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Split TypeFolder and FallibleTypeFolder

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This commit is contained in:
Michael Goulet 2025-04-14 15:10:43 +00:00
parent 13b4734e31
commit c774adcbb5
10 changed files with 396 additions and 187 deletions
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60
compiler/rustc_macros/src/type_foldable.rs
View file

@ -14,31 +14,33 @@ pub(super) fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_m
s.add_bounds(synstructure::AddBounds::Generics);
s.bind_with(|_| synstructure::BindStyle::Move);
let try_body_fold = s.each_variant(|vi| {
let bindings = vi.bindings();
vi.construct(|_, index| {
let bind = &bindings[index];
// retain value of fields with #[type_foldable(identity)]
if has_ignore_attr(&bind.ast().attrs, "type_foldable", "identity") {
bind.to_token_stream()
} else {
quote! {
::rustc_middle::ty::TypeFoldable::try_fold_with(#bind, __folder)?
}
}
})
});
let body_fold = s.each_variant(|vi| {
let bindings = vi.bindings();
vi.construct(|_, index| {
let bind = &bindings[index];
let mut fixed = false;
// retain value of fields with #[type_foldable(identity)]
bind.ast().attrs.iter().for_each(|x| {
if !x.path().is_ident("type_foldable") {
return;
}
let _ = x.parse_nested_meta(|nested| {
if nested.path.is_ident("identity") {
fixed = true;
}
Ok(())
});
});
if fixed {
if has_ignore_attr(&bind.ast().attrs, "type_foldable", "identity") {
bind.to_token_stream()
} else {
quote! {
::rustc_middle::ty::TypeFoldable::try_fold_with(#bind, __folder)?
::rustc_middle::ty::TypeFoldable::fold_with(#bind, __folder)
}
}
})
@ -51,8 +53,32 @@ pub(super) fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_m
self,
__folder: &mut __F
) -> Result<Self, __F::Error> {
Ok(match self { #body_fold })
Ok(match self { #try_body_fold })
}
fn fold_with<__F: ::rustc_middle::ty::TypeFolder<::rustc_middle::ty::TyCtxt<'tcx>>>(
self,
__folder: &mut __F
) -> Self {
match self { #body_fold }
}
},
)
}
fn has_ignore_attr(attrs: &[syn::Attribute], name: &'static str, meta: &'static str) -> bool {
let mut ignored = false;
attrs.iter().for_each(|attr| {
if !attr.path().is_ident(name) {
return;
}
let _ = attr.parse_nested_meta(|nested| {
if nested.path.is_ident(meta) {
ignored = true;
}
Ok(())
});
});
ignored
}

9
compiler/rustc_middle/src/infer/canonical.rs
View file

@ -39,15 +39,6 @@ pub type CanonicalVarInfo<'tcx> = ir::CanonicalVarInfo<TyCtxt<'tcx>>;
pub type CanonicalVarValues<'tcx> = ir::CanonicalVarValues<TyCtxt<'tcx>>;
pub type CanonicalVarInfos<'tcx> = &'tcx List<CanonicalVarInfo<'tcx>>;
impl<'tcx> ty::TypeFoldable<TyCtxt<'tcx>> for CanonicalVarInfos<'tcx> {
fn try_fold_with<F: ty::FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::fold_list(self, folder, |tcx, v| tcx.mk_canonical_var_infos(v))
}
}
/// When we canonicalize a value to form a query, we wind up replacing
/// various parts of it with canonical variables. This struct stores
/// those replaced bits to remember for when we process the query

4
compiler/rustc_middle/src/mir/syntax.rs
View file

@ -931,6 +931,8 @@ pub enum TerminatorKind<'tcx> {
asm_macro: InlineAsmMacro,
/// The template for the inline assembly, with placeholders.
#[type_foldable(identity)]
#[type_visitable(ignore)]
template: &'tcx [InlineAsmTemplatePiece],
/// The operands for the inline assembly, as `Operand`s or `Place`s.
@ -941,6 +943,8 @@ pub enum TerminatorKind<'tcx> {
/// Source spans for each line of the inline assembly code. These are
/// used to map assembler errors back to the line in the source code.
#[type_foldable(identity)]
#[type_visitable(ignore)]
line_spans: &'tcx [Span],
/// Valid targets for the inline assembly.

