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Uplift EarlyBinder

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This commit is contained in:
Michael Goulet 2024-05-26 20:45:37 -04:00
parent bbcdb4fd3e
commit 993553ceb8
13 changed files with 679 additions and 613 deletions
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1
Cargo.lock
View File

@ -4686,6 +4686,7 @@ dependencies = [
"rustc_span", "rustc_span",
"rustc_type_ir_macros", "rustc_type_ir_macros",
"smallvec", "smallvec",
"tracing",
] ]
[[package]] [[package]]

9
compiler/rustc_middle/src/ty/consts.rs
View File

@ -184,6 +184,15 @@ impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> {
Const::new_var(tcx, vid, ty) Const::new_var(tcx, vid, ty)
} }
fn new_bound(
interner: TyCtxt<'tcx>,
debruijn: ty::DebruijnIndex,
var: ty::BoundVar,
ty: Ty<'tcx>,
) -> Self {
Const::new_bound(interner, debruijn, var, ty)
}
fn new_anon_bound( fn new_anon_bound(
tcx: TyCtxt<'tcx>, tcx: TyCtxt<'tcx>,
debruijn: ty::DebruijnIndex, debruijn: ty::DebruijnIndex,

104
compiler/rustc_middle/src/ty/fold.rs
View File

@ -3,7 +3,9 @@ use rustc_data_structures::fx::FxIndexMap;
use rustc_hir::def_id::DefId; use rustc_hir::def_id::DefId;
use tracing::{debug, instrument}; use tracing::{debug, instrument};
pub use rustc_type_ir::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable}; pub use rustc_type_ir::fold::{
shift_region, shift_vars, FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable,
};
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
// Some sample folders // Some sample folders
@ -412,103 +414,3 @@ impl<'tcx> TyCtxt<'tcx> {
Binder::bind_with_vars(inner, bound_vars) Binder::bind_with_vars(inner, bound_vars)
} }
} }
///////////////////////////////////////////////////////////////////////////
// Shifter
//
// Shifts the De Bruijn indices on all escaping bound vars by a
// fixed amount. Useful in instantiation or when otherwise introducing
// a binding level that is not intended to capture the existing bound
// vars. See comment on `shift_vars_through_binders` method in
// `rustc_middle/src/ty/generic_args.rs` for more details.
struct Shifter<'tcx> {
tcx: TyCtxt<'tcx>,
current_index: ty::DebruijnIndex,
amount: u32,
}
impl<'tcx> Shifter<'tcx> {
pub fn new(tcx: TyCtxt<'tcx>, amount: u32) -> Self {
Shifter { tcx, current_index: ty::INNERMOST, amount }
}
}
impl<'tcx> TypeFolder<TyCtxt<'tcx>> for Shifter<'tcx> {
fn interner(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
&mut self,
t: ty::Binder<'tcx, T>,
) -> ty::Binder<'tcx, T> {
self.current_index.shift_in(1);
let t = t.super_fold_with(self);
self.current_index.shift_out(1);
t
}
fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
match *r {
ty::ReBound(debruijn, br) if debruijn >= self.current_index => {
let debruijn = debruijn.shifted_in(self.amount);
ty::Region::new_bound(self.tcx, debruijn, br)
}
_ => r,
}
}
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
match *ty.kind() {
ty::Bound(debruijn, bound_ty) if debruijn >= self.current_index => {
let debruijn = debruijn.shifted_in(self.amount);
Ty::new_bound(self.tcx, debruijn, bound_ty)
}
_ if ty.has_vars_bound_at_or_above(self.current_index) => ty.super_fold_with(self),
_ => ty,
}
}
fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
if let ty::ConstKind::Bound(debruijn, bound_ct) = ct.kind()
&& debruijn >= self.current_index
{
let debruijn = debruijn.shifted_in(self.amount);
ty::Const::new_bound(self.tcx, debruijn, bound_ct, ct.ty())
} else {
ct.super_fold_with(self)
}
}
fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
if p.has_vars_bound_at_or_above(self.current_index) { p.super_fold_with(self) } else { p }
}
}
pub fn shift_region<'tcx>(
tcx: TyCtxt<'tcx>,
region: ty::Region<'tcx>,
amount: u32,
) -> ty::Region<'tcx> {
match *region {
ty::ReBound(debruijn, br) if amount > 0 => {
ty::Region::new_bound(tcx, debruijn.shifted_in(amount), br)
}
_ => region,
}
}
pub fn shift_vars<'tcx, T>(tcx: TyCtxt<'tcx>, value: T, amount: u32) -> T
where
T: TypeFoldable<TyCtxt<'tcx>>,
{
debug!("shift_vars(value={:?}, amount={})", value, amount);
if amount == 0 || !value.has_escaping_bound_vars() {
return value;
}
value.fold_with(&mut Shifter::new(tcx, amount))
}

