Regression: rustc crashes on Windows trying to build lib/rustlib/x86_64-pc-windows-msvc/lib/libstd.rlib

[nico]

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Trying to update rustc from df0295f07175acc7325ce3ca4152eb05752af1f2 to f90f898fa53de89a1cb274442c90c410075ae731 in Chromium, we hit an ICE. So far I've only seen it on a bot and don't have a local repro yet.

Error output

The full error log is at https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket/8762255204440933329/+/u/compile__with_patch_/stdout?format=raw

Excerpt:

Backtrace

``` FAILED: 444ffa45-8bad-4945-8d57-26a434e09e2b RUST local_rustc_sysroot/lib/rustlib/x86_64-pc-windows-msvc/lib/libstd.rlib stderr: error: internal compiler error: compiler\rustc_mir_transform\src\coverage\spans.rs:434:49: invalid attempt to unwrap a None some_prev thread 'rustc' panicked at C:\b\s\w\ir\cache\builder\src\third_party\rust-src\compiler\rustc_errors\src\lib.rs:1113:75: Box stack backtrace: 0: 0x7ffb7e23a2f5 - ::fmt::hd599614fd193bada 1: 0x7ffb7e26ef8b - core::fmt::write::hda39c3c02411710a 2: 0x7ffb7e243201 - std::fs::DirBuilder::_create::h5d831723ad01bc5b 3: 0x7ffb7e23bc24 - std::panicking::default_hook::h66d8ac9069df83d4 4: 0x7ffb7e23b4ba - std::panicking::default_hook::h66d8ac9069df83d4 5: 0x7ffb74047612 - once_cell[96842b08614cf476]::imp::initialize_or_wait 6: 0x7ffb7e23c60d - std::panicking::rust_panic_with_hook::hcc951e9133c0ca78 7: 0x7ffb73dc5f2a - rustc_errors[4b6d00e9ad1f5418]::markdown::create_stdout_bufwtr 8: 0x7ffb73dc3cc9 - rustc_errors[4b6d00e9ad1f5418]::markdown::create_stdout_bufwtr 9: 0x7ffb76f489b9 - rustc_query_system[d461914d3def57f8]::query::job::report_cycle 10: 0x7ffb73dcb42c - ::diagnostic_builder_emit_producing_guarantee 11: 0x7ffb73bedd9e - ::fmt 12: 0x7ffb73bc7f94 - ::fmt 13: 0x7ffb73bc4571 - ::into_diagnostic_arg 14: 0x7ffb73bc450f - ::into_diagnostic_arg 15: 0x7ffb76f37045 - rustc_middle[3d57c46152fca3ab]::util::bug::bug_fmt 16: 0x7ffb7280d620 - ::run_pass 17: 0x7ffb72809f95 - ::run_pass 18: 0x7ffb72855d3f - ::drop_style 19: 0x7ffb72904863 - rustc_mir_transform[b009732a92ad6572]::mir_promoted 20: 0x7ffb7309fa64 - ::depth_limit_error 21: 0x7ffb7317c8e1 - rustc_query_impl[835115f851c09ed8]::query_callbacks 22: 0x7ffb74d4a502 - once_cell[96842b08614cf476]::imp::initialize_or_wait 23: 0x7ffb74daa86f - once_cell[96842b08614cf476]::imp::initialize_or_wait 24: 0x7ffb72e21dac - rustc_borrowck[6d4f4eabd77ba1f0]::mir_borrowck 25: 0x7ffb7309f9ff - ::depth_limit_error 26: 0x7ffb74bb6bdc - once_cell[96842b08614cf476]::imp::initialize_or_wait 27: 0x7ffb74d59688 - once_cell[96842b08614cf476]::imp::initialize_or_wait 28: 0x7ffb730cd43f - rustc_query_impl[835115f851c09ed8]::profiling_support::alloc_self_profile_query_strings 29: 0x7ffb722e618b - rustc_interface[80035a4c85fe31c5]::passes::start_codegen 30: 0x7ffb740c4445 - once_cell[96842b08614cf476]::imp::initialize_or_wait 31: 0x7ffb722e1407 - rustc_interface[80035a4c85fe31c5]::passes::analysis 32: 0x7ffb730a5f0d - ::depth_limit_error 33: 0x7ffb731806a8 - rustc_query_impl[835115f851c09ed8]::query_callbacks 34: 0x7ffb74c78c8a - once_cell[96842b08614cf476]::imp::initialize_or_wait 35: 0x7ffb74bbd353 - once_cell[96842b08614cf476]::imp::initialize_or_wait 36: 0x7ffb721a22ef - 37: 0x7ffb7406f674 - once_cell[96842b08614cf476]::imp::initialize_or_wait 38: 0x7ffb74048b52 - once_cell[96842b08614cf476]::imp::initialize_or_wait 39: 0x7ffb7403d1ce - once_cell[96842b08614cf476]::imp::initialize_or_wait 40: 0x7ffb740514c6 - once_cell[96842b08614cf476]::imp::initialize_or_wait 41: 0x7ffb721a759a - <::panic_nounwind::Zst as rustc_middle[3d57c46152fca3ab]::mir::interpret::error::MachineStopType>::add_args 42: 0x7ffb7e23d02c - std::sys::windows::thread::Thread::new::h74332cb458a081a6 43: 0x7ffbc6ae7034 - BaseThreadInitThunk 44: 0x7ffbc82226a1 - RtlUserThreadStart ```

It looks like https://github.com/rust-lang/rust/commits/master/compiler/rustc_errors/src was edited quite a bit 4 days ago by @nnethercote; maybe the stack trace will make sense to them.

I'll try to add more information as I get it.

[nico]

(upstream issue: https://bugs.chromium.org/p/chromium/issues/detail?id=1509925)

[nico]

(Our last update included Rust changes up to Nov 28, so the rustc_errors changes on Dec 1 are in scope too. Apologies if this is some very central code and the bug is likely in a caller than in that code in particular! I don't know very much about rustc's internal structure.)

[nico]

I managed to reproduce the problem locally. Here's the error log that rustc asks me to upload:

rustc-ice-2023-12-08T19_42_07-2444121.txt

[nnethercote]

The relevant parts of the stack trace:

  15:     0x7ffb76f37045 - rustc_middle[3d57c46152fca3ab]::util::bug::bug_fmt
  16:     0x7ffb7280d620 - <rustc_mir_transform[b009732a92ad6572]::coverage::InstrumentCoverage as rustc_middle[3d57c46152fca3ab]::mir::MirPass>::run_pass
  17:     0x7ffb72809f95 - <rustc_mir_transform[b009732a92ad6572]::coverage::InstrumentCoverage as rustc_middle[3d57c46152fca3ab]::mir::MirPass>::run_pass
  18:     0x7ffb72855d3f - <rustc_mir_transform[b009732a92ad6572]::elaborate_drops::Elaborator as rustc_mir_dataflow[17d83a6078baa8de]::elaborate_drops::DropElaborator>::drop_style
  19:     0x7ffb72904863 - rustc_mir_transform[b009732a92ad6572]::mir_promoted

This looks like a problem in InstrumentCoverage, which is a MIR pass. I don't know anything about it beyond that. Maybe @saethlin or @cjgillot might know?

[Urgau]

Seems like a duplicate of https://github.com/rust-lang/rust/issues/118643. Which I think will be fixed by https://github.com/rust-lang/rust/pull/118666.

cc @Zalathar

[Zalathar]

Yeah, from the panic message this looks like the same issue.

[Zalathar]

This should now be fixed in 1.76.0-nightly (06e02d5b2 2023-12-09).

[nico]

Yes, we're no longer seeing this, thanks!