Co-authored-by: Cldfire <cldfire@3grid.net>

They are now unnecessary for projects written in Rust, since
backtrace-rs used by the standard library has only Rust dependencies.

This has been put in place to patch over an ICE caused when we encounter
a non-static lifetime in a const generic during borrow checking. This
restriction may be relaxed in the future, but we need more discussion
before then, and in the meantime we should still deal with this ICE.

Fixes issue rust-lang#60814

This commit extends current well-formedness checking to apply to foreign
function declarations, re-using the existing machinery for regular
functions. In doing this, later parts of the compiler (such as the
`improper_ctypes` lint) can rely on being operations not failing as a
result of invalid code which would normally be caught earlier.

Signed-off-by: David Wood <david@davidtw.co>

Closes rust-lang#66770.

Fix debug assertion in typeck

Fixes rust-lang#72410

Impl Default for ranges

Couldn't find an issue about it.

`Range` and friends probably can implement `Default` if `Idx: Default`. For example, the following would be possible:

```rust
#[derive(Default)]
struct Foo(core::ops::RangeToInclusive<u64>);

let _ = [1, 2, 3].get(core::ops::Range::default());

core::ops::RangeFrom::<u8>::default().take(20).for_each(|x| { dbg!(x); });

fn stuff<T: Default>() { let instance = T::default(); ... more stuff }
stuff::<core::ops::RangeTo<f32>>();
```

Maybe there are some concerns about safety or misunderstandings?

…gn-fn-decl, r=ecstatic-morse

wf: check foreign fn decls for well-formedness

Fixes rust-lang#73252 and fixes rust-lang#73253.

This PR extends current well-formedness checking to apply to foreign function declarations, re-using the existing machinery for regular functions. In doing this, later parts of the compiler (such as the `improper_ctypes` lint) can rely on being operations not failing as a result of invalid code which would normally be caught earlier.

…akis

disallow non-static lifetimes in const generics

Disallow non-static lifetimes in const generics in order to to patch over an ICE caused when we encounter a non-static lifetime in a const generic during borrow checking. This restriction may be relaxed in the future, but we need more discussion before then, and in the meantime we should still deal with this ICE.

Fixes issue rust-lang#60814

…=eddyb

test caching opt_const_param_of on disc

Followup to rust-lang#74113, implements parts of rust-lang#74360

Tried caching `opt_const_param_of` on disk and adding an early exit if `tcx.dep_kind(def_id) != DefKind::AnonConst`.

Ended up causing a perf regression instead, so we just remove the FIXME and a short note to `opt_const_param_of`.

r? @eddyb

…omez

Ayu theme: Use different background color for Run button

Make it clearer that there is a button Run there.

Demo in rust-lang#74501 (comment) .

…meGomez

Fix search input focus in ayu theme

Closes rust-lang#74496.

Before:

![image](https://user-images.githubusercontent.com/13814214/87868463-d0c8fe80-c963-11ea-9003-aa578d869e98.png)

After:

![image](https://user-images.githubusercontent.com/13814214/87868467-dc1c2a00-c963-11ea-89a8-1280f68ff9df.png)

Update sanitizer docs

* Document AddressSanitizer memory leak detection defaults.
* Remove CC & CFLAGS from MemorySanitizer example - they are now unnecessary for pure Rust projects (backtrace-rs moved away from libbacktrace).

…be_uninit_extra, r=kennytm

Fix duplicate maybe_uninit_extra attribute

Introduced in rust-lang#72414

…tau, r=dtolnay

Stabilize TAU constant.

Closes rust-lang#66770.

…up, r=Manishearth

Improve "important traits" popup display on mobile

I implemented what @XAMPPRocky suggested in the [internals thread topic](https://internals.rust-lang.org/t/feedback-on-important-traits-rustdoc-feature/12752/18). I can confirm it works nicely.

r? @Manishearth

@Manishearth: By the way: I realized that when you click on the "i", you have to click again to make the popup disappear. Do you want me to extend the popup removal to any click outside the popup?

Fix an ICE on an invalid `binding @ ...` in a tuple struct pattern

Fixes rust-lang#74539.

update backtrace-rs

Hopefully fixes rust-lang#74484
r? @alexcrichton