Merge pull request #20100 from ShoyuVanilla/ignore-sized-hierarchy

Backport new sized-hierarchy trait bounds in old ways

crates/hir-def/src/lang_item.rs

@@ -308,6 +308,8 @@ impl LangItem {
 language_item_table! {
 //  Variant name,            Name,                     Getter method name,         Target                  Generic requirements;
     Sized,                   sym::sized,               sized_trait,                Target::Trait,          GenericRequirement::Exact(0);
+    MetaSized,               sym::meta_sized,          sized_trait,                Target::Trait,          GenericRequirement::Exact(0);
+    PointeeSized,            sym::pointee_sized,       sized_trait,                Target::Trait,          GenericRequirement::Exact(0);
     Unsize,                  sym::unsize,              unsize_trait,               Target::Trait,          GenericRequirement::Minimum(1);
     /// Trait injected by `#[derive(PartialEq)]`, (i.e. "Partial EQ").
     StructuralPeq,           sym::structural_peq,      structural_peq_trait,       Target::Trait,          GenericRequirement::None;

crates/hir-ty/src/lower.rs

@@ -581,11 +581,28 @@ impl<'a> TyLoweringContext<'a> {
         match bound {
             &TypeBound::Path(path, TraitBoundModifier::None) | &TypeBound::ForLifetime(_, path) => {
                 // FIXME Don't silently drop the hrtb lifetimes here
-                if let Some((trait_ref, ctx)) = self.lower_trait_ref_from_path(path, self_ty) {
+                if let Some((trait_ref, mut ctx)) =
-                    if !ignore_bindings {
+                    self.lower_trait_ref_from_path(path, self_ty.clone())
-                        assoc_bounds = ctx.assoc_type_bindings_from_type_bound(trait_ref.clone());
+                {
+                    // FIXME(sized-hierarchy): Remove this bound modifications once we have implemented
+                    // sized-hierarchy correctly.
+                    let meta_sized = LangItem::MetaSized
+                        .resolve_trait(ctx.ty_ctx().db, ctx.ty_ctx().resolver.krate());
+                    let pointee_sized = LangItem::PointeeSized
+                        .resolve_trait(ctx.ty_ctx().db, ctx.ty_ctx().resolver.krate());
+                    if meta_sized.is_some_and(|it| it == trait_ref.hir_trait_id()) {
+                        // Ignore this bound
+                    } else if pointee_sized.is_some_and(|it| it == trait_ref.hir_trait_id()) {
+                        // Regard this as `?Sized` bound
+                        ctx.ty_ctx().unsized_types.insert(self_ty);
+                    } else {
+                        if !ignore_bindings {
+                            assoc_bounds =
+                                ctx.assoc_type_bindings_from_type_bound(trait_ref.clone());
+                        }
+                        clause =
+                            Some(crate::wrap_empty_binders(WhereClause::Implemented(trait_ref)));
                     }
-                    clause = Some(crate::wrap_empty_binders(WhereClause::Implemented(trait_ref)));
                 }
             }
             &TypeBound::Path(path, TraitBoundModifier::Maybe) => {
@@ -945,8 +962,32 @@ pub(crate) fn generic_predicates_for_param_query(
         | WherePredicate::TypeBound { target, bound, .. } => {
             let invalid_target = { ctx.lower_ty_only_param(*target) != Some(param_id) };
             if invalid_target {
-                // If this is filtered out without lowering, `?Sized` is not gathered into `ctx.unsized_types`
+                // FIXME(sized-hierarchy): Revisit and adjust this properly once we have implemented
-                if let TypeBound::Path(_, TraitBoundModifier::Maybe) = bound {
+                // sized-hierarchy correctly.
+                // If this is filtered out without lowering, `?Sized` or `PointeeSized` is not gathered into
+                // `ctx.unsized_types`
+                let lower = || -> bool {
+                    match bound {
+                        TypeBound::Path(_, TraitBoundModifier::Maybe) => true,
+                        TypeBound::Path(path, _) | TypeBound::ForLifetime(_, path) => {
+                            let TypeRef::Path(path) = &ctx.store[path.type_ref()] else {
+                                return false;
+                            };
+                            let Some(pointee_sized) =
+                                LangItem::PointeeSized.resolve_trait(ctx.db, ctx.resolver.krate())
+                            else {
+                                return false;
+                            };
+                            // Lower the path directly with `Resolver` instead of PathLoweringContext`
+                            // to prevent diagnostics duplications.
+                            ctx.resolver.resolve_path_in_type_ns_fully(ctx.db, path).is_some_and(
+                                |it| matches!(it, TypeNs::TraitId(tr) if tr == pointee_sized),
+                            )
+                        }
+                        _ => false,
+                    }
+                }();
+                if lower {
                     ctx.lower_where_predicate(pred, true).for_each(drop);
                 }
                 return false;

