feat(tazjin/german-string): add Drop impl for transient strings r/8523

All of these strings are currently transient (the storage class is not yet
represented anywhere), and the ones that are heap allocated need to be
deallocated when the transient string dies.

Change-Id: Iba0ca926df5db7594f304c5d5318db9d69c6f42c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12235
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 17 insertions, 0 deletions

diff --git a/users/tazjin/german-string/src/lib.rs b/users/tazjin/german-string/src/lib.rs
index c35cb3ad4464..813cd5b1e515 100644
--- a/users/tazjin/german-string/src/lib.rs
+++ b/users/tazjin/german-string/src/lib.rs
@@ -65,4 +65,21 @@ impl GermanString {
             GermanString(GSRepr { large })
         }
     }
+
+    fn len(&self) -> usize {
+        // SAFETY: The length field is located in the same location for both
+        // variants, reading it from either is safe.
+        unsafe { self.0.small.len as usize }
+    }
+}
+
+impl Drop for GermanString {
+    fn drop(&mut self) {
+        if self.len() > 12 {
+            let layout = Layout::array::<u8>(self.len()).unwrap();
+            unsafe {
+                std::alloc::dealloc(self.0.large.data, layout);
+            }
+        }
+    }
 }