self.substs[..subst_count]);
ty::ExistentialTraitRef { def_id, substs }
}
pub fn with_self_ty(
&self,
tcx: TyCtxt<'tcx>,
self_ty: Ty<'tcx>,
) -> ty::ProjectionPredicate<'tcx> {
// otherwise the escaping regions would be captured by the binders
debug_assert!(!self_ty.has_escaping_bound_vars());
ty::ProjectionPredicate {
projection_ty: tcx
.mk_alias_ty(self.def_id, [self_ty.into()].into_iter().chain(self.substs)),
term: self.term,
}
}
pub fn erase_self_ty(
tcx: TyCtxt<'tcx>,
projection_predicate: ty::ProjectionPredicate<'tcx>,
) -> Self {
// Assert there is a Self.
projection_predicate.projection_ty.substs.type_at(0);
Self {
def_id: projection_predicate.projection_ty.def_id,
substs: tcx.mk_substs(&projection_predicate.projection_ty.substs[1..]),
term: projection_predicate.term,
}
}
}
impl<'tcx> PolyExistentialProjection<'tcx> {
pub fn with_self_ty(
&self,
tcx: TyCtxt<'tcx>,
self_ty: Ty<'tcx>,
) -> ty::PolyProjectionPredicate<'tcx> {
self.map_bound(|p| p.with_self_ty(tcx, self_ty))
}
pub fn item_def_id(&self) -> DefId {
self.skip_binder().def_id
}
}
/// Region utilities
impl<'tcx> Region<'tcx> {
pub fn kind(self) -> RegionKind<'tcx> {
*self.0.0
}
pub fn get_name(self) -> Option<Symbol> {
if self.has_name() {
match *self {
ty::ReEarlyBound(ebr) => Some(ebr.name),
ty::ReLateBound(_, br) => br.kind.get_name(),
ty::ReFree(fr) => fr.bound_region.get_name(),
ty::ReStatic => Some(kw::StaticLifetime),
ty::RePlaceholder(placeholder) => placeholder.bound.kind.get_name(),
_ => None,
}
} else {
None
}
}
pub fn get_name_or_anon(self) -> Symbol {
match self.get_name() {
Some(name) => name,
None => sym::anon,
}
}
/// Is this region named by the user?
pub fn has_name(self) -> bool {
match *self {
ty::ReEarlyBound(ebr) => ebr.has_name(),
ty::ReLateBound(_, br) => br.kind.is_named(),
ty::ReFree(fr) => fr.bound_region.is_named(),
ty::ReStatic => true,
ty::ReVar(..) => false,
ty::RePlaceholder(placeholder) => placeholder.bound.kind.is_named(),
ty::ReErased => false,
ty::ReError(_) => false,
}
}
#[inline]
pub fn is_error(self) -> bool {
matches!(*self, ty::ReError(_))
}
#[inline]
pub fn is_static(self) -> bool {
matches!(*self, ty::ReStatic)
}
#[inline]
pub fn is_erased(self) -> bool {
matches!(*self, ty::ReErased)
}
#[inline]
pub fn is_late_bound(self) -> bool {
matches!(*self, ty::ReLateBound(..))
}
#[inline]
pub fn is_placeholder(self) -> bool {
matches!(*self, ty::RePlaceholder(..))
}
#[inline]
pub fn bound_at_or_above_binder(self, index: ty::DebruijnIndex) -> bool {
match *self {
ty::ReLateBound(debruijn, _) => debruijn >= index,
_ => false,
}
}
pub fn type_flags(self) -> TypeFlags {
let mut flags = TypeFlags::empty();
match *self {
ty::ReVar(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
flags = flags | TypeFlags::HAS_RE_INFER;
}
ty::RePlaceholder(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
}
ty::ReEarlyBound(..) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
flags = flags | TypeFlags::HAS_RE_PARAM;
}
ty::ReFree { .. } => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
}
ty::ReStatic => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
}
ty::ReLateBound(..) => {
flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
}
ty::ReErased => {
flags = flags | TypeFlags::HAS_RE_ERASED;
}
ty::ReError(_) => {
flags = flags | TypeFlags::HAS_FREE_REGIONS;
}
}
debug!("type_flags({:?}) = {:?}", self, flags);
flags
}
/// Given an early-bound or free region, returns the `DefId` where it was bound.
