Fixes #29128

Most of the weird lifetime things and `inner` stuff seems like leftover cruft from `thread::scoped`. Should `JoinInner` just be removed/merged with `JoinHandle`?

Also is it okay to remove the `FnBox`? I'm not really sure why there were two allocations there...

Fixes #28947

r? @nrc

Re-submission of the closed PR #29054 with the additional rustfmt-zation of the full librand.

Closes https://github.com/rust-lang/rust/issues/29120.

https://github.com/rust-lang/rust/blob/master/src/libcore/iter.rs#L1541

r? @alexcrichton 

Fixes #28947

https://github.com/rust-lang/rust/blob/master/src/libcore/iter.rs#L1541

This PR turns statically known erroneous code (e.g. numeric overflow) into a warning and continues normal code-generation to emit the same code that would have been generated without `check_const` detecting that the result can be computed at compile-time.

<del>It's not done yet, as I don't know how to properly emit a lint from trans. I can't seem to extract the real lint level of the item the erroneous expression is in.</del> It's an unconditional warning now.

r? @pnkfelix 

cc @nikomatsakis 

* [RFC 1229 text](https://github.com/rust-lang/rfcs/blob/master/text/1229-compile-time-asserts.md)
* RFC PR: rust-lang/rfcs#1229
* tracking issue: https://github.com/rust-lang/rust/issues/28238

The escaped form isn't pretty, but this should be a very rare error.
Having a general binary-escaping string creation function might be a
good idea, though.

Closes #29122

The escaped form isn't pretty, but this should be a very rare error.
Having a general binary-escaping string creation function might be a
good idea, though.

Closes #29122

Fixes #29073. 

`rbml::writer::Encoder::unsafe_clone` had no users across the entire
repo.

Change the spacing/order of lines in the final pointer conversion example to make it more clear.

Very small change, can be rolled up.

When going through the docs, it is not clear that binary files cannot be tested. Additionally, it is hard to find the proper structure of a Rust crate and it took me several hours of looking through the docs to find the crates and modules section. I think we can link to it from here and it will be beneficial to those who are coming to the language.

this PR adds notes for missing `PartialEq` and `PartialOrd`. I've added a test case but it seems like `NOTE` is ignored by the test runner.

#28837

Closes #27105.

Fixes #29037.
Fixes #29106.

r? @pnkfelix 
CC @Gankro 

Fixes : #19668 

r? @Manishearth 

Closes https://github.com/rust-lang/rust/issues/28750
`Arm` and `Generics` don't have spans at all, so it's not a visitor's problem, `visit_struct_def` was fixed in https://github.com/rust-lang/rust/pull/28816

While working on #28711 I found out that 

*  src/libcoretest/clone.rs 
* src/libcoretest/fmt/float.rs  
* src/libcoretest/intrinsics.rs 

are not used. I am not sure if removing them is the right way to go. If it makes sense to keep (and fix and enable) them, I would be happy to update the PR.

Closes #27105.

trans: Use an isize to count the number of registers so we don't underflow for fn's with > 7 args in debug builds.

This PR solves the following issues (or at least help users to understand the problem):

```Rust
#![crate_name = "b"]
#![crate_type = "rlib"]

pub fn his_function_has_a_very_long_name_and_should_make_cargo_doc_explodes_because_it_will_want_to_make_a_filename_with_it_in_excess_of_the_max_filename_length_for_most_filesystem_this_is_not_yet_long_enough_i_need_moreis_function_has_a_very_long_name_and_should_make_cargo_doc_explodes_because_it_will_want_to_make_a_filename_with_it_in_excess_of_the_max_filename_length_for_most_filesystem_this_is_not_yet_long_enough_i_need_more_() {}
```

```Rust
#![crate_name = "b"]
#![crate_type = "rlib"]

pub struct his_function_has_a_very_long_name_and_should_make_cargo_doc_explodes_because_it_will_want_to_make_a_filename_with_it_in_excess_of_the_max_filename_length_for_most_filesystem_this_is_not_yet_long_enough_i_need_moreis_function_has_a_very_long_name_and_should_make_cargo_doc_explodes_because_it_will_want_to_make_a_filename_with_it_in_excess_of_the_max_filename_length_for_most_filesystem_this_is_not_yet_long_enough_i_need_more_;
```

For the maximum filename length chosen, @gkoz gave me [this link](http://unix.stackexchange.com/a/32834).

This change has two consequences:

1. It makes `Arc<T>` and `Rc<T>` covariant in `T`.

2. It causes the compiler to reject code that was unsound with respect
to dropck. See compile-fail/issue-29106.rs for an example of code that
no longer compiles. Because of this, this is a [breaking-change].

Fixes #29037.
Fixes #29106.

Fixed some typos and changed the link to the link to crates-and-modules to be dynamic.