[doc]:fix error code example

library/core/src/mem/mod.rs

@@ -1337,20 +1337,20 @@ impl<T> SizedTypeProperties for T {}
 /// type B = Wrapper<u8, i8>;
 ///
 /// // Not necessarily identical even though `u8` and `i8` have the same layout!
-/// // assert!(mem::offset_of!(A, 1), mem::offset_of!(B, 1));
+/// // assert_eq!(mem::offset_of!(A, 1), mem::offset_of!(B, 1));
 ///
 /// #[repr(transparent)]
 /// struct U8(u8);
 ///
 /// type C = Wrapper<u8, U8>;
 ///
 /// // Not necessarily identical even though `u8` and `U8` have the same layout!
-/// // assert!(mem::offset_of!(A, 1), mem::offset_of!(C, 1));
+/// // assert_eq!(mem::offset_of!(A, 1), mem::offset_of!(C, 1));
 ///
 /// struct Empty<T>(core::marker::PhantomData<T>);
 ///
 /// // Not necessarily identical even though `PhantomData` always has the same layout!
-/// // assert!(mem::offset_of!(Empty<u8>, 0), mem::offset_of!(Empty<i8>, 0));
+/// // assert_eq!(mem::offset_of!(Empty<u8>, 0), mem::offset_of!(Empty<i8>, 0));
 /// ```
 ///
 /// [explicit `repr` attribute]: https://doc.rust-lang.org/reference/type-layout.html#representations