Symlink creation on Windows has in the past basically required admin;
it’s being opened up a bit in the Creators Update, so that at least
people who have put their computers into Developer Mode will be able to
create symlinks without special privileges. (Microsoft are being
cautious about it all; the Developer Mode requirement makes it so that
it this won’t be as helpful as I’d like, but it’s still an improvement
over requiring admin.)

Because of compatibility concerns, they’ve hidden this new functionality
behind a new flag in the CreateSymbolicLink dwFlags:
SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE. So we add this flag in
order to join the party.

Older Windows doesn’t like this new flag, though, so if we encounter
ERROR_INVALID_PARAMETER we try again without the new flag.

Sources:

- https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/
  is the official announcement (search for CreateSymbolicLink)

- https://news.ycombinator.com/item?id=13096354 on why the new flag.

- https://twitter.com/richturn_ms/status/818167548269051905 confirming
  that Developer Mode will still be required.

Show a conventional way to use process::exit when destructors are considered important and also
mention that the same caveats wrt destructors apply to exec as well.

rustdoc would output the full path to the binary when calling it with
the `-h` or `--help` flags. This is undesired behavior. It has been
replaced with a hardcoded string `rustdoc` to fix the issue.

Fixes rust-lang#39310

The versions show up in rustdoc.

fixes rust-lang/rls#160

…igured

Although signatures with anonymous parameters may not be deprecated or
removed at this point, the team seems to agree that the ability to have
an anonymous parameter is unfortunate historical baggage, and that we
shouldn't create new code that uses it.

Context: rust-lang#33417 (comment)

We should be sure to add our build system entry point!

Closes rust-lang#39476

These methods enable socket reads without side-effects. That is,
repeated calls to peek() return identical data. This is accomplished
by providing the POSIX flag MSG_PEEK to the underlying socket read
operations.

This also moves the current implementation of recv_from out of the
platform-independent sys_common and into respective sys/windows and
sys/unix implementations. This allows for more platform-dependent
implementations.

This allows builtin derives to be registered and
resolved, just like other derive types.

This removes the expand_derives function, and sprinkles
the functionality throughout the Invocation Collector,
Expander and Resolver.

This implements rust-lang#39288.

Thanks to @steveklabnik and @oli-obk for their review comments :)

Remove attr-variant-data.rs since it relies on quirks
in legacy custom derive resolution (undefined derives
only print a warning).

Add a new test which uses a defined proc macro derive,
and tests pretty printing of proc macro derive
attributes.

The stabilizing commit is 5056a43, which is not in 1.14, but is (at
time of writing) on the 1.16 beta branch.

Expand documentation of process::exit and exec

Show a conventional way to use process::exit when destructors are considered important and also
mention that the same caveats wrt destructors apply to exec as well.

…ymlink-creation, r=alexcrichton

Support unprivileged symlink creation in Windows

Symlink creation on Windows has in the past basically required admin; it’s being opened up a bit in the Creators Update, so that at least people who have put their computers into Developer Mode will be able to create symlinks without special privileges. (It’s unclear from what Microsoft has said whether Developer Mode will be required in the final Creators Update release, but sadly I expect it still will be, so this *still* won’t be as helpful as I’d like.)

Because of compatibility concerns, they’ve hidden this new functionality behind a new flag in the CreateSymbolicLink dwFlags: `SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE`. So we add this flag in order to join the party.

Sources:

- https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/ is the official announcement (search for CreateSymbolicLink)

- https://news.ycombinator.com/item?id=13096354 on why the new flag.

Add 128-bit atomics

This is currently only supported on AArch64 since that is the only target which unconditionally supports 128-bit atomic operations.

cc rust-lang#35118

Add peek APIs to std::net

Adds "peek" APIs to `std::net` sockets, including:
- `UdpSocket.peek()`
- `UdpSocket.peek_from()`
- `TcpStream.peek()`

These methods enable socket reads without side-effects. That is, repeated calls to `peek()` return identical data. This is accomplished by providing the POSIX flag `MSG_PEEK` to the underlying socket read operations.

This also moves the current implementation of `recv_from` out of the platform-independent `sys_common` and into respective `sys/windows` and `sys/unix` implementations. This allows for more platform-dependent implementations where necessary.

Fixes rust-lang#38980

…ikomatsakis

Add warning for () to ! switch

With feature(never_type) enabled diverging type variables will default to `!` instead of `()`. This can cause breakages where a trait is resolved on such a type.

This PR emits a future-compatibility warning when it sees this happen.

…lexcrichton

branchless .filter(_).count()

I found that the branchless version is only slower if we have little to no branch misses, which usually isn't the case. I notice speedups between -5% (perfect prediction) and 60% (real world data).

…xcrichton

Tell emscripten to remove exception handling code when panic=abort

Fixes rust-lang#36900

Provide Entry-like API for Option

This implements rust-lang#39288.

I am wondering whether to use std::intrinsics::unreachable!() here. Both seems fine to me (the second match optimizes away in release mode).

…richton

Fix full path being output with `rustdoc -h`

rustdoc would output the full path to the binary when calling it with
the `-h` or `--help` flags. This is undesired behavior. It has been
replaced with a hardcoded string `rustdoc` to fix the issue.

Fixes rust-lang#39310

Fix a few impl stability attributes

The versions show up in rustdoc.

…eyfried

Expand derive macros in the MacroExpander

This removes the expand_derives function, and sprinkles the functionality throughout the Invocation Collector, Expander and Resolver.

Fixes rust-lang#39326

r? @jseyfried

…, r=nikomatsakis

Don't suggest to use things which weren't found either

Fixes rust-lang#38054

The best code I can come up with, suggestions are welcome.

Basically, removing ```. Did you mean to use `DoesntExist1`?``` in the code below, because it is useless.

```rust
error[E0432]: unresolved import `DoesntExist1`
 --> src/lib.rs:1:5
  |
1 | use DoesntExist1;
  |     ^^^^^^^^^^^^ no `DoesntExist1` in the root

error[E0432]: unresolved import `DoesntExist2`
 --> src/lib.rs:2:5
  |
2 | use DoesntExist2;
  |     ^^^^^^^^^^^^ no `DoesntExist2` in the root. Did you mean to use `DoesntExist1`?
```

save-analysis: be more paranoid about generated paths

fixes rust-lang/rls#160

…, r=jseyfried

Change tracking issue for `proc_macro` feature to rust-lang#38356

r? @jseyfried

Fix bootstrap.py issues with new rustbuild build system (fixes rust-lang#39469)

…, r=alexcrichton

Add a name for the parameter to `TryFrom::try_from`.

Although signatures with anonymous parameters may not be deprecated or removed at this point, the team seems to agree that the ability to have an anonymous parameter is unfortunate historical baggage, and that we shouldn't create new code that uses it.

Context: rust-lang#33417 (comment)

rustbuild: Add x.py to source tarballs

We should be sure to add our build system entry point!

Closes rust-lang#39476

…hton

README path correction

…ilization_version, r=petrochenkov

correct version in which more_struct_aliases was/will be stable

The stabilizing commit is 5056a43, which is not in 1.14, but is (at
time of writing) on the 1.16 beta branch. [See discussion](rust-lang#39282 (comment)).