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Panic: "thread 'main' panicked at 'attempt to subtract with overflow'" #8
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confirm v0.4.1 bugs (Manjaro), v0.4.0 - works good.
RUST_BACKTRACE=1 ./so how to setup async rust thread 'main' panicked at 'byte index 18446744073709551615 is out of bounds of ` function](https://github.com/rust-lang-nursery/futures-rs/blob/0.3.1/futures-util/src/future/ `', /rust/lib/rustlib/src/rust/src/libcore/str/mod.rs:2052:47 stack backtrace: 0: backtrace::backtrace::libunwind::trace at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86 1: backtrace::backtrace::trace_unsynchronized at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66 2: std::sys_common::backtrace::_print_fmt at src/libstd/sys_common/backtrace.rs:78 3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt at src/libstd/sys_common/backtrace.rs:59 4: core::fmt::write at src/libcore/fmt/mod.rs:1069 5: std::io::Write::write_fmt at src/libstd/io/mod.rs:1504 6: std::sys_common::backtrace::_print at src/libstd/sys_common/backtrace.rs:62 7: std::sys_common::backtrace::print at src/libstd/sys_common/backtrace.rs:49 8: std::panicking::default_hook::{{closure}} at src/libstd/panicking.rs:198 9: std::panicking::default_hook at src/libstd/panicking.rs:218 10: std::panicking::rust_panic_with_hook at src/libstd/panicking.rs:511 11: rust_begin_unwind at src/libstd/panicking.rs:419 12: core::panicking::panic_fmt at src/libcore/panicking.rs:111 13: core::str::slice_error_fail at src/libcore/str/mod.rs:0 14: core::str::traits::<impl core::slice::SliceIndex<str> for core::ops::range::RangeFrom<usize>>::index::{{closure}} 15: termimad::wrap::hard_wrap_composite 16: termimad::text::FmtText::from_text 17: so::term::Term::print 18: so::run::{{closure}} 19: std::thread::local::LocalKey<T>::with 20: so::main 21: std::rt::lang_start_internal::{{closure}}::{{closure}} at src/libstd/rt.rs:52 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
although other requests work fine
@Ethan3600 Thanks for the issue. Unfortunately I'm having trouble reproducing it, but it seems to be coming from
termimadespecially if you've determined thatprint_inlineworks fine. The difference (or at least one important difference) is thatprint_texttakes into account your terminal width and wraps things nicely. So, it looks much better than using the inline version, and I'd rather keep it if I can. If you have the time, it would be helpful if you could check out this branch, run your query, and paste the output here. Then I can take that information and give it to the author oftermimad.And yes I desperately need to add logging and debug flags 🙈
@D1mon Are you positive? I'm not sure how that could be; while I did do some refactoring / reorganization around printing, for both v0.4.0 and v0.4.1 we call
termimad::MadSkin::print_texton the answer markdown. And there was no change to the termimad version between those two tags (assuming you are building with--locked). Also, the error message that you're getting is different than the original issue description, so it could be a separate issue.@samtay thanks for explaining that! Here's what I got from running the query again:
(it actually prints out a lot more stuff, but it looks like there's a bunch of markdown from stackoverflow)
Terminal size: Ok((190, 51)) Calling skin.print_text with: BEGIN (removed the stuff that came back from stackoverflow) END thread 'main' panicked at 'attempt to subtract with overflow', /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/minimad-0.6.4/src/compound.rs:117:19 stack backtrace: 0: backtrace::backtrace::libunwind::trace at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86 1: backtrace::backtrace::trace_unsynchronized at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66 2: std::sys_common::backtrace::_print_fmt at src/libstd/sys_common/backtrace.rs:78 3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt at src/libstd/sys_common/backtrace.rs:59 4: core::fmt::write at src/libcore/fmt/mod.rs:1076 5: std::io::Write::write_fmt at src/libstd/io/mod.rs:1537 6: std::sys_common::backtrace::_print at src/libstd/sys_common/backtrace.rs:62 7: std::sys_common::backtrace::print at src/libstd/sys_common/backtrace.rs:49 8: std::panicking::default_hook::{{closure}} at src/libstd/panicking.rs:198 9: std::panicking::default_hook at src/libstd/panicking.rs:217 10: std::panicking::rust_panic_with_hook at src/libstd/panicking.rs:526 11: rust_begin_unwind at src/libstd/panicking.rs:437 12: core::panicking::panic_fmt at src/libcore/panicking.rs:85 13: core::panicking::panic at src/libcore/panicking.rs:50 14: minimad::compound::Compound::cut_tail at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/minimad-0.6.4/src/compound.rs:117 15: termimad::wrap::hard_wrap_composite