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Rewrite docs for std::ptr #49767

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Merged
merged 9 commits into from
May 15, 2018
Merged

Rewrite docs for std::ptr #49767

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8b8091d
Rewrite docs for `std::ptr`
ecstatic-morse Apr 6, 2018
ee259e4
Change `write_bytes` test causing UB to `no_run`
ecstatic-morse Apr 7, 2018
b564c4a
Fix example for `ptr::replace`
ecstatic-morse Apr 8, 2018
6eceb94
Don't link "Undefined Behavior" heading
ecstatic-morse Apr 8, 2018
422b616
Fix broken link in `write_unaligned` docs
ecstatic-morse Apr 8, 2018
d7ce9a2
Fix broken relative links
ecstatic-morse Apr 8, 2018
d7209d5
Fix various nits from PR review
ecstatic-morse Apr 9, 2018
e350ba4
Use the "Safety" heading instead of "Undefined Behavior"
May 9, 2018
827251e
Shorten ownership safety discussion in `read_volatile`
May 9, 2018
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Change write_bytes test causing UB to no_run 
This also fixes improper text wrapping.
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@ecstatic-morse
ecstatic-morse committed Apr 7, 2018
commit ee259e4dd340f9532511b7249e4eb961f111b63f
13 changes: 7 additions & 6 deletions src/libcore/intrinsics.rs
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Expand Up @@ -992,11 +992,11 @@ extern "rust-intrinsic" {
///
/// * The two regions of memory must *not* overlap.
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This should be at the top, since all the other conditions are just "things that are true of any pointer accesses" (which suggests to me that they can potentially be omitted or centralized in the top-level module documentation and just linked?)

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I think it would be a good idea to document the requirements for stores and loads at the top-level. My concern was that people coming to the docs from a search engine may not see the top-level documentation. There was also talk in #36450 of specifying alignment requirements for every function in std::ptr.

I'd like some clarification on what the precise requirements for loads and stores are regarding initializing memory, and what the precise definition of "valid" memory is.

///
/// Additionally, if `T` is not [`Copy`](../marker/trait.Copy), only the region at `src` *or* the
/// region at `dst` can be used or dropped after calling
/// `copy_nonoverlapping`. `copy_nonoverlapping` creates bitwise copies of
/// `T`, regardless of whether `T: Copy`, which can result in undefined
/// behavior if both copies are used.
/// Additionally, if `T` is not [`Copy`](../marker/trait.Copy), only the
/// region at `src` *or* the region at `dst` can be used or dropped after
/// calling `copy_nonoverlapping`. `copy_nonoverlapping` creates bitwise
/// copies of `T`, regardless of whether `T: Copy`, which can result in
/// undefined behavior if both copies are used.
///
/// [Undefined Behavior]: ../../reference/behavior-considered-undefined.html
///
Expand Down Expand Up @@ -1149,7 +1149,7 @@ extern "rust-intrinsic" {
///
/// Creating an invalid value:
///
/// ```ignore
/// ```no_run
/// use std::{mem, ptr};
///
/// let mut v = Box::new(0i32);
Expand All @@ -1161,6 +1161,7 @@ extern "rust-intrinsic" {
/// }
///
/// // At this point, using or dropping `v` results in undefined behavior.
/// // v = Box::new(0i32); // ERROR
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
Expand Down