crates/ide-assists/src/handlers/generate_enum_is_method.rs

@@ -1,3 +1,5 @@
+use std::slice;
+
 use ide_db::assists::GroupLabel;
 use stdx::to_lower_snake_case;
 use syntax::ast::HasVisibility;
@@ -52,7 +54,7 @@ pub(crate) fn generate_enum_is_method(acc: &mut Assists, ctx: &AssistContext<'_>
     let fn_name = format!("is_{}", &to_lower_snake_case(&variant_name.text()));
 
     // Return early if we've found an existing new fn
-    let impl_def = find_struct_impl(ctx, &parent_enum, &[fn_name.clone()])?;
+    let impl_def = find_struct_impl(ctx, &parent_enum, slice::from_ref(&fn_name))?;
 
     let target = variant.syntax().text_range();
     acc.add_group(

crates/ide-assists/src/handlers/generate_enum_projection_method.rs

@@ -1,3 +1,5 @@
+use std::slice;
+
 use ide_db::assists::GroupLabel;
 use itertools::Itertools;
 use stdx::to_lower_snake_case;
@@ -148,7 +150,7 @@ fn generate_enum_projection_method(
     let fn_name = format!("{fn_name_prefix}_{}", &to_lower_snake_case(&variant_name.text()));
 
     // Return early if we've found an existing new fn
-    let impl_def = find_struct_impl(ctx, &parent_enum, &[fn_name.clone()])?;
+    let impl_def = find_struct_impl(ctx, &parent_enum, slice::from_ref(&fn_name))?;
 
     let target = variant.syntax().text_range();
     acc.add_group(

crates/ide/src/inlay_hints/bounds.rs

@@ -143,7 +143,7 @@ fn foo<T>() {}
                                             file_id: FileId(
                                                 1,
                                             ),
-                                            range: 135..140,
+                                            range: 446..451,
                                         },
                                     ),
                                 ),

crates/intern/src/symbol/symbols.rs

@@ -438,6 +438,8 @@ define_symbols! {
     shr,
     simd,
     sized,
+    meta_sized,
+    pointee_sized,
     skip,
     slice_len_fn,
     Some,

crates/test-utils/src/minicore.rs

@@ -26,7 +26,7 @@
 //!     deref: sized
 //!     derive:
 //!     discriminant:
-//!     drop:
+//!     drop: sized
 //!     env: option
 //!     eq: sized
 //!     error: fmt
@@ -37,7 +37,7 @@
 //!     future: pin
 //!     coroutine: pin
 //!     dispatch_from_dyn: unsize, pin
-//!     hash:
+//!     hash: sized
 //!     include:
 //!     index: sized
 //!     infallible:
@@ -77,33 +77,46 @@
 
 pub mod marker {
     // region:sized
+    #[lang = "pointee_sized"]
+    #[fundamental]
+    #[rustc_specialization_trait]
+    #[rustc_coinductive]
+    pub trait PointeeSized {}
+
+    #[lang = "meta_sized"]
+    #[fundamental]
+    #[rustc_specialization_trait]
+    #[rustc_coinductive]
+    pub trait MetaSized: PointeeSized {}
+
     #[lang = "sized"]
     #[fundamental]
     #[rustc_specialization_trait]
-    pub trait Sized {}
+    #[rustc_coinductive]
+    pub trait Sized: MetaSized {}
     // endregion:sized
 
