ICE with rustc 1.64.0-nightly (27eb6d701 2022-07-04) running on x86_64-unknown-linux-gnu

[andrewdavidmackenzie]

Maintainer's Note

This is a bug with recent nightly versions as documented here, and likely due to MIR inlining in rust-lang/rust#91743. The last known working commit is nightly-x86_64-unknown-linux-gnu installed - rustc 1.64.0-nightly (7425fb293 2022-06-30). See this comment further below for a deeper description of the issue. This is now a tracking issue for rust-lang/rust#98833.

The original post is unmodified below.

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Description

My projects nightly cron Github Action build has started failing when compiling minimal-lexical recently, I presume due to an update to rustc nightly...

Here is a failing build log:

https://github.com/andrewdavidmackenzie/flow/runs/7201189157?check_suite_focus=true#step:12:229

It seems to be deep in my dependency tree via wax -> nom -> minimal-lexical, and I have wax on 0.5.0 which is the latest, so not sure there is much I can do on my end?

[Alexhuszagh]

Description

My projects nightly cron Github Action build has started failing when compiling minimal-lexical recently, I presume due to an update to rustc nightly...

Here is a failing build log:

https://github.com/andrewdavidmackenzie/flow/runs/7201189157?check_suite_focus=true#step:12:229

It seems to be deep in my dependency tree via wax -> nom -> minimal-lexical, and I have wax on 0.5.0 which is the latest, so not sure there is much I can do on my end?

I'm a little bit swamped with the release of cross v0.2.3 but I'll be working on this shortly. Sorry for the delay, I've been backlogged.

[andrewdavidmackenzie]

Hi, any progress? Can I help? Have a bunch of builds from dependabot piling up, but all failing due to this.

[Alexhuszagh]

I think this is more than just a bug in lexical, but I'll take a deep dive. We're running into this in a few other libraries I maintain.

[Alexhuszagh]

Can you try with CARGO_INCREMENTAL=0, just as a test? Running cargo clean on a relatively complex build system fixed ICEs in one library I maintain, so I think this might be an issue with incremental compilation. This doesn't reproduce either just building lexical alone. I'm using:

18:57 $ cargo +nightly --version
cargo 1.64.0-nightly (b1dd22e66 2022-07-09)

And then cargo +nightly build and cargo +nightly test both pass. I've got a reproducing failure in cross, so we should be able to bisect the version that caused this.

[Alexhuszagh]

This isn't a lexical issue: this is the issue in question rust-lang/rust#98833. Specifically, this comment documents the likely offending commit.

Bisection says

searched nightlies: from nightly-2022-06-29 to nightly-2022-07-03
regressed nightly: nightly-2022-07-03
searched commit range: rust-lang/rust@46b8c23...f2d9393
regressed commit: rust-lang/rust@0075bb4
bisected with cargo-bisect-rustc v0.6.1

So, rust-lang/rust#91743

I'll keep this open as a tracking issue, but this isn't a bug in lexical, and is an upstream issue. Hopefully you find a working solution, such as using an older nightly in the meantime.

[andrewdavidmackenzie]

It's failing in my GH Action. I do have cargo cached. So I tried changing the key to do an effective reset of the cache. No change.

[Alexhuszagh]

I'll try building your project with various nightlies since it seemed that nightly-2022-06-29-x86_64-unknown-linux-gnu did not work, which should be before the regression based on this workflow. I'll try using cargo-bisect-rustc to see where the issue is. Even if I can't fix this (ICEs are generally not an issue in libraries unless they do something very unusual, which lexical does not do).

(Note that this may take a while, your package doesn't compile very quickly and I believe I need the full context to check this).

[Alexhuszagh]

FYI: If you want to help (this will likely be filed as a bug on Rust itself), using cargo-bisect-rustc with all the necessary dependencies installed and the failing action would be very useful. You would be using a custom script, and the start and end points can be toggled as per the description. Once I have more information on what's failing and the dependencies, I can help you get started with using the tool.

[Alexhuszagh]

I'm using a Fedora 36 host machine, and ran the following:

$ rustup toolchain install nightly-2022-06-29-x86_64-unknown-linux-gnu
$ cargo +nightly-2022-06-29 build --manifest-path flowc/Cargo.toml

I also tried it with nightly-2022-07-17-x86_64-unknown-linux-gnu and nothing reproduces, so this seems very difficult to debug. If you can get a reproducible case, that would likely be necessary for me to bisect this.