Commit Graph

31 Commits

Author SHA1 Message Date
Bastian Kauschke
d51b71a35a add tracking issue 2020-08-01 07:49:24 +02:00
Bastian Kauschke
e75ffb0f1c use Iter<'_, [T; N]> in array_chunks 2020-07-31 08:25:23 +02:00
Bastian Kauschke
a410ebc5ea add note to array_chunks 2020-07-31 08:24:57 +02:00
Bastian Kauschke
95fa63e63f liballoc export ArrayChunks 2020-07-30 10:50:35 +02:00
Bastian Kauschke
d27007fd6d add tests for array_chunks 2020-07-30 10:50:34 +02:00
Bastian Kauschke
d405347f09 adds slice::array_chunks 2020-07-30 10:50:34 +02:00
Bastian Kauschke
870b7cbb11 improve chunks + windows err on size 0 2020-07-30 10:50:34 +02:00
Manish Goregaokar
2050128302
Rollup merge of #74910 - RalfJung:fence, r=Mark-Simulacrum
fence docs: fix example Mutex

Fixes https://github.com/rust-lang/rust/issues/74808

Cc @pca006132
2020-07-29 16:38:31 -07:00
Manish Goregaokar
0f9b7bd80f
Rollup merge of #74902 - rust-lang:into_raw_non_null, r=dtolnay
Remove deprecated unstable `{Box,Rc,Arc}::into_raw_non_null` functions

FCP: https://github.com/rust-lang/rust/issues/47336#issuecomment-619369613
2020-07-29 16:38:28 -07:00
Manish Goregaokar
c07998e0e7
Rollup merge of #74852 - lzutao:inline-rm-tostring, r=nnethercote
Explain why inlining default ToString impl

Trying to remove inline attribute from default ToString impl causes regression.
Perf result at <https://github.com/rust-lang/rust/pull/74852#issuecomment-664812994>.
2020-07-29 16:38:22 -07:00
Manish Goregaokar
35226766c9
Rollup merge of #74819 - tmiasko:format-spec, r=joshtriplett
Point towards `format_spec`; it is in other direction
2020-07-29 16:38:20 -07:00
Manish Goregaokar
acad0a0517
Rollup merge of #74742 - poliorcetics:ip-addr-remove-rejected-errata, r=nikomatsakis
Remove links to rejected errata 4406 for RFC 4291

Fixes #74198.

For now I simply removed the links, the docs seems clear enough to me but I'm no expert in the domain so don't hesitate to correct me if more is needed.

cc @ghanan94.

@rustbot modify labels: T-doc, T-libs
2020-07-29 16:38:19 -07:00
bors
6fd4c3f20f Auto merge of #72488 - KodrAus:stabilize/const_type_id, r=nikomatsakis
Stabilize const_type_id feature

The tracking issue for `const_type_id` points to the ill-fated #41875. So I'm re-energizing `TypeId` shenanigans by opening this one up to see if there's anything blocking us from stabilizing the constification of type ids.

Will wait for CI before pinging teams/groups.

-----

This PR stabilizes the `const_type_id` feature, which allows `TypeId::of` (and the underlying unstable intrinsic) to be called in constant contexts.

There are some [sanity tests](https://github.com/rust-lang/rust/blob/master/src/test/ui/consts/const-typeid-of-rpass.rs) that demonstrate its usage, but I’ve included some more below.