47
compiler/rustc_middle/src/ty/generic_args.rs
View file

@ -17,7 +17,7 @@ use smallvec::SmallVec;
use crate::ty::codec::{TyDecoder, TyEncoder};
use crate::ty::{
self, ClosureArgs, CoroutineArgs, CoroutineClosureArgs, FallibleTypeFolder, InlineConstArgs,
Lift, List, Ty, TyCtxt, TypeFoldable, TypeVisitable, TypeVisitor, VisitorResult,
Lift, List, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeVisitable, TypeVisitor, VisitorResult,
walk_visitable_list,
};
@ -337,6 +337,14 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArg<'tcx> {
GenericArgKind::Const(ct) => ct.try_fold_with(folder).map(Into::into),
}
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
match self.unpack() {
GenericArgKind::Lifetime(lt) => lt.fold_with(folder).into(),
GenericArgKind::Type(ty) => ty.fold_with(folder).into(),
GenericArgKind::Const(ct) => ct.fold_with(folder).into(),
}
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for GenericArg<'tcx> {
@ -606,6 +614,27 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for GenericArgsRef<'tcx> {
}
}
0 => Ok(self),
_ => ty::util::try_fold_list(self, folder, |tcx, v| tcx.mk_args(v)),
}
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
// See justification for this behavior in `try_fold_with`.
match self.len() {
1 => {
let param0 = self[0].fold_with(folder);
if param0 == self[0] { self } else { folder.cx().mk_args(&[param0]) }
}
2 => {
let param0 = self[0].fold_with(folder);
let param1 = self[1].fold_with(folder);
if param0 == self[0] && param1 == self[1] {
self
} else {
folder.cx().mk_args(&[param0, param1])
}
}
0 => self,
_ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_args(v)),
}
}
@ -641,6 +670,22 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx>> {
Ok(folder.cx().mk_type_list(&[param0, param1]))
}
}
_ => ty::util::try_fold_list(self, folder, |tcx, v| tcx.mk_type_list(v)),
}
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
// See comment justifying behavior in `try_fold_with`.
match self.len() {
2 => {
let param0 = self[0].fold_with(folder);
let param1 = self[1].fold_with(folder);
if param0 == self[0] && param1 == self[1] {
self
} else {
folder.cx().mk_type_list(&[param0, param1])
}
}
_ => ty::util::fold_list(self, folder, |tcx, v| tcx.mk_type_list(v)),
}
}

7
compiler/rustc_middle/src/ty/mod.rs
View file

@ -537,6 +537,13 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Term<'tcx> {
ty::TermKind::Const(ct) => ct.try_fold_with(folder).map(Into::into),
}
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
match self.unpack() {
ty::TermKind::Ty(ty) => ty.fold_with(folder).into(),
ty::TermKind::Const(ct) => ct.fold_with(folder).into(),
}
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Term<'tcx> {

