Fish panic at `src/history/file.rs:372:5`

[wrvsrx]

Behavior

When I type in fish-shell and trigger fish's auto complementation, such error happens randomly:

thread '<unnamed>' panicked at src/history/file.rs:372:5:
assertion failed: line.starts_with(b"- cmd")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fish crashed, please report a bug.
fish: Job 1, 'fish' terminated by signal SIGABRT (Abort)

Environment

• fish version: 4.0.0

• os version: NixOS 25.05

• installed plugin:

  • tide 6.1.1

Reproduce

I haven't found a method to reproduce crashing stablely

1. Open two fish shell
2. Type sleep 10 in first shell and enter
3. Type something in another shell
4. Second shell might crash

[krobelus]

I don't know how this can happen, maybe you can capture some debug info if it's reproducible

[wrvsrx]

I can't consistently reproduce this issue. I'll try to debug it when I have time.

[krobelus]

Try to 1. always run fish in debug mode (`cargo install --debug`) for better debug info 2. capture the byte offset of the corrupted history item within the history file, by attaching `gdb` to the crashing shell or on the coredump (`coredumpctl gdb`) 3. look at the region in the history file around that corrupted offset. Maybe this will give some hints. The crashing shell should see a prefix of that history file (until the history file is rewritten for deduplication purposes). The other shell appending something should be invisible to the crashing shell (because it only reads the prefix before anything was appended). So in the debugger you can also check the HistoryFileContents size at the time of the crash, does it wrongly include items from other concurrent shells? 4. See if it's triggered by your history file (for example `set -U fish_history sandbox` will use a separate history in all shells) 5. Check if you're using an unusual file system, and if it happens if you use a different one. (though unlikely) 6. Check if it depends on your configuration; are you using `history append` or `history merge` anywhere?