This gives us an extra rustc-src.tar.xz, which is 33% smaller than the .tar.gz!

This commit adds a new `-Z` flag to the compiler for use when bootstrapping the
compiler itself. We want to be able to use crates.io crates, but we also want
the usage of such crates to be as ergonomic as possible! To that end compiler
crates are a little tricky in that the crates.io crates are not annotated as
unstable, nor do they expect to pull in unstable dependencies.

To cover all these situations it's intended that the compiler will forever now
bootstrap with `-Z force-unstable-if-unmarked`. This flags serves a dual purpose
of forcing crates.io crates to themselves be unstable while also allowing them
to use other "unstable" crates.io crates. This should mean that adding a
dependency to compiler no longer requires upstream modification with
unstable/staged_api attributes for inclusion!

There's no shell interpreting the file paths under the new Rusty
rust-installer, so we don't need to use `sanitize_sh` for it.  Plus,
the drive-letter transformation is actually harmful for the now-native
Windows rust-installer to understand those paths.

These are now no longer necessary with `-Z force-unstable-if-unmarked`

Removes unused macros from:
  * libcore
  * libcollections
    The last use of these two macros was removed in commit
    b64c9d5
    when the char_range_at_reverse function was been removed.
  * librustc_errors
    Their last use was removed by commits
    2f2c3e1
    and 11dc974.
  * libsyntax_ext
  * librustc_trans
    Also, put the otry macro in back/msvc/mod.rs under the
    same cfg argument as the places that use it.

This seems both to be a safe, conservative choice,
and it sidesteps the cycle in rust-lang#41936.

Fixes rust-lang#41936.

This fix an issue where the compiler panics even if there is no
error when passed with the `-Z treat-err-as-bug` option.

Fixes rust-lang#35886.

…richton

Update to the Rusty rust-installer

This updates the rust-installer submodule to the new version written in Rust (rust-lang/rust-installer#62), now moved to `src/tools/rust-installer` and invoked in `dist.rs` as a cargo-based tool command.  All of the former shell-script invocations now invoke the tool, otherwise keeping the same arguments as before.

As a small bonus, `rustc-src` now also uses the same tarball generator, so it gains a smaller `.tar.xz` too.

Fixes rust-lang#41569.  r? @alexcrichton

…ons, r=eddyb

rustc: Add a new `-Z force-unstable-if-unmarked` flag

This commit adds a new `-Z` flag to the compiler for use when bootstrapping the
compiler itself. We want to be able to use crates.io crates, but we also want
the usage of such crates to be as ergonomic as possible! To that end compiler
crates are a little tricky in that the crates.io crates are not annotated as
unstable, nor do they expect to pull in unstable dependencies.

To cover all these situations it's intended that the compiler will forever now
bootstrap with `-Z force-unstable-if-unmarked`. This flags serves a dual purpose
of forcing crates.io crates to themselves be unstable while also allowing them
to use other "unstable" crates.io crates. This should mean that adding a
dependency to compiler no longer requires upstream modification with
unstable/staged_api attributes for inclusion!

Remove wrong or outdated info from CString docs.

None

doc: break into 2 sentences

Upgrade some comments to doc comments

Fix typo in Iterator::size_hint example comment

Annotate the license exceptions

Include the crate's root module in save-analysis

r? @eddyb

…steveklabnik

Fix search when looking to sources

Before:

<img width="1440" alt="screen shot 2017-05-11 at 22 33 28" src="https://cloud.githubusercontent.com/assets/3050060/25970761/03fd2ade-369a-11e7-9fd6-783c23455589.png">

After:

<img width="1440" alt="screen shot 2017-05-11 at 22 34 05" src="https://cloud.githubusercontent.com/assets/3050060/25970770/09ac71ce-369a-11e7-9038-559f414e07b5.png">

r? @rust-lang/docs

rustc_trans: do not attempt to truncate an i1 const to i1.

Fixes rust-lang#41744 by skipping the truncation when it'd be a noop anyway.

Remove unused macros from the codebase

Thanks to the lint I've implemented in rust-lang#41907 I've found some unused macros inside the rustc codebase.

…oerce-unsized-cycle, r=eddyb

use equality in the coerce-unsized check

This seems both to be a safe, conservative choice, and it sidesteps the cycle in rust-lang#41849. Note that, before I converted variance into proper queries, we were using a hybrid of subtyping and equality, due to the presence of a flag that forced invariance if variance had not yet been computed. (Also, Coerce Unsized is unstable.)

Fixes rust-lang#41936.

r? @eddyb

Fix unexpected panic with the -Z treat-err-as-bug option

This fix an issue where the compiler panics even if there is no error when passed with the `-Z treat-err-as-bug` option.

Fixes rust-lang#35886.

r? @Mark-Simulacrum