This commit adds a variant of the `thread_local!` macro as a new
`thread_local_const_init!` macro which requires that the initialization
expression is constant (e.g. could be stuck into a `const` if so
desired). This form of thread local allows for a more efficient
implementation of `LocalKey::with` both if the value has a destructor
and if it doesn't. If the value doesn't have a destructor then `with`
should desugar to exactly as-if you use `#[thread_local]` given
sufficient inlining.
The purpose of this new form of thread locals is to precisely be
equivalent to `#[thread_local]` on platforms where possible for values
which fit the bill (those without destructors). This should help close
the gap in performance between `thread_local!`, which is safe, relative
to `#[thread_local]`, which is not easy to use in a portable fashion.
Update docs for unsafe_op_in_unsafe_fn stability.
The unsafe_op_in_unsafe_fn lint was stabilized in #79208, but the bottom of this documentation wasn't updated.
I'm just guessing at the reason here, hopefully it is close to correct. The only discussion I found is https://github.com/rust-lang/rust/issues/71668#issuecomment-730399862 which didn't really explain the thought process behind the decision.
Update books
## nomicon
1 commits in 6fe476943afd53a9a6e91f38a6ea7bb48811d8ff..8551afbb2ca6f5ea37fe58380318b209785e4e02
2021-03-10 07:28:57 +0900 to 2021-04-01 21:58:50 +0900
- Add example of thinking about Send/Sync's soundness (rust-lang-nursery/nomicon#259)
## reference
10 commits in fd97729e2d82f8b08d68a31c9bfdf0c37a7fd542..e1abb17cd94cd5a8a374b48e1bc8134a2208ed48
2021-03-28 14:29:19 -0700 to 2021-04-07 08:09:48 -0700
- Update introduction.md (rust-lang-nursery/reference#1004)
- clarify UB for raw ptr deref (rust-lang-nursery/reference#1000)
- Update lint level documentation. (rust-lang-nursery/reference#998)
- Add rustdoc to tool lints. (rust-lang-nursery/reference#997)
- Link to ptr::addr_of on raw pointer docs (rust-lang-nursery/reference#993)
- apply rust-lang-nursery/reference#950 to STYLE.md (rust-lang-nursery/reference#980)
- Tuple Passover rust-lang-nursery/reference#2 (rust-lang-nursery/reference#990)
- Fix typo in macros-by-example.md (rust-lang-nursery/reference#996)
- Clarify object safety rules for methods striked from the vtable (rust-lang-nursery/reference#965)
- Add const generic args to const contexts. (rust-lang-nursery/reference#995)
## rust-by-example
1 commits in 29d91f591c90dd18fdca6d23f1a9caf9c139d0d7..c80f0b09fc15b9251825343be910c08531938ab2
2021-03-23 09:03:39 -0300 to 2021-04-08 10:28:17 -0300
- fix compile bug with panic! (rust-lang/rust-by-example#1433)
## rustc-dev-guide
11 commits in 0687daac28939c476df51778f5a1d1aff1a3fddf..a9bd2bbf31e4f92b5d3d8e80b22839d0cc7a2022
2021-03-28 13:33:56 -0400 to 2021-04-09 18:12:21 -0400
- Improve formatting and update info in "method lookup" section
- Change wording a bit: `module` => `crate`
- fix typo (rust-lang/rustc-dev-guide#1107)
- fix typo
- Mention CI build of LLVM in build instruction
- Fix rustdocs test command typo (rust-lang/rustc-dev-guide#1103)
- Update the "LLVM updates" section
- Fix a link about Rustdoc internals
- Add quickstart for adding a new optimization (rust-lang/rustc-dev-guide#1094)
- Add back example of {{cwd}} (rust-lang/rustc-dev-guide#1099)
- Document test input normalization
## embedded-book
1 commits in d3f2ace94d51610cf3e3c265705bb8416d37f8e4..569c3391f5c0cc43433bc77831d17f8ff4d76602
2021-03-17 07:53:09 +0000 to 2021-04-07 08:32:11 +0000
- Make it easier to copy and paste example commands. (rust-embedded/book#289)
Fix join_paths error display.