/// For example, consider the regions in this snippet of code:
///
/// ```ignore (illustrative)
/// impl<'a> Foo {
/// // ^^ -- early bound, declared on an impl
///
/// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
/// // ^^ ^^ ^ anonymous, late-bound
/// // | early-bound, appears in where-clauses
/// // late-bound, appears only in fn args
/// {..}
/// }
/// ```
///
/// Here, `free_region_binding_scope('a)` would return the `DefId`
/// of the impl, and for all the other highlighted regions, it
/// would return the `DefId` of the function. In other cases (not shown), this
/// function might return the `DefId` of a closure.
pub fn free_region_binding_scope(self, tcx: TyCtxt<'_>) -> DefId {
match *self {
ty::ReEarlyBound(br) => tcx.parent(br.def_id),
ty::ReFree(fr) => fr.scope,
_ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
}
}
/// True for free regions other than `'static`.
pub fn is_free(self) -> bool {
matches!(*self, ty::ReEarlyBound(_) | ty::ReFree(_))
}
/// True if `self` is a free region or static.
pub fn is_free_or_static(self) -> bool {
match *self {
ty::ReStatic => true,
_ => self.is_free(),
}
}
pub fn is_var(self) -> bool {
matches!(self.kind(), ty::ReVar(_))
}
pub fn as_var(self) -> RegionVid {
match self.kind() {
ty::ReVar(vid) => vid,
_ => bug!("expected region {:?} to be of kind ReVar", self),
}
}
}
/// Type utilities
impl<'tcx> Ty<'tcx> {
#[inline(always)]
pub fn kind(self) -> &'tcx TyKind<'tcx> {
&self.0.0
}
#[inline(always)]
pub fn flags(self) -> TypeFlags {
self.0.0.flags
}
#[inline]
pub fn is_unit(self) -> bool {
match self.kind() {
Tuple(ref tys) => tys.is_empty(),
_ => false,
}
}
#[inline]
pub fn is_never(self) -> bool {
matches!(self.kind(), Never)
}
#[inline]
pub fn is_primitive(self) -> bool {
self.kind().is_primitive()
}
#[inline]
pub fn is_adt(self) -> bool {
matches!(self.kind(), Adt(..))
}
#[inline]
pub fn is_ref(self) -> bool {
matches!(self.kind(), Ref(..))
}
#[inline]
pub fn is_ty_var(self) -> bool {
matches!(self.kind(), Infer(TyVar(_)))
}
#[inline]
pub fn ty_vid(self) -> Option<ty::TyVid> {
match self.kind() {
&Infer(TyVar(vid)) => Some(vid),
_ => None,
}
}
#[inline]
pub fn is_ty_or_numeric_infer(self) -> bool {
matches!(self.kind(), Infer(_))
}
#[inline]
pub fn is_phantom_data(self) -> bool {
if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
}
#[inline]
pub fn is_bool(self) -> bool {
*self.kind() == Bool
}
/// Returns `true` if this type is a `str`.
#[inline]
pub fn is_str(self) -> bool {
*self.kind() == Str
}
#[inline]
pub fn is_param(self, index: u32) -> bool {
match self.kind() {
ty::Param(ref data) => data.index == index,
_ => false,
}
}
#[inline]
pub fn is_slice(self) -> bool {
matches!(self.kind(), Slice(_))
}
#[inline]
pub fn is_array_slice(self) -> bool {
match self.kind() {
Slice(_) => true,
RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_)),
_ => false,
}
}
#[inline]
pub fn is_array(self) -> bool {
matches!(self.kind(), Array(..))
}
#[inline]
pub fn is_simd(self) -> bool {
match self.kind() {
Adt(def, _) => def.repr().simd(),
_ => false,
}
}
pub fn sequence_element_type(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
match self.kind() {
Array(ty, _) | Slice(ty) => *ty,
Str => tcx.types.u8,
_ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
}
}
pub fn simd_size_and_type(self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
match self.kind() {
Adt(def, substs) => {
assert!(def.repr().simd(), "`simd_size_and_type` called on non-SIMD type");
let variant = def.non_enum_variant();
let f0_ty = variant.fields[FieldIdx::from_u32(0)].ty(tcx, substs);
match f0_ty.kind() {
// If the first field is an array, we assume it is the only field and its
// elements are the SIMD components.
Array(f0_elem_ty, f0_len) => {
// FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
// The way we evaluate the `N` in `[T; N]` here only works since we use
// `simd_size_and_type` post-monomorphization. It will probably start to ICE
// if we use it in generic code. See the `simd-array-trait` ui test.
