The whole keyword docs thing is pretty new in Rust's history and needs
some work before it's a shining gem. Here's hoping I can provide that.

I basically shoved in a bunch of the most important information from the
reference and the book, along with leaving links to both at the end. I
don't think keyword docs need to have complete detail, just all the
broad strokes, so if someone's confused about a usage of a keyword they
can look at the std documentation for that keyword.

It's pretty basic and could do with more details, but it's a good
starter until someone else improves it.

Turns out writing docs on keywords that are used in multiple different
places in entirely different contexts gets a little harder. I put a
footnote on `*const` syntax just to make sure you can find it if need
be, but it might need more detail.

Mostly addressing notes on ambiguous syntax and spurious newlines.

I think it might be used in some other things, but I'm not fluent enough
at sifting through the rust compiler's source code to find every use of
a specific keyword.

This leaves the question of how to document the `extern` keyword, what
with how much overlap it has with `crate`, but that's used with ABI
stuff so that should be fine.

This commit also splits out linky-line-thingies into two lines, which
judging from the source code for tidy, should be enough to make it shut
up and accept me for who I am, dammit.

It didn't strictly need to be reworked and I'm not sure my version is
better, but oh well, I'm doing it for consistency.

Most of these will eventually be filled, but right now travis-ci enjoys
complaining about the fact that there's links that lead nowhere, so
they're gone. Hopefully someone remembers to re-add them later.

Thanks to @Centril for these.

Dangit. I really thought I got them all.

Given the following code, compile successfuly:

```
macro_rules! test {
    (
        fn fun() -> Option<Box<$t:ty>>;
    ) => {
        fn fun(x: $t) -> Option<Box<$t>>
        { Some(Box::new(x)) }
    }
}

test! {
    fn fun() -> Option<Box<i32>>;
}
```

Aaron Hill pointed out that unnecessary parens around a macro call
(paradigmatically, `format!`) yielded a suggestion of hideous
macro-expanded code. (The slightly unusual choice of using the
pretty-printer to compose suggestions was quite recently commented on
in the commit message for 1081bbb ("abolish ICE when pretty-printing
async block"), but without any grounds to condemn it as a 𝘣𝘢𝘥
choice. Hill's report provides the grounds.) `span_to_snippet` is
fallable as far as the type system is concerned (because, who knows,
macros or something), so the pretty-printing can live on in the
oft-neglected `else` branch.

Resolves rust-lang#55109.

Changes:
````
new_ret_no_self: add sample from rust-lang#3313 to Known Problems section.
Support multiline comments and hopefully fix panic
Check for comments in collapsible ifs
Resolve ICE in needless range loop lint
RIIR update_lints: Update changelog links
Rename if_let_redundant_pattern_matching to redundant_pattern_matching
Add lint for redundant pattern matching for explicit return boolean
Fix issue rust-lang#3322: reword help message for len_zero
Simplify manual_memcpy suggestion in some cases
Fix dogfood
Update known problems for unnecessary_fold
RIIR update_lints: Replace lint count in README.md
Rename `active_lints` to `usable_lints`
Add comment on WalkDir vs. fs::read_dir
sort_by -> sort_by_key
Some more documentation for clippy_dev
Use `WalkDir` to also gather from subdirectories
Avoid linting `boxed_local` on trait implementations.
Website: Make lint categories linkable
Restore clippy_dummy's placeholder name
Swap order of methods in `needless_range_loop` suggestion in some cases
Revert "Exclude pattern guards from unnecessary_fold lint"
Exclude pattern guards from unnecessary_fold lint
````

The example was not as clear as it could be because it was making an assumption about the structure of the data in order to multiply the number of collection elements by the item size. This change demonstrates the idea more straightforwardly, without the calculation.

Felix S. Klock II pointed out that this suggestion (introduced in
pull-request rust-lang#43178 / eac7410) was being issued for one-field-struct
expected types (in which case it is misleading and outright wrong),
even though it was only intended for one-field enum-variants (most
notably, `Some`). Particularly tender-hearted code-historians may be
inclined to show mercy towards the author of rust-lang#43178 on the grounds
that it's somewhat confusing that struct field definitions are given
in a type called `ty::VariantDef`.

Add a conditional to adhere to the original intent. (It would be
possible to generalize to structs, but not obviously net desirable.)
This adds a level of indentation, so the diff here is going to be
easier to read in ignore-whitespace mode (`-w`).

Resolves rust-lang#55250.

Suggest using `'static` when a lifetime is missing in the return type
with a structured suggestion instead of a note.

Co-Authored-By: estebank <esteban@kuber.com.ar>

I was reading through the release notes to find something and noticed
some small grammatical and consistency issues.

Fixes a SSE2 bug.

This was added in the fortnight this PR spent stale. I'm hoping this
one-liner fixes it.

This UI test is sensitive to backtrace output, so it should make sure
that backtraces are not enabled by the environment.

I confirmed that it fails on:
rustdoc 1.30.0-beta.12 (96a2298 2018-10-04)
and passes on:
rustdoc 1.31.0-nightly (f99911a 2018-10-23)

Add a basic summary and an example to From `ChildStdin`, `ChildStdout`,
`ChildStderr`, `File` implementations.

Thanks to @LukasKalbertodt for catching this. Addresses a comment
raised in rust-lang#55169 after it was merged.

It was confusingly named (`is_zero` would have been better), and it didn't even
reliably test for "is this value 0 at run-time" because out-of-bounds pointers
*can* be 0.

… r=cramertj

Add doc for impl From for Waker

As part of issue rust-lang#51430 (cc @skade).

The impl is very simple, so not sure if we need to go into any details.

