From 13eb8adefd937080f3772a2baf290e85879a3b24 Mon Sep 17 00:00:00 2001
From: soruh <mail@soruh.de>
Date: Fri, 31 Jul 2026 02:12:42 +0200
Subject: [PATCH] Preserve erased vector on conversion failure

---
 src/lib.rs   |  6 +++---
 src/tests.rs | 17 +++++++++++------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 44cc16a..82fbaac 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -153,9 +153,9 @@ impl TypeErasedVec {
     ///
     /// # Errors
     /// Returns the original `TypeErasedVec` if `T` does not have the same `Layout`.
-    pub fn try_into_vec<T>(mut self) -> Result<Vec<T>, Self> {
-        if let Some(mut guard) = self.try_as_type::<T>() {
-            Ok(guard.take())
+    pub fn try_into_vec<T>(self) -> Result<Vec<T>, Self> {
+        if self.layout == Layout::new::<T>() {
+            Ok(self.into_vec())
         } else {
             Err(self)
         }
diff --git a/src/tests.rs b/src/tests.rs
index 7bbaf2a..0a46970 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -352,23 +352,28 @@ fn test_conversion_methods() {
 
 #[test]
 fn test_try_into_vec_failure_and_recovery() {
-    let vec = Vec::<u32>::with_capacity(5);
+    let drop_count = Rc::new(Cell::new(0));
+    let mut vec = Vec::with_capacity(5);
+    vec.push(DropTracker::new(drop_count.clone()));
     let initial_cap = vec.capacity();
 
     let erased = TypeErasedVec::new(vec);
 
-    let Err(recovered_erased) = erased.try_into_vec::<u64>() else {
+    let Err(recovered_erased) = erased.try_into_vec::<()>() else {
         panic!("try_into_vec succeeded with mismatched layout");
     };
 
-    assert_erased_state(&recovered_erased, 0, Layout::new::<u32>());
+    assert_erased_state(&recovered_erased, 1, Layout::new::<DropTracker>());
     assert!(recovered_erased.capacity() >= initial_cap);
+    assert_eq!(drop_count.get(), 0);
 
-    let Ok(restored) = recovered_erased.try_into_vec::<u32>() else {
-        panic!("try_into_vec failed after recovery");
-    };
+    // SAFETY: The failed conversion preserved the original `DropTracker` elements.
+    let restored = unsafe { recovered_erased.cast_into_vec::<DropTracker>() };
 
+    assert_eq!(restored.len(), 1);
     assert!(restored.capacity() >= initial_cap);
+    drop(restored);
+    assert_eq!(drop_count.get(), 1);
 }
 
 #[test]