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Derive GenericTypeVisitable for RegionConstraint _correctly_ #160914

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rust-bors merged 5 commits into from
Aug 23, 2026
Merged

Derive GenericTypeVisitable for RegionConstraint _correctly_ #160914

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47ecf35
misc: replace `TypeParameterTransform` with a standard type
ada4a Aug 5, 2026
490a5de
make `#[derive(GenericTypeVisitable)]` no longer a no-op in rustc
ada4a Jul 31, 2026
cc31dec
make GenericTypeVisitable an unsafe trait
ada4a Jul 31, 2026
ce92005
implement `#[generic_type_visitable(bounds(...))]`
ada4a Aug 5, 2026
d75b165
fix `GenericTypeVisitable` derive for `RegionConstraint`
ada4a Aug 5, 2026
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55 changes: 32 additions & 23 deletions compiler/rustc_type_ir/src/generic_visit.rs
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Expand Up @@ -20,29 +20,35 @@ use crate::Interner;
/// This trait is implemented for every type that can be visited,
/// providing the skeleton of the traversal.
///
/// To implement this conveniently, use the derive macro located in
/// `rustc_macros`.
pub trait GenericTypeVisitable<V> {
/// ## Safety
///
/// A manual implementation **must visit** every field.
///
/// Therefore, it is advised to instead derive this using the derive
/// macro located in `rustc_macros`.
pub unsafe trait GenericTypeVisitable<V> {
Comment thread
JonathanBrouwer marked this conversation as resolved.
fn generic_visit_with(&self, visitor: &mut V);
}

///////////////////////////////////////////////////////////////////////////
// Traversal implementations.

impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for &T {
unsafe impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for &T {
fn generic_visit_with(&self, visitor: &mut V) {
T::generic_visit_with(*self, visitor)
}
}

impl<V, T: GenericTypeVisitable<V>, U: GenericTypeVisitable<V>> GenericTypeVisitable<V> for (T, U) {
unsafe impl<V, T: GenericTypeVisitable<V>, U: GenericTypeVisitable<V>> GenericTypeVisitable<V>
for (T, U)
{
fn generic_visit_with(&self, visitor: &mut V) {
self.0.generic_visit_with(visitor);
self.1.generic_visit_with(visitor);
}
}

impl<V, A: GenericTypeVisitable<V>, B: GenericTypeVisitable<V>, C: GenericTypeVisitable<V>>
unsafe impl<V, A: GenericTypeVisitable<V>, B: GenericTypeVisitable<V>, C: GenericTypeVisitable<V>>
GenericTypeVisitable<V> for (A, B, C)
{
fn generic_visit_with(&self, visitor: &mut V) {
Expand All @@ -52,7 +58,7 @@ impl<V, A: GenericTypeVisitable<V>, B: GenericTypeVisitable<V>, C: GenericTypeVi
}
}

impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for Option<T> {
unsafe impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for Option<T> {
fn generic_visit_with(&self, visitor: &mut V) {
match self {
Some(v) => v.generic_visit_with(visitor),
Expand All @@ -61,7 +67,7 @@ impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for Option<T> {
}
}

impl<V, T: GenericTypeVisitable<V>, E: GenericTypeVisitable<V>> GenericTypeVisitable<V>
unsafe impl<V, T: GenericTypeVisitable<V>, E: GenericTypeVisitable<V>> GenericTypeVisitable<V>
for Result<T, E>
{
fn generic_visit_with(&self, visitor: &mut V) {
Expand All @@ -72,54 +78,56 @@ impl<V, T: GenericTypeVisitable<V>, E: GenericTypeVisitable<V>> GenericTypeVisit
}
}

impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for Arc<T> {
unsafe impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for Arc<T> {
fn generic_visit_with(&self, visitor: &mut V) {
(**self).generic_visit_with(visitor)
}
}

impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for Box<T> {
unsafe impl<V, T: ?Sized + GenericTypeVisitable<V>> GenericTypeVisitable<V> for Box<T> {
fn generic_visit_with(&self, visitor: &mut V) {
(**self).generic_visit_with(visitor)
}
}

impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for Vec<T> {
unsafe impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for Vec<T> {
fn generic_visit_with(&self, visitor: &mut V) {
self.iter().for_each(|it| it.generic_visit_with(visitor));
}
}

impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for ThinVec<T> {
unsafe impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for ThinVec<T> {
fn generic_visit_with(&self, visitor: &mut V) {
self.iter().for_each(|it| it.generic_visit_with(visitor));
}
}

impl<V, T: GenericTypeVisitable<V>, const N: usize> GenericTypeVisitable<V> for SmallVec<[T; N]> {
unsafe impl<V, T: GenericTypeVisitable<V>, const N: usize> GenericTypeVisitable<V>
for SmallVec<[T; N]>
{
fn generic_visit_with(&self, visitor: &mut V) {
self.iter().for_each(|it| it.generic_visit_with(visitor));
}
}

impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for [T] {
unsafe impl<V, T: GenericTypeVisitable<V>> GenericTypeVisitable<V> for [T] {
fn generic_visit_with(&self, visitor: &mut V) {
self.iter().for_each(|it| it.generic_visit_with(visitor));
}
}

impl<V, T: GenericTypeVisitable<V>, Ix: Idx> GenericTypeVisitable<V> for IndexVec<Ix, T> {
unsafe impl<V, T: GenericTypeVisitable<V>, Ix: Idx> GenericTypeVisitable<V> for IndexVec<Ix, T> {
fn generic_visit_with(&self, visitor: &mut V) {
self.iter().for_each(|it| it.generic_visit_with(visitor));
}
}

impl<S, V> GenericTypeVisitable<V> for std::hash::BuildHasherDefault<S> {
unsafe impl<S, V> GenericTypeVisitable<V> for std::hash::BuildHasherDefault<S> {
fn generic_visit_with(&self, _visitor: &mut V) {}
}

#[expect(rustc::default_hash_types, rustc::potential_query_instability)]
impl<
unsafe impl<
Visitor,
Key: GenericTypeVisitable<Visitor>,
Value: GenericTypeVisitable<Visitor>,
Expand All @@ -133,7 +141,7 @@ impl<
}

#[expect(rustc::default_hash_types, rustc::potential_query_instability)]
impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisitable<V>
unsafe impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisitable<V>
for std::collections::HashSet<T, S>
{
fn generic_visit_with(&self, visitor: &mut V) {
Expand All @@ -142,7 +150,7 @@ impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisit
}
}

impl<
unsafe impl<
Visitor,
Key: GenericTypeVisitable<Visitor>,
Value: GenericTypeVisitable<Visitor>,
Expand All @@ -155,7 +163,7 @@ impl<
}
}

impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisitable<V>
unsafe impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisitable<V>
for indexmap::IndexSet<T, S>
{
fn generic_visit_with(&self, visitor: &mut V) {
Expand All @@ -167,7 +175,7 @@ impl<V, T: GenericTypeVisitable<V>, S: GenericTypeVisitable<V>> GenericTypeVisit
macro_rules! trivial_impls {
( $($ty:ty),* $(,)? ) => {
$(
impl<V>
unsafe impl<V>
GenericTypeVisitable<V> for $ty
{
fn generic_visit_with(&self, _visitor: &mut V) {}
Expand All @@ -176,7 +184,7 @@ macro_rules! trivial_impls {
};
}

impl<T: ?Sized, V> GenericTypeVisitable<V> for std::marker::PhantomData<T> {
unsafe impl<T: ?Sized, V> GenericTypeVisitable<V> for std::marker::PhantomData<T> {
fn generic_visit_with(&self, _visitor: &mut V) {}
}

Expand Down Expand Up @@ -215,6 +223,7 @@ trivial_impls!(
rustc_abi::ExternAbi,
);

impl<I: Interner, V> GenericTypeVisitable<V> for crate::FnSigKind<I> {
// SAFETY: `FnSigKind` is a packed representation, therefore visiting its fields doesn't make sense
unsafe impl<I: Interner, V> GenericTypeVisitable<V> for crate::FnSigKind<I> {
fn generic_visit_with(&self, _visitor: &mut V) {}
}
2 changes: 0 additions & 2 deletions compiler/rustc_type_ir/src/lib.rs
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Expand Up @@ -66,7 +66,6 @@ mod const_kind;
mod flags;
mod fold;
mod generic_arg;
#[cfg(not(feature = "nightly"))]
mod generic_visit;
mod infer_ctxt;
mod interner;
Expand Down Expand Up @@ -97,7 +96,6 @@ pub use const_kind::*;
pub use flags::*;
pub use fold::*;
pub use generic_arg::*;
#[cfg(not(feature = "nightly"))]
pub use generic_visit::*;
pub use infer_ctxt::*;
pub use interner::*;
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_type_ir/src/region_constraint.rs
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Expand Up @@ -117,8 +117,8 @@ pub enum RegionConstraint<I: Interner, S = ()> {
/// and there may wind up being assumptions we can use to prove this when we're in a smaller universe.
PlaceholderTyOutlives(I::Ty, Region<I>, S),

And(Box<[RegionConstraint<I, S>]>),
Or(Box<[RegionConstraint<I, S>]>),
And(#[generic_type_visitable(bounds())] Box<[RegionConstraint<I, S>]>),
Or(#[generic_type_visitable(bounds())] Box<[RegionConstraint<I, S>]>),
}

/// A solver region constraint together with the span that caused each leaf constraint.
Expand Down
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