rust: enable the `pin_macro` feature

This feature enables the use of the `pin!` macro for the `stack_pin_init!`
macro. This feature is already stabilized in Rust version 1.68.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20230408122429.1103522-2-y86-dev@protonmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/lib.rs

@@ -18,6 +18,7 @@
 #![feature(dispatch_from_dyn)]
 #![feature(generic_associated_types)]
 #![feature(new_uninit)]
+#![feature(pin_macro)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
 

scripts/Makefile.build

@@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := core_ffi_c,new_uninit
+rust_allowed_features := core_ffi_c,new_uninit,pin_macro
 
 rust_common_cmd = \
 	RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \