Brson's "someday" list


What kind of people are you picturing as “Rust reps”, and what needs to be done to organize this? I think I understand Rust philosophically and am eager to use it more, and in fact I’ve nicknamed myself “Rust evangelist” on my company’s internal IM client. However, I haven’t actually done any coding in Rust beyond some tutorials, because we currently use C++ at work, and my family life has been pretty all-consuming outside of work these last few years.


@BatmanAoD Regarding “Rust reps”, the kernel of the idea came from a conversation I had with @Manishearth where he mentioned that he was at a non-Rust related Mozilla event, and people were excited to talk to him about Rust. And I have that experience a fair bit too - I tell people I work on Rust and they’re excited to hear about it. So it seems to me there’s a lot of recognition we could achieve just by having Rust folks seen in various relevant social settings.

So the way I pictured it is that we would have people just get out and attend the normal industry events they usually would (though maybe more-so - I know I don’t get out enough), and be known as “the Rust guy/girl”. In particular, we’re in a phase where we’re in a period where we’re trying to raise the profile of Rust in the Mozilla community, so I figured we would start by just having Rust folks go to Mozilla events (there are a lot of them). That’s really safe: they would be welcome there and not have much risk of coming off as pushy sales people. We could of course also think about expanding to all sorts of events in relevant industries.

The big risk though with such an imitative is representing Rust poorly. It’s easy for evangelism to turn into salesmanship or zealotry, and some already have a negative opinion of the boundless enthusiasm of Rust fans. So we’d want to make sure reps were well prepared with an approach that is consistent with Rust values.


I’ve been working on something like this. Basically, docker + travis + appveyor to test as many (cross) targets as possible. The repository is here. So far I count a test coverage of 21 of 49 targets.

My original goal was to create something where we could test our binary releases of std because, right now, those are untested on most platforms but I guess this could be turned into a general purpose cross testing framework for other Rust projects.


That makes sense.

I do think that the really big problem right now is incorrect assumptions about Rust based on what little people have heard about it. For instance, in a discussion in which I was criticizing C++14’s failure to permit std::function to contain a std::unqiue_ptr (or any other non-copyable object), someone was defending C++ by stating that my original design had a “logical” error, and that in fact “given the pedal-to-the-metal nature of C++, this specific issue is unavoidable”. (This idea among the C++ community that all of its flaws are necessary flaws for a “power language” is frighteningly prevalent.) I explained that this issue would be avoidable if std::function supported move-semantics, and that this gave me the feeling that C++'s move-semantics are a “tacked-on” part of the language rather than a core part of the design as in Rust. The person responded by saying that his “theory” was that Rust handles this situation is “garbage-collected pointers”. I of course explained that Rust does not have garbage collection, but I think the discussion highlights a fairly common misunderstanding–that memory-safe languages necessarily use garbage collection. And in the C++ community, garbage collection seems to be anathema (despite the fact that Bjarne Stroustrup has stated that he has no doubt C++ will some day incorporate garbage collection–a prediction I think is actually pretty unlikely).


@japaric Yay, this is exactly what I was hoping for! Do you know why so many targets are red (and why the badge says the build is passing)? I updated the op to link to your project.


I’ve updated the op with the following new tasks:


Do you know why so many targets are red?

So right now I’m running all these tests on all the non-windows targets:

  • println!("Hello, world!")
  • panic!()
  • Basic unit testing: #[test], #[should_panic]
  • catch_panic
  • libc_test
  • unit tests of each standard crate (e.g. libcollectionstest)

The current HEAD of the repository now runs all these tests even if one of them fails (I basically re-implemented make's “keep going” flag) and report at the end which tests failed (if any). That report looks like this:


That’s for the aarch64-unknown-linux-gnu.