191
compiler/rustc_middle/src/ty/structural_impls.rs
View file

@ -6,20 +6,19 @@
use std::fmt::{self, Debug};
use rustc_abi::TyAndLayout;
use rustc_ast::InlineAsmTemplatePiece;
use rustc_hir::def::Namespace;
use rustc_hir::def_id::LocalDefId;
use rustc_span::Span;
use rustc_span::source_map::Spanned;
use rustc_type_ir::{ConstKind, VisitorResult, try_visit};
use rustc_type_ir::{ConstKind, TypeFolder, VisitorResult, try_visit};
use super::print::PrettyPrinter;
use super::{GenericArg, GenericArgKind, Pattern, Region};
use crate::infer::canonical::CanonicalVarInfos;
use crate::mir::PlaceElem;
use crate::ty::print::{FmtPrinter, Printer, with_no_trimmed_paths};
use crate::ty::{
self, FallibleTypeFolder, InferConst, Lift, Term, TermKind, Ty, TyCtxt, TypeFoldable,
TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitor,
self, FallibleTypeFolder, Lift, Term, TermKind, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable,
TypeSuperVisitable, TypeVisitable, TypeVisitor,
};
impl fmt::Debug for ty::TraitDef {
@ -271,6 +270,7 @@ TrivialTypeTraversalImpls! {
crate::ty::AssocKind,
crate::ty::BoundRegion,
crate::ty::BoundVar,
crate::ty::InferConst,
crate::ty::Placeholder<crate::ty::BoundRegion>,
crate::ty::Placeholder<crate::ty::BoundTy>,
crate::ty::Placeholder<ty::BoundVar>,
@ -337,24 +337,6 @@ impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::AdtDef<'tcx> {
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::fold_list(self, folder, |tcx, v| tcx.mk_poly_existential_predicates(v))
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<ty::Const<'tcx>> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::fold_list(self, folder, |tcx, v| tcx.mk_const_list(v))
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Pattern<'tcx> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
@ -363,6 +345,11 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Pattern<'tcx> {
let pat = (*self).clone().try_fold_with(folder)?;
Ok(if pat == *self { self } else { folder.cx().mk_pat(pat) })
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
let pat = (*self).clone().fold_with(folder);
if pat == *self { self } else { folder.cx().mk_pat(pat) }
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Pattern<'tcx> {
@ -378,6 +365,10 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Ty<'tcx> {
) -> Result<Self, F::Error> {
folder.try_fold_ty(self)
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
folder.fold_ty(self)
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Ty<'tcx> {
@ -436,6 +427,45 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Ty<'tcx> {
Ok(if *self.kind() == kind { self } else { folder.cx().mk_ty_from_kind(kind) })
}
fn super_fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
let kind = match *self.kind() {
ty::RawPtr(ty, mutbl) => ty::RawPtr(ty.fold_with(folder), mutbl),
ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
ty::Adt(tid, args) => ty::Adt(tid, args.fold_with(folder)),
ty::Dynamic(trait_ty, region, representation) => {
ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder), representation)
}
ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
ty::FnDef(def_id, args) => ty::FnDef(def_id, args.fold_with(folder)),
ty::FnPtr(sig_tys, hdr) => ty::FnPtr(sig_tys.fold_with(folder), hdr),
ty::UnsafeBinder(f) => ty::UnsafeBinder(f.fold_with(folder)),
ty::Ref(r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl),
ty::Coroutine(did, args) => ty::Coroutine(did, args.fold_with(folder)),
ty::CoroutineWitness(did, args) => ty::CoroutineWitness(did, args.fold_with(folder)),
ty::Closure(did, args) => ty::Closure(did, args.fold_with(folder)),
ty::CoroutineClosure(did, args) => ty::CoroutineClosure(did, args.fold_with(folder)),
ty::Alias(kind, data) => ty::Alias(kind, data.fold_with(folder)),
ty::Pat(ty, pat) => ty::Pat(ty.fold_with(folder), pat.fold_with(folder)),
ty::Bool
| ty::Char
| ty::Str
| ty::Int(_)
| ty::Uint(_)
| ty::Float(_)
| ty::Error(_)
| ty::Infer(_)
| ty::Param(..)
| ty::Bound(..)
| ty::Placeholder(..)
| ty::Never
| ty::Foreign(..) => return self,
};
if *self.kind() == kind { self } else { folder.cx().mk_ty_from_kind(kind) }
}
}
impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for Ty<'tcx> {
@ -496,6 +526,10 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Region<'tcx> {
) -> Result<Self, F::Error> {
folder.try_fold_region(self)
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
folder.fold_region(self)
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Region<'tcx> {
@ -511,6 +545,10 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
) -> Result<Self, F::Error> {
folder.try_fold_predicate(self)
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
folder.fold_predicate(self)
}
}
// FIXME(clause): This is wonky
@ -521,6 +559,10 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Clause<'tcx> {
) -> Result<Self, F::Error> {
Ok(folder.try_fold_predicate(self.as_predicate())?.expect_clause())
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
folder.fold_predicate(self.as_predicate()).expect_clause()
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
@ -543,6 +585,11 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
let new = self.kind().try_fold_with(folder)?;
Ok(folder.cx().reuse_or_mk_predicate(self, new))
}
fn super_fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
let new = self.kind().fold_with(folder);
folder.cx().reuse_or_mk_predicate(self, new)
}
}
impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Predicate<'tcx> {
@ -563,15 +610,6 @@ impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Clauses<'tcx> {
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Clauses<'tcx> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::fold_list(self, folder, |tcx, v| tcx.mk_clauses(v))
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Const<'tcx> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
@ -579,6 +617,10 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for ty::Const<'tcx> {
) -> Result<Self, F::Error> {
folder.try_fold_const(self)
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
folder.fold_const(self)
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for ty::Const<'tcx> {
@ -606,6 +648,20 @@ impl<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for ty::Const<'tcx> {
};
if kind != self.kind() { Ok(folder.cx().mk_ct_from_kind(kind)) } else { Ok(self) }
}
fn super_fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
let kind = match self.kind() {
ConstKind::Param(p) => ConstKind::Param(p.fold_with(folder)),
ConstKind::Infer(i) => ConstKind::Infer(i.fold_with(folder)),
ConstKind::Bound(d, b) => ConstKind::Bound(d.fold_with(folder), b.fold_with(folder)),
ConstKind::Placeholder(p) => ConstKind::Placeholder(p.fold_with(folder)),
ConstKind::Unevaluated(uv) => ConstKind::Unevaluated(uv.fold_with(folder)),
ConstKind::Value(v) => ConstKind::Value(v.fold_with(folder)),
ConstKind::Error(e) => ConstKind::Error(e.fold_with(folder)),
ConstKind::Expr(e) => ConstKind::Expr(e.fold_with(folder)),
};
if kind != self.kind() { folder.cx().mk_ct_from_kind(kind) } else { self }
}
}
impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Const<'tcx> {
@ -639,20 +695,9 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for rustc_span::ErrorGuaranteed {
) -> Result<Self, F::Error> {
Ok(self)
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for InferConst {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
_folder: &mut F,
) -> Result<Self, F::Error> {
Ok(self)
}
}
impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for InferConst {
fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, _visitor: &mut V) -> V::Result {
V::Result::output()
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, _folder: &mut F) -> Self {
self
}
}
@ -683,23 +728,9 @@ impl<'tcx, T: TypeFoldable<TyCtxt<'tcx>> + Debug + Clone> TypeFoldable<TyCtxt<'t
span: self.span.try_fold_with(folder)?,
})
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [InlineAsmTemplatePiece] {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
_folder: &mut F,
) -> Result<Self, F::Error> {
Ok(self)
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [Span] {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
_folder: &mut F,
) -> Result<Self, F::Error> {
Ok(self)
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
Spanned { node: self.node.fold_with(folder), span: self.span.fold_with(folder) }
}
}
@ -710,13 +741,37 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<LocalDefId> {
) -> Result<Self, F::Error> {
Ok(self)
}
}
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<PlaceElem<'tcx>> {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::fold_list(self, folder, |tcx, v| tcx.mk_place_elems(v))
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, _folder: &mut F) -> Self {
self
}
}
macro_rules! list_fold {
($($ty:ty : $mk:ident),+ $(,)?) => {
$(
impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for $ty {
fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Result<Self, F::Error> {
ty::util::try_fold_list(self, folder, |tcx, v| tcx.$mk(v))
}
fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(
self,
folder: &mut F,
) -> Self {
ty::util::fold_list(self, folder, |tcx, v| tcx.$mk(v))
}
}
)*
}
}
list_fold! {
ty::Clauses<'tcx> : mk_clauses,
&'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> : mk_poly_existential_predicates,
&'tcx ty::List<PlaceElem<'tcx>> : mk_place_elems,
CanonicalVarInfos<'tcx> : mk_canonical_var_infos,
}