     // region:send
     pub unsafe auto trait Send {}
 
-    impl<T: ?Sized> !Send for *const T {}
+    impl<T: PointeeSized> !Send for *const T {}
-    impl<T: ?Sized> !Send for *mut T {}
+    impl<T: PointeeSized> !Send for *mut T {}
     // region:sync
-    unsafe impl<T: Sync + ?Sized> Send for &T {}
+    unsafe impl<T: Sync + PointeeSized> Send for &T {}
-    unsafe impl<T: Send + ?Sized> Send for &mut T {}
+    unsafe impl<T: Send + PointeeSized> Send for &mut T {}
     // endregion:sync
     // endregion:send
 
     // region:sync
     pub unsafe auto trait Sync {}
 
-    impl<T: ?Sized> !Sync for *const T {}
+    impl<T: PointeeSized> !Sync for *const T {}
-    impl<T: ?Sized> !Sync for *mut T {}
+    impl<T: PointeeSized> !Sync for *mut T {}
     // endregion:sync
 
     // region:unsize
     #[lang = "unsize"]
-    pub trait Unsize<T: ?Sized> {}
+    pub trait Unsize<T: PointeeSized>: PointeeSized {}
     // endregion:unsize
 
     // region:unpin
@@ -120,7 +133,7 @@ pub mod marker {
     // endregion:derive
 
     mod copy_impls {
-        use super::Copy;
+        use super::{Copy, PointeeSized};
 
         macro_rules! impl_copy {
             ($($t:ty)*) => {
@@ -137,9 +150,9 @@ pub mod marker {
             bool char
         }
 
-        impl<T: ?Sized> Copy for *const T {}
+        impl<T: PointeeSized> Copy for *const T {}
-        impl<T: ?Sized> Copy for *mut T {}
+        impl<T: PointeeSized> Copy for *mut T {}
-        impl<T: ?Sized> Copy for &T {}
+        impl<T: PointeeSized> Copy for &T {}
         impl Copy for ! {}
     }
     // endregion:copy
@@ -151,7 +164,7 @@ pub mod marker {
 
     // region:phantom_data
     #[lang = "phantom_data"]
-    pub struct PhantomData<T: ?Sized>;
+    pub struct PhantomData<T: PointeeSized>;
     // endregion:phantom_data
 
     // region:discriminant
@@ -206,9 +219,11 @@ pub mod default {
 
 // region:hash
 pub mod hash {
+    use crate::marker::PointeeSized;
+
     pub trait Hasher {}
 
-    pub trait Hash {
+    pub trait Hash: PointeeSized {
         fn hash<H: Hasher>(&self, state: &mut H);
     }
 
@@ -221,10 +236,11 @@ pub mod hash {
 
 // region:cell
 pub mod cell {
+    use crate::marker::PointeeSized;
     use crate::mem;
 
     #[lang = "unsafe_cell"]
-    pub struct UnsafeCell<T: ?Sized> {
+    pub struct UnsafeCell<T: PointeeSized> {
         value: T,
     }
 
@@ -238,7 +254,7 @@ pub mod cell {
         }
     }
 
-    pub struct Cell<T: ?Sized> {
+    pub struct Cell<T: PointeeSized> {
         value: UnsafeCell<T>,
     }
 
@@ -357,7 +373,7 @@ pub mod convert {
     // endregion:from
 
     // region:as_ref
-    pub trait AsRef<T: ?Sized> {
+    pub trait AsRef<T: crate::marker::PointeeSized>: crate::marker::PointeeSized {
         fn as_ref(&self) -> &T;
     }
     // endregion:as_ref
@@ -368,9 +384,11 @@ pub mod convert {
 
 pub mod mem {
     // region:manually_drop
+    use crate::marker::PointeeSized;
+
     #[lang = "manually_drop"]
     #[repr(transparent)]
-    pub struct ManuallyDrop<T: ?Sized> {
+    pub struct ManuallyDrop<T: PointeeSized> {
         value: T,
     }
 