506
compiler/rustc_middle/src/ty/generic_args.rs
View File

@ -1,10 +1,10 @@
// Generic arguments. // Generic arguments.
use crate::ty::codec::{TyDecoder, TyEncoder}; use crate::ty::codec::{TyDecoder, TyEncoder};
use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable}; use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
use crate::ty::sty::{ClosureArgs, CoroutineArgs, CoroutineClosureArgs, InlineConstArgs}; use crate::ty::sty::{ClosureArgs, CoroutineArgs, CoroutineClosureArgs, InlineConstArgs};
use crate::ty::visit::{TypeVisitable, TypeVisitableExt, TypeVisitor}; use crate::ty::visit::{TypeVisitable, TypeVisitor};
use crate::ty::{self, Lift, List, ParamConst, Ty, TyCtxt}; use crate::ty::{self, Lift, List, Ty, TyCtxt};
use rustc_ast_ir::visit::VisitorResult; use rustc_ast_ir::visit::VisitorResult;
use rustc_ast_ir::walk_visitable_list; use rustc_ast_ir::walk_visitable_list;
@ -12,19 +12,15 @@ use rustc_data_structures::intern::Interned;
use rustc_errors::{DiagArgValue, IntoDiagArg}; use rustc_errors::{DiagArgValue, IntoDiagArg};
use rustc_hir::def_id::DefId; use rustc_hir::def_id::DefId;
use rustc_macros::extension; use rustc_macros::extension;
use rustc_macros::{ use rustc_macros::{HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
Decodable, Encodable, HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable,
};
use rustc_serialize::{Decodable, Encodable}; use rustc_serialize::{Decodable, Encodable};
use rustc_type_ir::WithCachedTypeInfo; use rustc_type_ir::WithCachedTypeInfo;
use smallvec::SmallVec; use smallvec::SmallVec;
use tracing::debug;
use core::intrinsics; use core::intrinsics;
use std::marker::PhantomData; use std::marker::PhantomData;
use std::mem; use std::mem;
use std::num::NonZero; use std::num::NonZero;
use std::ops::Deref;
use std::ptr::NonNull; use std::ptr::NonNull;
pub type GenericArgKind<'tcx> = rustc_type_ir::GenericArgKind<TyCtxt<'tcx>>; pub type GenericArgKind<'tcx> = rustc_type_ir::GenericArgKind<TyCtxt<'tcx>>;
@ -576,500 +572,6 @@ impl<'tcx, T: TypeVisitable<TyCtxt<'tcx>>> TypeVisitable<TyCtxt<'tcx>> for &'tcx
} }
} }
/// Similar to [`super::Binder`] except that it tracks early bound generics, i.e. `struct Foo<T>(T)`
/// needs `T` instantiated immediately. This type primarily exists to avoid forgetting to call
/// `instantiate`.
///
/// If you don't have anything to `instantiate`, you may be looking for
/// [`instantiate_identity`](EarlyBinder::instantiate_identity) or [`skip_binder`](EarlyBinder::skip_binder).
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
#[derive(Encodable, Decodable, HashStable)]
pub struct EarlyBinder<'tcx, T> {
value: T,
_tcx: PhantomData<&'tcx ()>,
}
/// For early binders, you should first call `instantiate` before using any visitors.
impl<'tcx, T> !TypeFoldable<TyCtxt<'tcx>> for ty::EarlyBinder<'tcx, T> {}
impl<'tcx, T> !TypeVisitable<TyCtxt<'tcx>> for ty::EarlyBinder<'tcx, T> {}
impl<'tcx, T> EarlyBinder<'tcx, T> {
pub fn bind(value: T) -> EarlyBinder<'tcx, T> {
EarlyBinder { value, _tcx: PhantomData }
}
pub fn as_ref(&self) -> EarlyBinder<'tcx, &T> {
EarlyBinder { value: &self.value, _tcx: PhantomData }
}
pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<'tcx, U>
where
F: FnOnce(&T) -> U,
{
self.as_ref().map_bound(f)
}
pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<'tcx, U>
where
F: FnOnce(T) -> U,
{
let value = f(self.value);
EarlyBinder { value, _tcx: PhantomData }
}
pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<'tcx, U>, E>
where
F: FnOnce(T) -> Result<U, E>,
{
let value = f(self.value)?;
Ok(EarlyBinder { value, _tcx: PhantomData })
}
pub fn rebind<U>(&self, value: U) -> EarlyBinder<'tcx, U> {
EarlyBinder { value, _tcx: PhantomData }
}
/// Skips the binder and returns the "bound" value.
/// This can be used to extract data that does not depend on generic parameters
/// (e.g., getting the `DefId` of the inner value or getting the number of
/// arguments of an `FnSig`). Otherwise, consider using
/// [`instantiate_identity`](EarlyBinder::instantiate_identity).
///
/// To skip the binder on `x: &EarlyBinder<'tcx, T>` to obtain `&T`, leverage
/// [`EarlyBinder::as_ref`](EarlyBinder::as_ref): `x.as_ref().skip_binder()`.
///
/// See also [`Binder::skip_binder`](super::Binder::skip_binder), which is
/// the analogous operation on [`super::Binder`].
pub fn skip_binder(self) -> T {
self.value
}
}
impl<'tcx, T> EarlyBinder<'tcx, Option<T>> {
pub fn transpose(self) -> Option<EarlyBinder<'tcx, T>> {
self.value.map(|value| EarlyBinder { value, _tcx: PhantomData })
}
}
impl<'tcx, 's, I: IntoIterator> EarlyBinder<'tcx, I>
where
I::Item: TypeFoldable<TyCtxt<'tcx>>,
{
pub fn iter_instantiated(
self,
tcx: TyCtxt<'tcx>,
args: &'s [GenericArg<'tcx>],
) -> IterInstantiated<'s, 'tcx, I> {
IterInstantiated { it: self.value.into_iter(), tcx, args }
}
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
/// but on an iterator of `TypeFoldable` values.
pub fn instantiate_identity_iter(self) -> I::IntoIter {
self.value.into_iter()
}
}
pub struct IterInstantiated<'s, 'tcx, I: IntoIterator> {
it: I::IntoIter,
tcx: TyCtxt<'tcx>,
args: &'s [GenericArg<'tcx>],
}
impl<'tcx, I: IntoIterator> Iterator for IterInstantiated<'_, 'tcx, I>
where
I::Item: TypeFoldable<TyCtxt<'tcx>>,
{
type Item = I::Item;
fn next(&mut self) -> Option<Self::Item> {
Some(
EarlyBinder { value: self.it.next()?, _tcx: PhantomData }
.instantiate(self.tcx, self.args),
)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.it.size_hint()
}
}
impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiated<'_, 'tcx, I>
where
I::IntoIter: DoubleEndedIterator,
I::Item: TypeFoldable<TyCtxt<'tcx>>,
{
fn next_back(&mut self) -> Option<Self::Item> {
Some(
EarlyBinder { value: self.it.next_back()?, _tcx: PhantomData }
.instantiate(self.tcx, self.args),
)
}
}
impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiated<'_, 'tcx, I>
where
I::IntoIter: ExactSizeIterator,
I::Item: TypeFoldable<TyCtxt<'tcx>>,
{
}
impl<'tcx, 's, I: IntoIterator> EarlyBinder<'tcx, I>
where
I::Item: Deref,
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
{
pub fn iter_instantiated_copied(
self,
tcx: TyCtxt<'tcx>,
args: &'s [GenericArg<'tcx>],
) -> IterInstantiatedCopied<'s, 'tcx, I> {
IterInstantiatedCopied { it: self.value.into_iter(), tcx, args }
}
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
/// but on an iterator of values that deref to a `TypeFoldable`.
pub fn instantiate_identity_iter_copied(
self,
) -> impl Iterator<Item = <I::Item as Deref>::Target> {
self.value.into_iter().map(|v| *v)
}
}
pub struct IterInstantiatedCopied<'a, 'tcx, I: IntoIterator> {
it: I::IntoIter,
tcx: TyCtxt<'tcx>,
args: &'a [GenericArg<'tcx>],
}
impl<'tcx, I: IntoIterator> Iterator for IterInstantiatedCopied<'_, 'tcx, I>
where
I::Item: Deref,
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
{
type Item = <I::Item as Deref>::Target;
fn next(&mut self) -> Option<Self::Item> {
self.it.next().map(|value| {
EarlyBinder { value: *value, _tcx: PhantomData }.instantiate(self.tcx, self.args)
})
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.it.size_hint()
}
}
impl<'tcx, I: IntoIterator> DoubleEndedIterator for IterInstantiatedCopied<'_, 'tcx, I>
where
I::IntoIter: DoubleEndedIterator,
I::Item: Deref,
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
{
fn next_back(&mut self) -> Option<Self::Item> {
self.it.next_back().map(|value| {
EarlyBinder { value: *value, _tcx: PhantomData }.instantiate(self.tcx, self.args)
})
}
}
impl<'tcx, I: IntoIterator> ExactSizeIterator for IterInstantiatedCopied<'_, 'tcx, I>
where
I::IntoIter: ExactSizeIterator,
I::Item: Deref,
<I::Item as Deref>::Target: Copy + TypeFoldable<TyCtxt<'tcx>>,
{
}
pub struct EarlyBinderIter<'tcx, T> {
t: T,
_tcx: PhantomData<&'tcx ()>,
}
impl<'tcx, T: IntoIterator> EarlyBinder<'tcx, T> {
pub fn transpose_iter(self) -> EarlyBinderIter<'tcx, T::IntoIter> {
EarlyBinderIter { t: self.value.into_iter(), _tcx: PhantomData }
}
}
impl<'tcx, T: Iterator> Iterator for EarlyBinderIter<'tcx, T> {