36
compiler/rustc_middle/src/ty/util.rs
View file

@ -1647,6 +1647,42 @@ pub fn fold_list<'tcx, F, L, T>(
list: L,
folder: &mut F,
intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> L,
) -> L
where
F: TypeFolder<TyCtxt<'tcx>>,
L: AsRef<[T]>,
T: TypeFoldable<TyCtxt<'tcx>> + PartialEq + Copy,
{
let slice = list.as_ref();
let mut iter = slice.iter().copied();
// Look for the first element that changed
match iter.by_ref().enumerate().find_map(|(i, t)| {
let new_t = t.fold_with(folder);
if new_t != t { Some((i, new_t)) } else { None }
}) {
Some((i, new_t)) => {
// An element changed, prepare to intern the resulting list
let mut new_list = SmallVec::<[_; 8]>::with_capacity(slice.len());
new_list.extend_from_slice(&slice[..i]);
new_list.push(new_t);
for t in iter {
new_list.push(t.fold_with(folder))
}
intern(folder.cx(), &new_list)
}
None => list,
}
}
/// Does the equivalent of
/// ```ignore (illustrative)
/// let v = self.iter().map(|p| p.try_fold_with(folder)).collect::<SmallVec<[_; 8]>>();
/// folder.tcx().intern_*(&v)
/// ```
pub fn try_fold_list<'tcx, F, L, T>(
list: L,
folder: &mut F,
intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> L,
) -> Result<L, F::Error>
where
F: FallibleTypeFolder<TyCtxt<'tcx>>,