Gradually expanding libstd's keyword documentation

I'm working on adding new keywords to the documentation and refreshing the incomplete older ones, and I'm hoping that I can eventually add all the standalone-usable keywords after a bunch of incremental work. It would be cool to see the keywords section of std's docs be a definitive reference as to what each keyword means when you see it, and that's what I'm aiming towards with this work.

I'm far from a Rust expert so there will inevitably be things to fix in this, also I'm not sure if this should be a bunch of quickly-merged PRs or one gradually-updated PR that gets merged once it's done.

…ocs, r=GuillaumeGomez

update tcp stream documentation

A small styling issue that seemed inconsistent here when compared to other places (such as https://doc.rust-lang.org/beta/std/net/struct.TcpListener.html).

Accept `Option<Box<$t:ty>>` in macro argument

Given the following code, compile successfuly:

```
macro_rules! test {
    (
        fn fun() -> Option<Box<$t:ty>>;
    ) => {
        fn fun(x: $t) -> Option<Box<$t>>
        { Some(Box::new(x)) }
    }
}

test! {
    fn fun() -> Option<Box<i32>>;
}
```

Fix rust-lang#25274.

in which unused-parens suggestions heed what the user actually wrote

Aaron Hill pointed out that unnecessary parens around a macro call (paradigmatically, `format!`) yielded a suggestion of hideous macro-expanded code. `span_to_snippet` is fallable as far as the type system is concerned, so the pretty-printing can live on in the oft-neglected `else` branch.

Resolves rust-lang#55109.

Suggest appropriate syntax on missing lifetime specifier in return type

Suggest using `'static` when a lifetime is missing in the return type
with a structured suggestion instead of a note.

Fix rust-lang#55170.

Documents `From` implementations for `Stdio`

This PR solves part of rust-lang#51430 by adding a basic summary and an example to each `impl From` inside `process` module (`ChildStdin`, `ChildStdout`, `ChildStderr`, `File`).

It does not document if the conversions allocate memory and how expensive they are.

submodules: update clippy from 5afdf8b to b1d0343

Just a routine update.

Changes:
````
new_ret_no_self: add sample from rust-lang#3313 to Known Problems section.
Support multiline comments and hopefully fix panic
Check for comments in collapsible ifs
Resolve ICE in needless range loop lint
RIIR update_lints: Update changelog links
Rename if_let_redundant_pattern_matching to redundant_pattern_matching
Add lint for redundant pattern matching for explicit return boolean
Fix issue rust-lang#3322: reword help message for len_zero
Simplify manual_memcpy suggestion in some cases
Fix dogfood
Update known problems for unnecessary_fold
RIIR update_lints: Replace lint count in README.md
Rename `active_lints` to `usable_lints`
Add comment on WalkDir vs. fs::read_dir
sort_by -> sort_by_key
Some more documentation for clippy_dev
Use `WalkDir` to also gather from subdirectories
Avoid linting `boxed_local` on trait implementations.
Website: Make lint categories linkable
Restore clippy_dummy's placeholder name
Swap order of methods in `needless_range_loop` suggestion in some cases
Revert "Exclude pattern guards from unnecessary_fold lint"
Exclude pattern guards from unnecessary_fold lint
````

…xample, r=joshtriplett

Clarified code example in char primitive doc

The example was not as clear as it could be because it was making an assumption about the structure of the data in order to multiply the number of elements in the slice by the item size. This change demonstrates the idea more straightforwardly, without needing a calculation, by just comparing the size of the slices.

Fix a typo in the documentation of RangeInclusive

only issue "variant of the expected type" suggestion for enums

This suggestion (introduced in pull-request rust-lang#43178 / eac7410) was being issued for one-field-struct expected types (in which case it is misleading and outright wrong), even though it was only intended for one-field enum-variants (most notably, `Some`).

Add a conditional to adhere to the original intent. (It would be possible to generalize to structs, but not obviously net desirable.) This adds a level of indentation, so the diff here is going to be
easier to read in [ignore-whitespace mode](rust-lang@b0d3d3b9?w=1).

Resolves rust-lang#55250.

r? @pnkfelix

…meGomez

Correct trailing ellipsis in name_from_pat

r? @GuillaumeGomez

fix typos in various places

Remove redundant clone

…ents, r=Aaronepower

Do some copy editing on the release notes

I was reading through the release notes to find something and noticed
some small grammatical and consistency issues.

I'm happy to revert any of these changes if folks disagree with them!

Update stdsimd submodule

Fixes a SSE2 bug. (rust-lang#55249)

…omatsakis

Set RUST_BACKTRACE=0 for rustdoc-ui/failed-doctest-output.rs

This UI test is sensitive to backtrace output, so it should make sure
that backtraces are not enabled by the environment.

…t-jemalloc-ctl, r=nikomatsakis

Regression test for rust-lang#54478.

This is a regression test for rust-lang#54478.

I confirmed that it fails on:
rustdoc 1.30.0-beta.12 (96a2298 2018-10-04)
and passes on:
rustdoc 1.31.0-nightly (f99911a 2018-10-23)

Fix rust-lang#54478

…lett

Fix doc for new copysign functions

Thanks to @LukasKalbertodt for catching this. Addresses a comment raised in rust-lang#55169 after it was merged.

Operands no longer appear in places

Fix an outdated comment.

Remove is_null

It was confusingly named (`is_zero` would have been better, as someone pointed out somewhere but I forgot who or where), and it didn't even reliably test for "is this value 0 at run-time" because out-of-bounds pointers *can* be 0.

It's not used in rustc, and miri only really needs `is_null_ptr` and `to_bytes() == 0`, so let's just kill this method.

r? @oli-obk

… r=pietroalbini

Backports the release notes update from stable to master.

r? @ghost