rustdoc: Hide `#text` in doc-tests

Since `#![attr]` and `#[attr]` are the only valid syntax that start with `#`, we can just special case those two tokens.

Fixes https://github.com/rust-lang/rust/issues/83284.

RustWrapper: work around unification of diagnostic handlers

This lets me build against llvm/main as of March 23rd, 2021. I'm not
entirely sure this is _correct_, but it appears to be functionally
identical to what was done in LLVM: existing callsites of
setInlineAsmDiagnosticHandler were moved to SetDiagnosticHandler() on
the context object, which we already set up in both places that we
called setInlineAsmDiagnosticHandler().

Added CharIndices::offset function

The CharIndices iterator has a field internally called front_offset, that I think would be very useful to have access to.

You can already do something like ``char_indices.next().map(|(offset, _)| offset)``, but that is wordy, in addition to not handling the case where the iterator has ended, where you'd want the offset to be equal to the length.

I'm very new to the open source world and the rust repository, so I'm sorry if I missed a step or did something weird.

Improve rebuilding behaviour of BinaryHeap::retain.

This changes `BinaryHeap::retain` such that it doesn't always fully rebuild the heap, but only rebuilds the parts for which that's necessary.

This makes use of the fact that retain gives out `&T`s and not `&mut T`s.

Retaining every element or removing only elements at the end results in no rebuilding at all. Retaining most elements results in only reordering the elements that got moved (those after the first removed element), using the same logic as was already used for `append`.

cc `@KodrAus` `@sfackler` - We briefly discussed this possibility in the meeting last week while we talked about stabilization of this function (#71503).

Since `#![attr]` and `#[attr]` are the only valid syntax that start with `#`, we can just special case those two tokens.

Use arrayvec 0.7, drop smallvec 0.6

With the arrival of min const generics, many alt-vec libraries have
updated to use it in some way and arrayvec is no exception. Use the
latest with minor refactoring.

Also, rustc_workspace_hack is the only user of smallvec 0.6 in the
entire tree, so drop it.

This lets me build against llvm/main as of March 23rd, 2021. I'm not
entirely sure this is _correct_, but it appears to be functionally
identical to what was done in LLVM: existing callsites of
setInlineAsmDiagnosticHandler were moved to SetDiagnosticHandler() on
the context object, which we already set up in both places that we
called setInlineAsmDiagnosticHandler().

Rollup of 7 pull requests

Successful merges:

 - #84343 (Remove `ScopeTree::closure_tree`)
 - #84376 (Uses flex to fix formatting of h1 at any width)
 - #84377 (Followup to #83944)
 - #84396 (Update LLVM submodule)
 - #84402 (Move `sys_common::rwlock::StaticRWLock` etc. to `sys::unix::rwlock`)
 - #84404 (Check for intrinsics before coercing to a function pointer)
 - #84413 (Remove `sys::args::Args::inner_debug` and use `Debug` instead)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Remove `sys::args::Args::inner_debug` and use `Debug` instead

This removes the method `sys::args::Args::inner_debug` on all platforms and implements `Debug` for `Args` instead.

I believe this creates a more natural API for the different platforms under `sys`: export a type `Args: Debug + Iterator + ...` vs. `Args: Iterator + ...` and with a method `inner_debug`.

Check for intrinsics before coercing to a function pointer

Return an error if coercing function items / non-capturing closures
to a common function pointer type would require reifying an intrinsic.

Turns ICE reported in #84297 into a proper error.

Move `sys_common::rwlock::StaticRWLock` etc. to `sys::unix::rwlock`

This moves `sys_common::rwlock::StaticRwLock`, `RWLockReadGuard` and `RWLockWriteGuard` to `sys::unix::rwlock`. They are already `#[cfg(unix)]` and don't need to be in `sys_common`.

Update LLVM submodule

Fixes #83467

Followup to #83944

Some cleanups requested by ``@nikomatsakis``

r? ``@nikomatsakis``

Uses flex to fix formatting of h1 at any width

Fixes #84354.

Remove `ScopeTree::closure_tree`

Seems to be dead code since #50649.

Implement indexing slices with pairs of core::ops::Bound<usize>

Closes #49976.

I am not sure about code duplication between `check_range` and `into_maybe_range`. Should be former implemented in terms of the latter? Also this PR doesn't address code duplication between `impl SliceIndex for Range*`.

It now doesn't fully rebuild the heap, but only the parts that are
necessary.

Rename AssociatedItems to AssocItems
Signed-off-by: NRustin-Liu <rustin.liu@gmail.com>

Part of https://github.com/rust-lang/rust/issues/60163#issuecomment-605308641

bootstrap: Restore missing --bulk-dirs for rust-docs, rustc-docs

The `--bulk-dirs` argument was removed for rust-docs in commit c768ce13 and rustc-docs in commit 8ca46fc7 (#79788), presumably by mistake; that slowed down installation of rust-docs from under a second to some twenty *minutes*.  Restoring `--bulk-dirs` reverses this slowdown.

Fixes #80684.

Cc `@pietroalbini.`

With the arrival of min const generics, many alt-vec libraries have
updated to use it in some way and arrayvec is no exception. Use the
latest with minor refactoring.