10
compiler/rustc_type_ir/src/binder.rs
View file

@ -122,6 +122,10 @@ impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Binder<I, T> {
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
folder.try_fold_binder(self)
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
folder.fold_binder(self)
}
}
impl<I: Interner, T: TypeVisitable<I>> TypeVisitable<I> for Binder<I, T> {
@ -135,7 +139,11 @@ impl<I: Interner, T: TypeFoldable<I>> TypeSuperFoldable<I> for Binder<I, T> {
self,
folder: &mut F,
) -> Result<Self, F::Error> {
self.try_map_bound(|ty| ty.try_fold_with(folder))
self.try_map_bound(|t| t.try_fold_with(folder))
}
fn super_fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
self.map_bound(|t| t.fold_with(folder))
}
}

192
compiler/rustc_type_ir/src/fold.rs
View file

@ -45,6 +45,7 @@
//! - u.fold_with(folder)
//! ```
use std::convert::Infallible;
use std::mem;
use std::sync::Arc;
@ -56,12 +57,6 @@ use crate::inherent::*;
use crate::visit::{TypeVisitable, TypeVisitableExt as _};
use crate::{self as ty, Interner, TypeFlags};
#[cfg(feature = "nightly")]
type Never = !;
#[cfg(not(feature = "nightly"))]
type Never = std::convert::Infallible;
/// This trait is implemented for every type that can be folded,
/// providing the skeleton of the traversal.
///
@ -82,18 +77,24 @@ pub trait TypeFoldable<I: Interner>: TypeVisitable<I> + Clone {
///
/// For types of interest (such as `Ty`), the implementation of this method
/// calls a folder method specifically for that type (such as
/// `F::try_fold_ty`). This is where control transfers from `TypeFoldable`
/// to `TypeFolder`.
/// `F::try_fold_ty`). This is where control transfers from [`TypeFoldable`]
/// to [`FallibleTypeFolder`].
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error>;
/// A convenient alternative to `try_fold_with` for use with infallible
/// folders. Do not override this method, to ensure coherence with
/// `try_fold_with`.
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
match self.try_fold_with(folder) {
Ok(t) => t,
}
}
/// The entry point for folding. To fold a value `t` with a folder `f`
/// call: `t.fold_with(f)`.
///
/// For most types, this just traverses the value, calling `fold_with`
/// on each field/element.
///
/// For types of interest (such as `Ty`), the implementation of this method
/// calls a folder method specifically for that type (such as
/// `F::fold_ty`). This is where control transfers from `TypeFoldable`
/// to `TypeFolder`.
///
/// Same as [`TypeFoldable::try_fold_with`], but not fallible. Make sure to keep
/// the behavior in sync across functions.
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self;
}
// This trait is implemented for types of interest.
@ -112,11 +113,7 @@ pub trait TypeSuperFoldable<I: Interner>: TypeFoldable<I> {
/// A convenient alternative to `try_super_fold_with` for use with
/// infallible folders. Do not override this method, to ensure coherence
/// with `try_super_fold_with`.
fn super_fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
match self.try_super_fold_with(folder) {
Ok(t) => t,
}
}
fn super_fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self;
}
/// This trait is implemented for every infallible folding traversal. There is
@ -128,7 +125,7 @@ pub trait TypeSuperFoldable<I: Interner>: TypeFoldable<I> {
/// A blanket implementation of [`FallibleTypeFolder`] will defer to
/// the infallible methods of this trait to ensure that the two APIs
/// are coherent.
pub trait TypeFolder<I: Interner>: FallibleTypeFolder<I, Error = Never> {
pub trait TypeFolder<I: Interner>: Sized {
fn cx(&self) -> I;
fn fold_binder<T>(&mut self, t: ty::Binder<I, T>) -> ty::Binder<I, T>
@ -195,42 +192,6 @@ pub trait FallibleTypeFolder<I: Interner>: Sized {
}
}
// This blanket implementation of the fallible trait for infallible folders
// delegates to infallible methods to ensure coherence.
impl<I: Interner, F> FallibleTypeFolder<I> for F
where
F: TypeFolder<I>,
{
type Error = Never;
fn cx(&self) -> I {
TypeFolder::cx(self)
}
fn try_fold_binder<T>(&mut self, t: ty::Binder<I, T>) -> Result<ty::Binder<I, T>, Never>
where
T: TypeFoldable<I>,
{
Ok(self.fold_binder(t))
}
fn try_fold_ty(&mut self, t: I::Ty) -> Result<I::Ty, Never> {
Ok(self.fold_ty(t))
}
fn try_fold_region(&mut self, r: I::Region) -> Result<I::Region, Never> {
Ok(self.fold_region(r))
}
fn try_fold_const(&mut self, c: I::Const) -> Result<I::Const, Never> {
Ok(self.fold_const(c))
}
fn try_fold_predicate(&mut self, p: I::Predicate) -> Result<I::Predicate, Never> {
Ok(self.fold_predicate(p))
}
}
///////////////////////////////////////////////////////////////////////////
// Traversal implementations.
@ -238,6 +199,10 @@ impl<I: Interner, T: TypeFoldable<I>, U: TypeFoldable<I>> TypeFoldable<I> for (T
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<(T, U), F::Error> {
Ok((self.0.try_fold_with(folder)?, self.1.try_fold_with(folder)?))
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
(self.0.fold_with(folder), self.1.fold_with(folder))
}
}
impl<I: Interner, A: TypeFoldable<I>, B: TypeFoldable<I>, C: TypeFoldable<I>> TypeFoldable<I>
@ -253,6 +218,10 @@ impl<I: Interner, A: TypeFoldable<I>, B: TypeFoldable<I>, C: TypeFoldable<I>> Ty
self.2.try_fold_with(folder)?,
))
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
