r? @brson

This is only for implementations defined in the same crate as the trait they
implement.

This does not implement lazy symbol resolution yet.

10% win or so for small crates.

This removes the stacking of type parameters that occurs when invoking
trait methods, and fixes all places in the standard library that were
relying on it. It is somewhat awkward in places; I think we'll probably
want something like the `Foo::<for T>::new()` syntax.

For example, `foo::<T>::bar::<U>`.

This doesn't enforce that the type parameters are in the right
positions, however.

They are still present as part of the borrow check.

I've added a testcase, as mentioned in #5783

Fixes for #8625 to prevent assigning to `&mut` in borrowed or aliasable locations. The old code was insufficient in that it failed to catch bizarre cases like `& &mut &mut`. 

r? @pnkfelix

`target_library_in_workspace` is imported but unused:
~/rust/src/librustpkg/tests.rs:21:48: 21:75 warning: unused import [-W unused-imports (default)]

`UnsafeAtomicRcBox` → `UnsafeArc` (#7674), and `AtomicRcBoxData` → `ArcData` to reflect this.

Also, the inner pointer of `UnsafeArc` is now `*mut ArcData`, which avoids some transmutes to `~`: i.e. less chance of mistakes.

As for now, rekillable is an unsafe function, instead, it should behave
just like unkillable by encapsulating unsafe code within an unsafe
block.

This patch does that and removes unsafe blocks that were encapsulating
rekillable calls throughout rust's libs.

Fixes #8232

Closes #6002 

There is consensus that the current implementation should be changed or
removed, so removing it seems like the right decision for now.

Closes #6002

There is consensus that the current implementation should be changed or
removed, so removing it seems like the right decision for now.

Fix #6887.  (or rather, a bug injected by my prior commit for fixing that bug.)

This means that fewer `transmute`s are required, so there is less
chance of a `transmute` not having the corresponding `forget`
(possibly leading to use-after-free, etc).

This callstack changed when the FFI did. I am still a little frightened by
this suppression.

cc #8253

r? anyone. Now, rustpkg --version does something useful!