panic on compile of basic Serenity example

[amyipdev]

Code

use std::env;

use serenity::{async_trait, Client, client::{EventHandler, Context}, model::channel::Message, all::GatewayIntents};

struct Handler;

#[async_trait]
impl EventHandler for Handler {
    async fn message(&self, ctx: Context, msg: Message) {
        if msg.content == "!ping" {
            if let Err(w) = msg.channel_id.say(&ctx.http, "Pong!").await {
                println!("Error sending message: {w:?}");
            }
        }
    }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let token = env::var("WATCH306_TOKEN")?;
    let intents = GatewayIntents::GUILD_MESSAGES | GatewayIntents::MESSAGE_CONTENT;
    let mut client = Client::builder(&token, intents).event_handler(Handler).await?;
    if let Err(w) = client.start().await {
        eprintln!("Client error: {w:?}");
    }
}

Meta

rustc --version --verbose:

rustc 1.76.0 (07dca489a 2024-02-04)
binary: rustc
commit-hash: 07dca489ac2d933c78d3c5158e3f43beefeb02ce
commit-date: 2024-02-04
host: x86_64-unknown-linux-gnu
release: 1.76.0
LLVM version: 17.0.6

Error output

   Compiling watch306 v0.1.0 (/home/amy/dev/watch306)
thread 'rustc' panicked at library/alloc/src/raw_vec.rs:571:5:
capacity overflow
stack backtrace:
   0:     0x7f73aabed6f6 - std::backtrace_rs::backtrace::libunwind::trace::hbee8a7973eeb6c93
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f73aabed6f6 - std::backtrace_rs::backtrace::trace_unsynchronized::hc8ac75eea3aa6899
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f73aabed6f6 - std::sys_common::backtrace::_print_fmt::hc7f3e3b5298b1083
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys_common/backtrace.rs:68:5
   3:     0x7f73aabed6f6 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hbb235daedd7c6190
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f73aac3ff40 - core::fmt::rt::Argument::fmt::h76c38a80d925a410
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/core/src/fmt/rt.rs:142:9
   5:     0x7f73aac3ff40 - core::fmt::write::h3ed6aeaa977c8e45
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/core/src/fmt/mod.rs:1120:17   6:     0x7f73aabe153f - std::io::Write::write_fmt::h78b18af5775fedb5
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/io/mod.rs:1810:15
   7:     0x7f73aabed4d4 - std::sys_common::backtrace::_print::h5d645a07e0fcfdbb
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f73aabed4d4 - std::sys_common::backtrace::print::h85035a511aafe7a8
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f73aabf0267 - std::panicking::default_hook::{{closure}}::hcce8cea212785a25
  10:     0x7f73aabeffc9 - std::panicking::default_hook::hf5fcb0f213fe709a
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/panicking.rs:292:9
  11:     0x7f73a7a1461c - std[79729d9c385e1623]::panicking::update_hook::<alloc[6df67106ebca92c0]::boxed::Box<rustc_driver_impl[66ed8fdbde15dc6c]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7f73aabf09b6 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hbc5ccf4eb663e1e5
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/alloc/src/boxed.rs:2029:9
  13:     0x7f73aabf09b6 - std::panicking::rust_panic_with_hook::h095fccf1dc9379ee
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/panicking.rs:783:13  14:     0x7f73aabf06c9 - std::panicking::begin_panic_handler::{{closure}}::h032ba12139b353db
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/panicking.rs:649:13  15:     0x7f73aabedbf6 - std::sys_common::backtrace::__rust_end_short_backtrace::h9259bc2ff8fd0f76
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys_common/backtrace.rs:171:18
  16:     0x7f73aabf0460 - rust_begin_unwind
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/panicking.rs:645:5
  17:     0x7f73aac3c645 - core::panicking::panic_fmt::h784f20a50eaab275
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/core/src/panicking.rs:72:14  18:     0x7f73aac2d98f - alloc::raw_vec::capacity_overflow::hefb917d2eb4d2968
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/alloc/src/raw_vec.rs:571:5
  19:     0x7f73a9b46ae4 - rustc_incremental[9a504be5dec41bc5]::persist::load::setup_dep_graph
  20:     0x7f73a9af2945 - <rustc_interface[bf5cafa581ab7832]::queries::Queries>::global_ctxt
  21:     0x7f73a98fe568 - rustc_interface[bf5cafa581ab7832]::interface::run_compiler::<core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>, rustc_driver_impl[66ed8fdbde15dc6c]::run_compiler::{closure#0}>::{closure#0}
  22:     0x7f73a9a2c7db - std[79729d9c385e1623]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[bf5cafa581ab7832]::util::run_in_thread_with_globals<rustc_interface[bf5cafa581ab7832]::interface::run_compiler<core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>, rustc_driver_impl[66ed8fdbde15dc6c]::run_compiler::{closure#0}>::{closure#0}, core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>>
  23:     0x7f73a9a2c639 - <<std[79729d9c385e1623]::thread::Builder>::spawn_unchecked_<rustc_interface[bf5cafa581ab7832]::util::run_in_thread_with_globals<rustc_interface[bf5cafa581ab7832]::interface::run_compiler<core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>, rustc_driver_impl[66ed8fdbde15dc6c]::run_compiler::{closure#0}>::{closure#0}, core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f975038e3cc9791c]::result::Result<(), rustc_span[7a149c27976a99e7]::ErrorGuaranteed>>::{closure#1} as core[f975038e3cc9791c]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  24:     0x7f73aabfa8e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h12de4fc57affb195
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/alloc/src/boxed.rs:2015:9
  25:     0x7f73aabfa8e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h3c619f45059d5cf1
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/alloc/src/boxed.rs:2015:9
  26:     0x7f73aabfa8e5 - std::sys::unix::thread::Thread::new::thread_start::hbac657605e4b7389
                               at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/sys/unix/thread.rs:108:17
  27:     0x7f73a4cac897 - start_thread
  28:     0x7f73a4d3380c - clone3
  29:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.76.0 (07dca489a 2024-02-04) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
error: could not compile `watch306` (bin "watch306")

