samples: rust: add in-place initialisation sample

This is a modified version of rust_minimal that is initialised in-place.

Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Author: wedsonaf

samples/rust/Kconfig

@@ -20,6 +20,17 @@ config SAMPLE_RUST_MINIMAL
 
 	  If unsure, say N.
 
+config SAMPLE_RUST_INPLACE
+	tristate "Minimal in-place"
+	help
+	  This option builds the Rust minimal module with in-place
+	  initialisation.
+
+	  To compile this as a module, choose M here:
+	  the module will be called rust_inplace.
+
+	  If unsure, say N.
+
 config SAMPLE_RUST_PRINT
 	tristate "Printing macros"
 	help

samples/rust/Makefile

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_SAMPLE_RUST_MINIMAL)		+= rust_minimal.o
+obj-$(CONFIG_SAMPLE_RUST_INPLACE)		+= rust_inplace.o
 obj-$(CONFIG_SAMPLE_RUST_PRINT)			+= rust_print.o
 
 subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS)		+= hostprogs

samples/rust/rust_inplace.rs

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust minimal in-place sample.
+
+use kernel::prelude::*;
+
+module! {
+    type: RustInPlace,
+    name: "rust_inplace",
+    author: "Rust for Linux Contributors",
+    description: "Rust minimal in-place sample",
+    license: "GPL",
+}
+
+#[pin_data(PinnedDrop)]
+struct RustInPlace {
+    numbers: Vec<i32>,
+}
+
+impl kernel::InPlaceModule for RustInPlace {
+    fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
+        pr_info!("Rust minimal sample (init)\n");
+        pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
+        try_pin_init!(Self {
+            numbers: {
+                let mut numbers = Vec::new();
+                numbers.try_push(72)?;
+                numbers.try_push(108)?;
+                numbers.try_push(200)?;
+                numbers
+            },
+        })
+    }
+}
+
+#[pinned_drop]
+impl PinnedDrop for RustInPlace {
+    fn drop(self: Pin<&mut Self>) {
+        pr_info!("My numbers are {:?}\n", self.numbers);
+        pr_info!("Rust minimal inplace sample (exit)\n");
+    }
+}

scripts/Makefile.build

@@ -262,7 +262,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := new_uninit,impl_trait_in_assoc_type
+rust_allowed_features := new_uninit,return_position_impl_trait_in_trait
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree