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Auto merge of #117572 - RalfJung:addr_of, r=cuviper

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update and clarify addr_of docs

This updates the docs to match https://github.com/rust-lang/reference/pull/1387. Cc `@rust-lang/opsem`

`@chorman0773` not sure if you had anything else you wanted to say here, I'd be happy to get your feedback. :)

Fixes https://github.com/rust-lang/rust/issues/114902, so Cc `@joshlf`
This commit is contained in:
bors 2023-11-10 08:04:47 +00:00
commit 17d0a45f5d
1 changed files with 24 additions and 6 deletions
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30
library/core/src/ptr/mod.rs
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@ -1999,9 +1999,18 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// as all other references. This macro can create a raw pointer *without* creating
/// a reference first.
///
/// Note, however, that the `expr` in `addr_of!(expr)` is still subject to all
/// the usual rules. In particular, `addr_of!(*ptr::null())` is Undefined
/// Behavior because it dereferences a null pointer.
/// The `expr` in `addr_of!(expr)` is evaluated as a place expression, but never loads
/// from the place or requires the place to be dereferenceable. This means that
/// `addr_of!(*ptr)` is defined behavior even if `ptr` is null, dangling, or misaligned.
/// Note however that `addr_of!((*ptr).field)` still requires the projection to
/// `field` to be in-bounds, using the same rules as [`offset`].
///
/// Note that `Deref`/`Index` coercions (and their mutable counterparts) are applied inside
/// `addr_of!` like everywhere else, in which case a reference is created to call `Deref::deref` or
/// `Index::index`, respectively. The statements above only apply when no such coercions are
/// applied.
///
/// [`offset`]: pointer::offset
///
/// # Example
///
@ -2039,9 +2048,18 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
/// as all other references. This macro can create a raw pointer *without* creating
/// a reference first.
///
/// Note, however, that the `expr` in `addr_of_mut!(expr)` is still subject to all
/// the usual rules. In particular, `addr_of_mut!(*ptr::null_mut())` is Undefined
/// Behavior because it dereferences a null pointer.
/// The `expr` in `addr_of_mut!(expr)` is evaluated as a place expression, but never loads
/// from the place or requires the place to be dereferenceable. This means that
/// `addr_of_mut!(*ptr)` is defined behavior even if `ptr` is null, dangling, or misaligned.
/// Note however that `addr_of_mut!((*ptr).field)` still requires the projection to
/// `field` to be in-bounds, using the same rules as [`offset`].
///
/// Note that `Deref`/`Index` coercions (and their mutable counterparts) are applied inside
/// `addr_of_mut!` like everywhere else, in which case a reference is created to call `Deref::deref`
/// or `Index::index`, respectively. The statements above only apply when no such coercions are
/// applied.
///
/// [`offset`]: pointer::offset
///
/// # Examples
///