diff --git a/rust/pin-init/internal/src/init.rs b/rust/pin-init/internal/src/init.rs
index a0b3c3790d43..11affa76d1fc 100644
--- a/rust/pin-init/internal/src/init.rs
+++ b/rust/pin-init/internal/src/init.rs
@@ -103,17 +103,15 @@ pub(crate) fn expand(
         |(_, err)| Box::new(err),
     );
     let slot = format_ident!("slot");
-    let (has_data_trait, data_trait, get_data, init_from_closure) = if pinned {
+    let (has_data_trait, get_data, init_from_closure) = if pinned {
         (
             format_ident!("HasPinData"),
-            format_ident!("PinData"),
             format_ident!("__pin_data"),
             format_ident!("pin_init_from_closure"),
         )
     } else {
         (
             format_ident!("HasInitData"),
-            format_ident!("InitData"),
             format_ident!("__init_data"),
             format_ident!("init_from_closure"),
         )
@@ -157,8 +155,7 @@ fn assert_zeroable<T: ?::core::marker::Sized>(_: *mut T)
             #path::#get_data()
         };
         // Ensure that `#data` really is of type `#data` and help with type inference:
-        let init = ::pin_init::__internal::#data_trait::make_closure::<_, #error>(
-            #data,
+        let init = #data.__make_closure::<_, #error>(
             move |slot| {
                 #zeroable_check
                 #this
diff --git a/rust/pin-init/internal/src/pin_data.rs b/rust/pin-init/internal/src/pin_data.rs
index 90f6b05b957c..713a43c27826 100644
--- a/rust/pin-init/internal/src/pin_data.rs
+++ b/rust/pin-init/internal/src/pin_data.rs
@@ -447,6 +447,16 @@ impl #impl_generics ::core::marker::Copy for __ThePinData #ty_generics
         impl #impl_generics __ThePinData #ty_generics
             #whr
         {
+            /// Type inference helper function.
+            #[inline(always)]
+            #vis fn __make_closure<__F, __E>(self, f: __F) -> __F
+            where
+                __F: FnOnce(*mut #struct_name #ty_generics) ->
+                    ::core::result::Result<::pin_init::__internal::InitOk, __E>,
+            {
+                f
+            }
+
             #field_accessors
         }
 
@@ -461,13 +471,6 @@ unsafe fn __pin_data() -> Self::PinData {
                 __ThePinData { __phantom: ::pin_init::__internal::PhantomInvariant::new() }
             }
         }
-
-        // SAFETY: TODO
-        unsafe impl #impl_generics ::pin_init::__internal::PinData for __ThePinData #ty_generics
-            #whr
-        {
-            type Datee = #struct_name #ty_generics;
-        }
     }
 }
 
diff --git a/rust/pin-init/src/__internal.rs b/rust/pin-init/src/__internal.rs
index 010e8bfc6cd3..d7fdcfef41d2 100644
--- a/rust/pin-init/src/__internal.rs
+++ b/rust/pin-init/src/__internal.rs
@@ -113,30 +113,12 @@ pub unsafe fn new() -> Self {
 ///
 /// Only the `init` module is allowed to use this trait.
 pub unsafe trait HasPinData {
-    type PinData: PinData;
+    type PinData;
 
     #[expect(clippy::missing_safety_doc)]
     unsafe fn __pin_data() -> Self::PinData;
 }
 
-/// Marker trait for pinning data of structs.
-///
-/// # Safety
-///
-/// Only the `init` module is allowed to use this trait.
-pub unsafe trait PinData: Copy {
-    type Datee: ?Sized + HasPinData;
-
-    /// Type inference helper function.
-    #[inline(always)]
-    fn make_closure<F, E>(self, f: F) -> F
-    where
-        F: FnOnce(*mut Self::Datee) -> Result<InitOk, E>,
-    {
-        f
-    }
-}
-
 /// This trait is automatically implemented for every type. It aims to provide the same type
 /// inference help as `HasPinData`.
 ///
@@ -144,30 +126,12 @@ fn make_closure<F, E>(self, f: F) -> F
 ///
 /// Only the `init` module is allowed to use this trait.
 pub unsafe trait HasInitData {
-    type InitData: InitData;
+    type InitData;
 
     #[expect(clippy::missing_safety_doc)]
     unsafe fn __init_data() -> Self::InitData;
 }
 
-/// Same function as `PinData`, but for arbitrary data.
-///
-/// # Safety
-///
-/// Only the `init` module is allowed to use this trait.
-pub unsafe trait InitData: Copy {
-    type Datee: ?Sized + HasInitData;
-
-    /// Type inference helper function.
-    #[inline(always)]
-    fn make_closure<F, E>(self, f: F) -> F
-    where
-        F: FnOnce(*mut Self::Datee) -> Result<InitOk, E>,
-    {
-        f
-    }
-}
-
 pub struct AllData<T: ?Sized>(PhantomInvariant<T>);
 
 impl<T: ?Sized> Clone for AllData<T> {
@@ -178,9 +142,15 @@ fn clone(&self) -> Self {
 
 impl<T: ?Sized> Copy for AllData<T> {}
 
-// SAFETY: TODO.
-unsafe impl<T: ?Sized> InitData for AllData<T> {
-    type Datee = T;
+impl<T: ?Sized> AllData<T> {
+    /// Type inference helper function.
+    #[inline(always)]
+    pub fn __make_closure<F, E>(self, f: F) -> F
+    where
+        F: FnOnce(*mut T) -> Result<InitOk, E>,
+    {
+        f
+    }
 }
 
 // SAFETY: TODO.