[discussion] `ErrorKind::CrossesDevices` from `io_error_more`

[GrigorenkoPV]

@rustbot label C-discussion

Main tracking issue: #86442

Background

The io_error_more feature introduced 21 new variants into ErrorKind. They were FCP'd back in December 2022, but there appeared to be quite a lot of disagreement about 4 of the added variants, so the stabilization (#106375) got stalled for over twenty months. Thankfully, the 17 uncontroversial variants got stabilized in #128316, so now we just need to iron out a satisfactory design for the remaining 4 variants, and then they can be stabilized too.

In order to not block any of the remaining variants on each other and to not intertwine the discussions, I've created 4 separate issues, which summarize the concerns & suggestions voiced up until this point and can serve as a place for further discussion.

• FilesystemLoop: [discussion] ErrorKind::FilesystemLoop from io_error_more #130188
• FilesystemQuotaExceeded: [discussion] ErrorKind::FilesystemQuotaExceeded from io_error_more #130190
• CrossesDevices: you are here
• InvalidFilename: [discussion] ErrorKind::InvalidFilename from io_error_more #130192

CrossesDevices

Currently corresponds to EXDEV on Unix and ERROR_NOT_SAME_DEVICE on Windows. (#86442 (comment))

Current docs description:

Cross-device or cross-filesystem (hard) link or rename.

NotSameDevice

I think NotSameDevice is a better name than CrossesDevices. For me, it expresses its meaning more clearly. FWIW, the Linux man page also uses the word "same" to describe EXDEV: oldpath and newpath are not on the same mounted filesystem.

Also, I find NotSameDevice to be stylistically more consistent with the other existing and proposed error identifiers.

Originally posted by kalcutter in #86442 (comment)

Would you also consider NotSameDevice instead of CrossesDevices?

Originally posted by kalcutter in #106375 (comment)

I personally don't think we should rename CrossesDevices.

Originally posted by Josh Triplett in #106375 (comment)

[dtolnay]

@rfcbot fcp merge

I propose stabilizing CrossesDevices if there are 2 other team members on board. As of #106375 (comment), Josh prefers this name.

Alternatively, if 2 other team members prefer a rename to NotSameDevice, I propose stabilizing NotSameDevice.

[rfcbot]

Team member @dtolnay has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[joshtriplett]

Checked my box for CrossesDevices.

[joshtriplett]

Ping @Amanieu @BurntSushi @m-ou-se