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Mention functions pointers in the documentation

This commit is contained in:
Alexis Bourget 2020-06-16 23:33:23 +02:00
parent a647c0cd68
commit 15cd51af5e
1 changed files with 7 additions and 5 deletions
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12
src/libcore/mem/mod.rs
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@ -581,11 +581,12 @@ pub const fn needs_drop<T>() -> bool {
/// This means that, for example, the padding byte in `(u8, u16)` is not
/// necessarily zeroed.
///
/// There is no guarantee that an all-zero byte-pattern represents a valid value of
/// some type `T`. For example, the all-zero byte-pattern is not a valid value
/// for reference types (`&T` and `&mut T`). Using `zeroed` on such types
/// causes immediate [undefined behavior][ub] because [the Rust compiler assumes][inv]
/// that there always is a valid value in a variable it considers initialized.
/// There is no guarantee that an all-zero byte-pattern represents a valid value
/// of some type `T`. For example, the all-zero byte-pattern is not a valid value
/// for reference types (`&T`, `&mut T` and functions pointers). Using `zeroed` on
/// such types on such types causes immediate [undefined behavior][ub] because
/// [the Rust compiler assumes][inv] that there always is a valid value in a
/// variable it considers initialized.
///
/// This has the same effect as [`MaybeUninit::zeroed().assume_init()`][zeroed].
/// It is useful for FFI sometimes, but should generally be avoided.
@ -612,6 +613,7 @@ pub const fn needs_drop<T>() -> bool {
/// use std::mem;
///
/// let _x: &i32 = unsafe { mem::zeroed() }; // Undefined behavior!
/// let _y: fn() = unsafe { mem::zeroed() }; // And again !
/// ```
#[inline(always)]
#[stable(feature = "rust1", since = "1.0.0")]