mk: Don't build any docs with --disable-docs.
rustc: Use rust strings for failure arguments

This avoids having to perform conversions from `*u8` to `&'static str` which can
suck in a good deal of code.

Closes #14442
native: Ignore stdio fds with /dev/null

When spawning a process, stdio file descriptors can be configured to be ignored,
which basically means that they'll be closed. Currently this is done by
literally closing the file descriptors in the child, but this can have adverse
side effects if the child process then opens a new file descriptor, assigning it
to a stdio number.

To work around the problems of the child, this commit alters the process
spawning code to map stdio fds to /dev/null on unix (and a similar equivalent on
windows) when they are specified as being ignored. This should allow spawned
programs to have more expected behavior when opening new files.

Closes #14456
rustc: clarify warning about native deps for a staticlib.

This adjusts the "unlinked native library" warning one receives when
compiling with `crate_type="staticlib"`. The warning is just trying to
tell the user that they need to link against these libraries, but the
old text wasn't making this obvious; the new text says this explicitly.
Don't enable libcpp for llvm by default.
std: Remove format_strbuf!()

This was only ever a transitionary macro.
Issue #13933: Remove transmute_mut from IO

The IO libraries casted self to mut so they can pass it to seek(SEEK_CUR, 0).
Fix this by introducing a private seek function that takes &self
  - of course one should be careful with it if he lacks an
    exclusive reference to self.
Issue #13933: Remove transmute_mut from Arc

directly use the internal pointer instead.
Doc: `static mut` is unsafe too

According to the corresponding section, accessing a mutable static variable requires `unsafe` too, and I believe it counts as as language level feature. Add it to the relevant list in the Unsafety section.
rustc: Accept PartialOrd/PartialOrdEq for Eq/Ord

This is a transitionary step towards completing #12517. This change modifies the
compiler to accept Partial{Ord,Eq} as deriving modes which will currently expand
to implementations of PartialOrd and PartialEq (synonyms for Eq/Ord).

After a snapshot, all of deriving(Eq, Ord) will be removed, and after a snapshot
of that, TotalEq/TotalOrd will be renamed to Eq/Ord.
Rename PatUniq to PatBox. Fixes part of #13910.
debuginfo: Add documentation comments to debuginfo.rs

Conflicts:
	src/librustc/middle/trans/debuginfo.rs
debuginfo: Make DWARF representation of enums uniform.

So far the DWARF information for enums was different
for regular enums, univariant enums, Option-like enums,
etc. Regular enums were encoded as unions of structs,
while the other variants were encoded as bare structs.

With the changes in this PR all enums are encoded as
unions so that debuggers can reconstruct if something
originally was a struct, a univariant enum, or an
Option-like enum. For the latter case, information
about the Null variant is encoded into the union field
name. This information can then be used by the
debugger to print a None value actually as None
instead of Some(0x0).
std: Recreate a `rand` module

This commit shuffles around some of the `rand` code, along with some
reorganization. The new state of the world is as follows:

* The librand crate now only depends on libcore. This interface is experimental.
* The standard library has a new module, `std::rand`. This interface will
  eventually become stable.

Unfortunately, this entailed more of a breaking change than just shuffling some
names around. The following breaking changes were made to the rand library:

* Rng::gen_vec() was removed. This has been replaced with Rng::gen_iter() which
  will return an infinite stream of random values. Previous behavior can be
  regained with `rng.gen_iter().take(n).collect()`

* Rng::gen_ascii_str() was removed. This has been replaced with
  Rng::gen_ascii_chars() which will return an infinite stream of random ascii
  characters. Similarly to gen_iter(), previous behavior can be emulated with
  `rng.gen_ascii_chars().take(n).collect()`

* {IsaacRng, Isaac64Rng, XorShiftRng}::new() have all been removed. These all
  relied on being able to use an OSRng for seeding, but this is no longer
  available in librand (where these types are defined). To retain the same
  functionality, these types now implement the `Rand` trait so they can be
  generated with a random seed from another random number generator. This allows
  the stdlib to use an OSRng to create seeded instances of these RNGs.

* Rand implementations for `Box<T>` and `@T` were removed. These seemed to be
  pretty rare in the codebase, and it allows for librand to not depend on
  liballoc.  Additionally, other pointer types like Rc<T> and Arc<T> were not
  supported.  If this is undesirable, librand can depend on liballoc and regain
  these implementations.

* The WeightedChoice structure is no longer built with a `Vec<Weighted<T>>`,
  but rather a `&mut [Weighted<T>]`. This means that the WeightedChoice
  structure now has a lifetime associated with it.

* The `sample` method on `Rng` has been moved to a top-level function in the
  `rand` module due to its dependence on `Vec`.

cc #13851

[breaking-change]
Replace StrAllocating.into_owned() with .into_string()

We already have into_string(), but it was implemented in terms of
into_owned(). Flip it around and deprecate into_owned().

Remove a few spurious calls to .into_owned() that existed in libregex
and librustdoc.
remove /build from .gitignore since there is build/
Rename OSRng to OsRng

According to Rust's style guide acronyms in type names should be
CamelCase.

[breaking-change]
Revert erroneous fix to tutorial
syntax: Fix span on illegal ABI errors

Fixes #8537
Fixes #14499
Make Arc::make_unique check weak refs; add make_unique to Rc

This patch makes `Arc::make_unique` examine the number of weak
references as well as strong references, which is required for safety.

It also adds a `make_unique` method to the `Rc` type for consistency.

Closes #14521.