at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/wrap.rs:137 16: termimad::wrap::hard_wrap_lines at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/wrap.rs:172 17: termimad::text::FmtText::from_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/text.rs:44 18: termimad::text::FmtText::from at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/text.rs:32 19: termimad::skin::MadSkin::term_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/skin.rs:208 20: termimad::skin::MadSkin::print_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/skin.rs:243 21: so::term::Term::print at src/term.rs:52 22: so::run::{{closure}} at src/main.rs:86 23: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:74 24: tokio::runtime::enter::Enter::block_on::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/enter.rs:163 25: tokio::coop::with_budget::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:127 26: std::thread::local::LocalKey<T>::try_with at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/thread/local.rs:263 27: std::thread::local::LocalKey<T>::with at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/thread/local.rs:239 28: tokio::coop::with_budget at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:120 29: tokio::coop::budget at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:96 30: tokio::runtime::enter::Enter::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/enter.rs:163 31: tokio::runtime::thread_pool::ThreadPool::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/thread_pool/mod.rs:82 32: tokio::runtime::Runtime::block_on::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/mod.rs:446 33: tokio::runtime::context::enter at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/context.rs:72 34: tokio::runtime::handle::Handle::enter at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/handle.rs:76 35: tokio::runtime::Runtime::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/mod.rs:441 36: so::main at src/main.rs:21 37: std::rt::lang_start::{{closure}} at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/rt.rs:67 38: std::rt::lang_start_internal::{{closure}} at src/libstd/rt.rs:52 39: std::panicking::try::do_call at src/libstd/panicking.rs:348 40: std::panicking::try at src/libstd/panicking.rs:325 41: std::panic::catch_unwind at src/libstd/panic.rs:394 42: std::rt::lang_start_internal at src/libstd/rt.rs:51 43: std::rt::lang_start at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/rt.rs:67 44: main 45: __libc_start_main 46: _start note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
Oh, I actually wanted to see what's between the BEGIN & END tags; this is what
termimadis actually trying to print, so it should give us a reproducible example.Whoops! Sorry! Here it is (sorry if github is interpreting the markdown. Couldn't find a way to make it ignore it):
△ Projects/tools/so RUST_BACKTRACE=1 target/debug/so how to setup async rust debug-termimad-panic 16m :: ⬢ Terminal size: Ok((190, 51)) Calling skin.print_text with: BEGIN You are conflating a few concepts. [Concurrency is not parallelism](https://stackoverflow.com/q/1050222/155423), and `async` and `await` are tools for *concurrency*, which may sometimes mean they are also tools for parallelism. Additionally, whether a future is immediately polled or not is orthogonal to the syntax chosen. # `async` / `await` The keywords `async` and `await` exist to make creating and interacting with asynchronous code easier to read and look more like "normal" synchronous code. This is true in all of the languages that have such keywords, as far as I am aware. ## Simpler code This is code that creates a future that adds two numbers when polled **before** ``` fn long_running_operation(a: u8, b: u8) -> impl Future<Output = u8> { struct Value(u8, u8); impl Future for Value { type Output = u8; fn poll(self: Pin<&mut Self>, _ctx: &mut Context) -> Poll<Self::Output> { Poll::Ready(self.0 + self.1) } } Value(a, b) } ``` **after** ``` async fn long_running_operation(a: u8, b: u8) -> u8 { a + b } ``` Note that the "before" code is basically the [implementation of today's `poll_fn` function](https://github.com/rust-lang-nursery/futures-rs/blob/0.3.1/futures-util/src/future/poll_fn.rs#L48-L56) See also [Peter Hall's answer](https://stackoverflow.com/a/52839157/155423) about how keeping track of many variables can be made nicer. ## References One of the potentially surprising things about `async`/`await` is that it enables a specific pattern that wasn't possible before: using references in futures. Here's some code that fills up a buffer with a value in an asynchronous manner: **before** ``` use std::io; fn fill_up<'a>(buf: &'a mut [u8]) -> impl Future<Output = io::Result<usize>> + 'a { futures::future::lazy(move |_| { for b in buf.iter_mut() { *b = 42 } Ok(buf.len()) }) } fn foo() -> impl Future<Output = Vec<u8>> { let mut data = vec![0; 8]; fill_up(&mut data).map(|_| data) } ``` This fails to compile: ```none error[E0597]: `data` does not live long enough --> src/main.rs:33:17 | 33 | fill_up_old(&mut data).map(|_| data) | ^^^^^^^^^ borrowed value does not live long enough 34 | } | - `data` dropped here while still borrowed | = note: borrowed value must be valid for the static lifetime... error[E0505]: cannot move out of `data` because it is borrowed --> src/main.rs:33:32 | 33 | fill_up_old(&mut data).map(|_| data) | --------- ^^^ ---- move occurs due to use in closure | | | | | move out of `data` occurs here | borrow of `data` occurs here | = note: borrowed value must be valid for the static lifetime... ``` **after** ``` use std::io; async fn fill_up(buf: &mut [u8]) -> io::Result<usize> { for b in buf.iter_mut() { *b = 42 } Ok(buf.len()) } async fn foo() -> Vec<u8> { let mut data = vec![0; 8]; fill_up(&mut data).await.expect("IO failed"); data } ``` This works! # Calling an `async` function does not run anything The implementation and design of a `Future` and the entire system around futures, on the other hand, is unrelated to the keywords `async` and `await`. Indeed, Rust has a thriving asynchronous ecosystem (such as with Tokio) before the `async` / `await` keywords ever existed. The same was true for JavaScript. ## Why aren't `Future`s polled immediately on creation? For the most authoritative answer, check out [this comment from withoutboats](https://github.com/rust-lang/rfcs/pull/2394#issuecomment-382399020) on the RFC pull request: > A fundamental difference between Rust's futures and those from other > languages is that Rust's futures do not do anything unless polled. The > whole system is built around this: for example, cancellation is > dropping the future for precisely this reason. In contrast, in other > languages, calling an async fn spins up a future that starts executing > immediately. > > A point about this is that async & await in Rust are not inherently > concurrent constructions. If you have a program that only uses async & > await and no concurrency primitives, the code in your program will > execute in a defined, statically known, linear order. Obviously, most > programs will use some kind of concurrency to schedule multiple, > concurrent tasks on the event loop, but they don't have to. What this > means is that you can - trivially - locally guarantee the ordering of > certain events, even if there is nonblocking IO performed in between > them that you want to be asynchronous with some larger set of nonlocal > events (e.g. you can strictly control ordering of events inside of a > request handler, while being concurrent with many other request > handlers, even on two sides of an await point). > > This property gives Rust's async/await syntax the kind of local > reasoning & low-level control that makes Rust what it is. Running up > to the first await point would not inherently violate that - you'd > still know when the code executed, it would just execute in two > different places depending on whether it came before or after an > await. However, I think the decision made by other languages to start > executing immediately largely stems from their systems which > immediately schedule a task concurrently when you call an async fn > (for example, that's the impression of the underlying problem I got > from the Dart 2.0 document). Some of the Dart 2.0 background is covered by [this discussion from munificent](https://www.reddit.com/r/rust/comments/8aaywk/async_await_in_rust_a_full_proposal/dwxjjo2/): > Hi, I'm on the Dart team. Dart's async/await was designed mainly by > Erik Meijer, who also worked on async/await for C#. In C#, async/await > is synchronous to the first await. For Dart, Erik and others felt that > C#'s model was too confusing and instead specified that an async > function always yields once before executing any code. > > At the time, I and another on my team were tasked with being the > guinea pigs to try out the new in-progress syntax and semantics in our > package manager. Based on that experience, we felt async functions > should run synchronously to the first await. Our arguments were > mostly: > > 1. Always yielding once incurs a performance penalty for no good reason. In most cases, this doesn't matter, but in some it really > does. Even in cases where you can live with it, it's a drag to bleed a > little perf everywhere. > > 1. Always yielding means certain patterns cannot be implemented using async/await. In particular, it's really common to have code like > (pseudo-code here): > > getThingFromNetwork(): > if (downloadAlreadyInProgress): > return cachedFuture > > cachedFuture = startDownload() > return cachedFuture > > In other words, you