On unix, the error from `join_paths` looked like this:
```
path segment contains separator `58`
```
This PR changes it to look like this:
```
path segment contains separator `:`
```
Move `std::sys_common::alloc` to new module `std::sys::common`
6b56603e35/library/std/src/sys_common/mod.rs (L7-L13)
It was my impression that the goal for `std::sys` has changed from extracting it into a separate crate to making std work with features. However the fact remains that there is a lot of interdependence between `sys` and `sys_common`, this is because `sys_common` contains two types of code:
- abstractions over the different platform implementations in `std::sys` (for example [`std::sys_common::mutex`](https://github.com/rust-lang/rust/blob/master/library/std/src/sys_common/mutex.rs))
- code shared between platforms (for example [`std::sys_common::alloc`](https://github.com/rust-lang/rust/blob/master/library/std/src/sys_common/alloc.rs))
This PR attempts to address this by adding a new module `common` to `std::sys` which will contain code shared between platforms, `alloc.rs` in this case but more can be moved over in the future.
add lint deref_nullptr detecting when a null ptr is dereferenced
fixes#83856
changelog: add lint that detect code like
```rust
unsafe {
&*core::ptr::null::<i32>()
};
unsafe {
addr_of!(std::ptr::null::<i32>())
};
let x: i32 = unsafe {*core::ptr::null()};
let x: i32 = unsafe {*core::ptr::null_mut()};
unsafe {*(0 as *const i32)};
unsafe {*(core::ptr::null() as *const i32)};
```
```
warning: Dereferencing a null pointer causes undefined behavior
--> src\main.rs:5:26
|
5 | let x: i32 = unsafe {*core::ptr::null()};
| ^^^^^^^^^^^^^^^^^^
| |
| a null pointer is dereferenced
| this code causes undefined behavior when executed
|
= note: `#[warn(deref_nullptr)]` on by default
```
Limitation:
It does not detect code like
```rust
const ZERO: usize = 0;
unsafe {*(ZERO as *const i32)};
```
or code where `0` is not directly a literal
rustdoc: links from items in a trait impl are inconsistent
Depending on where the struct implementing a trait is coming from, or the current page, the items in a trait impl are not linking to the same thing:
|item| trait page, implementors| trait page, implementations on Foreign Types|struct page, trait implementations|
|-|-|-|-|
|function| link to current impl|link to first impl in the list|link to trait def
|default function | not present |not present |link to trait def
|default function with custom impl|link to current impl|link to trait def |link to trait def
|constant| link to current impl|link to trait def |link to trait def
|associated type| link to current impl|link to trait def |link to trait def
||*missing link to trait def*|*function link wrong + missing link to current impl*|*missing link to current impl*|
<details>
<summary>rust code with those cases</summary>
```rust
pub trait MyTrait {
type Assoc;
const VALUE: u32;
fn trait_function(&self);
fn defaulted(&self) {}
fn defaulted_override(&self) {}
}
impl MyTrait for String {
/// will link to trait def
type Assoc = ();
/// will link to trait def
const VALUE: u32 = 5;
/// will link to first foreign implementor
fn trait_function(&self) {}
/// will link to trait def
fn defaulted_override(&self) {}
}
impl MyTrait for Vec<u8> {
/// will link to trait def
type Assoc = ();
/// will link to trait def
const VALUE: u32 = 5;
/// will link to first foreign implementor
fn trait_function(&self) {}
/// will link to trait def
fn defaulted_override(&self) {}
}
impl MyTrait for MyStruct {
/// in trait page, will link to current impl
///
/// in struct page, will link to trait def
type Assoc = bool;
/// in trait page, will link to current impl
///
/// in struct page, will link to trait def
const VALUE: u32 = 20;
/// in trait page, will link to current impl
///
/// in struct page, will link to trait def
fn trait_function(&self) {}
/// in trait page, will link to current impl
///
/// in struct page, will link to trait def
fn defaulted_override(&self) {}
}
pub struct MyStruct;
```
</details>
In this PR, I fixed all links to target the trait definition, and added an anchor-link to the current implementation appearing on mouse hover.
Avoid an `Option<Option<_>>`
By simply swapping the calls to `map` and `and_then` around the complexity of
handling an `Option<Option<_>>` disappears.
`@rustbot` modify labels +C-cleanup +T-compiler
Improve code example for length comparison
Small fix/improvement: it's much safer to check that you're under the length of an array rather than chacking that you're equal to it. It's even more true in case you update the length of the array while iterating.
Fix typo in error message
Also tweaked the message a bit by
- removing the hyphen, because in my opinion the hyphen makes the
message a bit harder to read, especially combined with the backticks;
- adding the word "be", because I think it's a bit clearer that way.
Update RELEASES.md
A couple of things that were missing in the release notes:
- `Div` and `Rem` by their `NonZero` variant is now implemented for all unsigned integers (#79134)
- Stabilization of `VecDeque::range` and `VecDeque::range_mut` (#79022, stabilization version corrected to 1.51.0 #80448)
- Deprecation of `spin_loop_hint` (#80966)
