fix wrong alignment used to (re)allocate a list

crates/compiler/gen_dev/src/generic64/mod.rs

@@ -2975,7 +2975,7 @@ impl<
         let list_b_layout = arg_layouts[1];
 
         // Load list alignment argument (u32).
-        self.load_layout_alignment(*ret_layout, Symbol::DEV_TMP);
+        self.load_layout_alignment(elem_layout, Symbol::DEV_TMP);
 
         // Load element_width argument (usize).
         self.load_layout_stack_size(elem_layout, Symbol::DEV_TMP2);

crates/compiler/test_gen/src/gen_list.rs

@@ -95,6 +95,22 @@ fn dec_list_literal() {
     );
 }
 
+#[test]
+#[cfg(any(feature = "gen-llvm", feature = "gen-wasm", feature = "gen-dev"))]
+fn dec_list_join() {
+    assert_evals_to!(
+        "List.concat [1.0dec, 2.0] [3.0, 4.0, 5.0]",
+        RocList::from_slice(&[
+            RocDec::from(1),
+            RocDec::from(2),
+            RocDec::from(3),
+            RocDec::from(4),
+            RocDec::from(5),
+        ]),
+        RocList<RocDec>
+    );
+}
+
 #[test]
 #[cfg(any(feature = "gen-llvm", feature = "gen-wasm", feature = "gen-dev"))]
 fn bool_list_concat() {

crates/roc_std/src/roc_list.rs

@@ -455,7 +455,7 @@ where
     T: PartialEq<U>,
 {
     fn eq(&self, other: &RocList<U>) -> bool {
-        self.deref() == other.deref()
+        self.as_slice() == other.as_slice()
     }
 }
 
@@ -812,5 +812,8 @@ mod tests {
         let b = a.clone();
 
         assert_eq!(a, b);
+
+        drop(a);
+        drop(b);
     }
 }