Hello and welcome to the eighth issue of This Week in Rust. Due to me being busy and forgetful over the weekend, this is a special issue, Last Week in Rust.

What's cooking on master?

Issue churn continues to be negative, -15 this week. A total of 63 PRs were merged.

Breaking Changes

There were impressively few breaking changes last week.

• You now need to pass --cfg debug to rustc to emit debug logging.
• mod.rs is now "blessed".. When loading mod foo;, rustc will now look for foo.rs, then foo/mod.rs, and will generate an error when both are present.
• A bunch of str functions were renamed or shuffled around to be more consistent.
• SmallIntSet was removed in favor for the more efficient, equivalent BitvSet.
• Bitv and Bitvset have switched to external iterators.
• extra::net and a bunch of other obsolete features have been removed.

Notable library additions, bugfixes, and cleanup

• Various TCP/UDP additions have been made in the new rt.
• Some more atomic operations have been added.
• A chain_mut_ref method was added to Option.
• Random access iterators have been implemented.
• Some missing memory orderings on atomic types have been added.
• workcache has seen a bunch of attention.
• DList has seen some more cleanup too.
• Timers have been added to the new rt.
• Vectors now implement slice_from and slice_to.

Notable compiler additions, bugfixes, and cleanup

• debuginfo for destructured locals and function args is now implemented.
• Raw representations are now consolidated.
• Impossible branches on constants are now omitted.
• It is now possible to link against crates with #[no_std].
• There is now a warning when matching against NaN, since it is impossible to match against NaN (NaN != NaN).
• A lot of default method and trait inheritance bugs have been fixed.
• uint enum discriminants are now allowed.
• The section placement of static and fn items is now configurable.
• Some trans naming modernization has occured.
• Some unnecessary branches and blocks have been removed, resulting in a 10% speedup of unoptimized rustc.

Documentation, tools, and other stuff

• Some benchmarks, and some more benchmarks.
• Crnobog has fixed some Windows testsuite issues.
• Makefile dependencies have been fixed. rustc will never be invoked without its dependencies being built.
• rust-mode has been rewritten.
• There are some build system changes surrounding the --cfg debug changes.

Meetings

The Tuesday meeting was quite productive. A quick summary:

• Graydon wants to investigate using the Memory Pool System as the Rust GC, rather than a bespoke one. The MPS is a very mature and robust memory management library.
• The buildbots now collect and report some metrics as JSON. Take a poke in http://static.rust-lang.org/build-metrics/<git-sha1>/<builder>/<slave>/<metricsfile>.json if you're interested.
• pcwalton proposes allowing Self in impls, like in trait definitions.
• There was some discussion of destructors taking self by value.
• There was a proposal to remove *mut, but it can be useful. There was no consensus.
• There was also some discussion on closures and mutable captures. I don't really have enough context to understand the conversation, something to do with "thunks".
• Removing &const was discussed as well. The "plan is that we add a lint flag but document it as a reserved word", as it doesn't really seem to be useful.

Discussion + Blog posts

• Iterator Blocks for Rust
• RFC: Removing *T
• dherman's OSCON slides
• Mozilla is hiring a Rust research engineer
• An alpha release of the MongoDB Driver
• A fairly useless benchmark of random number generation

Projects

• color-rs: A library that provides types and conversions for working with various color formats.
• grease-bench: a runtimeless benchmarker
• rustfind, a "jump to definition" tool
• RustyXML, a pure-Rust XML parser