Make std::future a re-export of core::future
After 1a764a7ef59b9cb2eb31658625a6a7dacc3d819b, there are no `std::future`-specific items (except for `cfg(bootstrap)` items removed in 93eed402adbe9e7a532995500d50716d52eefee9). So, instead of defining `std` own module, we can re-export the `core::future` directly.
Implement Error for &(impl Error)
Opening this up just to see what it breaks. It's unfortunate that `&(impl Error)` doesn't actually implement `Error`. If this direct approach doesn't work out then I'll try something different, like an `Error::by_ref` method.
**EDIT:** This is a super low-priority experiment so feel free to cancel it for more important crater runs! 🙂
-----
# Stabilization Report
## Why?
We've been working for the last few years to try "fix" the `Error` trait, which is probably one of the most fundamental in the whole standard library. One of its issues is that we commonly expect you to work with abstract errors through `dyn Trait`, but references and smart pointers over `dyn Trait` don't actually implement the `Error` trait. If you have a `&dyn Error` or a `Box<dyn Error>` you simply can't pass it to a method that wants a `impl Error`.
## What does this do?
This stabilizes the following trait impl:
```rust
impl<'a, T: Error + ?Sized + 'static> Error for &'a T;
```
This means that `&dyn Error` will now satisfy a `impl Error` bound.
It doesn't do anything with `Box<dyn Error>` directly. We discussed how we could do `Box<dyn Error>` in the thread here (and elsewhere in the past), but it seems like we need something like lattice-based specialization or a sprinkling of snowflake compiler magic to make that work. Having said that, with this new impl you _can_ now get a `impl Error` from a `Box<dyn Error>` by dereferencing it.
## What breaks?
A crater run revealed a few crates broke with something like the following:
```rust
// where e: &'short &'long dyn Error
err.source()
```
previously we'd auto-deref that `&'short &'long dyn Error` to return a `Option<&'long dyn Error>` from `source`, but now will call directly on `&'short impl Error`, so will return a `Option<&'short dyn Error>`. The fix is to manually deref:
```rust
// where e: &'short &'long dyn Error
(*err).source()
```
In the recent Libs meeting we considered this acceptable breakage.
Remove delay-binding for Win XP and Vista
The minimum supported Windows version is now Windows 7. Windows XP
and Windows Vista are no longer supported; both are already broken, and
require extra steps to use.
This commit removes the delayed-binding support for Windows API
functions that are present on all supported Windows targets. This has
several benefits: Removes needless complexity. Removes a load and
dynamic call on hot paths in mutex acquire / release. This may have
performance benefits.
* "Drop official support for Windows XP"
https://github.com/rust-lang/compiler-team/issues/378
* "Firefox has ended support for Windows XP and Vista"
https://support.mozilla.org/en-US/kb/end-support-windows-xp-and-vista
Inline methods of Path and OsString
These methods are not generic, and therefore aren't candidates for cross-crate inlining without an `#[inline]` attribute.
More clear documentation for NonNull<T>
Rephrase and hopefully clarify the discussion of covariance in `NonNull<T>` documentation.
I'm very much not an expert so someone should definitely double check the correctness of what I'm saying. At the same time, the new language makes more sense to me, so hopefully it also is more logical to others whose knowledge of covariance basically begins and ends with the [Rustonomicon chapter](https://doc.rust-lang.org/nomicon/subtyping.html).
Related to #48929.
Change branching in `iter.skip()`
Optimize branching in `Skip`, which was brought up in #80416.
This assumes that if `next` is called, it's likely that there will be more calls to `next`, and the branch for skip will only be hit once thus it's unlikely to take that path. Even w/o the `unlikely` intrinsic, it compiles more efficiently, I believe because the path where `next` is called is always taken.
It should be noted there are very few places in the compiler where `Skip` is used, so probably won't have a noticeable perf impact.
