Fix: SmallVec::leak() to panic on inline storage (GHSA-5h7v-3586-wm8c)

Author: ksj1230

src/lib.rs

@@ -1682,6 +1682,9 @@ impl<T, const N: usize> SmallVec<T, N> {
     }
 
     pub fn leak<'a>(self) -> &'a mut [T] {
+        if !self.spilled() {
+            panic!("SmallVec::leak() called on inline (stack) SmallVec, which cannot be safely leaked");
+        }
         let mut me = ManuallyDrop::new(self);
         unsafe { core::slice::from_raw_parts_mut(me.as_mut_ptr(), me.len()) }
     }