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Hello and welcome to another issue of This Week in Rust! Rust is a systems language pursuing the trifecta: safety, concurrency, and speed. This is a weekly summary of its progress and community. Want something mentioned? Tweet us at @ThisWeekInRust or send us a pull request. Want to get involved? We love contributions.
This Week in Rust is openly developed on GitHub. If you find any errors in this week's issue, please submit a PR.
Updates from Rust Community
News & Blog Posts

Rust 2018: the home stretch.
Microsoft announces using Rust to build some of its Azure IoT functionality.
Learning SIMD with Rust by finding planets.
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llvm-tools

, a new rustup component for binary inspection (objdump, nm, size) and profiling (profdata).
How much Rust in Firefox?
A rusty go at channels.
Better HTTP upgrades with hyper.
Our Vision for wasm-bindgen.
The Embedded WG newsletter 6.
[podcast] Rusty Spike Podcast - episode 35. Rust 1.27, new books, Microsoft, Eclipse, converting C to Rust, the Rust 2018 preview, the Rust 2018 roadmap, and RFCs.
[podcast] New Rustacean news – Rust 1.27. Stable SIMD, dyn trait, rustfix and the alpha release of the Rust 2018 Edition Preview.

Crate of the Week
This week's crate is datafrog, the lightweight embeddable datalog engine that powers Rust's non-lexical lifetimes (NLL). Thanks to Jules Kerssemakers for the suggestion.
Submit your suggestions and votes for next week!
Call for Participation
Always wanted to contribute to open-source projects but didn't know where to start? Every week we highlight some tasks from the Rust community for you to pick and get started!
Some of these tasks may also have mentors available, visit the task page for more information.

[good first issue] wasm-bindgen: Expose bindings to ALL the global JS things.
Get started with these beginner-friendly issues.

If you are a Rust project owner and are looking for contributors, please submit tasks here.
Updates from Rust Core
174 pull requests were merged in the last week

did you mean to block nightlies on clippy? (a big leap forward on the way to stable clippy!)
llvm: add DWARF for discriminated unions
libc: simplify the stdbuild section
allow irrefutable
let
patterns (RFC #2086)
loosened rules involving statics mentioning other statics
obligation forest cleanup
suggestion for 'static impl Trait return
fix incorrect type mismatch label pointing at return type
use literal span for concrete type suggestion
improve the error message when
#[panic_implementation]
is missing
point to lifetime spans on lifetime errors
add modifier keyword spans to hir::Visibility; improve unreachable-pub, private-no-mangle lint suggestions
provide existing ref suggestions for more E0308 errors
Self
in where clauses may not be object safe
suggest correct comparison against negative literal
lint to favor
..=
over
...
range patterns; migrate to
..=
throughout codebase
detect overflows of non u32 shifts
HirId
-ification, continued
optimize
places_conflict
to avoid complex vectors etc.
NLL: better move errors
NLL: bad error message when converting anonymous lifetime to
'static
NLL: introduce dirty list to liveness, eliminate
ins
vector
convert NLL ops to caches
avoid needless allocations in
liveness_of_locals
speed up compilation of large constant arrays
implement
#[macro_export(local_inner_macros)]
use
Ident
s in HIR and remove emulation of hygiene with gensyms
always check type_dependent_defs
fix ICEs when using continue as an array length inside closures (inside loop conditions)
add error for using null characters in
#[export_name]
don't inspect the generated existential type items
don't ICE when performing
lower_pattern_unadjusted
on a
TyError
make the public API of the
alloc
crate a subset of
std
new safe associated functions for
PinMut
make custom trait object for
Future
generic
optimize sum of Durations by using custom function
add
str::split_ascii_whitespace
Arc
: remove unused allocation from
Weak::new()
make
BTreeMap::clone()
not allocate when cloning an empty tree
make
FileMap::
{
lines
,
multibyte_chars
,
non_narrow_chars
} non-mutable
implement
PartialEq
between
&str
and
OsString
park
/
park_timeout
: prohibit spurious wakeups in next
park
fix possibly endless loop in
ReadDir
iterator
stabilize
Iterator::flatten
stabilize
to_bytes
and
from_bytes
for integers
cargo: remove all 4
Rc
clones in
min_candidates
cargo: display a one line progress of what crates are currently built
cargo: remove redundant hashmap
rustdoc: minify css
crates.io:
dyn
all the things
crates.io: forbid tarballs with hard links being uploaded

Approved RFCs
Changes to Rust follow the Rust RFC (request for comments) process. These are the RFCs that were approved for implementation this week:

RFC 2345: Allow panicking in constants.
RFC 2296: Add
Option::replace
to the core library.
RFC 2344: Allow
loop
in constant evaluation.
RFC 2302: Tuple struct construction with
Self(v1, v2, ..)
.
RFC 2397: Introduce
#[do_not_recommend]
to control errors for trait impls.
Amend RFC 0430: Allow underscores between numbers in CamelCase names.

Final Comment Period
Every week the team announces the 'final comment period' for RFCs and key PRs which are reaching a decision. Express your opinions now.
RFCs

[disposition: postpone] String reflection.

Tracking Issues & PRs

[disposition: merge] Tracking issue for
ToOwned::clone_into
(
toowned_clone_into
).
[disposition: merge] Tracking issue for
Rc::downcast
(
rc_downcast
feature).
[disposition: merge] Respect -Z no-verify during LTO.
[disposition: merge] impl Clone for
Box<CStr>
,
Box<OsStr>
,
Box<Path>
.
[disposition: merge] Add
#[repr(transparent)]
to some libcore types.
[disposition: close] Add
TryFrom<{integer}>
for
bool
.

New RFCs

[url=https://github.com/rust-lang/rfcs/pull/2492]Existential types with external definition.
Add a replace_with method to Option.

Upcoming Events
Online

Asia

Jul 19. Tokyo, JP - Rust Meetup #9 in Shibuya.

Europe

North America

If you are running a Rust event please add it to the calendar to get it mentioned here. Email the Rust Community Team for access.

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