type Item = EarlyBinder<'tcx, T::Item>;
fn next(&mut self) -> Option<Self::Item> {
self.t.next().map(|value| EarlyBinder { value, _tcx: PhantomData })
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.t.size_hint()
}
}
impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>>> ty::EarlyBinder<'tcx, T> {
pub fn instantiate(self, tcx: TyCtxt<'tcx>, args: &[GenericArg<'tcx>]) -> T {
let mut folder = ArgFolder { tcx, args, binders_passed: 0 };
self.value.fold_with(&mut folder)
}
/// Makes the identity replacement `T0 => T0, ..., TN => TN`.
/// Conceptually, this converts universally bound variables into placeholders
/// when inside of a given item.
///
/// For example, consider `for<T> fn foo<T>(){ .. }`:
/// - Outside of `foo`, `T` is bound (represented by the presence of `EarlyBinder`).
/// - Inside of the body of `foo`, we treat `T` as a placeholder by calling
/// `instantiate_identity` to discharge the `EarlyBinder`.
pub fn instantiate_identity(self) -> T {
self.value
}
/// Returns the inner value, but only if it contains no bound vars.
pub fn no_bound_vars(self) -> Option<T> {
if !self.value.has_param() { Some(self.value) } else { None }
}
}
///////////////////////////////////////////////////////////////////////////
// The actual instantiation engine itself is a type folder.
struct ArgFolder<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
args: &'a [GenericArg<'tcx>],
/// Number of region binders we have passed through while doing the instantiation
binders_passed: u32,
}
impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for ArgFolder<'a, 'tcx> {
#[inline]
fn interner(&self) -> TyCtxt<'tcx> {
self.tcx
}
fn fold_binder<T: TypeFoldable<TyCtxt<'tcx>>>(
&mut self,
t: ty::Binder<'tcx, T>,
) -> ty::Binder<'tcx, T> {
self.binders_passed += 1;
let t = t.super_fold_with(self);
self.binders_passed -= 1;
t
}
fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
#[cold]
#[inline(never)]
fn region_param_out_of_range(data: ty::EarlyParamRegion, args: &[GenericArg<'_>]) -> ! {
bug!(
"Region parameter out of range when instantiating in region {} (index={}, args = {:?})",
data.name,
data.index,
args,
)
}
#[cold]
#[inline(never)]
fn region_param_invalid(data: ty::EarlyParamRegion, other: GenericArgKind<'_>) -> ! {
bug!(
"Unexpected parameter {:?} when instantiating in region {} (index={})",
other,
data.name,
data.index
)
}
// Note: This routine only handles regions that are bound on
// type declarations and other outer declarations, not those
// bound in *fn types*. Region instantiation of the bound
// regions that appear in a function signature is done using
// the specialized routine `ty::replace_late_regions()`.
match *r {
ty::ReEarlyParam(data) => {
let rk = self.args.get(data.index as usize).map(|k| k.unpack());
match rk {
Some(GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
Some(other) => region_param_invalid(data, other),
None => region_param_out_of_range(data, self.args),
}
}
ty::ReBound(..)
| ty::ReLateParam(_)
| ty::ReStatic
| ty::RePlaceholder(_)
| ty::ReErased
| ty::ReError(_) => r,
ty::ReVar(_) => bug!("unexpected region: {r:?}"),
}
}
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
if !t.has_param() {
return t;
}
match *t.kind() {
ty::Param(p) => self.ty_for_param(p, t),
_ => t.super_fold_with(self),
}
}
fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
if let ty::ConstKind::Param(p) = c.kind() {
self.const_for_param(p, c)
} else {
c.super_fold_with(self)
}
}
}
impl<'a, 'tcx> ArgFolder<'a, 'tcx> {
fn ty_for_param(&self, p: ty::ParamTy, source_ty: Ty<'tcx>) -> Ty<'tcx> {
// Look up the type in the args. It really should be in there.
let opt_ty = self.args.get(p.index as usize).map(|k| k.unpack());
let ty = match opt_ty {
Some(GenericArgKind::Type(ty)) => ty,
Some(kind) => self.type_param_expected(p, source_ty, kind),
None => self.type_param_out_of_range(p, source_ty),
};
self.shift_vars_through_binders(ty)
}
#[cold]
#[inline(never)]
fn type_param_expected(&self, p: ty::ParamTy, ty: Ty<'tcx>, kind: GenericArgKind<'tcx>) -> ! {
bug!(
"expected type for `{:?}` ({:?}/{}) but found {:?} when instantiating, args={:?}",
p,
ty,
p.index,
kind,
self.args,
)
}
#[cold]
#[inline(never)]
fn type_param_out_of_range(&self, p: ty::ParamTy, ty: Ty<'tcx>) -> ! {
bug!(
"type parameter `{:?}` ({:?}/{}) out of range when instantiating, args={:?}",
p,
ty,
p.index,
self.args,
)
}
fn const_for_param(&self, p: ParamConst, source_ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
// Look up the const in the args. It really should be in there.
let opt_ct = self.args.get(p.index as usize).map(|k| k.unpack());
let ct = match opt_ct {
Some(GenericArgKind::Const(ct)) => ct,
Some(kind) => self.const_param_expected(p, source_ct, kind),
None => self.const_param_out_of_range(p, source_ct),
};
self.shift_vars_through_binders(ct)
}
#[cold]
#[inline(never)]
fn const_param_expected(
&self,
p: ty::ParamConst,
ct: ty::Const<'tcx>,
kind: GenericArgKind<'tcx>,
) -> ! {
bug!(
"expected const for `{:?}` ({:?}/{}) but found {:?} when instantiating args={:?}",
p,
ct,
p.index,
kind,
self.args,
)
}
#[cold]
#[inline(never)]
fn const_param_out_of_range(&self, p: ty::ParamConst, ct: ty::Const<'tcx>) -> ! {
bug!(
"const parameter `{:?}` ({:?}/{}) out of range when instantiating args={:?}",
p,
ct,
p.index,
self.args,
)
}
/// It is sometimes necessary to adjust the De Bruijn indices during instantiation. This occurs
/// when we are instantating a type with escaping bound vars into a context where we have
/// passed through binders. That's quite a mouthful. Let's see an example:
///
/// ```
/// type Func<A> = fn(A);
/// type MetaFunc = for<'a> fn(Func<&'a i32>);
/// ```
///
/// The type `MetaFunc`, when fully expanded, will be
/// ```ignore (illustrative)
/// for<'a> fn(fn(&'a i32))
/// // ^~ ^~ ^~~
/// // | | |
/// // | | DebruijnIndex of 2
/// // Binders
/// ```
/// Here the `'a` lifetime is bound in the outer function, but appears as an argument of the
/// inner one. Therefore, that appearance will have a DebruijnIndex of 2, because we must skip
/// over the inner binder (remember that we count De Bruijn indices from 1). However, in the
/// definition of `MetaFunc`, the binder is not visible, so the type `&'a i32` will have a
/// De Bruijn index of 1. It's only during the instantiation that we can see we must increase the
/// depth by 1 to account for the binder that we passed through.
///
/// As a second example, consider this twist:
///
/// ```
/// type FuncTuple<A> = (A,fn(A));
/// type MetaFuncTuple = for<'a> fn(FuncTuple<&'a i32>);
/// ```
///
/// Here the final type will be:
/// ```ignore (illustrative)
/// for<'a> fn((&'a i32, fn(&'a i32)))
/// // ^~~ ^~~
/// // | |
/// // DebruijnIndex of 1 |
/// // DebruijnIndex of 2
/// ```
/// As indicated in the diagram, here the same type `&'a i32` is instantiated once, but in the
/// first case we do not increase the De Bruijn index and in the second case we do. The reason
/// is that only in the second case have we passed through a fn binder.
fn shift_vars_through_binders<T: TypeFoldable<TyCtxt<'tcx>>>(&self, val: T) -> T {
debug!(
"shift_vars(val={:?}, binders_passed={:?}, has_escaping_bound_vars={:?})",
val,
self.binders_passed,
val.has_escaping_bound_vars()
);
if self.binders_passed == 0 || !val.has_escaping_bound_vars() {
return val;
}
let result = ty::fold::shift_vars(TypeFolder::interner(self), val, self.binders_passed);
debug!("shift_vars: shifted result = {:?}", result);
result
}
fn shift_region_through_binders(&self, region: ty::Region<'tcx>) -> ty::Region<'tcx> {
if self.binders_passed == 0 || !region.has_escaping_bound_vars() {
return region;
}
ty::fold::shift_region(self.tcx, region, self.binders_passed)
}
}
/// Stores the user-given args to reach some fully qualified path /// Stores the user-given args to reach some fully qualified path
/// (e.g., `<T>::Item` or `<T as Trait>::Item`). /// (e.g., `<T>::Item` or `<T as Trait>::Item`).
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]