As a simple example, you could create a constant item that contains some type ids:

```rust
use std::any::TypeId;

const TYPE_IDS: [TypeId; 2] = [
    TypeId::of::<u32>(),
    TypeId::of::<i32>(),
];

assert_eq!(TypeId::of::<u32>(), TYPE_IDS[0]);
```

Type ids can also now appear in associated constants. You could create a trait that associates each type with its constant type id:

```rust
trait Any where Self: 'static {
    const TYPE_ID: TypeId = TypeId::of::<Self>();
}

impl<T: 'static> Any for T { }

assert_eq!(TypeId::of::<usize>(), usize::TYPE_ID);
```

`TypeId::of` is generic, which we saw above in the way the generic `Self` argument was used. This has some implications for const evaluation. It means we can make trait impls evaluate differently depending on information that wasn't directly passed through the trait system. This violates the _parametricity_ property, which requires all instances of a generic function to behave the same way with respect to its generic parameters. That's not unique to `TypeId::of`, other generic const functions based on compiler intrinsics like `mem::align_of` can also violate parametricity. In practice Rust doesn't really have type parametricity anyway since it monomorphizes generics into concrete functions, so violating it using type ids isn’t new.

As an example of how impls can behave differently, you could combine constant type ids with the `const_if_match` feature to dispatch calls based on the type id of the generic `Self`, rather than based on information about `Self` that was threaded through trait bounds. It's like a rough-and-ready form of specialization:

```rust
#![feature(const_if_match)]

trait Specialized where Self: 'static {
    // An associated constant that determines the function to call
    // at compile-time based on `TypeId::of::<Self>`.
    const CALL: fn(&Self) = {
        const USIZE: TypeId = TypeId::of::<usize>();

        match TypeId::of::<Self>() {
            // Use a closure for `usize` that transmutes the generic `Self` to
            // a concrete `usize` and dispatches to `Self::usize`.
            USIZE => |x| Self::usize(unsafe { &*(x as *const Self as *const usize) }),
            // For other types, dispatch to the generic `Self::default`.
            _ => Self::default,
        }
    };

    fn call(&self) {
        // Call the function we determined at compile-time
        (Self::CALL)(self)
    }

    fn default(x: &Self);
    fn usize(x: &usize);
}

// Implement our `Specialized` trait for any `Debug` type.
impl<T: fmt::Debug + 'static> Specialized for T {
    fn default(x: &Self) {
        println!("default: {:?}", x);
    }

    fn usize(x: &usize) {
        println!("usize: {:?}", x);
    }
}

// Will print "usize: 42"
Specialized::call(&42usize);

// Will print "default: ()"
Specialized::call(&());
```

Type ids have some edges that this stabilization exposes to more contexts. It's possible for type ids to collide (but this is a bug). Since they can change between compiler versions, it's never valid to cast a type id to its underlying value.
2020-07-29 15:58:32 +00:00
Ralf Jung
897149a883 fence docs: fix example Mutex 2020-07-29 15:45:42 +02:00
Simon Sapin
1fb67363bf Remove deprecated unstable {Box,Rc,Arc}::into_raw_non_null functions
FCP: https://github.com/rust-lang/rust/issues/47336#issuecomment-619369613
2020-07-29 11:00:31 +02:00
Tomasz Miąsko
1b4a6a5183 Link to syntax section when referencing it 2020-07-29 10:43:40 +02:00
Lzu Tao
27e1b0632c Explain why inline default ToString impl 2020-07-29 07:38:06 +00:00
Imbolc
c4e44d7373
Update fs::remove_file docs
Mention that absence of file causes an error
2020-07-29 08:18:01 +03:00
bors
517385b31b Auto merge of #74894 - JohnTitor:rollup-4ine62a, r=JohnTitor
Rollup of 8 pull requests

Successful merges:

 - #74266 (Clean up E0720 explanation)
 - #74671 (add const generics array coercion test)
 - #74707 (Add str::[r]split_once)
 - #74814 (Fix RefUnwindSafe & UnwinsSafe impls for lazy::SyncLazy)
 - #74859 (Update outdated readme)
 - #74864 (ayu theme: Change doccomment color to `#a1ac88`)
 - #74872 (Enable to ping RISC-V group via triagebot)
 - #74891 (handle ConstEquate in rustdoc)

Failed merges:

r? @ghost
2020-07-29 01:38:00 +00:00
Yuki Okushi
bd91877636
Rollup merge of #74814 - matklad:unwind-safe, r=KodrAus
Fix RefUnwindSafe & UnwinsSafe impls for lazy::SyncLazy

I *think* we should implement those unconditionally with respect to `F`.