(f0_len.eval_target_usize(tcx, ParamEnv::empty()), *f0_elem_ty)
}
// Otherwise, the fields of this Adt are the SIMD components (and we assume they
// all have the same type).
_ => (variant.fields.len() as u64, f0_ty),
}
}
_ => bug!("`simd_size_and_type` called on invalid type"),
}
}
#[inline]
pub fn is_mutable_ptr(self) -> bool {
matches!(
self.kind(),
RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
| Ref(_, _, hir::Mutability::Mut)
)
}
/// Get the mutability of the reference or `None` when not a reference
#[inline]
pub fn ref_mutability(self) -> Option<hir::Mutability> {
match self.kind() {
Ref(_, _, mutability) => Some(*mutability),
_ => None,
}
}
#[inline]
pub fn is_unsafe_ptr(self) -> bool {
matches!(self.kind(), RawPtr(_))
}
/// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
#[inline]
pub fn is_any_ptr(self) -> bool {
self.is_ref() || self.is_unsafe_ptr() || self.is_fn_ptr()
}
#[inline]
pub fn is_box(self) -> bool {
match self.kind() {
Adt(def, _) => def.is_box(),
_ => false,
}
}
/// Panics if called on any type other than `Box<T>`.
pub fn boxed_ty(self) -> Ty<'tcx> {
match self.kind() {
Adt(def, substs) if def.is_box() => substs.type_at(0),
_ => bug!("`boxed_ty` is called on non-box type {:?}", self),
}
}
/// A scalar type is one that denotes an atomic datum, with no sub-components.
/// (A RawPtr is scalar because it represents a non-managed pointer, so its
/// contents are abstract to rustc.)
#[inline]
pub fn is_scalar(self) -> bool {
matches!(
self.kind(),
Bool | Char
| Int(_)
| Float(_)
| Uint(_)
| FnDef(..)
| FnPtr(_)
| RawPtr(_)
| Infer(IntVar(_) | FloatVar(_))
)
}
/// Returns `true` if this type is a floating point type.
#[inline]
pub fn is_floating_point(self) -> bool {
matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
}
#[inline]
pub fn is_trait(self) -> bool {
matches!(self.kind(), Dynamic(_, _, ty::Dyn))
}
#[inline]
pub fn is_dyn_star(self) -> bool {
matches!(self.kind(), Dynamic(_, _, ty::DynStar))
}
#[inline]
pub fn is_enum(self) -> bool {
matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
}
#[inline]
pub fn is_union(self) -> bool {
matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
}
#[inline]
pub fn is_closure(self) -> bool {
matches!(self.kind(), Closure(..))
}
#[inline]
pub fn is_generator(self) -> bool {
matches!(self.kind(), Generator(..))
}
#[inline]
pub fn is_integral(self) -> bool {
matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
}
#[inline]
pub fn is_fresh_ty(self) -> bool {
matches!(self.kind(), Infer(FreshTy(_)))
}
#[inline]
pub fn is_fresh(self) -> bool {
matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
}
#[inline]
pub fn is_char(self) -> bool {
matches!(self.kind(), Char)
}
#[inline]
pub fn is_numeric(self) -> bool {
self.is_integral() || self.is_floating_point()
}
#[inline]
pub fn is_signed(self) -> bool {
matches!(self.kind(), Int(_))
}
#[inline]
pub fn is_ptr_sized_integral(self) -> bool {
matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
}
#[inline]
pub fn has_concrete_skeleton(self) -> bool {
!matches!(self.kind(), Param(_) | Infer(_) | Error(_))
}
/// Checks whether a type recursively contains another type
///
/// Example: `Option<()>` contains `()`
pub fn contains(self, other: Ty<'tcx>) -> bool {
struct ContainsTyVisitor<'tcx>(Ty<'tcx>);
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTyVisitor<'tcx> {
type BreakTy = ();
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
if self.0 == t { ControlFlow::Break(()) } else { t.super_visit_with(self) }
}
}
let cf = self.visit_with(&mut ContainsTyVisitor(other));
cf.is_break()
}
/// Checks whether a type recursively contains any closure
///
/// Example: `Option<[closure@file.rs:4:20]>` returns true
pub fn contains_closure(self) -> bool {
struct ContainsClosureVisitor;
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsClosureVisitor {
type BreakTy = ();
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
if let ty::Closure(_, _) = t.kind() {
ControlFlow::Break(())
} else {
t.super_visit_with(self)
}
}
}
let cf = self.visit_with(&mut ContainsClosureVisitor);
cf.is_break()
}
/// Returns the type and mutability of `*ty`.
