…ies.

Note: this Warns rather than error on shadowing problems involving labels.
We took this more conservative option mostly due to issues with
hygiene being broken for labels and/or lifetimes.

Add FIXME regarding non-hygienic comparison.

… bodies.

…tests.

…y checks.

This avoids various ICEs, e.g. premature calls to cat_expr that yield
the dreaded "cat_expr Errd" ICE.

Close rust-lang#23729
Close rust-lang#23827
Close rust-lang#24356

This is an implementation of [RFC 1030][rfc] which adds these traits to the
prelude and additionally removes all inherent `into_iter` methods on collections
in favor of the trait implementation (which is now accessible by default).

[rfc]: rust-lang/rfcs#1030

This is technically a breaking change due to the prelude additions and removal
of inherent methods, but it is expected that essentially no code breaks in
practice.

[breaking-change]
Closes rust-lang#24538

Words struct was stabilied by mistake. Unstabilize.

Cleaning out more deprecated items

Conflicts:
	src/libcore/result.rs

This commit removes all the old casting/generic traits from `std::num` that are
no longer in use by the standard library. This additionally removes the old
`strconv` module which has not seen much use in quite a long time. All generic
functionality has been supplanted with traits in the `num` crate and the
`strconv` module is supplanted with the [rust-strconv crate][rust-strconv].

[rust-strconv]: https://github.com/lifthrasiir/rust-strconv

This is a breaking change due to the removal of these deprecated crates, and the
alternative crates are listed above.

[breaking-change]

Conflicts:
	src/libstd/num/strconv.rs

This API was exercised in a few tests and mirrors the `from_str_radix`
functionality of the integer types.

Conflicts:
	src/doc/trpl/traits.md
	src/libstd/sys/windows/fs2.rs

Conflicts:
	src/librustc_data_structures/lib.rs

Conflicts:
	src/test/run-pass/task-stderr.rs

This allows `io::Error` values to be stored in `Arc` properly.

Because this requires `Sync` of any value passed to `io::Error::new()`
and modifies the relevant `convert::From` impls, this is a

[breaking-change]

Fixes rust-lang#24049.

which get mentioned in an associated type are constrained.  Arguably we
should just require that all regions are constrained, but that is more
of a breaking change.

Conflicts:
	src/librustc_typeck/collect.rs

multiple kinds of parameters (regions and types, specifically)

Conflicts:
	src/librustc_typeck/collect.rs