6
compiler/rustc_middle/src/ty/mod.rs
View File

@ -114,9 +114,9 @@ pub use self::rvalue_scopes::RvalueScopes;
pub use self::sty::{ pub use self::sty::{
AliasTy, Article, Binder, BoundTy, BoundTyKind, BoundVariableKind, CanonicalPolyFnSig, AliasTy, Article, Binder, BoundTy, BoundTyKind, BoundVariableKind, CanonicalPolyFnSig,
ClosureArgs, ClosureArgsParts, CoroutineArgs, CoroutineArgsParts, CoroutineClosureArgs, ClosureArgs, ClosureArgsParts, CoroutineArgs, CoroutineArgsParts, CoroutineClosureArgs,
CoroutineClosureArgsParts, CoroutineClosureSignature, FnSig, GenSig, InlineConstArgs, CoroutineClosureArgsParts, CoroutineClosureSignature, EarlyBinder, FnSig, GenSig,
InlineConstArgsParts, ParamConst, ParamTy, PolyFnSig, TyKind, TypeAndMut, UpvarArgs, InlineConstArgs, InlineConstArgsParts, ParamConst, ParamTy, PolyFnSig, TyKind, TypeAndMut,
VarianceDiagInfo, UpvarArgs, VarianceDiagInfo,
}; };
pub use self::trait_def::TraitDef; pub use self::trait_def::TraitDef;
pub use self::typeck_results::{ pub use self::typeck_results::{

14
compiler/rustc_middle/src/ty/region.rs
View File

@ -138,6 +138,14 @@ impl<'tcx> Region<'tcx> {
} }
impl<'tcx> rustc_type_ir::inherent::Region<TyCtxt<'tcx>> for Region<'tcx> { impl<'tcx> rustc_type_ir::inherent::Region<TyCtxt<'tcx>> for Region<'tcx> {
fn new_bound(
interner: TyCtxt<'tcx>,
debruijn: ty::DebruijnIndex,
var: ty::BoundRegion,
) -> Self {
Region::new_bound(interner, debruijn, var)
}
fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self { fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
Region::new_bound(tcx, debruijn, ty::BoundRegion { var, kind: ty::BoundRegionKind::BrAnon }) Region::new_bound(tcx, debruijn, ty::BoundRegion { var, kind: ty::BoundRegionKind::BrAnon })
} }
@ -340,6 +348,12 @@ pub struct EarlyParamRegion {
pub name: Symbol, pub name: Symbol,
} }
impl rustc_type_ir::inherent::ParamLike for EarlyParamRegion {
fn index(self) -> u32 {
self.index
}
}
impl std::fmt::Debug for EarlyParamRegion { impl std::fmt::Debug for EarlyParamRegion {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
// FIXME(BoxyUwU): self.def_id goes first because of `erased-regions-in-hidden-ty.rs` being impossible to write // FIXME(BoxyUwU): self.def_id goes first because of `erased-regions-in-hidden-ty.rs` being impossible to write

17
compiler/rustc_middle/src/ty/sty.rs
View File

@ -40,6 +40,7 @@ pub type TypeAndMut<'tcx> = ir::TypeAndMut<TyCtxt<'tcx>>;
pub type AliasTy<'tcx> = ir::AliasTy<TyCtxt<'tcx>>; pub type AliasTy<'tcx> = ir::AliasTy<TyCtxt<'tcx>>;
pub type FnSig<'tcx> = ir::FnSig<TyCtxt<'tcx>>; pub type FnSig<'tcx> = ir::FnSig<TyCtxt<'tcx>>;
pub type Binder<'tcx, T> = ir::Binder<TyCtxt<'tcx>, T>; pub type Binder<'tcx, T> = ir::Binder<TyCtxt<'tcx>, T>;
pub type EarlyBinder<'tcx, T> = ir::EarlyBinder<TyCtxt<'tcx>, T>;
pub trait Article { pub trait Article {
fn article(&self) -> &'static str; fn article(&self) -> &'static str;
@ -954,6 +955,12 @@ pub struct ParamTy {
pub name: Symbol, pub name: Symbol,
} }
impl rustc_type_ir::inherent::ParamLike for ParamTy {
fn index(self) -> u32 {
self.index
}
}
impl<'tcx> ParamTy { impl<'tcx> ParamTy {
pub fn new(index: u32, name: Symbol) -> ParamTy { pub fn new(index: u32, name: Symbol) -> ParamTy {
ParamTy { index, name } ParamTy { index, name }
@ -982,6 +989,12 @@ pub struct ParamConst {
pub name: Symbol, pub name: Symbol,
} }
impl rustc_type_ir::inherent::ParamLike for ParamConst {
fn index(self) -> u32 {
self.index
}
}
impl ParamConst { impl ParamConst {
pub fn new(index: u32, name: Symbol) -> ParamConst { pub fn new(index: u32, name: Symbol) -> ParamConst {
ParamConst { index, name } ParamConst { index, name }
@ -1423,6 +1436,10 @@ impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
Ty::new_var(tcx, vid) Ty::new_var(tcx, vid)
} }
fn new_bound(interner: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundTy) -> Self {
Ty::new_bound(interner, debruijn, var)
}
fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self { fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
Ty::new_bound(tcx, debruijn, ty::BoundTy { var, kind: ty::BoundTyKind::Anon }) Ty::new_bound(tcx, debruijn, ty::BoundTy { var, kind: ty::BoundTyKind::Anon })
} }