(self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
}
}
impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Option<T> {
@ -262,6 +231,10 @@ impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Option<T> {
None => None,
})
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
Some(self?.fold_with(folder))
}
}
impl<I: Interner, T: TypeFoldable<I>, E: TypeFoldable<I>> TypeFoldable<I> for Result<T, E> {
@ -271,41 +244,61 @@ impl<I: Interner, T: TypeFoldable<I>, E: TypeFoldable<I>> TypeFoldable<I> for Re
Err(e) => Err(e.try_fold_with(folder)?),
})
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
match self {
Ok(v) => Ok(v.fold_with(folder)),
Err(e) => Err(e.fold_with(folder)),
}
}
}
fn fold_arc<T: Clone, E>(
mut arc: Arc<T>,
fold: impl FnOnce(T) -> Result<T, E>,
) -> Result<Arc<T>, E> {
// We merely want to replace the contained `T`, if at all possible,
// so that we don't needlessly allocate a new `Arc` or indeed clone
// the contained type.
unsafe {
// First step is to ensure that we have a unique reference to
// the contained type, which `Arc::make_mut` will accomplish (by
// allocating a new `Arc` and cloning the `T` only if required).
// This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
// panicking during `make_mut` does not leak the `T`.
Arc::make_mut(&mut arc);
// Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
// is `repr(transparent)`.
let ptr = Arc::into_raw(arc).cast::<mem::ManuallyDrop<T>>();
let mut unique = Arc::from_raw(ptr);
// Call to `Arc::make_mut` above guarantees that `unique` is the
// sole reference to the contained value, so we can avoid doing
// a checked `get_mut` here.
let slot = Arc::get_mut(&mut unique).unwrap_unchecked();
// Semantically move the contained type out from `unique`, fold
// it, then move the folded value back into `unique`. Should
// folding fail, `ManuallyDrop` ensures that the "moved-out"
// value is not re-dropped.
let owned = mem::ManuallyDrop::take(slot);
let folded = fold(owned)?;
*slot = mem::ManuallyDrop::new(folded);
// Cast back to `Arc<T>`.
Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
}
}
impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Arc<T> {
fn try_fold_with<F: FallibleTypeFolder<I>>(mut self, folder: &mut F) -> Result<Self, F::Error> {
// We merely want to replace the contained `T`, if at all possible,
// so that we don't needlessly allocate a new `Arc` or indeed clone
// the contained type.
unsafe {
// First step is to ensure that we have a unique reference to
// the contained type, which `Arc::make_mut` will accomplish (by
// allocating a new `Arc` and cloning the `T` only if required).
// This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
// panicking during `make_mut` does not leak the `T`.
Arc::make_mut(&mut self);
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
fold_arc(self, |t| t.try_fold_with(folder))
}
// Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
// is `repr(transparent)`.
let ptr = Arc::into_raw(self).cast::<mem::ManuallyDrop<T>>();
let mut unique = Arc::from_raw(ptr);
// Call to `Arc::make_mut` above guarantees that `unique` is the
// sole reference to the contained value, so we can avoid doing
// a checked `get_mut` here.
let slot = Arc::get_mut(&mut unique).unwrap_unchecked();
// Semantically move the contained type out from `unique`, fold
// it, then move the folded value back into `unique`. Should
// folding fail, `ManuallyDrop` ensures that the "moved-out"
// value is not re-dropped.
let owned = mem::ManuallyDrop::take(slot);
let folded = owned.try_fold_with(folder)?;
*slot = mem::ManuallyDrop::new(folded);
// Cast back to `Arc<T>`.
Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
match fold_arc::<T, Infallible>(self, |t| Ok(t.fold_with(folder))) {
Ok(t) => t,
}
}
}
@ -315,30 +308,51 @@ impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Box<T> {
*self = (*self).try_fold_with(folder)?;
Ok(self)
}
fn fold_with<F: TypeFolder<I>>(mut self, folder: &mut F) -> Self {
*self = (*self).fold_with(folder);
self
}
}
impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Vec<T> {
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
self.into_iter().map(|t| t.try_fold_with(folder)).collect()
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
self.into_iter().map(|t| t.fold_with(folder)).collect()
}
}
impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for ThinVec<T> {
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
self.into_iter().map(|t| t.try_fold_with(folder)).collect()
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
self.into_iter().map(|t| t.fold_with(folder)).collect()
}
}
impl<I: Interner, T: TypeFoldable<I>> TypeFoldable<I> for Box<[T]> {
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
Vec::from(self).try_fold_with(folder).map(Vec::into_boxed_slice)
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
Vec::into_boxed_slice(Vec::from(self).fold_with(folder))
}
}
impl<I: Interner, T: TypeFoldable<I>, Ix: Idx> TypeFoldable<I> for IndexVec<Ix, T> {
fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
self.raw.try_fold_with(folder).map(IndexVec::from_raw)
}
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self {
IndexVec::from_raw(self.raw.fold_with(folder))
}
}
///////////////////////////////////////////////////////////////////////////