@@ -381,7 +399,7 @@ pub mod mem {
     }
 
     // region:deref
-    impl<T: ?Sized> crate::ops::Deref for ManuallyDrop<T> {
+    impl<T: PointeeSized> crate::ops::Deref for ManuallyDrop<T> {
         type Target = T;
         fn deref(&self) -> &T {
             &self.value
@@ -428,7 +446,7 @@ pub mod mem {
 pub mod ptr {
     // region:drop
     #[lang = "drop_in_place"]
-    pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    pub unsafe fn drop_in_place<T: crate::marker::PointeeSized>(to_drop: *mut T) {
         unsafe { drop_in_place(to_drop) }
     }
     pub const unsafe fn read<T>(src: *const T) -> T {
@@ -444,7 +462,7 @@ pub mod ptr {
     // region:pointee
     #[lang = "pointee_trait"]
     #[rustc_deny_explicit_impl(implement_via_object = false)]
-    pub trait Pointee {
+    pub trait Pointee: crate::marker::PointeeSized {
         #[lang = "metadata_type"]
         type Metadata: Copy + Send + Sync + Ord + Hash + Unpin;
     }
@@ -452,12 +470,14 @@ pub mod ptr {
     // region:non_null
     #[rustc_layout_scalar_valid_range_start(1)]
     #[rustc_nonnull_optimization_guaranteed]
-    pub struct NonNull<T: ?Sized> {
+    pub struct NonNull<T: crate::marker::PointeeSized> {
         pointer: *const T,
     }
     // region:coerce_unsized
-    impl<T: ?Sized, U: ?Sized> crate::ops::CoerceUnsized<NonNull<U>> for NonNull<T> where
+    impl<T: crate::marker::PointeeSized, U: crate::marker::PointeeSized>
-        T: crate::marker::Unsize<U>
+        crate::ops::CoerceUnsized<NonNull<U>> for NonNull<T>
+    where
+        T: crate::marker::Unsize<U>,
     {
     }
     // endregion:coerce_unsized
@@ -478,42 +498,44 @@ pub mod ptr {
 pub mod ops {
     // region:coerce_unsized
     mod unsize {
-        use crate::marker::Unsize;
+        use crate::marker::{PointeeSized, Unsize};
 
         #[lang = "coerce_unsized"]
-        pub trait CoerceUnsized<T: ?Sized> {}
+        pub trait CoerceUnsized<T> {}
 
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<&'a mut U> for &'a mut T {}
-        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b mut T {}
+        impl<'a, 'b: 'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<&'a U> for &'b mut T {}
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for &'a mut T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*mut U> for &'a mut T {}
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a mut T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*const U> for &'a mut T {}
 
-        impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+        impl<'a, 'b: 'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<&'a U> for &'b T {}
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for &'a T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*const U> for &'a T {}
 
-        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+        impl<T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*mut U> for *mut T {}
-        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
+        impl<T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*const U> for *mut T {}
-        impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
+        impl<T: PointeeSized + Unsize<U>, U: PointeeSized> CoerceUnsized<*const U> for *const T {}
     }
     pub use self::unsize::CoerceUnsized;
     // endregion:coerce_unsized
 
     // region:deref
     mod deref {
+        use crate::marker::PointeeSized;
+
         #[lang = "deref"]
-        pub trait Deref {
+        pub trait Deref: PointeeSized {
             #[lang = "deref_target"]
             type Target: ?Sized;
             fn deref(&self) -> &Self::Target;
         }
 
-        impl<T: ?Sized> Deref for &T {
+        impl<T: PointeeSized> Deref for &T {
             type Target = T;
             fn deref(&self) -> &T {
                 loop {}
             }
         }
-        impl<T: ?Sized> Deref for &mut T {
+        impl<T: PointeeSized> Deref for &mut T {
             type Target = T;
             fn deref(&self) -> &T {
                 loop {}
@@ -521,19 +543,19 @@ pub mod ops {
         }
         // region:deref_mut
         #[lang = "deref_mut"]
-        pub trait DerefMut: Deref {
+        pub trait DerefMut: Deref + PointeeSized {
             fn deref_mut(&mut self) -> &mut Self::Target;
         }
         // endregion:deref_mut
 
         // region:receiver
         #[lang = "receiver"]
-        pub trait Receiver {
+        pub trait Receiver: PointeeSized {
             #[lang = "receiver_target"]
             type Target: ?Sized;
         }
 
