add test

Author: dianne

tests/ui/pin/dont-deref-coerce-pinned-value.rs

@@ -0,0 +1,13 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/153438>: when there's a type
+//! expectation on `pin!`'s result, make sure we don't deref-coerce the argument to
+//! `Pin::new_unchecked` to get its type to match up. That violates the pinning invariant, leading
+//! to unsoundness!
+//@ check-pass
+
+use std::pin::{Pin, pin};
+
+fn wrong_pin<T>(data: &mut T, callback: impl FnOnce(Pin<&mut T>)) {
+    callback(pin!(data));
+}
+
+fn main() {}