This commit removes all unstable and deprecated functions in the standard
library. A release was recently cut (1.3) which makes this a good time for some
spring cleaning of the deprecated functions.
This commit is an implementation of [RFC 1184][rfc] which tweaks the behavior of
the `#![no_std]` attribute and adds a new `#![no_core]` attribute. The
`#![no_std]` attribute now injects `extern crate core` at the top of the crate
as well as the libcore prelude into all modules (in the same manner as the
standard library's prelude). The `#![no_core]` attribute disables both std and
core injection.
[rfc]: https://github.com/rust-lang/rfcs/pull/1184
The following APIs were all marked with a `#[stable]` tag:
* process::Child::id
* error::Error::is
* error::Error::downcast
* error::Error::downcast_ref
* error::Error::downcast_mut
* io::Error::get_ref
* io::Error::get_mut
* io::Error::into_inner
* hash::Hash::hash_slice
* hash::Hasher::write_{i,u}{8,16,32,64,size}
The first paragraph of the docs of the Cursor struct ([src](ff6c6ce917/src/libstd/io/cursor.rs (L18-L21))) contains a Markdown link. In listings (like <http://doc.rust-lang.org/nightly/std/io/>), this won't get rendered:

The hotfix would be to change the link by reference:
```rust
/// A `Cursor` wraps another type and provides it with a [`Seek`][seek]
/// implementation.
///
/// [seek]: trait.Seek.html
```
to a direct link:
```rust
/// A `Cursor` wraps another type and provides it with a
/// [`Seek`](trait.Seek.html) implementation.
```
_I have not tested this as I don't have access to a machine for compiling Rust right now._
(This seems to be a more general issue, but I think I have seen this mentioned before. This PR is just to hotfix on particular occurrence. Rustdoc seems to only read the first paragraph of a doc string for the description in index pages, and _after that_ convert Markdown to HTML.)
r? @steveklabnik
The following APIs were all marked with a `#[stable]` tag:
* process::Child::id
* error::Error::is
* error::Error::downcast
* error::Error::downcast_ref
* error::Error::downcast_mut
* io::Error::get_ref
* io::Error::get_mut
* io::Error::into_inner
* hash::Hash::hash_slice
* hash::Hasher::write_{i,u}{8,16,32,64,size}
The first paragraph of the docs of the Cursor struct contains a Markdown
link. In listings, this won't get rendered. (Rustdoc seems to split off the
first paragraph and after that convert Markdown to HTML.)
Many of these have long since reached their stage of being obsolete, so this
commit starts the removal process for all of them. The unstable features that
were deprecated are:
* cmp_partial
* fs_time
* hash_default
* int_slice
* iter_min_max
* iter_reset_fuse
* iter_to_vec
* map_in_place
* move_from
* owned_ascii_ext
* page_size
* read_and_zero
* scan_state
* slice_chars
* slice_position_elem
* subslice_offset
These provide various special readers, so point their docs to their
constructor functions in a manner consistent with everything else.
r? @alexcrichton
Mostly through adding examples.
r? @alexcrichton
I'm going to be doing a bunch of these today, but I figured I'd keep it one PR per struct, since the last 'all the things in one PR' ended up taking a week to actually land.
In a followup to PR #26849, improve one more location for I/O where
we can use `Vec::resize` to ensure better performance when zeroing
buffers.
Use the `vec![elt; n]` macro everywhere we can in the tree. It replaces
`repeat(elt).take(n).collect()` which is more verbose, requires type
hints, and right now produces worse code. `vec![]` is preferable for vector
initialization.
The `vec![]` replacement touches upon one I/O path too, Stdin::read
for windows, and that should be a small improvement.
r? @alexcrichton