[PATCH v2 11/20] rust: pin-init: internal: pin_data: enable self-referential support

[Gary Guo <gary@garyguo.net>]

Enable self-referential support, and add example and test cases.

Acked-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/pin-init/examples/selfref.rs      | 35 ++++++++++++++++++++++++++++++++++
 rust/pin-init/internal/src/pin_data.rs |  7 -------
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/rust/pin-init/examples/selfref.rs b/rust/pin-init/examples/selfref.rs
new file mode 100644
index 000000000000..b5cdf96b6d1c
--- /dev/null
+++ b/rust/pin-init/examples/selfref.rs
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#![allow(clippy::disallowed_names)]
+
+use pin_init::*;
+
+#[pin_data]
+struct SelfRef {
+    part: &'str str,
+    str: String,
+}
+
+fn use_self_ref() {
+    stack_pin_init!(let foo = pin_init!(SelfRef {
+        str: "hello world".to_owned(),
+        part: &str[..5],
+    }));
+
+    // Access via projection.
+    println!("{}", foo.as_mut().project().part);
+
+    // Access via accessor.
+    println!("{}", foo.part());
+
+    // Access via `with_project`, gives mutable reference.
+    foo.as_mut().with_project(|proj| {
+        *proj.part = &proj.str[5..];
+    });
+
+    println!("{}", foo.part());
+}
+
+fn main() {
+    use_self_ref();
+}
diff --git a/rust/pin-init/internal/src/pin_data.rs b/rust/pin-init/internal/src/pin_data.rs
index d851f13a1099..6b2c0b1f96b5 100644
--- a/rust/pin-init/internal/src/pin_data.rs
+++ b/rust/pin-init/internal/src/pin_data.rs
@@ -422,13 +422,6 @@ fn expand(
         }
     }
 
-    if info.self_referential {
-        dcx.error(
-            &info.struct_.ident,
-            "self-referential support is not fully implemented",
-        );
-    }
-
     let struct_def = generate_struct_def(&info);
     let unpin_impl = generate_unpin_impl(&info);
     let drop_impl = generate_drop_impl(&info);

-- 
2.54.0