have an async operation that you can call multiple times before it completes. Later calls use the same > previously-created pending future. You want to ensure you don't start > the operation multiple times. That means you need to synchronously > check the cache before starting the operation. > > If async functions are async from the start, the above function can't use async/await. > > We pleaded our case, but ultimately the language designers stuck with > async-from-the-top. This was several years ago. > > That turned out to be the wrong call. The performance cost is real > enough that many users developed a mindset that "async functions are > slow" and started avoiding using it even in cases where the perf hit > was affordable. Worse, we see nasty concurrency bugs where people > think they can do some synchronous work at the top of a function and > are dismayed to discover they've created race conditions. Overall, it > seems users do not naturally assume an async function yields before > executing any code. > > So, for Dart 2, we are now taking the very painful breaking change to > change async functions to be synchronous to the first await and > migrating all of our existing code through that transition. I'm glad > we're making the change, but I really wish we'd done the right thing > on day one. > > I don't know if Rust's ownership and performance model place different > constraints on you where being async from the top really is better, > but from our experience, sync-to-the-first-await is clearly the better > trade-off for Dart. [cramert replies](https://www.reddit.com/r/rust/comments/8aaywk/async_await_in_rust_a_full_proposal/dwxqgpy) (note that some of this syntax is outdated now): > If you need code to execute immediately when a function is called > rather than later on when the future is polled, you can write your > function like this: > > fn foo() -> impl Future<Item=Thing> { > println!("prints immediately"); > async_block! { > println!("prints when the future is first polled"); > await!(bar()); > await!(baz()) > } > } ## Code examples These examples use the async support in Rust 1.39 and the futures crate 0.3.1. ### Literal transcription of the C# code ``` use futures; // 0.3.1 async fn long_running_operation(a: u8, b: u8) -> u8 { println!("long_running_operation"); a + b } fn another_operation(c: u8, d: u8) -> u8 { println!("another_operation"); c * d } async fn foo() -> u8 { println!("foo"); let sum = long_running_operation(1, 2); another_operation(3, 4); sum.await } fn main() { let task = foo(); futures::executor::block_on(async { let v = task.await; println!("Result: {}", v); }); } ``` If you called `foo`, the sequence of events in Rust would be: 1. Something implementing `Future<Output = u8>` is returned. That's it. No "actual" work is done yet. If you take the result of `foo` and drive it towards completion (by polling it, in this case via `futures::executor::block_on`), then the next steps are: 2. Something implementing `Future<Output = u8>` is returned from calling `long_running_operation` (it does not start work yet). 2. `another_operation` does work as it is synchronous. 2. the `.await` syntax causes the code in `long_running_operation` to start. The `foo` future will continue to return "not ready" until the computation is done. The output would be: ```none foo another_operation long_running_operation Result: 3 ``` Note that there are no thread pools here: this is all done on a single thread. ### `async` blocks You can also use `async` blocks: ``` use futures::{future, FutureExt}; // 0.3.1 fn long_running_operation(a: u8, b: u8) -> u8 { println!("long_running_operation"); a + b } fn another_operation(c: u8, d: u8) -> u8 { println!("another_operation"); c * d } async fn foo() -> u8 { println!("foo"); let sum = async { long_running_operation(1, 2) }; let oth = async { another_operation(3, 4) }; let both = future::join(sum, oth).map(|(sum, _)| sum); both.await } ``` Here we wrap synchronous code in an `async` block and then wait for both actions to complete before this function will be complete. Note that wrapping synchronous code like this is *not* a good idea for anything that will actually take a long time; see https://stackoverflow.com/q/41932137/155423 for more info. ### With a threadpool ``` // Requires the `thread-pool` feature to be enabled use futures::{executor::ThreadPool, future, task::SpawnExt, FutureExt}; async fn foo(pool: &mut ThreadPool) -> u8 { println!