the use of lazily evaluated alternatives when appropriate. These
comments are intended to echo a clippy lint on the same topic (see
https://rust-lang-nursery.github.io/rust-clippy/master/index.html#or_fun_call)

Report lint names in json diagnostics

This allows tools like `rustfix` to have whitelists for what to automatically apply and what not.

typeck: suggest use of match_default_bindings feature

Fixes #45383.
Updates #42640.

r? @nikomatsakis
cc @tschottdorf

This needs a UI test, but thought I'd get some early feedback.

save-analysis: support unions

r? @EddyB

Improve display of error E0308

Ref. Forgetting to call a variant constructor causes a confusing error message #35241.

This PR modifies [`note_type_err`](https://github.com/rust-lang/rust/blob/b7041bfab3a83702a8026fb7a18d8ea7d54cc648/src/librustc/infer/error_reporting/mod.rs#L669-L674) to display a `help` message when a `TyFnPtr` or `TyFnDef` are found and the return type, of the function or function pointer, is the same as the type that is expected.

The output of compiling

```rust
struct Foo(u32);

fn test() -> Foo { Foo }

fn main() {}
```

is now

```bash
$ rustc src/test/ui/issue-35241.rs
error[E0308]: mismatched types
  --> src/test/ui/issue-35241.rs:13:20
   |
13 | fn test() -> Foo { Foo }
   |              ---   ^^^ expected struct `Foo`, found fn item
   |              |
   |              expected `Foo` because of return type
   |
   = help: did you mean `Foo { /* fields */ }`?
   = note: expected type `Foo`
              found type `fn(u32) -> Foo {Foo::{{constructor}}}`

error: aborting due to previous error
```

Emit crate disambiguators in save-analysis data

Needed for https://github.com/nrc/rls-analysis/issues/93.
Blocked by https://github.com/nrc/rls-data/pull/11. (For now, this pulls my branch [rls-data/crate-source](https://github.com/Xanewok/rls-data/tree/crate-source))

This will allow to disambiguate different crates types/versions when indexing resulting save-analysis data (most importantly allow to support bin+lib and different crate versions).

r? @nrc

Bring back slice::ref_slice as slice::from_ref.

These functions were deprecated and removed in 1.5, but such simple
functionality shouldn't require using unsafe code, and it isn't
cluttering libstd too much.

The original removal was quite contentious (see #27774), since then
we've had precedent for including such nuggets of functionality (see rust-lang/rfcs#1789),
and @nikomatsakis has provided a lot of use cases in https://github.com/rust-lang/rfcs/pull/1789#issuecomment-314640034.
Hence this PR.

I'm not too sure what to do with stability, feel free to correct me.
It seems pointless to go through stabilization for these functions though.

cc @aturon

enable non-lexical lifetimes in the MIR borrow checker

This PR, joint work with @spastorino, fills out the NLL infrastructure and integrates it with the borrow checker. **Don't get too excited:** it includes still a number of hacks (the subtyping code is particularly hacky). However, it *does* kinda' work. =)

The final commit demonstrates this by including a test that -- with both the AST borrowck and MIR borrowck -- reports an error by default. But if you pass `-Znll`, you only get an error from the AST borrowck, demonstrating that the integration succeeds:

```
struct MyStruct {
    field: String
}

fn main() {
    let mut my_struct = MyStruct { field: format!("Hello") };

    let value = &my_struct.field;
    if value.is_empty() {
        my_struct.field.push_str("Hello, world!");
        //~^ ERROR cannot borrow (Ast)
    }
}
```

incr.comp.: Implement compiler diagnostic persistence.

This PR implements storing and loading diagnostics that the compiler generates and thus allows for emitting warnings during incremental compilation without actually re-evaluating the thing the warning originally came from. It also lays some groundwork for storing and loading type information and MIR in the incr. comp. cache.

~~It is still work in progress:~~
- ~~There's still some documentation to be added.~~
- ~~The way anonymous queries are handled might lead to duplicated emissions of warnings. Not sure if there is a better way or how frequent such duplication would be in practice.~~

Diagnostic message duplication is addressed separately in #45519.

r? @nikomatsakis

rustc_typeck: use subtyping on the LHS of binops.

Fixes #45425.

r? @nikomatsakis

Rollup of 14 pull requests

- Successful merges: #45450, #45579, #45602, #45619, #45624, #45644, #45646, #45648, #45649, #45650, #45652, #45660, #45664, #45671
- Failed merges:

Tidy: track rustc_const_unstable feature gates as well

This is important for the unstable book stub generation.

Fix incorrect error type in Read::byte docs

None

Suggest renaming import if names clash

Closes https://github.com/rust-lang/rust/issues/32354.

The output for the example in the issue looks like this:

```
~/p/local-rust-dev-testing ❯❯❯ cargo +local-s1 build
   Compiling local-rust-dev-testing v0.1.0 (file:///home/cldfire/programming_projects/local-rust-dev-testing)
error[E0252]: the name `ConstructorExtension` is defined multiple times
  --> src/main.rs:49:5
   |
48 | use extension1::ConstructorExtension;
   |     -------------------------------- previous import of the trait `ConstructorExtension` here
49 | use extension2::ConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ConstructorExtension` reimported here
   |
   = note: `ConstructorExtension` must be defined only once in the type namespace of this module
help: You can use `as` to change the binding name of the import
   |
49 | use extension2::ConstructorExtension as OtherConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...
```

This is my first PR that touches the compiler in any way, so if there's something else I need to do here (e.g. add a test), please let me know :).

More fixes for x86_64-unknown-linux-gnux32

This update libc (all libc testing are passing) and fixes NR_GETRANDOM.

Fix all but one run-pass test (lto-unwind.rs, see https://github.com/rust-lang/rust/issues/45416)

Take crate-type into account when generating symbol export lists (linker version scripts)

r? @alexcrichton
cc https://github.com/rust-lang/rust/issues/45613

Add a hint what `BufRead` functions do on EOF

Update doc comment for the Unix extension module

It was a bit outdated, claimed to be able to do less than it actually
could.

Count type aliases used in patterns as usage by dead_code lint

Fixes #45614.

edit and fix bad spacing of inner-attribute-not-allowed note

This multiline string literal was missing a backslash, leaving an awkward
newline and 35 spaces in the middle of the message.

But while we're here, the existing message seems kind of long in comparison to
similar notes: to cut it down, we excise the mentions of doc comments, which
seems sensible because we know that this erroneous attribute is not a doc
comment (notice the `is_sugared_doc: false` at the end of the function; if it
had been a doc comment, that error would get set in the `token::DocComment`
match branch of `parse_outer_attributes`).

bootstrap: Add missing cputype matching for sparc64

Trying to configure rust natively on sparc64-unknown-linux-gnu currently fails with:

```
root@deb4g:/local_scratch/glaubitz/rust/rust# ./configure --host=sparc64-unknown-linux-gnu --enable-local-rust --local-rust-root=/usr/local
configure: processing command line
configure:
configure: build.host           := ['sparc64-unknown-linux-gnu']
configure: build.rustc          := /usr/local/bin/rustc
configure: build.cargo          := /usr/local/bin/cargo
configure: build.rustc          := /usr/local/bin/rustc
configure: build.cargo          := /usr/local/bin/cargo
configure: build.configure-args := ['--host=sparc64-unknown-linux-gnu', '--enable ...
unknown cpu type: sparc64
root@deb4g:/local_scratch/glaubitz/rust/rust#
```

This is trivially fixed by defining sparc64 as a valid cputype.

Support Dragonfly when building Openssl

Optimize some span operations

Do not decode span data twice/thrice/etc unnecessarily.
Applied to stable hashing and all methods in `impl Span`.

Follow up to https://github.com/rust-lang/rust/pull/44646
r? @michaelwoerister

Document that call expressions also represent ADT constructors.

This is a rather obscure part of the language.

Fix title heading overlap in rust doc

Fixes #45158.

To be noted that this margin only appears when a title is the first element.

<img width="1440" alt="screen shot 2017-10-22 at 16 08 44" src="https://user-images.githubusercontent.com/3050060/31862746-6411070e-b743-11e7-9a75-4159e1f7f1d6.png">

r? @rust-lang/docs

remove the `T: Sync` requirement for `RwLock<T>: Send`

That requirement makes sense for containers like `Arc` that don't
uniquely own their contents, but `RwLock` is not one of those.

This restriction was added in https://github.com/rust-lang/rust/commit/380d23b5d4b9fb8f5f0ebf178590f61528b2483e, but it's not clear why. @hniksic
and I [were discussing this on reddit](https://www.reddit.com/r/rust/comments/763o7r/blog_posts_introducing_lockfree_rust_comparing/dobcvbm/). I might be totally wrong about this change being sound, but I'm super curious to find out :)

Improve sidebar rendering and add methods list

I suppose it can be reviewed as is, but this is just the first step of a more global plan.

cc @rust-lang/docs @nical

And a screenshot of course:

<img width="1440" alt="screen shot 2017-10-10 at 23 38 45" src="https://user-images.githubusercontent.com/3050060/31412170-657beaf6-ae14-11e7-9f01-1e562a034595.png">

Improve the display of error E0308 for structs by adding a "did you
mean" span label.

Implement TryFrom<&[T]> for &[T; N]

There are many cases where a buffer with a static compile-time size is preferred over a slice with a dynamic size. This allows for performing a checked conversion from `&[T]` to `&[T; N]`. This may also lead to compile-time optimizations involving `[T; N]` such as loop unrolling.

This is my first PR to Rust, so I'm not sure if discussion of this change should happen here or does it need its own RFC? I figured these changes would be a subset of #33417.

This is kind of a hack but it works...

This is important for the unstable book stub generation.