So far I’m seeing the targets fail for these reasons:

  • catch_panic: this doesn’t work on the i686-musl target. This is a legit failure and has been reported to the rust-lang/rust issue tracker.
  • libc_test: these seem to be due to the glibc/toolchain version I’m using. Note that the test suite doesn’t actually fail, instead it doesn’t even compile (compiling libc-test involves compiling an auto-generated C file, that file doesn’t compile). Most of the targets that appear as failing in my repo pass the test suite on the libc repo, but the libc repo is using older glibcs/toolchains. cf. rust-lang/libc#23 and rust-lang/libc#357
  • QEMU is broken for this arch: This is the case for powerpc64le. qemu-ppc64le segfaults when I try to run any binary for this architecture. cf. Debian bug
  • libstd’s unit tests segfault: This only happens on cross targets whose unit tests are run under QEMU. And I think these may be false positive caused by QEMU limitation of handling several threads. Because I’ve tested a few of these targets locally (also under QEMU) but running only the test that fails (instead of the whole test suite) and on some runs the test passes and on some runs the test segfaults. NOTE that in all cases (also in the repository), I always run unit tests with RUST_TEST_THREADS=1 to limit the number of unit tests that runs concurrently to one but a single unit test may still spawn several threads.
  • libstd’s unit tests hang: Pretty much the same as above. I think this may be caused by QEMU.

These are the libstd unit tests I’ve seen fail so far:


I’ve yet to dig deeper into these unit tests to figure out which are real failures and which are false positives with 100% certainty though.

The good news is that all the other standard crates (libcoretest, librand, etc) pass their test suites with 100% success on all the targets :tada:.

and why the badge says the build is passing

I think you were observing the build result of a branch that was not yet merged. The badge is no longer green now :-).


Thanks for the details. This is great stuff.


Updating with:


Updated with:




Updated op with these. A lot are pretty opaque. Sorry about that.


  • write security roadmap
  • write release qa checklist
  • investigate rustup disk usage during transactions
  • change rustup to panic=abort
  • write rust packaging guidelines
  • get rustup working via powershell one-liner
  • add cargo-template quickstart instructions to error-chain docs
  • set up static linking for msvc rustc
  • fix rustup windows dojob issue (make cargo and rustup use the same dojob code)
  • simple crates in need - extract these from rustup/cargo and share
    • copy_dir
    • remove_dir_all
    • dojob
    • flock
    • symlink_dir
    • homedir
  • implement the update framework



What’s this one?


Sounds like you should be able to just run cargo template quickstart my-new-project and get a project setup to use error-chain.


Neat. Should it work in conjunction with this PR for cargo or some other way?


I believe my intent was to make compatible with, in anticipation of compatibility with your cargo PR in the future.


Templating was merged into Cargo yesterday.

The following project can be used as a quickstart template (I made a PR to use {{name}} and {{author}} templates:


Thanks @ehiggs!


@ehiggs What is the cargo command to instantiate the error-chain directly from the error-chain repo ( I’d like the error-chain docs to say something like

To get started run:

$ cargo template whatever

(Obviously fill in with the correct syntax)


$ cargo new --template whatever

Currently there is a bug in that particular template where the name and author aren’t actually templated but I have a PR to fix it.


Here’s some commentary about the ‘simple crates’:

16:32 simple crates - there are a number of unbelievably common functions i end up reimplementing a lot 16:32 and poorly 16:33 copy_dir is just a recursive directory copy. not sure if there’s a good crate for this yet 16:34 sometimes one needs to do a copy but ignoring dotfiles. i open code this with walk_dir 16:34 but there should be a common copy_dir that covers most cases and just works 16:34 remove_dir_all is broken in std on windows 16:34 so people always reimplement in 16:34 *it 16:35 while it should be fixed in std, in the meantime somebody should just publish a working version 16:35 dojob is a common routine that cargo, rustbuild and rustup use to create process groups on Windows for killing multiple processes 16:35 but they all implement it diferently and some are missing fixes 16:36 symlink_dir would be a crate that creates symlinks to directories correctly on windows, using directory junctions 16:37 homedir would be an implementation of std::env::home that uses cargo/rustup’s definition. I consider std incorrect when it considers HOME on Windows.