27
compiler/rustc_type_ir_macros/src/lib.rs
View file

@ -83,7 +83,7 @@ fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
s.add_where_predicate(parse_quote! { I: Interner });
s.add_bounds(synstructure::AddBounds::Fields);
s.bind_with(|_| synstructure::BindStyle::Move);
let body_fold = s.each_variant(|vi| {
let body_try_fold = s.each_variant(|vi| {
let bindings = vi.bindings();
vi.construct(|_, index| {
let bind = &bindings[index];
@ -99,6 +99,22 @@ fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
})
});
let body_fold = s.each_variant(|vi| {
let bindings = vi.bindings();
vi.construct(|_, index| {
let bind = &bindings[index];
// retain value of fields with #[type_foldable(identity)]
if has_ignore_attr(&bind.ast().attrs, "type_foldable", "identity") {
bind.to_token_stream()
} else {
quote! {
::rustc_type_ir::TypeFoldable::fold_with(#bind, __folder)
}
}
})
});
// We filter fields which get ignored and don't require them to implement
// `TypeFoldable`. We do so after generating `body_fold` as we still need
// to generate code for them.
@ -111,7 +127,14 @@ fn type_foldable_derive(mut s: synstructure::Structure<'_>) -> proc_macro2::Toke
self,
__folder: &mut __F
) -> Result<Self, __F::Error> {
Ok(match self { #body_fold })
Ok(match self { #body_try_fold })
}
fn fold_with<__F: ::rustc_type_ir::TypeFolder<I>>(
self,
__folder: &mut __F
) -> Self {
match self { #body_fold }
}
},
)