The collections debug helpers no longer prefix output with the
collection name, in line with the current conventions for Debug
implementations. Implementations that want to preserve the current
behavior can simply add a `try!(write!(fmt, "TypeName "));` at the
beginning of the `fmt` method.

[breaking-change]

Port of pcwalton removal of `#[unsafe_destructor]` check.

Earlier commits impose rules on lifetimes that make generic destructors safe; thus we no longer need the `#[unsafe_destructor]` attribute nor its associated check.

----

So remove the check for the unsafe_destructor attribute.

And remove outdated compile-fail tests from when lifetime-parameteric dtors were disallowed/unsafe.

In addition, when one uses the attribute without the associated feature, report that the attribute is deprecated.

However, I do not think this is a breaking-change, because the attribute and feature are still currently accepted by the compiler. (After the next snapshot that has this commit, we can remove the feature itself and the attribute as well.)

----

I consider this to:

Fix #22196

(technically there is still the post snapshot work of removing the last remnants of the feature and the attribute, but the ticket can still be closed in my opinion).

Earlier commits impose rules on lifetimes that make generic
destructors safe; thus we no longer need the `#[unsafe_destructor]`
attribute nor its associated check.

----

So remove the check for the unsafe_destructor attribute.

And remove outdated compile-fail tests from when lifetime-parameteric
dtors were disallowed/unsafe.

In addition, when one uses the attribute without the associated
feature, report that the attribute is deprecated.

However, I do not think this is a breaking-change, because the
attribute and feature are still currently accepted by the compiler.
(After the next snapshot that has this commit, we can remove the
feature itself and the attribute as well.)

----

I consider this to:

Fix #22196

(techincally there is still the post snapshot work of removing the
last remants of the feature and the attribute, but the ticket can
still be closed in my opinion).

All methods are inlined into Iterator with `Self: Sized` bounds to make
sure Iterator is still object safe.

[breaking-change]

This is blocked on ICEs: https://gist.github.com/sfackler/5aff7c57cf8d896e2c6f
Seem to be similar to #23281.

All methods are inlined into Iterator with `Self: Sized` bounds to make
sure Iterator is still object safe.

[breaking-change]

Also convert [T]'s Debug impl. The behavior of the alternate flag here's
changing.

The collections debug helpers no longer prefix output with the
collection name, in line with the current conventions for Debug
implementations. Implementations that want to preserve the current
behavior can simply add a `try!(write!(fmt, "TypeName "));` at the
beginning of the `fmt` method.

[breaking-change]

None

- Successful merges: #23332, #23751, #23788, #23803, #23804
- Failed merges: 

r? @steveklabnik

Pretty much what it says on the tin.

Fixes #23748

I found the arbitrary `10` surprising. A better method name, in such a case, would be `grow_by_10` :)

curl's progress meter would otherwise interfere with sudo's password prompt.

In addition, add the -f flag to make sure 4xx status codes are treated as errors.

r? @brson 

r? @steveklabnik

The Send bound is an unnecessary restriction, and though provided as a convenience, can't be removed by downstream code.

The removal of this bound is a [breaking-change] since it removes an implicit Send bound on all `E: Error` and all `Error` trait objects.

To migrate, consider if your code actually requires the Send bound and, if so, add it explicitly.

Fixes #23774

r? @aturon

Previously a panic was generated for recursive prints due to a double-borrow of
a `RefCell`. This was solved by the second borrow's output being directed
towards the global stdout instead of the per-thread stdout (still experimental
functionality).

After this functionality was altered, however, recursive prints still deadlocked
due to the overridden `write_fmt` method which locked itself first and then
wrote all the data. This was fixed by removing the override of the `write_fmt`
method. This means that unlocked usage of `write!` on a `Stdout`/`Stderr` may be
slower due to acquiring more locks, but it's easy to make more performant with a
call to `.lock()`.

Closes #23781

Previously a panic was generated for recursive prints due to a double-borrow of
a `RefCell`. This was solved by the second borrow's output being directed
towards the global stdout instead of the per-thread stdout (still experimental
functionality).

After this functionality was altered, however, recursive prints still deadlocked
due to the overridden `write_fmt` method which locked itself first and then
wrote all the data. This was fixed by removing the override of the `write_fmt`
method. This means that unlocked usage of `write!` on a `Stdout`/`Stderr` may be
slower due to acquiring more locks, but it's easy to make more performant with a
call to `.lock()`.

Closes #23781

Fixes #22716

The Send bound is an unnecessary restriction, and though provided as a
convenience, can't be removed by downstream code.

The removal of this bound is a [breaking-change] since it
removes an implicit Send bound on all `E: Error` and all
`Error` trait objects.

To migrate, consider if your code actually requires the Send
bound and, if so, add it explicitly.

Fixes #23774

Conflicts:
	src/test/auxiliary/static-function-pointer-aux.rs
	src/test/auxiliary/trait_default_method_xc_aux.rs
	src/test/run-pass/issue-4545.rs

Conflicts:
	src/test/run-pass/issue-13027.rs

Fixes #22716

Fixes #23748

Fixes #21668

`std::dynamic_library` is currently using `std::old_io::Path` specifically. This change brings the API in alignment with `std::fs::File` by having it take `std::path::AsPath`. The Windows code should work, but I admittedly haven't tried it (I don't have a Windows machine readily available right now).

r? @alexcrichton

Until some backwards-compatibility hazards are fixed in #23121,
these need to be unstable.

[breaking-change]

Fixes #23713.

Also tweaked a few things.

When testing whether a default method predicates are satisfiable,
combine normalization with this check so that we also skip the
default method if normalization fails. Fixes #23485.

r? @nrc (I tried to address your nit from before as well)

Fixes #11794

I mostly removed superflous examples which use the standard library.

I have one more quesiton here though: threads. They're mostly a library thing, at this point, right?