We have `File::create` for creating a file or opening an existing file,
but the secure way to guarantee creating a new file requires a longhand
invocation via `OpenOptions`.

Add `File::create_new` to handle this case, to make it easier for people
to do secure file creation.

Signed-off-by: Nick Cameron <nrc@ncameron.org>

Signed-off-by: Nick Cameron <nrc@ncameron.org>

Signed-off-by: Nick Cameron <nrc@ncameron.org>

I refactored the code:
- Removed handling of methods, as it felt entirely unnecessary
- Removed clippy utils (obviously...)
- Used some shiny compiler features
  (let-else is very handy for lints 👀)
- I also renamed the lint to `for_loop_over_fallibles` (note: no `s`).
  I'm not sure what's the naming convention here, so maybe I'm wrong.

if the iterator is used after the loop, we need to use `.by_ref()`

The loop could contain `break;` that won't work with an `if let`

Signed-off-by: Nick Cameron <nrc@ncameron.org>

This was missed in rust-lang#100642

Signed-off-by: Nick Cameron <nrc@ncameron.org>

Signed-off-by: Nick Cameron <nrc@ncameron.org>

The macro warn_ was named like that because it the
keyword warn is a built-in attribute and at the time
this macro was created the word 'warning' was also
taken.

However it is no longer the case and we can rename
warn_ to warning.

Signed-off-by: Nick Cameron <nrc@ncameron.org>

I wrote this code in 2017 back when std::fs::write wasn't available.
Also, use the t macro from tidy.

std::io: migrate ReadBuf to BorrowBuf/BorrowCursor

This PR replaces `ReadBuf` (used by the `Read::read_buf` family of methods) with `BorrowBuf` and `BorrowCursor`.

The general idea is to split `ReadBuf` because its API is large and confusing. `BorrowBuf` represents a borrowed buffer which is mostly read-only and (other than for construction) deals only with filled vs unfilled segments. a `BorrowCursor` is a mostly write-only view of the unfilled part of a `BorrowBuf` which distinguishes between initialized and uninitialized segments. For `Read::read_buf`, the caller would create a `BorrowBuf`, then pass a `BorrowCursor` to `read_buf`.

In addition to the major API split, I've made the following smaller changes:

* Removed some methods entirely from the API (mostly the functionality can be replicated with two calls rather than a single one)
* Unified naming, e.g., by replacing initialized with init and assume_init with set_init
* Added an easy way to get the number of bytes written to a cursor (`written` method)

As well as simplifying the API (IMO), this approach has the following advantages:

* Since we pass the cursor by value, we remove the 'unsoundness footgun' where a malicious `read_buf` could swap out the `ReadBuf`.
* Since `read_buf` cannot write into the filled part of the buffer, we prevent the filled part shrinking or changing which could cause underflow for the caller or unexpected behaviour.

## Outline

```rust
pub struct BorrowBuf<'a>

impl Debug for BorrowBuf<'_>

impl<'a> From<&'a mut [u8]> for BorrowBuf<'a>
impl<'a> From<&'a mut [MaybeUninit<u8>]> for BorrowBuf<'a>

impl<'a> BorrowBuf<'a> {
    pub fn capacity(&self) -> usize
    pub fn len(&self) -> usize
    pub fn init_len(&self) -> usize
    pub fn filled(&self) -> &[u8]
    pub fn unfilled<'this>(&'this mut self) -> BorrowCursor<'this, 'a>
    pub fn clear(&mut self) -> &mut Self
    pub unsafe fn set_init(&mut self, n: usize) -> &mut Self
}

pub struct BorrowCursor<'buf, 'data>

impl<'buf, 'data> BorrowCursor<'buf, 'data> {
    pub fn clone<'this>(&'this mut self) -> BorrowCursor<'this, 'data>
    pub fn capacity(&self) -> usize
    pub fn written(&self) -> usize
    pub fn init_ref(&self) -> &[u8]
    pub fn init_mut(&mut self) -> &mut [u8]
    pub fn uninit_mut(&mut self) -> &mut [MaybeUninit<u8>]
    pub unsafe fn as_mut(&mut self) -> &mut [MaybeUninit<u8>]
    pub unsafe fn advance(&mut self, n: usize) -> &mut Self
    pub fn ensure_init(&mut self) -> &mut Self
    pub unsafe fn set_init(&mut self, n: usize) -> &mut Self
    pub fn append(&mut self, buf: &[u8])
}
```

## TODO

* ~~Migrate non-unix libs and tests~~
* ~~Naming~~
  * ~~`BorrowBuf` or `BorrowedBuf` or `SliceBuf`? (We might want an owned equivalent for the async IO traits)~~
  * ~~Should we rename the `readbuf` module? We might keep the name indicate it includes both the buf and cursor variations and someday the owned version too. Or we could change it. It is not publicly exposed, so it is not that important~~.
  * ~~`read_buf` method: we read into the cursor now, so the `_buf` suffix is a bit weird.~~
* ~~Documentation~~
* Tests are incomplete (I adjusted existing tests, but did not add new ones).

cc rust-lang#78485, rust-lang#94741
supersedes: rust-lang#95770, rust-lang#93359
fixes rust-lang#93305

…sleywiser

Add GDB/LLDB pretty-printers for NonZero types

Add GDB/LLDB pretty-printers for `NonZero` types.
These pretty-printers were originally implemented for IntelliJ Rust by ``@Kobzol`` in intellij-rust/intellij-rust#5270.