[New impl](https://godbolt.org/z/85rdj4)
[Old impl](https://godbolt.org/z/Wc74rh)
[Some additional asm examples](https://godbolt.org/z/feKzoz) although they really don't have a ton of difference between them.
Add doc aliases for memory allocations
This patch adds doc aliases for various C allocation functions, making it possible to search for the C-equivalent of a function and finding the (safe) Rust counterpart:
- `Vec::with_capacity` / `Box::new` / `vec!` -> alloc + malloc, allocates memory
- `Box::new_zeroed` -> calloc, allocates zeroed-out memory
- `Vec::{reserve,reserve_exact,try_reserve_exact,shrink_to_fit,shrink_to}` -> realloc, reallocates a previously allocated slice of memory
It's worth noting that `Vec::new` does not allocate, so we don't link to it. Instead people are probably looking for `Vec::with_capacity` or `vec!`. I hope this will allow people comfortable with the system allocation APIs to make it easier to find what they may be looking for.
Thanks!
Enforce statically that `MIN_NON_ZERO_CAP` is calculated at compile time
Previously, it would usually get computed by LLVM, but this enforces it. This removes the need for the comment saying "LLVM is smart enough".
I don't expect this to make a performance difference, but I do think it makes the performance properties easier to reason about.
Document why not use concat! in dbg! macro
Original title: Reduce code generated by `dbg!` macro
The expanded code before/after: <https://rust.godbolt.org/z/hE3j95>.
---
We cannot use `concat!` since `file!` could contains `{` or the expression is a block (`{ .. }`).
Using it will generated malformed format strings.
So let's document this reason why we don't use `concat!` macro at all.
Expand docs on Iterator::intersperse
Unstable feature in #79524. This expands on the docs to bring them more in line with how other methods of `Iterator` are demonstrated.
The minimum supported Windows version is now Windows 7. Windows XP
and Windows Vista are no longer supported; both are already broken, and
require extra steps to use.
This commit removes the delayed-binding support for Windows API
functions that are present on all supported Windows targets. This has
several benefits: Removes needless complexity. Removes a load and
dynamic call on hot paths in mutex acquire / release. This may have
performance benefits.
* "Drop official support for Windows XP"
https://github.com/rust-lang/compiler-team/issues/378
* "Firefox has ended support for Windows XP and Vista"
https://support.mozilla.org/en-US/kb/end-support-windows-xp-and-vista
Fix broken links with `--document-private-items` in the standard library
As it was suggested in #81037 `SpecFromIter` is not
in the scope and therefore we get a warning when we try to
do document private intems in `rust/library/alloc/`.
This addresses #81037 by adding the trait in the scope as ```@jyn514```
suggested and also adding an `allow(unused_imports)` flag so that
the compiler does not complain, Since the trait is not used
per se in the code, it's just needed to have properly documented
docs.
Improve grammar in documentation of format strings
The docs previously were
* using some weird `<` and `>` around some nonterminals
* _correct me if these **did** have any meaning_
* using of a (not explicitly defined) `text` nonterminal that didn’t explicitly disallow productions containing `'{'` or `'}'`
* incorrect in not allowing for `x?` and `X?` productions of `type`
* unnecessarily ambiguous, both
* allowing `type` to be `''`, and
* using an optional `[type]`
* using inconsistent underscore/hyphenation style between `format_string` and `format_spec` vs `maybe-format`
_Rendered:_
_(current docs: https://doc.rust-lang.org/nightly/std/fmt/#syntax)_
```@rustbot``` modify labels: T-doc
Visualize vector while differentiating between stack and heap.
Inspired by cheats.rs, as this is probably the first place beginner go,
they could understand stack and heap, length and capacity with this. Not
sure if adding this means we should add to other places too.
Superseeds #76066
std: Update wasi-libc commit of the wasm32-wasi target
This brings in an implementation of `current_dir` and `set_current_dir`
(emulation in `wasi-libc`) as well as an updated version of finding
relative paths. This also additionally updates clang to the latest
release to build wasi-libc with.