1
compiler/rustc_type_ir/Cargo.toml
View File

@ -15,6 +15,7 @@ rustc_serialize = { path = "../rustc_serialize", optional = true }
rustc_span = { path = "../rustc_span", optional = true } rustc_span = { path = "../rustc_span", optional = true }
rustc_type_ir_macros = { path = "../rustc_type_ir_macros" } rustc_type_ir_macros = { path = "../rustc_type_ir_macros" }
smallvec = { version = "1.8.1", default-features = false } smallvec = { version = "1.8.1", default-features = false }
tracing = "0.1"
# tidy-alphabetical-end # tidy-alphabetical-end
[features] [features]

519
compiler/rustc_type_ir/src/binder.rs
View File

@ -1,12 +1,14 @@
use std::fmt::Debug; use std::fmt::Debug;
use std::hash::Hash; use std::hash::Hash;
use std::marker::PhantomData;
use std::ops::{ControlFlow, Deref}; use std::ops::{ControlFlow, Deref};
#[cfg(feature = "nightly")] #[cfg(feature = "nightly")]
use rustc_macros::HashStable_NoContext; use rustc_macros::{HashStable_NoContext, TyDecodable, TyEncodable};
use rustc_serialize::Decodable; use rustc_serialize::Decodable;
use tracing::debug;
use crate::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable}; use crate::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
use crate::inherent::*; use crate::inherent::*;
use crate::lift::Lift; use crate::lift::Lift;
use crate::visit::{Flags, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor}; use crate::visit::{Flags, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor};
@ -338,3 +340,516 @@ impl<I: Interner> TypeVisitor<I> for ValidateBoundVars<I> {
ControlFlow::Continue(()) ControlFlow::Continue(())
} }
} }
/// Similar to [`super::Binder`] except that it tracks early bound generics, i.e. `struct Foo<T>(T)`
/// needs `T` instantiated immediately. This type primarily exists to avoid forgetting to call
/// `instantiate`.
///
/// If you don't have anything to `instantiate`, you may be looking for
/// [`instantiate_identity`](EarlyBinder::instantiate_identity) or [`skip_binder`](EarlyBinder::skip_binder).
#[derive(derivative::Derivative)]
#[derivative(
Clone(bound = "T: Clone"),
Copy(bound = "T: Copy"),
PartialEq(bound = "T: PartialEq"),
Eq(bound = "T: Eq"),
Ord(bound = "T: Ord"),
PartialOrd(bound = "T: Ord"),
Hash(bound = "T: Hash"),
Debug(bound = "T: Debug")
)]
#[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
pub struct EarlyBinder<I: Interner, T> {
value: T,
_tcx: PhantomData<I>,
}
/// For early binders, you should first call `instantiate` before using any visitors.
#[cfg(feature = "nightly")]
impl<I: Interner, T> !TypeFoldable<I> for ty::EarlyBinder<I, T> {}
/// For early binders, you should first call `instantiate` before using any visitors.
#[cfg(feature = "nightly")]
impl<I: Interner, T> !TypeVisitable<I> for ty::EarlyBinder<I, T> {}
impl<I: Interner, T> EarlyBinder<I, T> {
pub fn bind(value: T) -> EarlyBinder<I, T> {
EarlyBinder { value, _tcx: PhantomData }
}
pub fn as_ref(&self) -> EarlyBinder<I, &T> {
EarlyBinder { value: &self.value, _tcx: PhantomData }
}
pub fn map_bound_ref<F, U>(&self, f: F) -> EarlyBinder<I, U>
where
F: FnOnce(&T) -> U,
{
self.as_ref().map_bound(f)
}
pub fn map_bound<F, U>(self, f: F) -> EarlyBinder<I, U>
where
F: FnOnce(T) -> U,
{
let value = f(self.value);
EarlyBinder { value, _tcx: PhantomData }
}
pub fn try_map_bound<F, U, E>(self, f: F) -> Result<EarlyBinder<I, U>, E>
where
F: FnOnce(T) -> Result<U, E>,
{
let value = f(self.value)?;
Ok(EarlyBinder { value, _tcx: PhantomData })
}
pub fn rebind<U>(&self, value: U) -> EarlyBinder<I, U> {
EarlyBinder { value, _tcx: PhantomData }
}
/// Skips the binder and returns the "bound" value.
/// This can be used to extract data that does not depend on generic parameters
/// (e.g., getting the `DefId` of the inner value or getting the number of
/// arguments of an `FnSig`). Otherwise, consider using
/// [`instantiate_identity`](EarlyBinder::instantiate_identity).
///
/// To skip the binder on `x: &EarlyBinder<I, T>` to obtain `&T`, leverage
/// [`EarlyBinder::as_ref`](EarlyBinder::as_ref): `x.as_ref().skip_binder()`.
///
/// See also [`Binder::skip_binder`](super::Binder::skip_binder), which is
/// the analogous operation on [`super::Binder`].
pub fn skip_binder(self) -> T {
self.value
}
}
impl<I: Interner, T> EarlyBinder<I, Option<T>> {
pub fn transpose(self) -> Option<EarlyBinder<I, T>> {
self.value.map(|value| EarlyBinder { value, _tcx: PhantomData })
}
}
impl<'s, I: Interner, Iter: IntoIterator> EarlyBinder<I, Iter>
where
Iter::Item: TypeFoldable<I>,
{
pub fn iter_instantiated(
self,
tcx: I,
args: &'s [I::GenericArg],
) -> IterInstantiated<'s, I, Iter> {
IterInstantiated { it: self.value.into_iter(), tcx, args }
}
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
/// but on an iterator of `TypeFoldable` values.
pub fn instantiate_identity_iter(self) -> Iter::IntoIter {
self.value.into_iter()
}
}
pub struct IterInstantiated<'s, I: Interner, Iter: IntoIterator> {
it: Iter::IntoIter,
tcx: I,
args: &'s [I::GenericArg],
}
impl<I: Interner, Iter: IntoIterator> Iterator for IterInstantiated<'_, I, Iter>
where
Iter::Item: TypeFoldable<I>,
{
type Item = Iter::Item;
fn next(&mut self) -> Option<Self::Item> {
Some(
EarlyBinder { value: self.it.next()?, _tcx: PhantomData }
.instantiate(self.tcx, self.args),
)
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.it.size_hint()
}
}
impl<I: Interner, Iter: IntoIterator> DoubleEndedIterator for IterInstantiated<'_, I, Iter>
where
Iter::IntoIter: DoubleEndedIterator,
Iter::Item: TypeFoldable<I>,
{
fn next_back(&mut self) -> Option<Self::Item> {
Some(
EarlyBinder { value: self.it.next_back()?, _tcx: PhantomData }
.instantiate(self.tcx, self.args),
)
}
}
impl<I: Interner, Iter: IntoIterator> ExactSizeIterator for IterInstantiated<'_, I, Iter>
where
Iter::IntoIter: ExactSizeIterator,
Iter::Item: TypeFoldable<I>,
{
}
impl<'s, I: Interner, Iter: IntoIterator> EarlyBinder<I, Iter>
where
Iter::Item: Deref,
<Iter::Item as Deref>::Target: Copy + TypeFoldable<I>,
{
pub fn iter_instantiated_copied(
self,
tcx: I,
args: &'s [I::GenericArg],
) -> IterInstantiatedCopied<'s, I, Iter> {
IterInstantiatedCopied { it: self.value.into_iter(), tcx, args }
}
/// Similar to [`instantiate_identity`](EarlyBinder::instantiate_identity),
/// but on an iterator of values that deref to a `TypeFoldable`.
pub fn instantiate_identity_iter_copied(
self,
) -> impl Iterator<Item = <Iter::Item as Deref>::Target> {
self.value.into_iter().map(|v| *v)
}
}
pub struct IterInstantiatedCopied<'a, I: Interner, Iter: IntoIterator> {
it: Iter::IntoIter,
tcx: I,
args: &'a [I::GenericArg],
}
impl<I: Interner, Iter: IntoIterator> Iterator for IterInstantiatedCopied<'_, I, Iter>
where
Iter::Item: Deref,
<Iter::Item as Deref>::Target: Copy + TypeFoldable<I>,
{
type Item = <Iter::Item as Deref>::Target;
fn next(&mut self) -> Option<Self::Item> {
self.it.next().map(|value| {
EarlyBinder { value: *value, _tcx: PhantomData }.instantiate(self.tcx, self.args)
})
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.it.size_hint()
}
}
impl<I: Interner, Iter: IntoIterator> DoubleEndedIterator for IterInstantiatedCopied<'_, I, Iter>
where
Iter::IntoIter: DoubleEndedIterator,
Iter::Item: Deref,
<Iter::Item as Deref>::Target: Copy + TypeFoldable<I>,
{
fn next_back(&mut self) -> Option<Self::Item> {
self.it.next_back().map(|value| {
EarlyBinder { value: *value, _tcx: PhantomData }.instantiate(self.tcx, self.args)
})
}
}
impl<I: Interner, Iter: IntoIterator> ExactSizeIterator for IterInstantiatedCopied<'_, I, Iter>
where
Iter::IntoIter: ExactSizeIterator,
Iter::Item: Deref,
<Iter::Item as Deref>::Target: Copy + TypeFoldable<I>,
{
}
pub struct EarlyBinderIter<I, T> {
t: T,
_tcx: PhantomData<I>,
}
impl<I: Interner, T: IntoIterator> EarlyBinder<I, T> {
