`rustc` error on Windows: The filename or extension is too long

[jszwedko]

Hi all!

I think we are running into the same issue described by #39644 but with rustc.exe rather than link.exe.

We have a project where we noticed that any PRs that introduce a new dependency were causing our Windows CI builds to fail with:

Caused by:
  The filename or extension is too long. (os error 206)

In the example failure below, it does seem like the rustc command is 33,184 characters, which would be over the 32,767 character limit mentioned in https://docs.microsoft.com/en-us/troubleshoot/windows-client/shell-experience/command-line-string-limitation.

Example failure:

https://github.com/vectordotdev/vector/runs/5157867395?check_suite_focus=true

Does that sound right to people? Do we need the same fix from #44094 but for the rustc invocation?

Meta

rustc --version --verbose:

rustc 1.58.1 (db9d1b20b 2022-01-20)
binary: rustc
commit-hash: db9d1b20bba1968c1ec1fc49616d4742c1725b4b
commit-date: 2022-01-20
host: x86_64-pc-windows-msvc
release: 1.58.1
LLVM version: 13.0.0

[jszwedko]

bazelbuild/rules_rust#1076 seems related.

[ChrisDenton]

Yes, for arguments longer than the 32,767 limit, you would need to load command-line flags from a path.

[jszwedko]

Yes, for arguments longer than the 32,767 limit, you would need to load command-line flags from a path.

Is that something we can do from outside? We are just executing cargo test which then calls rustc. I suppose maybe this issue should be moved over to https://github.com/rust-lang/cargo ?

[ChrisDenton]

I think so. It seems more like a bug with Cargo because I'm not sure there's much rustc can do here.

[jszwedko]

Yeah, I think so too. I opened rust-lang/cargo#10381 so I'll close this one out. Thanks for the pointer!