tests: add test to check cfgs working correctly

Signed-off-by: Benno Lossin <lossin@kernel.org>

Author: BennoLossin

tests/cfgs.rs

@@ -0,0 +1,24 @@
+#![cfg_attr(not(RUSTC_LINT_REASONS_IS_STABLE), feature(lint_reasons))]
+
+use pin_init::{pin_data, pin_init, PinInit};
+
+#[pin_data]
+pub struct Struct {
+    #[cfg(kernel)]
+    field_d: Field,
+    #[cfg(not(kernel))]
+    field_e: Field,
+}
+
+impl Struct {
+    pub fn new() -> impl PinInit<Self> {
+        pin_init!(Self {
+            #[cfg(kernel)]
+            field_d: Field {},
+            #[cfg(not(kernel))]
+            field_e: Field {},
+        })
+    }
+}
+
+struct Field {}