Also, rustc_workspace_hack is the only user of smallvec 0.6 in the
entire tree, so drop it.

Rollup of 12 pull requests

Successful merges:

 - #84013 (Replace all `fmt.pad` with `debug_struct`)
 - #84119 (Move `sys::vxworks` code to `sys::unix`)
 - #84212 (Replace `Void` in `sys` with never type)
 - #84251 (fix 'const-stable since' for NonZeroU*::new_unchecked)
 - #84301 (Document that `index` and `index_mut` can panic)
 - #84365 (Improve the docstrings of the `Lto` struct.)
 - #84378 (Fix broken doc link)
 - #84379 (Add GAT related tests)
 - #84380 (Write Rustdoc titles like "x in crate::mod - Rust")
 - #84390 (Format `Struct { .. }` on one line even with `{:#?}`.)
 - #84393 (Support `x.py doc std --open`)
 - #84406 (Remove `delete` alias from `mem::drop`.)

Failed merges:

 - #84387 (Move `sys_common::poison` to `sync::poison`)

r? `@ghost`
`@rustbot` modify labels: rollup

bump jobserver dependency

the newest jobserver version should slightly reduce context switches
in highly parallel build environments on linux kernels >= 5.6

Remove `delete` alias from `mem::drop`.

See https://github.com/rust-lang/rust/pull/81988#issuecomment-824168459 and https://github.com/rust-lang/rust/pull/81988#issuecomment-824213843

Support `x.py doc std --open`

I usually run this command:

```
./x.py doc std --stage 1 --jobs 8
```

Then I gave a try to `--open` and realized it wasn't working. I finally realized it was simply because it was only handling paths starting with `library`. This PR allows to handle both kinds of paths.

cc ``@jyn514``
r? ``@Mark-Simulacrum``

Rollup merge of #84390 - m-ou-se:make-debug-non-exhaustive-without-fields-a-little-bit-less-verbose, r=kennytm

Format `Struct { .. }` on one line even with `{:#?}`.

The result of `debug_struct("A").finish_non_exhaustive()` before this change:
```
A {
    ..
}
```
And after this change:
```
A { .. }
```

If there's any fields, the result stays unchanged:
```
A {
    field: value,
    ..
}

Write Rustdoc titles like "x in crate::mod - Rust"

This makes Rustdoc titles for items be like "Widget in cratename::blah::foo - Rust". Titles for modules and other non-items are unchanged, and still read like "cratename::blah::foo - Rust". This makes managing several open Rustdoc tabs easier.

![A screenshot of several open Rustdoc tabs](https://user-images.githubusercontent.com/10530973/115457675-d608f180-a1f2-11eb-87a8-838a32b4e3f7.png)

This also adds some tests for the new title behavior.

Closes #84371.

Add GAT related tests

Closes #79949
Closes #79636
Closes #78671
Closes #70303
Closes #70304
Closes #71176

Fix broken doc link

Improve the docstrings of the `Lto` struct.

This change is the result of [this zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Making.20sense.20of.20LTO.20modes.20in.20rustc).

Hopefully it makes things a little clearer. What do you think?

Document that `index` and `index_mut` can panic

I thought this was noteworthy and I think a bit more explicitness does no harm.

fix 'const-stable since' for NonZeroU*::new_unchecked

For the unsigned `NonZero` types, `new_unchecked` was const-stable from the start with https://github.com/rust-lang/rust/pull/50808. Fix the docs to accurately reflect that.

I think this `since` is also incorrect:
```rust
            #[stable(feature = "from_nonzero", since = "1.31.0")]
            impl From<$Ty> for $Int {
```
The signed nonzero types were only stabilized in 1.34, so that `From` impl certainly didn't exist before. But I had enough of digging through git histories after I figured out when `new_unchecked` became const-stable...^^

Replace `Void` in `sys` with never type

This PR replaces several occurrences in `sys` of the type `enum Void {}` with the Rust never type (`!`).
The name `Void` is unfortunate because in other languages (C etc.) it refers to a unit type, not an uninhabited type.

Note that the previous stabilization of the never type was reverted, however all uses here are implementation details and not publicly visible.

Move `sys::vxworks` code to `sys::unix`

Follow-up to #77666, `sys::vxworks` is almost identical to `sys::unix`, the only differences are the `rand`, `thread_local_dtor`, and `process` implementation. Since `vxworks` is `target_family = unix` anyway, there is no reason for the code not to live inside of `sys::unix` like all the other unix-OSes.

https://github.com/rust-lang/rust/blob/e41f378f825488a537b024fc3ed599d9c12fda96/compiler/rustc_target/src/spec/vxworks_base.rs#L12

``@rustbot`` label: +T-libs-impl

Replace all `fmt.pad` with `debug_struct`

This replaces any occurrence of:
- `f.pad("X")` with `f.debug_struct("X").finish()`
- `f.pad("X { .. }")` with `f.debug_struct("X").finish_non_exhaustive()`

This is in line with existing formatting code such as
https://github.com/rust-lang/rust/blob/125505306744a0a5bb01d62337260a95d9ff8d57/library/std/src/sync/mpsc/mod.rs#L1470-L1475

the newest jobserver version should slightly reduce context switches
in highly parallel build environments on linux kernels >= 5.6