Failure to clean up incremental compilation artifacts should not be a hard error

[Manishearth]

error: Failed to delete invalidated or incompatible incremental compilation session directory contents `/home/manishearth/mozilla/servo/target/debug/incremental/script-23kpbvowy6y9i/s-f8z0p73x3w-17kitl0-working/dep-graph.bin`: No such file or directory (os error 2).

This is basically rustc attempting to delete a file that no longer exists. This breaks the build, perhaps it should be a warning instead?

(I think you can get this kind of error if you keep around target dirs post rustup.)

[Centril]

r? @Zoxc

[Zoxc]

cc @michaelwoerister

[michaelwoerister]

Yeah, that could be handled more robustly. Especially if the error indicates that the file does not exist.

However, this is a strange case. The only code path triggering this just tries to delete all files in the directory:

rust/src/librustc_incremental/persist/fs.rs

Lines 378 to 385 in 79d8a0f

	pub fn delete_all_session_dir_contents(sess: &Session) -> io::Result<()> {
	let sess_dir_iterator = sess.incr_comp_session_dir().read_dir()?;
	for entry in sess_dir_iterator {
	let entry = entry?;
	safe_remove_file(&entry.path())?
	}
	Ok(())
	}

And the code even double-checks if that the file exists before trying to delete it. Is there some other process messing the incr. comp. dir?

[Manishearth]

I don't think so, I've turned off RLS in my editor because it's too much overhead for Servo, so there shouldn't be.

I think the directory may not have existed, I don't recall what the precise setup was (and that target dir is long gone now)

[michaelwoerister]

How often does this occur? I've never seen it.

[Manishearth]

I've seen it happen once

…

On Fri, Feb 1, 2019, 3:10 AM Michael Woerister ***@***.*** wrote: How often does this occur? I've never seen it. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#57958 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABivSKBEHT1b9UeiRtmo7Yq8GVh6Z8t_ks5vJCCUgaJpZM4aW3OG> .

[cdetrio]

I ran into this, and I was using rustup to switch rustc versions and rebuild a project. Also on a dep-graph.bin file in a directory that didn't exist.

[Marwes]

Seeing this frequently when building inside docker on travis https://travis-ci.org/gluon-lang/gluon-lang.org

[mati865]

Which systems are you using?
Maybe https://doc.rust-lang.org/stable/std/fs/fn.canonicalize.html is broken on some systems?

[Marwes]

This build were using https://github.com/rust-lang/docker-rust/blob/master/1.33.0/stretch/slim/Dockerfile (though it was the 1.32 version of rust)