format paniced

[fengyangsi]

I use chrono to translate timestamp to ISO format string in wasm program. And panic when call format function.

There was code

use worker::*;
use chrono::NaiveDateTime;

#[event(fetch)]
async fn main(req: Request, env: Env, ctx: Context) -> Result<Response> {
    panic::set_hook(Box::new(|_| {
        worker::console_error!("panic!");
    }));
    // this line didn't panic
    let now = NaiveDateTime::from_timestamp_millis(Date::now().as_millis() as i64).unwrap();
    // this line panic - format function
    Response::ok(now.format("%Y-%m-%dT%H:%M:%S%.f%:z").to_string())
}

    //panic
    now.format("%Y-%m-%dT%H:%M:%S%.f%:z")
    //also panic
    now.format("%+")

Cargo.toml

# https://github.com/rustwasm/wasm-pack/issues/1247
[package.metadata.wasm-pack.profile.release]
wasm-opt = false

[lib]
crate-type = ["cdylib"]

[dependencies]
chrono = "0.4.31"
worker = "0.0.18"

[profile.release]
lto = true
strip = true
codegen-units = 1

wrangler.toml

main = "build/worker/shim.mjs"
compatibility_date = "2023-11-20"

[build]
command = "worker-build"
#also panic when command = "worker-build --release"

[djc]

What is the panic message?

[fengyangsi]

What is the panic message?

panic occurred: panicked at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/alloc/src/string.rs:2460:14:
a Display implementation returned an error unexpectedly: Error
panic occurred: panicked at library/std/src/panicking.rs:135:9:
cannot modify the panic hook from a panicking thread

there are code

use worker::*;
use chrono::NaiveDateTime;
use std::panic;
#[event(fetch)]
async fn main(req: Request, env: Env, ctx: Context) -> Result<Response> {
    panic::set_hook(Box::new(|panic_info| {
        console_error!("panic occurred: {panic_info}");
    }));
    let now = NaiveDateTime::from_timestamp_millis(Date::now().as_millis() as i64).unwrap();
    Response::ok(now.format("%Y-%m-%dT%H:%M:%S%.f%:z").to_string())
}

[djc]

I'd like a full back trace, please -- I can't easily reproduce a WASM environment.

[fengyangsi]

I'd like a full back trace, please -- I can't easily reproduce a WASM environment.

Sorry but how to get full back trace?

I call panic::set_hook() and console panic_info, that's all it return.

[djc]

Usually with a RUST_BACKTRACE=1 environment variable, not sure how that works on WASM. Or maybe just get a clone of chrono and start wiring in some println!()s to figure out what code exactly is triggering the panic.

[davehorner]

I tried creating a test.

#[cfg(test)]
#[test]
/// now.format should not panic
fn assert_panic_nowformat() {
    let now = NaiveDateTime::from_timestamp_millis(NaiveDate::now().as_millis() as i64).unwrap();
    let ret = now.format("%Y-%m-%dT%H:%M:%S%.f%:z").to_string();
}

error[E0599]: no function or associated item named `now` found for struct `Date` in the current scope
  --> tests\panics.rs:25:58
   |
25 |     let now = NaiveDateTime::from_timestamp_millis(Date::now().as_millis() as i64).unwrap();
   |                                                          ^^^ function or associated item not found in `Date<_>`

warning: use of deprecated struct `chrono::Date`: Use `NaiveDate` or `DateTime<Tz>` instead

Date::now() doesn't exist for me on windows, I haven't setup a WASM build yet. I tried using NaiveDate::now() that also is not there. I can't compile the code provided at least on windows anyway.

[fengyangsi]

use chrono::NaiveDateTime;
fn main() {
    let t = NaiveDateTime::from_timestamp_millis(1662921288000).unwrap();
    let f = t.format("%+").to_string();
    println!("{f}");
}

