Remove code duplication

Remove whitespace

Update documentation for to_uppercase, to_lowercase
collections: move hashmap's example to the struct.

Most people go straight to the struct, not looking at the module, so the
example was well hidden.
auto merge of #12845 : eddyb/rust/vec-no-drop-flag, r=thestinger
Remove Rc's borrow method to avoid conflicts with RefCell's borrow in Rc<RefCell<T>>.
Implement automatic overloaded dereference.
Closes #7141.
Introduce a common recursion limit for auto-dereference and monomorphization.
Apply @nikomatsakis' nits and comments patch.
Region + borrow checker support and tests for overloaded autoderef.
compile-fail: Beef up borrowck test to include some scenarios where we borrow mutably twice in a row
Tweak comments
auto merge of #12610 : eddyb/rust/deref-now-auto, r=nikomatsakis

Enables the dereference overloads introduced by #12491 to be applied wherever automatic dereferences would be used (field accesses, method calls and indexing).
auto merge of #12849 : nick29581/rust/doubles, r=alexcrichton
auto merge of #12852 : itdaniher/rust/master, r=alexcrichton

This enables the lowering of llvm 64b intrinsics to hardware ops, resolving issues around `__kernel_cmpxchg64` on older kernels on ARM devices, and also enables use of the hardware floating point unit, resolving https://github.com/mozilla/rust/issues/10482.
auto merge of #12238 : ktt3ja/rust/lifetime-error-msg, r=nikomatsakis

For the following code snippet:

```rust
struct Foo { bar: int }
fn foo1(x: &Foo) -> &int {
    &x.bar
}
```

This PR generates the following error message:

```rust
test.rs:2:1: 4:2 note: consider using an explicit lifetime parameter as shown: fn foo1<'a>(x: &'a Foo) -> &'a int
test.rs:2 fn foo1(x: &Foo) -> &int {
test.rs:3     &x.bar
test.rs:4 }
test.rs:3:5: 3:11 error: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
test.rs:3     &x.bar
              ^~~~~~
```

Currently it does not support methods.
collections: Don't recurse in hashmap robin_hood

This switches a "tail call" to a manual loop to get around LLVM not optimizing
to a tail call.

Close #12860
auto merge of #12561 : pzol/rust/char-case, r=alexcrichton

Added common and simple case folding, i.e. mapping one to one character mapping. For more information see http://www.unicode.org/faq/casemap_charprop.html

Removed auto-generated dead code which wasn't used.
auto merge of #12573 : lbonn/rust/unrecurs, r=alexcrichton

As mentioned in #6109, ```mkdir_recursive``` doesn't really need to use recursive calls, so here is an iterative version.
The other points of the proposed overhaul (renaming and existing permissions) still need to be resolved.

I also bundled an iterative ```rmdir_recursive```, for the same reason.

Please do not hesitate to provide feedback on style as this is my first code change in rust.
std: Rename Chan/Port types and constructor

* Chan<T> => Sender<T>
* Port<T> => Receiver<T>
* Chan::new() => channel()
* constructor returns (Sender, Receiver) instead of (Receiver, Sender)
* local variables named `port` renamed to `rx`
* local variables named `chan` renamed to `tx`

Closes #11765
Refactored while_some (libstd/option.rs)

The old 'while' needed to match 2 times for each iteration. With the new
'loop' there is just one match needed.

I have also replaced 'blk' by 'f' to be more consistent with parameter
names in other functions that are implemented for Option
auto merge of #12815 : alexcrichton/rust/chan-rename, r=brson

* Chan<T> => Sender<T>
* Port<T> => Receiver<T>
* Chan::new() => channel()
* constructor returns (Sender, Receiver) instead of (Receiver, Sender)
* local variables named `port` renamed to `rx`
* local variables named `chan` renamed to `tx`

Closes #11765