The user code can't observe the closure in any way, and we poison lazy if the closure itself panics.

But I've never fully wrapped my head around `UnwindSafe` traits, so 🤷‍♂️
2020-07-29 09:24:19 +09:00
Yuki Okushi
6968b75bd0
Rollup merge of #74707 - matklad:split_once, r=dtolnay
Add str::[r]split_once

This is useful for quick&dirty parsing of key: value config pairs. Used a bunch in Cargo and rust-analyzer:

* https://github.com/rust-lang/cargo/search?q=splitn%282&unscoped_q=splitn%282
* https://github.com/rust-analyzer/rust-analyzer/search?q=split_delim&unscoped_q=split_delim

In theory, once const-generics are done, this functionality could be achieved without a dedicated method with

```rust
match s.splitn(delimier, 2).collect_array::<2>() {
  Some([prefix, suffix]) => todo!(),
  None => todo!(),
}
```

Even in that world, having a dedicated method seems clearer on the intention.

I am not sure about naming -- this is something I've just came up with yesterday, I don't know off the top of my head analogs in other languages.

If T-libs thinks this is a reasonable API to have, I'll open a tracking issue and add more thorough tests.
2020-07-29 09:24:17 +09:00
bors
4cca9505ea Auto merge of #74791 - tmiasko:raw-waker-inline, r=LukasKalbertodt
Add #[inline] to RawWaker::new

`RawWaker::new` is used when creating a new waker or cloning an existing one,
for example as in code below. The `RawWakerVTable::new` can be const evaluated,
but `RawWaker::new` itself cannot since waker pointer is not known at compile
time. Add `#[inline]` to avoid overhead of a function call.

```rust
unsafe fn clone_waker<W: Wake + Send + Sync + 'static>(waker: *const ()) -> RawWaker {
    unsafe { Arc::incr_strong_count(waker as *const W) };
    RawWaker::new(
        waker as *const (),
        &RawWakerVTable::new(clone_waker::<W>, wake::<W>, wake_by_ref::<W>, drop_waker::<W>),
    )
}
```
2020-07-28 23:45:05 +00:00
Alexis Bourget
90d00527d1 Add note to clearly mark the RFC as rejected 2020-07-28 18:53:35 +02:00
Alexis Bourget
dcce6cb511 Remove links to rejected errata 4406 for RFC 4291 2020-07-28 18:53:35 +02:00
Alex Crichton
83b493018a Update stdarch submodule
This commit updates the src/stdarch submodule primarily to include
rust-lang/stdarch#874 which updated and revamped WebAssembly SIMD
intrinsics and renamed WebAssembly atomics intrinsics. This is all
unstable surface area of the standard library so the changes should be
ok here. The SIMD updates also enable SIMD intrinsics to be used by any
program any any time, yay!

cc #74372, a tracking issue I've opened for the stabilization of SIMD
intrinsics
2020-07-28 09:41:09 -07:00
Aleksey Kladov
6e9dc7d9ff Add str::[r]split_once
This is useful for quick&dirty parsing of key: value config pairs
2020-07-28 09:58:20 +02:00
Aleksey Kladov
ed1439cea4 Fix RefUnwindSafe & UnwinsSafe impls for lazy::SyncLazy
The logic here is the same as for Send&Sync impls.
2020-07-28 09:51:08 +02:00
Tomasz Miąsko
0a51a9fb00 Add #[inline] to RawWaker::new 2020-07-28 06:14:52 +02:00
Ashley Mannix
e3856616ee bump const type id stabilization to 1.46.0 2020-07-28 13:30:29 +10:00
Ashley Mannix
cac16c9793 stabilize const_type_id feature 2020-07-28 13:30:29 +10:00
mark
2c31b45ae8 mv std libs to library/ 2020-07-27 19:51:13 -05:00