-        impl<P: ?Sized, T: ?Sized> Receiver for P
+        impl<P: PointeeSized, T: PointeeSized> Receiver for P
         where
             P: Deref<Target = T>,
         {
@@ -1006,18 +1028,18 @@ pub mod ops {
 
     // region:dispatch_from_dyn
     mod dispatch_from_dyn {
-        use crate::marker::Unsize;
+        use crate::marker::{PointeeSized, Unsize};
 
         #[lang = "dispatch_from_dyn"]
         pub trait DispatchFromDyn<T> {}
 
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<&'a U> for &'a T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> DispatchFromDyn<&'a U> for &'a T {}
 
-        impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<&'a mut U> for &'a mut T {}
+        impl<'a, T: PointeeSized + Unsize<U>, U: PointeeSized> DispatchFromDyn<&'a mut U> for &'a mut T {}
 
-        impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
+        impl<T: PointeeSized + Unsize<U>, U: PointeeSized> DispatchFromDyn<*const U> for *const T {}
 
-        impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
+        impl<T: PointeeSized + Unsize<U>, U: PointeeSized> DispatchFromDyn<*mut U> for *mut T {}
     }
     pub use self::dispatch_from_dyn::DispatchFromDyn;
     // endregion:dispatch_from_dyn
@@ -1025,15 +1047,17 @@ pub mod ops {
 
 // region:eq
 pub mod cmp {
+    use crate::marker::PointeeSized;
+
     #[lang = "eq"]
-    pub trait PartialEq<Rhs: ?Sized = Self> {
+    pub trait PartialEq<Rhs: PointeeSized = Self>: PointeeSized {
         fn eq(&self, other: &Rhs) -> bool;
         fn ne(&self, other: &Rhs) -> bool {
             !self.eq(other)
         }
     }
 
-    pub trait Eq: PartialEq<Self> {}
+    pub trait Eq: PartialEq<Self> + PointeeSized {}
 
     // region:derive
     #[rustc_builtin_macro]
@@ -1044,11 +1068,11 @@ pub mod cmp {
 
     // region:ord
     #[lang = "partial_ord"]
-    pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
+    pub trait PartialOrd<Rhs: PointeeSized = Self>: PartialEq<Rhs> + PointeeSized {
         fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>;
     }
 
-    pub trait Ord: Eq + PartialOrd<Self> {
+    pub trait Ord: Eq + PartialOrd<Self> + PointeeSized {
         fn cmp(&self, other: &Self) -> Ordering;
     }
 
@@ -1071,6 +1095,8 @@ pub mod cmp {
 
 // region:fmt
 pub mod fmt {
+    use crate::marker::PointeeSized;
+
     pub struct Error;
     pub type Result = crate::result::Result<(), Error>;
     pub struct Formatter<'a>;
@@ -1106,10 +1132,10 @@ pub mod fmt {
         }
     }
 
-    pub trait Debug {
+    pub trait Debug: PointeeSized {
         fn fmt(&self, f: &mut Formatter<'_>) -> Result;
     }
-    pub trait Display {
+    pub trait Display: PointeeSized {
         fn fmt(&self, f: &mut Formatter<'_>) -> Result;
     }
 
@@ -1268,7 +1294,7 @@ pub mod fmt {
         }
     }
 
-    impl<T: Debug + ?Sized> Debug for &T {
+    impl<T: Debug + PointeeSized> Debug for &T {
         fn fmt(&self, f: &mut Formatter<'_>) -> Result {
             (&**self).fmt(f)
         }
@@ -1512,6 +1538,8 @@ pub mod iter {
 
     mod traits {
         mod iterator {
+            use crate::marker::PointeeSized;
+
             #[doc(notable_trait)]
             #[lang = "iterator"]
             pub trait Iterator {
@@ -1543,7 +1571,7 @@ pub mod iter {
                 }
                 // endregion:iterators
             }
-            impl<I: Iterator + ?Sized> Iterator for &mut I {
+            impl<I: Iterator + PointeeSized> Iterator for &mut I {
                 type Item = I::Item;
                 fn next(&mut self) -> Option<I::Item> {
                     (**self).next()