Backtrace

thread 'rustc' panicked at library/alloc/src/raw_vec.rs:571:5:
capacity overflow
stack backtrace:
   0: rust_begin_unwind
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/std/src/panicking.rs:645:5
   1: core::panicking::panic_fmt
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/core/src/panicking.rs:72:14
   2: alloc::raw_vec::capacity_overflow
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library/alloc/src/raw_vec.rs:571:5
   3: rustc_incremental::persist::load::setup_dep_graph
   4: <rustc_interface::queries::Queries>::global_ctxt
   5: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#0}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.76.0 (07dca489a 2024-02-04) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
error: could not compile `watch306` (bin "watch306")

[Noratrieb]

I cannot reproduce this with your example (which errors, but fixing it also doesn't reproduce it). I don't know in which exact allocation it happens, but I feel like something about the incremental cache got corrupted, either because of a bug in rustc or some other external means. Without a reproduction, there isn't that much we can do.

[saethlin]

I'm quite sure it's one of these:

rust/compiler/rustc_query_system/src/dep_graph/serialized.rs

Lines 195 to 209 in b054da8

	let mut nodes = IndexVec::with_capacity(node_count);
	let mut fingerprints = IndexVec::with_capacity(node_count);
	let mut edge_list_indices = IndexVec::with_capacity(node_count);
	// This estimation assumes that all of the encoded bytes are for the edge lists or for the
	// fixed-size node headers. But that's not necessarily true; if any edge list has a length
	// that spills out of the size we can bit-pack into SerializedNodeHeader then some of the
	// total serialized size is also used by leb128-encoded edge list lengths. Neglecting that
	// contribution to graph_bytes means our estimation of the bytes needed for edge_list_data
	// slightly overshoots. But it cannot overshoot by much; consider that the worse case is
	// for a node with length 64, which means the spilled 1-byte leb128 length is 1 byte of at
	// least (34 byte header + 1 byte len + 64 bytes edge data), which is ~1%. A 2-byte leb128
	// length is about the same fractional overhead and it amortizes for yet greater lengths.
	let mut edge_list_data = Vec::with_capacity(
	graph_bytes - node_count * std::mem::size_of::<SerializedNodeHeader<D>>(),
	);

[amyipdev]

What's weird is that for me, adding Ok(()) to the end fixes it - so I wonder if based on that file that got sent it's something in checks for return types?

[saethlin]

On another issue, I tried to explain what I think is happening to cause this crash, you might find it interesting: #120582 (comment)

There's a compiler bug (possibly multiple) that have conspired to produce a corrupt file which is part of the build cache in target/, so if you make a source code change and invalidate that cache entry the corruption gets cleared. It's not really possible to reason about these things from the source code.

[amyipdev]

I don't know for sure whether that's the case - while a cargo clean did clear it up, simple source code file changes didn't (with the exception of adding in Ok(()), but even then removing it causes the issue to come up again)