///
/// The parameter `explicit` indicates if this is an *explicit* dereference.
/// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
pub fn builtin_deref(self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
match self.kind() {
Adt(def, _) if def.is_box() => {
Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
}
Ref(_, ty, mutbl) => Some(TypeAndMut { ty: *ty, mutbl: *mutbl }),
RawPtr(mt) if explicit => Some(*mt),
_ => None,
}
}
/// Returns the type of `ty[i]`.
pub fn builtin_index(self) -> Option<Ty<'tcx>> {
match self.kind() {
Array(ty, _) | Slice(ty) => Some(*ty),
_ => None,
}
}
pub fn fn_sig(self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
match self.kind() {
FnDef(def_id, substs) => tcx.fn_sig(*def_id).subst(tcx, substs),
FnPtr(f) => *f,
Error(_) => {
// ignore errors (#54954)
ty::Binder::dummy(FnSig::fake())
}
Closure(..) => bug!(
"to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
),
_ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
}
}
#[inline]
pub fn is_fn(self) -> bool {
matches!(self.kind(), FnDef(..) | FnPtr(_))
}
#[inline]
pub fn is_fn_ptr(self) -> bool {
matches!(self.kind(), FnPtr(_))
}
#[inline]
pub fn is_impl_trait(self) -> bool {
matches!(self.kind(), Alias(ty::Opaque, ..))
}
#[inline]
pub fn ty_adt_def(self) -> Option<AdtDef<'tcx>> {
match self.kind() {
Adt(adt, _) => Some(*adt),
_ => None,
}
}
/// Iterates over tuple fields.
/// Panics when called on anything but a tuple.
#[inline]
pub fn tuple_fields(self) -> &'tcx List<Ty<'tcx>> {
match self.kind() {
Tuple(substs) => substs,
_ => bug!("tuple_fields called on non-tuple"),
}
}
/// If the type contains variants, returns the valid range of variant indices.
//
// FIXME: This requires the optimized MIR in the case of generators.
#[inline]
pub fn variant_range(self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
match self.kind() {
TyKind::Adt(adt, _) => Some(adt.variant_range()),
TyKind::Generator(def_id, substs, _) => {
Some(substs.as_generator().variant_range(*def_id, tcx))
}
_ => None,
}
}
/// If the type contains variants, returns the variant for `variant_index`.
/// Panics if `variant_index` is out of range.
//
// FIXME: This requires the optimized MIR in the case of generators.
#[inline]
pub fn discriminant_for_variant(
self,
tcx: TyCtxt<'tcx>,
variant_index: VariantIdx,
) -> Option<Discr<'tcx>> {
match self.kind() {
TyKind::Adt(adt, _) if adt.variants().is_empty() => {
// This can actually happen during CTFE, see
// https://github.com/rust-lang/rust/issues/89765.
None
}
TyKind::Adt(adt, _) if adt.is_enum() => {
Some(adt.discriminant_for_variant(tcx, variant_index))
}
TyKind::Generator(def_id, substs, _) => {
Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
}
_ => None,
}
}
/// Returns the type of the discriminant of this type.
pub fn discriminant_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
match self.kind() {
ty::Adt(adt, _) if adt.is_enum() => adt.repr().discr_type().to_ty(tcx),
ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
ty::Param(_) | ty::Alias(..) | ty::Infer(ty::TyVar(_)) => {
let assoc_items = tcx.associated_item_def_ids(
tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
);
tcx.mk_projection(assoc_items[0], tcx.mk_substs(&[self.into()]))
}
ty::Bool
| ty::Char
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Adt(..)
| ty::Foreign(_)
| ty::Str
| ty::Array(..)
| ty::Slice(_)
| ty::RawPtr(_)
| ty::Ref(..)
| ty::FnDef(..)
| ty::FnPtr(..)
| ty::Dynamic(..)
| ty::Closure(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Never
| ty::Tuple(_)
| ty::Error(_)
| ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
ty::Bound(..)
| ty::Placeholder(_)
| ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
}
}
}
/// Returns the type of metadata for (potentially fat) pointers to this type,
/// and a boolean signifying if this is conditional on this type being `Sized`.
pub fn ptr_metadata_ty(
self,
tcx: TyCtxt<'tcx>,
normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
) -> (Ty<'tcx>, bool) {
let tail = tcx.struct_tail_with_normalize(self, normalize, || {});
match tail.kind() {
// Sized types
ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
| ty::Uint(_)
| ty::Int(_)
| ty::Bool
| ty::Float(_)
| ty::FnDef(..)
| ty::FnPtr(_)
| ty::RawPtr(..)
| ty::Char
| ty::Ref(..)
| ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Array(..)
| ty::Closure(..)
| ty::Never
| ty::Error(_)
// Extern types have metadata = ().
| ty::Foreign(..)
// If returned by `struct_tail_without_normalization` this is a unit struct
// without any fields, or not a struct, and therefore is Sized.
| ty::Adt(..)
// If returned by `struct_tail_without_normalization` this is the empty tuple,
// a.k.a. unit type, which is Sized
| ty::Tuple(..) => (tcx.types.unit, false),
ty::Str | ty::Slice(_) => (tcx.types.usize, false),
ty::Dynamic(..) => {
let dyn_metadata = tcx.require_lang_item(LangItem::DynMetadata, None);
(tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()]), false)
},
// type parameters only have unit metadata if they're sized, so return true
// to make sure we double check this during confirmation
ty::Param(_) | ty::Alias(..) => (tcx.types.unit, true),
ty::Infer(ty::TyVar(_))
| ty::Bound(..)
| ty::Placeholder(..)
| ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
bug!("`ptr_metadata_ty` applied to unexpected type: {:?} (tail = {:?})", self, tail)
}
}
}
/// When we create a closure, we record its kind (i.e., what trait
/// it implements) into its `ClosureSubsts` using a type
/// parameter. This is kind of a phantom type, except that the
/// most convenient thing for us to are the integral types. This
/// function converts such a special type into the closure
/// kind. To go the other way, use `closure_kind.to_ty(tcx)`.
///
/// Note that during type checking, we use an inference variable
/// to represent the closure kind, because it has not yet been
/// inferred. Once upvar inference (in `rustc_hir_analysis/src/check/upvar.rs`)
/// is complete, that type variable will be unified.
pub fn to_opt_closure_kind(self) -> Option<ty::ClosureKind> {
match self.kind() {
Int(int_ty) => match int_ty {
ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
_ => bug!("cannot convert type `{:?}` to a closure kind", self),
},
// "Bound" types appear in canonical queries when the
// closure type is not yet known
Bound(..) | Infer(_) => None,
Error(_) => Some(ty::ClosureKind::Fn),
_ => bug!("cannot convert type `{:?}` to a closure kind", self),
}
}
/// Fast path helper for testing if a type is `Sized`.
///
/// Returning true means the type is known to be sized. Returning
/// `false` means nothing -- could be sized, might not be.
///
/// Note that we could never rely on the fact that a type such as `[_]` is
/// trivially `!Sized` because we could be in a type environment with a
/// bound such as `[_]: Copy`. A function with such a bound obviously never
/// can be called, but that doesn't mean it shouldn't typecheck. This is why
/// this method doesn't return `Option<bool>`.
pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool {
match self.kind() {
ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
| ty::Uint(_)
| ty::Int(_)
| ty::Bool
| ty::Float(_)
| ty::FnDef(..)
| ty::FnPtr(_)
| ty::RawPtr(..)
| ty::Char
| ty::Ref(..)
| ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Array(..)
| ty::Closure(..)
| ty::Never
| ty::Error(_) => true,
ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
ty::Tuple(tys) => tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
ty::Adt(def, _substs) => def.sized_constraint(tcx).0.is_empty(),
ty::Alias(..) | ty::Param(_) | ty::Placeholder(..) => false,
ty::Infer(ty::TyVar(_)) => false,
ty::Bound(..) | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
}
}
}
/// Fast path helper for primitives which are always `Copy` and which
/// have a side-effect-free `Clone` impl.
///
/// Returning true means the type is known to be pure and `Copy+Clone`.
/// Returning `false` means nothing -- could be `Copy`, might not be.
