Many many many people ask in #rust about this libraries, having an
explanatory reason will probably help a lot.

Fix #25076.

r? @nikomatsakis 

Ideally this trait implementation would be unstable, requiring crates to opt-in
if they would like the functionality, but that's not currently how stability
works so the implementation needs to be removed entirely.

This may come back at a future date, but for now the conservative option is to
remove it.

[breaking-change]

My change in #24797 had a bug, described in that issue’s comments, and first discovered in issue #24918. This fixes it.

I tested this new `main.js` by changing the `main.js` content of [a rendered docs page](https://doc.rust-lang.org/std/option/) to this new content. The ‘[−]’ button worked again.

I am also including another related fix, because it would require manual merging if I made a separate pull request for it. The page-global ‘[−]’ button currently adds `#` to the end of the URL whenever it is clicked. I am changing its `href` from `#` to `javascript:void(0)` (the same as the `href` for section-specific ‘[−]’ links) to fix that.

Guard against overflow in `codemap::span_to_lines`.

(Revised/expanded version of PR #24976)

Make `span_to_lines` to return a `Result`.

In `diagnostic`, catch `Err` from `span_to_lines` and print `"(unprintable span)"` instead.

----

There a number of recent issues that report the bug here.  See e.g. #24761 and #24954.

This change *might* fix them. However, that is *not* its main goal. The main goals are:

 1. Make it possible for callers to recover from an error here, and

 2. Insert a more conservative check, in that we are also checking that the files match up.

----

As a drive-by, fix #24997 , which was causing my attempts to `make check-stage1` on an `--enable-debug` build to fail.

The last one (at least for the moment 😃).

r? @alexcrichton 

- Successful merges: #24576, #24966, #25052, #25131, #25137, #25138, #25139, #25141, #25142, #25144, #25146, #25148, #25154, #25156, #25160, #25173
- Failed merges: 

Nothing uses it anymore.

Remove printing of secret number at final source.

Edit version of #25150.
This commit depends on #25148.

Let me know if I didn't follow correct procedure - seems a trivial change and no one that can be automatically tested.

I noticed this feature added in https://github.com/rust-lang/rust/pull/23289 was missing from the `Search tricks`. Thanks!

r? @steveklabnik

Enhance Google-ability of `.fold()` by mentioning 'reduce' and 'inject' in the docs.

Motivation: [This thread on users.rust-lang.org](https://users.rust-lang.org/t/find-the-shortest-string-in-a-vector/1247)

https://github.com/rust-lang/rust/pull/25080/files#r29634986

r? @huonw 

I know this is the most trivial thing since it's *just* the model lexer, not the real lexer, but [it is simpler to read](https://github.com/rust-lang/rust/issues/15883#issuecomment-72906431) and it'd be great if it was up to date but [it's been rotting](https://github.com/rust-lang/rust/issues/22379) and this is a tiny bit of that.

Thanks!!!!!!

Unsafe destructors were removed, added remarks about needed feature gates.

cc #16676 
r? @steveklabnik 

The error message was misleading, so I adjusted it, and I also added the long diagnostics for this error (resolves one point in #24407).

I was unsure about how to phrase the error message. Is “generic parameter binding” the correct term for this?

For https://github.com/rust-lang/rust/issues/24407

This style inconsistency was noted at https://travis-ci.org/rust-lang/rust/builds/61583070#L371

To separate concerns, instead of checking the state of `#toggle-all-docs` by looking at its label text, I add or remove a class `will-expand` depending on whether the button’s next click will expand everything. (The `if` statement’s two branches were swapped as part of this change.)

I moved the desired text values to a function `labelForToggleButton`, so changing the values will be easier. I also note in a comment the other file where the text is duplicated.

To allow the labels of both types of toggle buttons to be uniformly set, I added a `span.inner` to the global button too.

I split the template in `render.rs` into multiple lines to make room for the `span`, and that adds whitespace around the `[` and `]` text elements. That seems to be okay, though – the page still looks the same.

I updated the CSS styling for `.collapse-toggle > .inner` to add a little extra space around the symbol, to make minus signs easier to identify. (`#toggle-all-docs > .inner` does not need the same style, since its text size is bigger, so it naturally puts more space around the symbol.)

So, I realize this is really late in the game so it's unlikely to be accepted but `FromRawFd`/`FromRawHandle` are necessary for fine grain control over file creation. For example, the current `OpenOptions` does not provide a way to avoid file creation races (there's no way to specify `O_EXCL` or the windows equivalent). Stabilizing these traits and their implementations will give 1.0 users fine-grain control over file creation without committing to any new complex APIs.  Additionally, `AsRawFd`/`AsRawHandle` are already stable so I feel that that stabilizing their inverses is a reasonably small change.

Disclaimer: I'm asking because my crate, tempfile, depends on this feature.

These constants were added in 6f54ce9a and
e8fbd1ce to a consts module that is behind a
gate.

I have not confirmed that these constants do indeed work on either OSX or iOS.

Depends on #24921. r? @alexcrichton 

cc #19986 

r? @Gankro 

The [UnsafeCell documentation says it is undefined behavior](http://doc.rust-lang.org/nightly/std/cell/struct.UnsafeCell.html), so people shouldn't do it.

This happened to catch one case in libstd that was doing this, and I switched that to use an UnsafeCell internally.

Closes #13146 

Closes #20626.

Closes #22463.

Closes #22258.

Closes #22037.

Closes #21701.

Closes #21562.

Closes #21177.

Nothing uses it anymore.