🐛 Fix fallback initializer generation for repr types

src/lib.rs

@@ -418,9 +418,17 @@ impl Member {
                 return quote!(this = this.#with_ident(#default););
             }
         }
+
+        // fallback when there is no setter
         let offset = self.offset;
         let base_ty = &self.base_ty;
-        quote!(this.0 |= (#default as #base_ty) << #offset;)
+        let repr_into = &self.repr_into;
+        let repr_from = &self.repr_from;
+        let bits = self.bits as u32;
+        quote!{
+            let mask = #base_ty::MAX >> (#base_ty::BITS - #bits);
+            this.0 = #repr_from(#repr_into(this.0) | (((#default as #base_ty) & mask) << #offset));
+        }
     }
 }
 

tests/test.rs

@@ -551,3 +551,17 @@ fn custom_inner() {
     assert_eq!(my_bitfield, MyBitfield::from_bits(CustomInner(0)));
     assert_eq!(my_bitfield.into_bits(), CustomInner(0));
 }
+
+#[test]
+fn default_without_setter() {
+    use endian_num::le16;
+
+    #[bitfield(u16, repr = le16, from = le16::from_ne, into = le16::to_ne)]
+    struct Test {
+        #[bits(14)]
+        f3: u16,
+        _reserved: bool,  // no setter
+        #[bits(1, access = RO)]  // no setter
+        reserved: bool
+    }
+}