add drop order test for destructuring assignments

Co-authored-by: Travis Cross <tc@traviscross.com>

Author: dianne

tests/ui/drop/destructuring-assignments.rs

@@ -0,0 +1,68 @@
+// Test drop order for destructuring assignments against
+// other expressions they should be consistent with.
+//
+// See:
+//
+// - https://github.com/rust-lang/rust/pull/145838
+//
+// Original author: TC
+// Date: 2025-08-30
+//@ edition: 2024
+//@ run-pass
+
+#![allow(unused_must_use)]
+
+fn main() {
+    assert_drop_order(1..=3, |e| {
+        &({ &raw const *&e.log(1) }, drop(e.log(2)));
+        drop(e.log(3));
+    });
+    assert_drop_order(1..=3, |e| {
+        { let _x; _x = &({ &raw const *&e.log(1) }, drop(e.log(2))); }
+        drop(e.log(3));
+    });
+    assert_drop_order(1..=3, |e| {
+        _ = &({ &raw const *&e.log(2) }, drop(e.log(1)));
+        drop(e.log(3));
+    });
+    assert_drop_order(1..=3, |e| {
+        { let _ = &({ &raw const *&e.log(2) }, drop(e.log(1))); }
+        drop(e.log(3));
+    });
+    assert_drop_order(1..=3, |e| {
+        let _x; let _y;
+        (_x, _y) = ({ &raw const *&e.log(2) }, drop(e.log(1)));
+        drop(e.log(3));
+    });
+}
+
+// # Test scaffolding...
+
+use core::cell::RefCell;
+
+struct DropOrder(RefCell<Vec<u64>>);
+struct LogDrop<'o>(&'o DropOrder, u64);
+
+impl DropOrder {
+    fn log(&self, n: u64) -> LogDrop<'_> {
+        LogDrop(self, n)
+    }
+}
+
+impl<'o> Drop for LogDrop<'o> {
+    fn drop(&mut self) {
+        self.0 .0.borrow_mut().push(self.1);
+    }
+}
+
+#[track_caller]
+fn assert_drop_order(
+    ex: impl IntoIterator<Item = u64>,
+    f: impl Fn(&DropOrder),
+) {
+    let order = DropOrder(RefCell::new(Vec::new()));
+    f(&order);
+    let order = order.0.into_inner();
+    let expected: Vec<u64> = ex.into_iter().collect();
+    assert_eq!(order, expected);
+}