tests: ui: compile-fail: init: add shadowing_field

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

Author: BennoLossin

tests/ui/compile-fail/init/shadowing_field.rs

@@ -0,0 +1,11 @@
+use pin_init::*;
+
+struct Foo {
+    x: usize,
+    y: usize,
+}
+
+fn main() {
+    let x = 42;
+    let _ = init!(Foo { x, y: x });
+}

tests/ui/compile-fail/init/shadowing_field.stderr

@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> tests/ui/compile-fail/init/shadowing_field.rs:10:13
+   |
+10 |     let _ = init!(Foo { x, y: x });
+   |             ^^^^^^^^^^^^^^^^^^^^^^
+   |             |
+   |             expected `usize`, found `&mut usize`
+   |             arguments to this function are incorrect
+   |
+note: function defined here
+  --> $RUST/core/src/ptr/mod.rs
+   |
+   | pub const unsafe fn write<T>(dst: *mut T, src: T) {
+   |                     ^^^^^
+   = note: this error originates in the macro `$crate::__init_internal` which comes from the expansion of the macro `init` (in Nightly builds, run with -Z macro-backtrace for more info)