///
/// This is mostly useful for optimizations, as there are the types
/// on which we can replace cloning with dereferencing.
pub fn is_trivially_pure_clone_copy(self) -> bool {
match self.kind() {
ty::Bool | ty::Char | ty::Never => true,
// These aren't even `Clone`
ty::Str | ty::Slice(..) | ty::Foreign(..) | ty::Dynamic(..) => false,
ty::Infer(ty::InferTy::FloatVar(_) | ty::InferTy::IntVar(_))
| ty::Int(..)
| ty::Uint(..)
| ty::Float(..) => true,
// The voldemort ZSTs are fine.
ty::FnDef(..) => true,
ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),
// A 100-tuple isn't "trivial", so doing this only for reasonable sizes.
ty::Tuple(field_tys) => {
field_tys.len() <= 3 && field_tys.iter().all(Self::is_trivially_pure_clone_copy)
}
// Sometimes traits aren't implemented for every ABI or arity,
// because we can't be generic over everything yet.
ty::FnPtr(..) => false,
// Definitely absolutely not copy.
ty::Ref(_, _, hir::Mutability::Mut) => false,
// Thin pointers & thin shared references are pure-clone-copy, but for
// anything with custom metadata it might be more complicated.
ty::Ref(_, _, hir::Mutability::Not) | ty::RawPtr(..) => false,
ty::Generator(..) | ty::GeneratorWitness(..) | ty::GeneratorWitnessMIR(..) => false,
// Might be, but not "trivial" so just giving the safe answer.
ty::Adt(..) | ty::Closure(..) => false,
// Needs normalization or revealing to determine, so no is the safe answer.
ty::Alias(..) => false,
ty::Param(..) | ty::Infer(..) | ty::Error(..) => false,
ty::Bound(..) | ty::Placeholder(..) => {
bug!("`is_trivially_pure_clone_copy` applied to unexpected type: {:?}", self);
}
}
}
/// If `self` is a primitive, return its [`Symbol`].
pub fn primitive_symbol(self) -> Option<Symbol> {
match self.kind() {
ty::Bool => Some(sym::bool),
ty::Char => Some(sym::char),
ty::Float(f) => match f {
ty::FloatTy::F32 => Some(sym::f32),
ty::FloatTy::F64 => Some(sym::f64),
},
ty::Int(f) => match f {
ty::IntTy::Isize => Some(sym::isize),
ty::IntTy::I8 => Some(sym::i8),
ty::IntTy::I16 => Some(sym::i16),
ty::IntTy::I32 => Some(sym::i32),
ty::IntTy::I64 => Some(sym::i64),
ty::IntTy::I128 => Some(sym::i128),
},
ty::Uint(f) => match f {
ty::UintTy::Usize => Some(sym::usize),
ty::UintTy::U8 => Some(sym::u8),
ty::UintTy::U16 => Some(sym::u16),
ty::UintTy::U32 => Some(sym::u32),
ty::UintTy::U64 => Some(sym::u64),
ty::UintTy::U128 => Some(sym::u128),
},
_ => None,
}
}
pub fn is_c_void(self, tcx: TyCtxt<'_>) -> bool {
match self.kind() {
ty::Adt(adt, _) => tcx.lang_items().get(LangItem::CVoid) == Some(adt.did()),
_ => false,
}
}
}
/// Extra information about why we ended up with a particular variance.
/// This is only used to add more information to error messages, and
/// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
/// may lead to confusing notes in error messages, it will never cause
/// a miscompilation or unsoundness.
///
/// When in doubt, use `VarianceDiagInfo::default()`
#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
pub enum VarianceDiagInfo<'tcx> {
/// No additional information - this is the default.
/// We will not add any additional information to error messages.
#[default]
None,
/// We switched our variance because a generic argument occurs inside
/// the invariant generic argument of another type.
Invariant {
/// The generic type containing the generic parameter
/// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
ty: Ty<'tcx>,
/// The index of the generic parameter being used
/// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
param_index: u32,
},
}
impl<'tcx> VarianceDiagInfo<'tcx> {
/// Mirrors `Variance::xform` - used to 'combine' the existing
/// and new `VarianceDiagInfo`s when our variance changes.
pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
// For now, just use the first `VarianceDiagInfo::Invariant` that we see
match self {
VarianceDiagInfo::None => other,
VarianceDiagInfo::Invariant { .. } => self,
}
}
}
// Some types are used a lot. Make sure they don't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
mod size_asserts {
use super::*;
use rustc_data_structures::static_assert_size;
// tidy-alphabetical-start
static_assert_size!(RegionKind<'_>, 28);
static_assert_size!(TyKind<'_>, 32);
// tidy-alphabetical-end
}