We only implemented Clone on `extern "Rust" fn`s (for up to 8
parameters). This didn't cover `extern "C"` or `unsafe` (or `unsafe
extern "C"`) `fn`s, but there's no reason why they shouldn't be
cloneable as well.

The new impls are marked unstable because the existing impl for `extern
"Rust" fn`s is.

Fixes rust-lang#24161.

The idea here is if you don't want rust in /usr/local
you can put something like this is your .profile:

export RUSTUP_PREFIX=$HOME/.local/rust
export PATH=$PATH:${RUSTUP_PREFIX}/bin
export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:${RUSTUP_PREFIX}/lib

Then when you run rustup, it will update the install
in ${RUSTUP_PREFIX} without having to remember to pass
an explicit --prefix argument every time.

Closes rust-lang#24091

Closes rust-lang#22289
Closes rust-lang#22370
Closes rust-lang#22384

particular to treat an AutoUnsize as as kind of "instantaneous" borrow
of the value being unsized. This prevents us from feeding uninitialized
data.

This caused a problem for the eager reborrow of comparison traits,
because that wound up introducing a "double AutoRef", which was not
being thoroughly checked before but turned out not to type check.
Fortunately, we can just remove that "eager reborrow" as it is no longer
needed now that `PartialEq` doesn't force both LHS and RHS to have the
same type (and even if we did have this problem, the better way would be
to lean on introducing a common supertype).

rust-installer never verifies.

~~I believe this should fix the issue. Opening a PR to ensure noone duplicates effort, I'm running check now.~~

Closes rust-lang#24091

Now that we have a `#[allow_internal_unstable]` attribute for macros there's no
need for these two `begin_unwind` functions to be stable. Right now the `panic!`
interface is the only one we wish to stabilize, so remove the stability markers
from these functions.

While this is a breaking change, it is highly unlikely to break any actual code.
It is recommended to use the `panic!` macro instead if it breaks explicit calls
into `std::rt`.

[breaking-change]
cc rust-lang#24208

This method hasn't really changed since is inception, and it can often be a
nice performance win for some situations. This method also imposes no burden on
implementors or users of `Clone` as it's just a default method on the side.

This commit stabilizes the old `io::Error::from_os_error` after being renamed to
use the `raw_os_error` terminology instead. This function is often useful when
writing bindings to OS functions but only actually converting to an I/O error at
a later point.

This commit removes pretty-expanded from all tests that wind up calling panic!
one way or another now that its internals are unstable.

Fix rust-lang#13993.
Fix rust-lang#17167.

libLTO fails to link here.

Seeking the `BufReader` discards the internal buffer (and adjusts the
offset appropriately when seeking with `SeekFrom::Current(_)`).

Seeking the `BufWriter` writes out its internal buffer before seeking.

…s, r=alexcrichton

We only implemented Clone on `extern "Rust" fn`s (for up to 8
parameters). This didn't cover `extern "C"` or `unsafe` (or
`unsafe extern "C"`) `fn`s, but there's no reason why they shouldn't be
cloneable as well.

The new impls are marked unstable because the existing impl for `extern
"Rust" fn`s is.

Fixes rust-lang#24161.

 The idea here is if you don't want rust in /usr/local
you can put something like this is your .profile:

```
export RUSTUP_PREFIX=$HOME/.local/rust
export PATH=$PATH:${RUSTUP_PREFIX}/bin
export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:${RUSTUP_PREFIX}/lib
```
Then when you run rustup, it will update the install
in ${RUSTUP_PREFIX} without having to remember to pass
an explicit --prefix argument every time.

…excrichton

 I'm not sure why this is failing.  This patch disables this test until I can figure out what is wrong.

 Modify the ExprUseVisitor to walk each part of an AutoRef, and in
particular to treat an AutoUnsize as as kind of \"instantaneous\" borrow
of the value being unsized. This prevents us from feeding uninitialized
data.

This caused a problem for the eager reborrow of comparison traits,
because that wound up introducing a \"double AutoRef\", which was not
being thoroughly checked before but turned out not to type check.
Fortunately, we can just remove that \"eager reborrow\" as it is no longer
needed now that `PartialEq` doesn't force both LHS and RHS to have the
same type (and even if we did have this problem, the better way would be
to lean on introducing a common supertype).

Fixes rust-lang#20791.

r? @nrc

 Closes rust-lang#22289
Closes rust-lang#22370
Closes rust-lang#22384

 This makes the default configuration fully optimized, with no debugging options, no llvm asserts, renames --enable-debug to --enable-debug-assertions, and adds --enable-debug as a blanket option that toggles various things, per rust-lang#17665. It does not add a `--enable-release` flag since that would be a no-op.

cc @nrc

Fixes rust-lang#22390
Fixes rust-lang#17081
Partially addresses rust-lang#17665

 r? @brson

I'm using this to integrate rustc with [american-fuzzy-lop](http://lcamtuf.coredump.cx/afl/). Building with afl instrumentation is no different from loading any other plugin library.

I'd like this PR to include a `run-make` test with a custom LLVM pass; however I'm not sure it's worth the trouble of building C++ code and linking LLVM from the test suite (are there existing tests that do this?)

…nd, r=huonw

 Now that we have a `#[allow_internal_unstable]` attribute for macros there's no
need for these two `begin_unwind` functions to be stable. Right now the `panic!`
interface is the only one we wish to stabilize, so remove the stability markers
from these functions.

While this is a breaking change, it is highly unlikely to break any actual code.
It is recommended to use the `panic!` macro instead if it breaks explicit calls
into `std::rt`.

[breaking-change]
cc rust-lang#24208

…r=aturon

 This method hasn't really changed since is inception, and it can often be a
nice performance win for some situations. This method also imposes no burden on
implementors or users of `Clone` as it's just a default method on the side.

…error, r=aturon

 This commit stabilizes the old `io::Error::from_os_error` after being renamed to
use the `raw_os_error` terminology instead. This function is often useful when
writing bindings to OS functions but only actually converting to an I/O error at
a later point.

…chton

 This is a really minor issue. I noticed some tests no longer need the ignore
tidy comment directive.

A quick grep turned up the following files:

    src/test/compile-fail/bad-mid-path-type-params.rs
    src/test/compile-fail/bad-sized.rs
    src/test/compile-fail/coherence-default-trait-impl.rs
    src/test/compile-fail/coherence-orphan.rs
    src/test/compile-fail/issue-8767.rs
    src/test/compile-fail/lint-stability.rs
    src/test/compile-fail/lint-uppercase-variables.rs
    src/test/compile-fail/typeck-default-trait-impl-outside-crate.rs
    src/test/compile-fail/use-after-move-implicity-coerced-object.rs
    src/test/debuginfo/gdb-pretty-std.rs

It didn't seem like it was worth opening an issue for this, but if that is not
the case (i.e. it is required), I'll open one up. Thanks!

 Can anyone take a look? Very trivial.