feat(memory): zero initialize upon failed cast

mun-lang · Apr 28, 2020 · 6b4c47d · 6b4c47d
1 parent 62aa7e4
commit 6b4c47d
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/crates/mun_memory/src/gc/mark_sweep.rs b/crates/mun_memory/src/gc/mark_sweep.rs
@@ -305,7 +305,7 @@ where
                             unsafe { NonNull::new_unchecked(src) },
                             unsafe { NonNull::new_unchecked(dest) },
                         ) {
-                            panic!("The Mun Runtime doesn't currently support casting from '{}' to '{}'", old_field.1.name(), new_field.1.name());
+                            // Failed to cast. Use the previously zero-initialized value instead
                         }
                     } else {
                         unsafe {

diff --git a/crates/mun_runtime/tests/memory.rs b/crates/mun_runtime/tests/memory.rs
@@ -276,7 +276,6 @@ fn map_struct_cast_fields1() {
 }
 
 #[test]
-#[should_panic]
 fn map_struct_cast_fields2() {
     let mut driver = TestDriver::new(
         r#"
@@ -291,7 +290,7 @@ fn map_struct_cast_fields2() {
     );
 
     let a = -2i16;
-    let _foo: StructRef = invoke_fn!(driver.runtime_mut(), "foo_new", a).unwrap();
+    let foo: StructRef = invoke_fn!(driver.runtime_mut(), "foo_new", a).unwrap();
 
     driver.update(
         r#"
@@ -300,6 +299,8 @@ fn map_struct_cast_fields2() {
         )
     "#,
     );
+
+    assert_eq!(foo.get::<u16>("0").unwrap(), 0);
 }
 
 #[test]