Part of rust-lang#29392.

Add a `File::create_new` constructor

We have `File::create` for creating a file or opening an existing file,
but the secure way to guarantee creating a new file requires a longhand
invocation via `OpenOptions`.

Add `File::create_new` to handle this case, to make it easier for people
to do secure file creation.

Uplift `clippy::for_loops_over_fallibles` lint into rustc

This PR, as the title suggests, uplifts [`clippy::for_loops_over_fallibles`] lint into rustc. This lint warns for code like this:
```rust
for _ in Some(1) {}
for _ in Ok::<_, ()>(1) {}
```
i.e. directly iterating over `Option` and `Result` using `for` loop.

There are a number of suggestions that this PR adds (on top of what clippy suggested):
1. If the argument (? is there a better name for that expression) of a `for` loop is a `.next()` call, then we can suggest removing it (or rather replacing with `.by_ref()` to allow iterator being used later)
   ```rust
    for _ in iter.next() {}
    // turns into
    for _ in iter.by_ref() {}
    ```
2. (otherwise) We can suggest using `while let`, this is useful for non-iterator, iterator-like things like [async] channels
   ```rust
   for _ in rx.recv() {}
   // turns into
   while let Some(_) = rx.recv() {}
   ```
3. If the argument type is `Result<impl IntoIterator, _>` and the body has a `Result<_, _>` type, we can suggest using `?`
   ```rust
   for _ in f() {}
   // turns into
   for _ in f()? {}
   ```
4. To preserve the original behavior and clear intent, we can suggest using `if let`
   ```rust
   for _ in f() {}
   // turns into
   if let Some(_) = f() {}
   ```
(P.S. `Some` and `Ok` are interchangeable depending on the type)

I still feel that the lint wording/look is somewhat off, so I'll be happy to hear suggestions (on how to improve suggestions :D)!

Resolves rust-lang#99272

[`clippy::for_loops_over_fallibles`]: https://rust-lang.github.io/rust-clippy/master/index.html#for_loops_over_fallibles

…g, r=JohnTitor

Stabilize `std::io::read_to_string`

Closes rust-lang#80218. 🎉

This PR stabilizes the `std::io::read_to_string` function, with the following public API:

```rust
pub fn read_to_string<R: Read>(reader: R) -> Result<String>;
```

It's analogous to `std::fs::read_to_string` for files, but it works on anything that implements `io::Read`, including `io::stdin()`.

See the tracking issue (rust-lang#80218) or documentation for details.

…tch-err, r=oli-obk

Improve const mismatch `FulfillmentError`

Fixes rust-lang#100414

…, r=thomcc

Use `DisplayBuffer` for socket addresses.

Continuation of rust-lang#100625 for socket addresses.

Renames `net::addr` to `net::addr::socket`, `net::ip` to `net::addr::ip` and `net::ip::display_buffer::IpDisplayBuffer` to `net::addr::display_buffer::DisplayBuffer`.

…, r=Mark-Simulacrum

Export Cancel from std::os::fortanix_sgx::usercalls::raw

This was missed in rust-lang#100642

cc `@raoulstrackx` and `@jethrogb`

…ds, r=spastorino

Do not report too many expr field candidates

When considering "this expressions' field has a {field/method}" suggestions:
1. Don't report methods that are out of scope
2. Use `span_suggestions` instead of reporting each field candidate, which caps the number of suggestions to 4
4. Blacklist some common traits like `Clone` and `Deref`

Fixes rust-lang#100894

Some papercuts on error::Error

Renames the chain method, since I chain could mean anything and doesn't refer to a chain of sources (cc rust-lang#58520) (and adds a comment explaining why sources is not a provided method on Error). Renames arguments to the request method from `req` to `demand` since the type is `Demand` rather than Request or Requisition.

r? `@yaahc`

…name-attr-warning, r=davidtwco

translations: rename warn_ to warning

## Description

This MR renames the the macro `warn_` to `warning`.

To give a little bit of context, as [explained](https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20diag.20translation/near/295074146) by `@davidtwco` in the Zulip channel, `warn_`  was named like that because the keyword `warn` is a built-in attribute and at the time this macro was created the word `warning` was also
taken.

However, it is no longer the case and we can rename `warn_` to `warning`.

Provide structured suggestion for `hashmap[idx] = val`

…er-errors

Use smaller span for suggestions

Extend attrs if local_def_id exists

Fixes rust-lang#101076

rustc_middle: Remove `Visibility::Invisible`

It had a different meaning in the past, but now it's only used as an implementation detail of import resolution.

…ark-Simulacrum

unstable-book-gen: use std::fs::write

I wrote this code in 2017 back when std::fs::write wasn't available.
Also, use the t macro from tidy.