dummy_value now returns error for non-nullable reference types

Author: Gentle

src/dummy.rs

@@ -59,14 +59,17 @@ pub fn dummy_func(store: &mut crate::Store, ty: FuncType, name: &str) -> Func {
 
 /// Construct a dummy value for the given value type.
 #[cfg(fuzzing)]
-pub fn dummy_value(val_ty: ValType) -> Val {
-    match val_ty {
+pub fn dummy_value(val_ty: ValType) -> Result<Val> {
+    Ok(match val_ty {
         ValType::I32 => Val::I32(0),
         ValType::I64 => Val::I64(0),
         ValType::F32 => Val::F32(0),
         ValType::F64 => Val::F64(0),
         ValType::V128 => Val::V128(0.into()),
         ValType::Ref(ref_type) => {
+            if !ref_type.is_nullable() {
+                anyhow::bail!("cannot create a dummy value for a non-nullable reference type");
+            }
             if ref_type.matches(&RefType::EXTERNREF) {
                 Val::ExternRef(None)
             } else if ref_type.matches(&RefType::FUNCREF) {
@@ -77,11 +80,14 @@ pub fn dummy_value(val_ty: ValType) -> Val {
                 panic!("Unknown RefType {:?}", ref_type);
             }
         }
-    }
+    })
 }
 
 /// Construct a sequence of dummy values for the given types.
 #[cfg(fuzzing)]
 pub fn dummy_values(val_tys: impl IntoIterator<Item = ValType>) -> Vec<Val> {
-    val_tys.into_iter().map(dummy_value).collect()
+    val_tys
+        .into_iter()
+        .filter_map(|ty| dummy_value(ty).ok())
+        .collect()
 }