("foo"); let sum = pool .spawn_with_handle(async { long_running_operation(1, 2) }) .unwrap(); let oth = pool .spawn_with_handle(async { another_operation(3, 4) }) .unwrap(); let both = future::join(sum, oth).map(|(sum, _)| sum); both.await } ``` END thread 'main' panicked at 'attempt to subtract with overflow', /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/minimad-0.6.4/src/compound.rs:117:19 stack backtrace: 0: backtrace::backtrace::libunwind::trace at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86 1: backtrace::backtrace::trace_unsynchronized at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66 2: std::sys_common::backtrace::_print_fmt at src/libstd/sys_common/backtrace.rs:78 3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt at src/libstd/sys_common/backtrace.rs:59 4: core::fmt::write at src/libcore/fmt/mod.rs:1076 5: std::io::Write::write_fmt at src/libstd/io/mod.rs:1537 6: std::sys_common::backtrace::_print at src/libstd/sys_common/backtrace.rs:62 7: std::sys_common::backtrace::print at src/libstd/sys_common/backtrace.rs:49 8: std::panicking::default_hook::{{closure}} at src/libstd/panicking.rs:198 9: std::panicking::default_hook at src/libstd/panicking.rs:217 10: std::panicking::rust_panic_with_hook at src/libstd/panicking.rs:526 11: rust_begin_unwind at src/libstd/panicking.rs:437 12: core::panicking::panic_fmt at src/libcore/panicking.rs:85 13: core::panicking::panic at src/libcore/panicking.rs:50 14: minimad::compound::Compound::cut_tail at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/minimad-0.6.4/src/compound.rs:117 15: termimad::wrap::hard_wrap_composite at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/wrap.rs:137 16: termimad::wrap::hard_wrap_lines at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/wrap.rs:172 17: termimad::text::FmtText::from_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/text.rs:44 18: termimad::text::FmtText::from at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/text.rs:32 19: termimad::skin::MadSkin::term_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/skin.rs:208 20: termimad::skin::MadSkin::print_text at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/termimad-0.8.24/src/skin.rs:243 21: so::term::Term::print at src/term.rs:52 22: so::run::{{closure}} at src/main.rs:86 23: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:74 24: tokio::runtime::enter::Enter::block_on::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/enter.rs:163 25: tokio::coop::with_budget::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:127 26: std::thread::local::LocalKey<T>::try_with at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/thread/local.rs:263 27: std::thread::local::LocalKey<T>::with at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/thread/local.rs:239 28: tokio::coop::with_budget at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:120 29: tokio::coop::budget at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/coop.rs:96 30: tokio::runtime::enter::Enter::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/enter.rs:163 31: tokio::runtime::thread_pool::ThreadPool::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/thread_pool/mod.rs:82 32: tokio::runtime::Runtime::block_on::{{closure}} at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/mod.rs:446 33: tokio::runtime::context::enter at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/context.rs:72 34: tokio::runtime::handle::Handle::enter at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/handle.rs:76 35: tokio::runtime::Runtime::block_on at /home/eyehuda/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-0.2.21/src/runtime/mod.rs:441 36: so::main at src/main.rs:21 37: std::rt::lang_start::{{closure}} at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/rt.rs:67 38: std::rt::lang_start_internal::{{closure}} at src/libstd/rt.rs:52 39: std::panicking::try::do_call at src/libstd/panicking.rs:348 40: std::panicking::try at src/libstd/panicking.rs:325 41: std::panic::catch_unwind at src/libstd/panic.rs:394 42: std::rt::lang_start_internal at src/libstd/rt.rs:51 43: std::rt::lang_start at /home/eyehuda/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libstd/rt.rs:67 44: main 45: __libc_start_main 46: _start note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.Awesome, thanks @Ethan3600 this is super helpful.
Reacted by Ethan Yehudasorry v0.4.0 - same error on query:
so how to setup async rustThanks for the quick turnaround. Seems to work on v0.4.2! This is such an awesome tool! Now I can ask my newbie Rust questions in style 😎
Describe the bug
The following command results in a the program crashing with the error
thread 'main' panicked at 'attempt to subtract with overflowso how to setup async rustTo Reproduce
Steps to reproduce the behavior:
so how to setup async rustEnvironment
so --version: so 0.4.1Additional context
I was able to make the error go away by doing the following:
Going to be honest with you here.. I don't Rust very well (tyring my best to learn!) and I have zero clue what the difference is between
print_textandprint_inlineis. Just wanted to throw that out there though.Stack trace: