See its documentation for more

inline(never) is better way to avoid optimizer to inline the function instead of cold.

- Reflect changes in x.py defaults
- Remove recommendation to use nightly for incremental; it works fine on
beta
- Remove note that incremental chooses stage 1 by default; stage 1 is
already the default
- Update Discord -> Zulip

Make the following methods of `Duration` unstable const under `duration_const_2`:
 - `from_secs_f64`
 - `from_secs_f32`
 - `mul_f64`
 - `mul_f32`
 - `div_f64`
 - `div_f32`

This results in all methods of `Duration` being (unstable) const.

Also adds tests for these methods in a const context, moved the test to `library` as part of rust-lang#76268.

Possible because of rust-lang#72449, which made the relevant `f32` and `f64` methods const.

Tracking issue: rust-lang#72440

Should been part of rust-lang#74163

suggest `where T: Foo` for the first bound on a trait, then suggest
`, T: Foo` when the suggested bound would add to an existing set of
`where` clauses. `where T: Foo` may be the first bound if `T` has a
default, because we'd rather suggest
```
trait A<T=()> where T: Copy
```
than
```
trait A<T: Copy=()>
```
for legibility reasons.

Also improve the docs for it a bit.

Co-authored-by: Esteban Küber <esteban@kuber.com.ar>

Some errors, like if rustc is broken, or dylib search path is wrong,
will only display non-JSON errors. Show those, too, to make it easier to
debug a problem.

Some cleanup changes and commenting

r? @nikomatsakis
Cc @eddyb

…test, r=jyn514

Ignored private doc test

Fixes rust-lang#76457.

r? @ehuss

Prefer asm! over llvm_asm! in core

Replace llvm_asm! with asm! in core.

x86 asm compare (in somecases I replaced generic type with String).
* https://rust.godbolt.org/z/59eEMv
* https://rust.godbolt.org/z/v78s6q
* https://rust.godbolt.org/z/7qYY41

remove orphaned files

Should been part of rust-lang#74163

…r=davidtwco

Introduce a PartitioningCx struct

This contains all the data used by the partitioning algorithm and allows that data to be used at each stage of the partitioning. This is useful for other approaches to partitioning which may want different pieces of the data available at each step.

cc @rust-lang/wg-incr-comp

…ion, r=estebank

fix syntax error in suggesting generic constraint in trait parameter

suggest `where T: Foo` for the first bound on a trait, then suggest
`, T: Foo` when the suggested bound would add to an existing set of
`where` clauses. `where T: Foo` may be the first bound if `T` has a
default, because we'd rather suggest
```
trait A<T=()> where T: Copy
```
than
```
trait A<T: Copy=()>
```
for legibility reasons.

the test case i added here is derived from [this reproduction](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=0bf3ace9f2a183d0bdbd748c6b8e3971):
```
struct B<T: Copy> {
    t: T
}

trait A<T = ()> {
    fn returns_constrained_type(&self, t: T) -> B<T> {
        B { t }
    }
}
```
where the suggested fix,
```
trait A<T = ()>, T: Copy { ... }
```
is in fact invalid syntax!

i also found an error in the existing suggestion for `trait Base<T = String>: Super<T>` where rustc would suggest `trait Base<T = String>: Super<T>, T: Copy`, but `T: Copy` is the first of the trait's `where` clauses and should be `where T: Copy` as well. the test for that suggestion expects invalid syntax, and has been revised to a compiler-pleasing `trait Base<T = String>: Super<T> where T: Copy`.

judging by rust-lang#70009 i'll.. cc @estebank ?

improve const infer error

cc rust-lang#72328

reduces it from
```
error[E0282]: type annotations needed
  --> src/main.rs:17:5
   |
17 |     Foo.bar().bar().bar().bar().baz();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: unable to infer the value of a const parameter
```
to
```
error[E0282]: type annotations needed
  --> $DIR/method-chain.rs:21:33
   |
LL |     Foo.bar().bar().bar().bar().baz();
   |                                 ^^^
   |
   = note: cannot infer the value of the const parameter `N`
```

r? @varkor

Simplify iter flatten struct doc

… r=jonas-schievink

⬆️ rust-analyzer

r? @ghost

Small docs improvements

@rustbot modify labels: T-doc T-compiler

…-Simulacrum

Fix generating rustc docs with non-default lib directory.

If `libdir` is set in `config.toml`, then the tool to generate the rustc docs was unable to run `rustc` because it could not find the shared libraries. The solution is to set the dylib search path to include the libdir.

I changed the API of `add_rustc_lib_path` to take `Command` instead of `Cargo` to try to share the code in several places. This is how it worked before rust-lang#64316, and I think this still retains the spirit of that change.

Fixes rust-lang#76702

…m, r=jyn514

Use intra-doc links in `core::mem`

Part of rust-lang#75080.

Last one for now!

---

@rustbot modify labels: A-intra-doc-links T-doc

…ulacrum

Test and fix Send and Sync traits of BTreeMap artefacts

Fixes rust-lang#76686.

I'm not quite sure what all this implies. E.g. comparing with the definitions for `NodeRef` in node.rs,  maybe an extra bound `T: 'a` is useful for something. The test compiles on stable/beta (apart from `drain_filter`) so I bet `Sync` is equally desirable.

r? @Mark-Simulacrum

Add a comment why `extern crate` is necessary for rustdoc

r? @ehuss

From rust-lang#74293 (comment).

…r=alexcrichton

Avoid printing dry run timings

This avoids a wall of text on CI with 0.000 as the likely time.

r? @alexcrichton

Update books

## nomicon

1 commits in 25854752549d44d76fbd7650e17cb4f167a0b8fb..6e57e64501f61873ab80cb78a07180a22751a5d6
2020-08-19 16:41:48 -0400 to 2020-09-14 11:40:23 -0400
- Fix API change to alloc::Global::grow. (rust-lang/nomicon#236)

## reference

3 commits in 25391dba46262f882fa846beefaff54a966a8fa5..56a13c082ee90736c08d6abdcd90462517b703d3
2020-09-02 07:22:55 -0700 to 2020-09-14 23:20:16 -0700
- Update the description of staticlib (rust-lang/reference#884)
- Rust 1.46 now allows more features in const fn (rust-lang/reference#883)
- Document the enum changes in RFC 2195 (rust-lang/reference#879)

## book

1 commits in e5ed97128302d5fa45dbac0e64426bc7649a558c..cb28dee95e5e50b793e6ba9291c5d1568d3ad72e
2020-08-31 12:53:40 -0500 to 2020-09-09 10:06:00 -0500
- Fixed the error message of invalid array element access in ch03.2 (rust-lang/book#2446)

Extract some intrinsics out of rustc_codegen_llvm

A significant amount of intrinsics do not actually need backend-specific behaviors to be implemented, instead relying on methods already in rustc_codegen_ssa. So, extract those methods out to rustc_codegen_ssa, so that each backend doesn't need to reimplement the same code.

Almost everything should be a pretty direct translation. A notable not-direct-translation is `add_with_overflow` and friends being changed to `bx.checked_binop`, but it's pretty simple.

I could have been a lot more aggressive here and pulled out way more methods, and add a few new methods in the rustc_codegen_ssa "API". However, because this is my second rustc PR, I thought that moving those to a follow-up PR and doing more incremental changes here would be better (and I guess ask if this work is even desired in the first place). I'm hoping to eventually remove the mess of intrinsic handling in the backend entirely, which would be hecking fantastic ✨