miri no longer builds after rust-lang/rust#64785

[rust-highfive]

Hello, this is your friendly neighborhood mergebot.
After merging PR #64785, I observed that the tool miri has failing tests.
A follow-up PR to the repository https://github.com/rust-lang/miri is needed to fix the fallout.

cc @Manishearth, do you think you would have time to do the follow-up work?
If so, that would be great!

cc @Manishearth, the PR reviewer, and @rust-lang/compiler -- nominating for prioritization.

[Manishearth]

I suspect miri just needs a compiletest update cc @RalfJung

[pnkfelix]

triage: P-medium. Removing nomination label.

[RalfJung]

@Manishearth So, the compiletest-update was semver-breaking?

[RalfJung]

The failure seems to be a panic in cargo...?

thread 'main' panicked at 'index out of bounds: the len is 2 but the index is 2', src/tools/cargo/src/cargo/util/cpu.rs:152:29

stack backtrace:

   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt

   1: core::fmt::write

   2: std::io::Write::write_fmt

   3: std::panicking::default_hook::{{closure}}

   4: std::panicking::default_hook

   5: std::panicking::rust_panic_with_hook

   6: std::panicking::continue_panic_fmt

   7: rust_begin_unwind

   8: core::panicking::panic_fmt

   9: core::panicking::panic_bounds_check

  10: cargo::util::cpu::State::current

  11: cargo::core::compiler::job_queue::JobQueue::new

  12: cargo::core::compiler::context::Context::compile

  13: cargo::ops::cargo_compile::compile_ws

  14: cargo::ops::cargo_compile::compile

  15: cargo::commands::build::exec

  16: cargo::cli::main

  17: cargo::main

  18: std::rt::lang_start::{{closure}}

  19: std::panicking::try::do_call

  20: __rust_maybe_catch_panic

  21: std::rt::lang_start_internal

  22: main

note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[Manishearth]

@RalfJung, not quite, nightly rustc broke compiletest and we play catch up with that since the nightly feature is "current nightly"

the cargo panic you're seeing is an osx bug in cargo that got fixed

[RalfJung]

the cargo panic you're seeing is an osx bug in cargo that got fixed

Is this a recent bug? It looks (in Miri CI) as if the bug occurred with stable cargo.

[mati865]

@RalfJung this bug recently appeared in nightly and got fixed on the next day. Could you cargo version from CI (after installing master toolchain)?

[Manishearth]

It's recent, but not on stable, maybe you're seeing something else.

[RalfJung]

FWIW, the trouble was that Travis on the auto branch used a beta cargo, not a stable one, due to caching.