auto merge of #12086 : huonw/rust/safe-json, r=kballard

The lexer and json were using `transmute(-1): char` as a sentinel value for EOF, which is invalid since `char` is strictly a unicode codepoint.

Fixing this allows for range asserts on chars since they always lie between 0 and 0x10FFFF.
doc: Modernize FAQs just slightly
auto merge of #12096 : brson/rust/morestack-addr, r=thestinger
auto merge of #12101 : csherratt/rust/master, r=alexcrichton

CowArc was crated before libsync and the merge request did not contain the required export change.
auto merge of #12098 : kballard/rust/from_utf8_lossy_tweak, r=huonw

MaybeOwned allows from_utf8_lossy to avoid allocation if there are no
invalid bytes in the input.

Before:
```
test str::bench::from_utf8_lossy_100_ascii                      ... bench:       183 ns/iter (+/- 5)
test str::bench::from_utf8_lossy_100_invalid                    ... bench:       341 ns/iter (+/- 15)
test str::bench::from_utf8_lossy_100_multibyte                  ... bench:       227 ns/iter (+/- 13)
test str::bench::from_utf8_lossy_invalid                        ... bench:       102 ns/iter (+/- 4)
test str::bench::is_utf8_100_ascii                              ... bench:         2 ns/iter (+/- 0)
test str::bench::is_utf8_100_multibyte                          ... bench:         2 ns/iter (+/- 0)
```

Now:
```
test str::bench::from_utf8_lossy_100_ascii                      ... bench:        96 ns/iter (+/- 4)
test str::bench::from_utf8_lossy_100_invalid                    ... bench:       318 ns/iter (+/- 10)
test str::bench::from_utf8_lossy_100_multibyte                  ... bench:       105 ns/iter (+/- 2)
test str::bench::from_utf8_lossy_invalid                        ... bench:       105 ns/iter (+/- 2)
test str::bench::is_utf8_100_ascii                              ... bench:         2 ns/iter (+/- 0)
test str::bench::is_utf8_100_multibyte                          ... bench:         2 ns/iter (+/- 0)
```
make: update dist target for renamed files

src/README.txt has been renamed in a30d61b05a, make dist is
thus failing as unable to find it.
This commit makes the dist target working again.

Signed-off-by: Luca Bruno <lucab@debian.org>
rustpkg has gone.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
auto merge of #12109 : omasanori/rust/small-fixes, r=sfackler

Most of them are to reduce warnings in testing builds.
auto merge of #12090 : bjz/rust/unimplemented, r=cmr

Adds a standardised placeholder for marking unfinished code.
Fixed error starting with uppercase

Error messages cleaned in librustc/middle

Error messages cleaned in libsyntax

Error messages cleaned in libsyntax more agressively

Error messages cleaned in librustc more aggressively

Fixed affected tests

Fixed other failing tests

Last failing tests fixed
make: update dist target after libextra split

libextra is currently being split into several crates. This commit adds
them all to the dist target in order to have them in the final tarballs.

Signed-off-by: Luca Bruno <lucab@debian.org>
auto merge of #12065 : mrshu/rust/error-formating-fix, r=alexcrichton

This pull request tries to fix #12050.

I went after these wrong errors quite aggressively so it might be that I also changed some strings that are not actual errors.

Please point those out and I will update this pull request accordingly.
auto merge of #12112 : lucab/rust/make-dist, r=alexcrichton

`make dist` or building from a generated tarball is currently not possible due to some files that have been renamed and the ongoing libextra split. This PR fixes all (current) issues in order to build rust from the .tar.gz source alone.
Remove unused ConstMutability
Make &mut borrows restrict aliasing

Fixes #11913
Update deriving to pass around the `cx` linearly
extra::test: add an opaque function to assist with accurate
benchmarking.

This allows a result to be marked as "used" by passing it to a function
LLVM cannot see inside. By making `iter` generic and using this
`black_box` on the result benchmarks can get this behaviour simply by
returning their computation.
arena: use the generic `bh.iter` to stop the benchmarks being DCE'd.

Before:

    test test::bench_nonpod_nonarena  ... bench:        62 ns/iter (+/- 6)
    test test::bench_pod_nonarena     ... bench:         0 ns/iter (+/- 0)

After:

    test test::bench_nonpod_nonarena  ... bench:       158 ns/iter (+/- 11)
    test test::bench_pod_nonarena     ... bench:        48 ns/iter (+/- 2)

The other tests show no change, but are adjusted to use the generic
return value of `.iter` anyway so that this doesn't change in future.
Fix infinite loop in MemReader::read_until.
Fix infinite loop in BufReader::read_until.