RUST_BACKTRACE=full cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.00s
     Running `target/debug/hello`
thread 'main' panicked at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/alloc/src/string.rs:2460:14:
a Display implementation returned an error unexpectedly: Error
stack backtrace:
   0:     0x5606f5b3f66c - std::backtrace_rs::backtrace::libunwind::trace::h67a838aed1f4d6ec
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x5606f5b3f66c - std::backtrace_rs::backtrace::trace_unsynchronized::h1d1786bb1962baf8
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x5606f5b3f66c - std::sys_common::backtrace::_print_fmt::h5a0b1f807a002d23
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x5606f5b3f66c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hf84ab6ad0b91784c
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x5606f5b5ef1c - core::fmt::rt::Argument::fmt::h28f463bd1fdabed5
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/fmt/rt.rs:138:9
   5:     0x5606f5b5ef1c - core::fmt::write::ha37c23b175e921b3
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/fmt/mod.rs:1114:21
   6:     0x5606f5b3d42e - std::io::Write::write_fmt::haa1b000741bcbbe1
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/io/mod.rs:1763:15
   7:     0x5606f5b3f454 - std::sys_common::backtrace::_print::h1ff1030b04dfb157
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x5606f5b3f454 - std::sys_common::backtrace::print::hb982056c6f29541c
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x5606f5b409d3 - std::panicking::default_hook::{{closure}}::h11f92f82c62fbd68
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:272:22
  10:     0x5606f5b406f4 - std::panicking::default_hook::hb8810fe276772c66
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:292:9
  11:     0x5606f5b40f55 - std::panicking::rust_panic_with_hook::hd2f0efd2fec86cb0
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:731:13
  12:     0x5606f5b40e51 - std::panicking::begin_panic_handler::{{closure}}::h3651b7fc4f61d784
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:609:13
  13:     0x5606f5b3fb96 - std::sys_common::backtrace::__rust_end_short_backtrace::hbc468e4b98c7ae04
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:170:18
  14:     0x5606f5b40ba2 - rust_begin_unwind
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:597:5
  15:     0x5606f5b0d185 - core::panicking::panic_fmt::h979245e2fdb2fabd
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/panicking.rs:72:14
  16:     0x5606f5b0d5e3 - core::result::unwrap_failed::h8c4b86241881fbbb
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/result.rs:1652:5
  17:     0x5606f5b0d9fe - core::result::Result<T,E>::expect::h1bf588d5c1a14540
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/result.rs:1034:23
  18:     0x5606f5b0ead2 - <T as alloc::string::ToString>::to_string::hb8d5d970ca5961bd
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/alloc/src/string.rs:2459:9
  19:     0x5606f5b0e54e - hello::main::hf9221dc4589f196b
                               at /home/yang/Codes/hello/src/main.rs:4:13
  20:     0x5606f5b0dabb - core::ops::function::FnOnce::call_once::h4f94d5cc56dccc29
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/ops/function.rs:250:5
  21:     0x5606f5b0e15e - std::sys_common::backtrace::__rust_begin_short_backtrace::h810b7239c1ae5331
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/sys_common/backtrace.rs:154:18
  22:     0x5606f5b0dbe1 - std::rt::lang_start::{{closure}}::h73936dde8a6a720e
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/rt.rs:166:18
  23:     0x5606f5b3addb - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::hf9057cfaeeb252e2
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/core/src/ops/function.rs:284:13
  24:     0x5606f5b3addb - std::panicking::try::do_call::h629e203a624883e4
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:504:40
  25:     0x5606f5b3addb - std::panicking::try::h7b61614724d6a4f1
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:468:19
  26:     0x5606f5b3addb - std::panic::catch_unwind::h354ac1c0268491d8
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panic.rs:142:14
  27:     0x5606f5b3addb - std::rt::lang_start_internal::{{closure}}::h919fee3c5ba8f617
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/rt.rs:148:48
  28:     0x5606f5b3addb - std::panicking::try::do_call::h54583f67455bff32
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:504:40
  29:     0x5606f5b3addb - std::panicking::try::hb0e12c4e01d39dc2
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panicking.rs:468:19
  30:     0x5606f5b3addb - std::panic::catch_unwind::h367b6339e3ca9a3b
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/panic.rs:142:14
  31:     0x5606f5b3addb - std::rt::lang_start_internal::ha5ce8533eaa0fda8
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/rt.rs:148:20
  32:     0x5606f5b0dbba - std::rt::lang_start::h82ede418019d1799
                               at /rustc/79e9716c980570bfd1f666e3b16ac583f0168962/library/std/src/rt.rs:165:17
  33:     0x5606f5b0e69e - main
  34:     0x7fe2d9bf424d - __libc_start_main
  35:     0x5606f5b0d8ba - _start
                               at /home/abuild/rpmbuild/BUILD/glibc-2.31/csu/../sysdeps/x86_64/start.S:120
  36:                0x0 - <unknown>

[djc]

Well, that trace has no chrono stack frames, so it doesn't help much. :(

[pitdicker]

Can you test it with Response::ok(now.format("%Y-%m-%dT%H:%M:%S%.f").to_string())?

I think the issue is %:z: NaiveDateTime does not have an offset that you can print.

[fengyangsi]

Can you test it with Response::ok(now.format("%Y-%m-%dT%H:%M:%S%.f").to_string())?

I think the issue is %:z: NaiveDateTime does not have an offset that you can print.

it works, didn't panic

[pitdicker]

Thank you for testing. That would make this issue a duplicate of #1096, and #1127 has the plan to return an error instead of panicking.

In your case you just want to convert a Unix timestamp to RFC 3339 format? Than something like this should do the trick:

use chrono::{Utc, TimeZone};
let response_str = Utc.timestamp_millis_opt(1662921288000).unwrap().to_rfc3339();