As discussed on issue #4819. This is a naive implementation, trusting LLVM to do the relevant optimizations. In the future this could be implemented more efficiently, but it's a start.
Closes#2647
This way it's much easier to add lints throughout compilation correctly, and
functions on impls can alter the way lints are emitted. This involved pretty much rewriting how lints are emitted. Beforehand, only items could alter the lint settings, so whenever a lint was added it had to be associated with whatever item id it was coming from. I removed this (possibly questionably) in favor of just specifying a span and a message when adding a lint. When lint checking comes around, it looks at all the lints and sees which node with attributes best encloses it and uses that level of linting. This means that all consumer code doesn't have to deal with what item things came from (especially because functions on impls aren't items). More details of this can be found in the code (and comments).
As a bonus, I managed to greatly simplify emission of lints in resolve.rs about unused imports. Now instead of it manually tracking what the lint level is, it's all moved over into the lint module (as is to be expected).
`str::from_slice` and `vec::from_slice` are changed to `str::to_owned` and `vec::to_owned`. (#6389)
Replace `at_vec::from_owned` and `at_vec::from_slice` with `at_vec::to_managed_consume` and `at_vec::to_managed`.
This is mostly for `std::rc` and `std::arc` (but I haven't implemented it for ARC yet).
Implementing it correctly for managed boxes is *very* non-trivial. It would probably require an unholy mix of reflection and TLS.
fail!() used to require owned strings but can handle static strings
now. Also, it can pass its arguments to fmt!() on its own, no need for
the caller to call fmt!() itself.
Also fix up all the fallout elsewhere throughout core. It's really nice being
able to have the prelude.
I'm not quite sure how resolution works with traits, but it seems to me like the public imports at the top-level of the core crate were leaking into the sub-crates, but that could also be working as intended. Regardless, things compile without the re-exports now.
r? @pcwalton
* Move `SharedMutableState`, `LittleLock`, and `Exclusive` from `core::unstable` to `core::unstable::sync`
* Modernize the `SharedMutableState` interface with methods
* Rename `SharedMutableState` to `UnsafeAtomicRcBox` to match `RcBox`.