pub fn transpose_iter(self) -> EarlyBinderIter<I, T::IntoIter> {
EarlyBinderIter { t: self.value.into_iter(), _tcx: PhantomData }
}
}
impl<I: Interner, T: Iterator> Iterator for EarlyBinderIter<I, T> {
type Item = EarlyBinder<I, T::Item>;
fn next(&mut self) -> Option<Self::Item> {
self.t.next().map(|value| EarlyBinder { value, _tcx: PhantomData })
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.t.size_hint()
}
}
impl<I: Interner, T: TypeFoldable<I>> ty::EarlyBinder<I, T> {
pub fn instantiate(self, tcx: I, args: &[I::GenericArg]) -> T {
let mut folder = ArgFolder { tcx, args, binders_passed: 0 };
self.value.fold_with(&mut folder)
}
/// Makes the identity replacement `T0 => T0, ..., TN => TN`.
/// Conceptually, this converts universally bound variables into placeholders
/// when inside of a given item.
///
/// For example, consider `for<T> fn foo<T>(){ .. }`:
/// - Outside of `foo`, `T` is bound (represented by the presence of `EarlyBinder`).
/// - Inside of the body of `foo`, we treat `T` as a placeholder by calling
/// `instantiate_identity` to discharge the `EarlyBinder`.
pub fn instantiate_identity(self) -> T {
self.value
}
/// Returns the inner value, but only if it contains no bound vars.
pub fn no_bound_vars(self) -> Option<T> {
if !self.value.has_param() { Some(self.value) } else { None }
}
}
///////////////////////////////////////////////////////////////////////////
// The actual instantiation engine itself is a type folder.
struct ArgFolder<'a, I: Interner> {
tcx: I,
args: &'a [I::GenericArg],
/// Number of region binders we have passed through while doing the instantiation
binders_passed: u32,
}
impl<'a, I: Interner> TypeFolder<I> for ArgFolder<'a, I> {
#[inline]
fn interner(&self) -> I {
self.tcx
}
fn fold_binder<T: TypeFoldable<I>>(&mut self, t: ty::Binder<I, T>) -> ty::Binder<I, T> {
self.binders_passed += 1;
let t = t.super_fold_with(self);
self.binders_passed -= 1;
t
}
fn fold_region(&mut self, r: I::Region) -> I::Region {
// Note: This routine only handles regions that are bound on
// type declarations and other outer declarations, not those
// bound in *fn types*. Region instantiation of the bound
// regions that appear in a function signature is done using
// the specialized routine `ty::replace_late_regions()`.
match r.kind() {
ty::ReEarlyParam(data) => {
let rk = self.args.get(data.index() as usize).map(|k| k.kind());
match rk {
Some(ty::GenericArgKind::Lifetime(lt)) => self.shift_region_through_binders(lt),
Some(other) => self.region_param_expected(data, r, other),
None => self.region_param_out_of_range(data, r),
}
}
ty::ReBound(..)
| ty::ReLateParam(_)
| ty::ReStatic
| ty::RePlaceholder(_)
| ty::ReErased
| ty::ReError(_) => r,
ty::ReVar(_) => panic!("unexpected region: {r:?}"),
}
}
fn fold_ty(&mut self, t: I::Ty) -> I::Ty {
if !t.has_param() {
return t;
}
match t.kind() {
ty::Param(p) => self.ty_for_param(p, t),
_ => t.super_fold_with(self),
}
}
fn fold_const(&mut self, c: I::Const) -> I::Const {
if let ty::ConstKind::Param(p) = c.kind() {
self.const_for_param(p, c)
} else {
c.super_fold_with(self)
}
}
}
impl<'a, I: Interner> ArgFolder<'a, I> {
fn ty_for_param(&self, p: I::ParamTy, source_ty: I::Ty) -> I::Ty {
// Look up the type in the args. It really should be in there.
let opt_ty = self.args.get(p.index() as usize).map(|k| k.kind());
let ty = match opt_ty {
Some(ty::GenericArgKind::Type(ty)) => ty,
Some(kind) => self.type_param_expected(p, source_ty, kind),
None => self.type_param_out_of_range(p, source_ty),
};
self.shift_vars_through_binders(ty)
}
#[cold]
#[inline(never)]
fn type_param_expected(&self, p: I::ParamTy, ty: I::Ty, kind: ty::GenericArgKind<I>) -> ! {
panic!(
"expected type for `{:?}` ({:?}/{}) but found {:?} when instantiating, args={:?}",
p,
ty,
p.index(),
kind,
self.args,
)
}
#[cold]
#[inline(never)]
fn type_param_out_of_range(&self, p: I::ParamTy, ty: I::Ty) -> ! {
panic!(
"type parameter `{:?}` ({:?}/{}) out of range when instantiating, args={:?}",
p,
ty,
p.index(),
self.args,
)
}
fn const_for_param(&self, p: I::ParamConst, source_ct: I::Const) -> I::Const {
// Look up the const in the args. It really should be in there.
let opt_ct = self.args.get(p.index() as usize).map(|k| k.kind());
let ct = match opt_ct {
Some(ty::GenericArgKind::Const(ct)) => ct,
Some(kind) => self.const_param_expected(p, source_ct, kind),
None => self.const_param_out_of_range(p, source_ct),
};
self.shift_vars_through_binders(ct)
}
#[cold]
#[inline(never)]
fn const_param_expected(
&self,
p: I::ParamConst,
ct: I::Const,
kind: ty::GenericArgKind<I>,
) -> ! {
panic!(
"expected const for `{:?}` ({:?}/{}) but found {:?} when instantiating args={:?}",
p,
ct,
p.index(),
kind,
self.args,
)
}
#[cold]
#[inline(never)]
fn const_param_out_of_range(&self, p: I::ParamConst, ct: I::Const) -> ! {
panic!(
"const parameter `{:?}` ({:?}/{}) out of range when instantiating args={:?}",
p,
ct,
p.index(),
self.args,
)
}
#[cold]
#[inline(never)]
fn region_param_expected(
&self,
ebr: I::EarlyParamRegion,
r: I::Region,
kind: ty::GenericArgKind<I>,
) -> ! {
panic!(
"expected region for `{:?}` ({:?}/{}) but found {:?} when instantiating args={:?}",
ebr,
r,
ebr.index(),
kind,
self.args,
)
}
#[cold]
#[inline(never)]
fn region_param_out_of_range(&self, ebr: I::EarlyParamRegion, r: I::Region) -> ! {
panic!(
"const parameter `{:?}` ({:?}/{}) out of range when instantiating args={:?}",
ebr,
r,
ebr.index(),
self.args,
)
}
/// It is sometimes necessary to adjust the De Bruijn indices during instantiation. This occurs
/// when we are instantating a type with escaping bound vars into a context where we have
/// passed through binders. That's quite a mouthful. Let's see an example:
///
/// ```
/// type Func<A> = fn(A);
/// type MetaFunc = for<'a> fn(Func<&'a i32>);
/// ```
///
/// The type `MetaFunc`, when fully expanded, will be
/// ```ignore (illustrative)
/// for<'a> fn(fn(&'a i32))
/// // ^~ ^~ ^~~
/// // | | |
/// // | | DebruijnIndex of 2
/// // Binders
/// ```
/// Here the `'a` lifetime is bound in the outer function, but appears as an argument of the
/// inner one. Therefore, that appearance will have a DebruijnIndex of 2, because we must skip
/// over the inner binder (remember that we count De Bruijn indices from 1). However, in the
/// definition of `MetaFunc`, the binder is not visible, so the type `&'a i32` will have a
/// De Bruijn index of 1. It's only during the instantiation that we can see we must increase the
/// depth by 1 to account for the binder that we passed through.
///
/// As a second example, consider this twist:
///
/// ```
/// type FuncTuple<A> = (A,fn(A));
/// type MetaFuncTuple = for<'a> fn(FuncTuple<&'a i32>);
/// ```
///
/// Here the final type will be:
/// ```ignore (illustrative)
/// for<'a> fn((&'a i32, fn(&'a i32)))
/// // ^~~ ^~~
/// // | |
/// // DebruijnIndex of 1 |
/// // DebruijnIndex of 2
/// ```
/// As indicated in the diagram, here the same type `&'a i32` is instantiated once, but in the
/// first case we do not increase the De Bruijn index and in the second case we do. The reason
/// is that only in the second case have we passed through a fn binder.
fn shift_vars_through_binders<T: TypeFoldable<I>>(&self, val: T) -> T {
debug!(
"shift_vars(val={:?}, binders_passed={:?}, has_escaping_bound_vars={:?})",
val,
self.binders_passed,
val.has_escaping_bound_vars()
);
if self.binders_passed == 0 || !val.has_escaping_bound_vars() {
return val;
}
let result = ty::fold::shift_vars(TypeFolder::interner(self), val, self.binders_passed);
debug!("shift_vars: shifted result = {:?}", result);
result
}
fn shift_region_through_binders(&self, region: I::Region) -> I::Region {
if self.binders_passed == 0 || !region.has_escaping_bound_vars() {
return region;
}
ty::fold::shift_region(self.tcx, region, self.binders_passed)
}
}

