Describe Sized requirements for mem::offset_of · model-checking/verify-rust-std@1862054 (original) (raw)

Original file line number	Diff line number	Diff line change
@@ -1266,6 +1266,20 @@ impl SizedTypeProperties for T {}
1266	1266	/// // ^^^ error[E0616]: field `private` of struct `Struct` is private
1267	1267	/// ```
1268	1268	///
	1269	+/// Only [`Sized`] fields are supported, but the container may be unsized:
	1270	+/// ```
	1271	+/// # use core::mem;
	1272	+/// #[repr(C)]
	1273	+/// pub struct Struct {
	1274	+/// a: u8,
	1275	+/// b: [u8],
	1276	+/// }
	1277	+///
	1278	+/// assert_eq!(mem::offset_of!(Struct, a), 0); // OK
	1279	+/// // assert_eq!(mem::offset_of!(Struct, b), 1);
	1280	+/// // ^^^ error[E0277]: doesn't have a size known at compile-time
	1281	+/// ```
	1282	+///
1269	1283	/// Note that type layout is, in general, [subject to change and
1270	1284	/// platform-specific](https://doc.rust-lang.org/reference/type-layout.html). If
1271	1285	/// layout stability is required, consider using an [explicit `repr` attribute].