96
compiler/rustc_type_ir/src/fold.rs
View File

@ -47,8 +47,10 @@
use rustc_index::{Idx, IndexVec}; use rustc_index::{Idx, IndexVec};
use std::mem; use std::mem;
use tracing::debug;
use crate::visit::TypeVisitable; use crate::inherent::*;
use crate::visit::{TypeVisitable, TypeVisitableExt as _};
use crate::{self as ty, Interner, Lrc}; use crate::{self as ty, Interner, Lrc};
#[cfg(feature = "nightly")] #[cfg(feature = "nightly")]
@ -325,3 +327,95 @@ impl<I: Interner, T: TypeFoldable<I>, Ix: Idx> TypeFoldable<I> for IndexVec<Ix,
self.raw.try_fold_with(folder).map(IndexVec::from_raw) self.raw.try_fold_with(folder).map(IndexVec::from_raw)
} }
} }
///////////////////////////////////////////////////////////////////////////
// Shifter
//
// Shifts the De Bruijn indices on all escaping bound vars by a
// fixed amount. Useful in instantiation or when otherwise introducing
// a binding level that is not intended to capture the existing bound
// vars. See comment on `shift_vars_through_binders` method in
// `rustc_middle/src/ty/generic_args.rs` for more details.
struct Shifter<I: Interner> {
tcx: I,
current_index: ty::DebruijnIndex,
amount: u32,
}
impl<I: Interner> Shifter<I> {
pub fn new(tcx: I, amount: u32) -> Self {
Shifter { tcx, current_index: ty::INNERMOST, amount }
}
}
impl<I: Interner> TypeFolder<I> for Shifter<I> {
fn interner(&self) -> I {
self.tcx
}
fn fold_binder<T: TypeFoldable<I>>(&mut self, t: ty::Binder<I, T>) -> ty::Binder<I, T> {
self.current_index.shift_in(1);
let t = t.super_fold_with(self);
self.current_index.shift_out(1);
t
}
fn fold_region(&mut self, r: I::Region) -> I::Region {
match r.kind() {
ty::ReBound(debruijn, br) if debruijn >= self.current_index => {
let debruijn = debruijn.shifted_in(self.amount);
Region::new_bound(self.tcx, debruijn, br)
}
_ => r,
}
}
fn fold_ty(&mut self, ty: I::Ty) -> I::Ty {
match ty.kind() {
ty::Bound(debruijn, bound_ty) if debruijn >= self.current_index => {
let debruijn = debruijn.shifted_in(self.amount);
Ty::new_bound(self.tcx, debruijn, bound_ty)
}
_ if ty.has_vars_bound_at_or_above(self.current_index) => ty.super_fold_with(self),
_ => ty,
}
}
fn fold_const(&mut self, ct: I::Const) -> I::Const {
match ct.kind() {
ty::ConstKind::Bound(debruijn, bound_ct) if debruijn >= self.current_index => {
let debruijn = debruijn.shifted_in(self.amount);
Const::new_bound(self.tcx, debruijn, bound_ct, ct.ty())
}
_ => ct.super_fold_with(self),
}
}
fn fold_predicate(&mut self, p: I::Predicate) -> I::Predicate {
if p.has_vars_bound_at_or_above(self.current_index) { p.super_fold_with(self) } else { p }
}
}
pub fn shift_region<I: Interner>(tcx: I, region: I::Region, amount: u32) -> I::Region {
match region.kind() {
ty::ReBound(debruijn, br) if amount > 0 => {
Region::new_bound(tcx, debruijn.shifted_in(amount), br)
}
_ => region,
}
}
pub fn shift_vars<I: Interner, T>(tcx: I, value: T, amount: u32) -> T
where
T: TypeFoldable<I>,
{
debug!("shift_vars(value={:?}, amount={})", value, amount);
if amount == 0 || !value.has_escaping_bound_vars() {
return value;
}
value.fold_with(&mut Shifter::new(tcx, amount))
}

11
compiler/rustc_type_ir/src/inherent.rs
View File

@ -29,6 +29,8 @@ pub trait Ty<I: Interner<Ty = Self>>:
fn new_var(interner: I, var: ty::TyVid) -> Self; fn new_var(interner: I, var: ty::TyVid) -> Self;
fn new_bound(interner: I, debruijn: ty::DebruijnIndex, var: I::BoundTy) -> Self;
fn new_anon_bound(interner: I, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self; fn new_anon_bound(interner: I, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self;
fn new_alias(interner: I, kind: ty::AliasTyKind, alias_ty: ty::AliasTy<I>) -> Self; fn new_alias(interner: I, kind: ty::AliasTyKind, alias_ty: ty::AliasTy<I>) -> Self;
@ -65,7 +67,10 @@ pub trait Region<I: Interner<Region = Self>>:
+ Into<I::GenericArg> + Into<I::GenericArg>
+ IntoKind<Kind = ty::RegionKind<I>> + IntoKind<Kind = ty::RegionKind<I>>
+ Flags + Flags
+ TypeVisitable<I>
{ {
fn new_bound(interner: I, debruijn: ty::DebruijnIndex, var: I::BoundRegion) -> Self;
fn new_anon_bound(interner: I, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self; fn new_anon_bound(interner: I, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self;
fn new_static(interner: I) -> Self; fn new_static(interner: I) -> Self;
@ -87,6 +92,8 @@ pub trait Const<I: Interner<Const = Self>>:
fn new_var(interner: I, var: ty::ConstVid, ty: I::Ty) -> Self; fn new_var(interner: I, var: ty::ConstVid, ty: I::Ty) -> Self;
fn new_bound(interner: I, debruijn: ty::DebruijnIndex, var: I::BoundConst, ty: I::Ty) -> Self;
fn new_anon_bound( fn new_anon_bound(
interner: I, interner: I,
debruijn: ty::DebruijnIndex, debruijn: ty::DebruijnIndex,
@ -162,3 +169,7 @@ pub trait BoundVarLike<I: Interner> {
fn assert_eq(self, var: I::BoundVarKind); fn assert_eq(self, var: I::BoundVarKind);
} }
pub trait ParamLike {
fn index(self) -> u32;
}

6
compiler/rustc_type_ir/src/interner.rs
View File

@ -65,7 +65,7 @@ pub trait Interner:
type Ty: Ty<Self>; type Ty: Ty<Self>;
type Tys: Tys<Self>; type Tys: Tys<Self>;
type FnInputTys: Copy + Debug + Hash + Eq + Deref<Target = [Self::Ty]> + TypeVisitable<Self>; type FnInputTys: Copy + Debug + Hash + Eq + Deref<Target = [Self::Ty]> + TypeVisitable<Self>;
type ParamTy: Copy + Debug + Hash + Eq; type ParamTy: Copy + Debug + Hash + Eq + ParamLike;
type BoundTy: Copy + Debug + Hash + Eq + BoundVarLike<Self>; type BoundTy: Copy + Debug + Hash + Eq + BoundVarLike<Self>;
type PlaceholderTy: PlaceholderLike; type PlaceholderTy: PlaceholderLike;
@ -81,14 +81,14 @@ pub trait Interner:
// Kinds of consts // Kinds of consts
type Const: Const<Self>; type Const: Const<Self>;
type PlaceholderConst: PlaceholderLike; type PlaceholderConst: PlaceholderLike;
type ParamConst: Copy + Debug + Hash + Eq; type ParamConst: Copy + Debug + Hash + Eq + ParamLike;
type BoundConst: Copy + Debug + Hash + Eq + BoundVarLike<Self>; type BoundConst: Copy + Debug + Hash + Eq + BoundVarLike<Self>;
type ValueConst: Copy + Debug + Hash + Eq; type ValueConst: Copy + Debug + Hash + Eq;
type ExprConst: Copy + DebugWithInfcx<Self> + Hash + Eq; type ExprConst: Copy + DebugWithInfcx<Self> + Hash + Eq;
// Kinds of regions // Kinds of regions
type Region: Region<Self>; type Region: Region<Self>;
type EarlyParamRegion: Copy + Debug + Hash + Eq; type EarlyParamRegion: Copy + Debug + Hash + Eq + ParamLike;
type LateParamRegion: Copy + Debug + Hash + Eq; type LateParamRegion: Copy + Debug + Hash + Eq;
type BoundRegion: Copy + Debug + Hash + Eq + BoundVarLike<Self>; type BoundRegion: Copy + Debug + Hash + Eq + BoundVarLike<Self>;
type PlaceholderRegion: PlaceholderLike; type PlaceholderRegion: PlaceholderLike;

2
compiler/rustc_type_ir/src/lib.rs
View File

@ -1,6 +1,6 @@
#![cfg_attr( #![cfg_attr(
feature = "nightly", feature = "nightly",
feature(associated_type_defaults, min_specialization, never_type, rustc_attrs) feature(associated_type_defaults, min_specialization, never_type, rustc_attrs, negative_impls)
)] )]
#![allow(rustc::usage_of_ty_tykind)] #![allow(rustc::usage_of_ty_tykind)]
#![cfg_attr(feature = "nightly", allow(internal_features))] #![cfg_attr(feature = "nightly", allow(internal_features))]