Running mill in source directory causes subsequent tasks to fail

[yilinwei]

Reproduction can be found here.

I've not tested on a different computer or OS.

[lefou]

Thanks for reporting and providing a reproduction.

After a first glace, I think it's because mill creates a socket file under out/mill-worker-*/io, which is not readable as a source file.

[tfenne]

I just got caught out by this. Accidentally ran mill deep down in a source directory, then spent 10-15 minutes trying to figure out why mill was generating such a cryptic error before stumbling on this issue. Putting my stack trace here so it's easier for others to find when searching issues:

$ mill _.test
[32/55] tools.test.sources
1 targets failed
tools.test.sources java.nio.file.FileSystemException: [...]/src/test/scala/com/[...]/out/mill-worker-BzhyNALGB6i84adFWul54iUnoFc=-1/io: Operation not supported on socket

[lefou]

I'm not sure what the best approach is to solve this issue. Maybe we should filter out socket files when searching for source files? Or vice versa, explicitly only collect "real" files?

[tfenne]

I don't know the internals of mill very well, but I wonder if it would be possible to abort early if no build file can be found and simply not write anything in that case?

[lefou]

Yeah, exiting mill with a good message in case a build.sc is missing is a good idea.

[timshen24]

HelloWorld.sources java.nio.file.FileSystemException: /Users/.../MillTest1/HelloWorld/src/main/scala/hello/out/mill-worker-dRTtqvVZYalRvhruw0ZliMCsBnA=-1/io: Operation not supported on socket
java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:100)
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:116)
java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:219)
java.base/java.nio.file.Files.newByteChannel(Files.java:371)
java.base/java.nio.file.Files.newByteChannel(Files.java:422)
java.base/java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:420)
java.base/java.nio.file.Files.newInputStream(Files.java:156)
os.Path.getInputStream(Path.scala:475)
os.read$inputStream$.apply(ReadWriteOps.scala:229)
mill.api.PathRef$.$anonfun$apply$2(PathRef.scala:47)
mill.api.PathRef$.$anonfun$apply$2$adapted(PathRef.scala:37)
scala.collection.IterableOnceOps.foreach(IterableOnce.scala:563)
scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:561)
scala.collection.AbstractIterable.foreach(Iterable.scala:919)
scala.collection.IterableOps$WithFilter.foreach(Iterable.scala:889)
mill.api.PathRef$.apply(PathRef.scala:37)
mill.scalalib.JavaModule.$anonfun$sources$4(JavaModule.scala:204)
mill.api.Result$Success.map(Result.scala:28)
mill.api.Result$Success.map(Result.scala:27)
mill.scalalib.JavaModule.$anonfun$sources$2(JavaModule.scala:204)
mill.define.Applicative$Applyer.$anonfun$zipMap$1(Applicative.scala:35)
mill.define.Task$MappedDest.evaluate(Task.scala:396)

I encountered the same problem, can anyone help me?

[lefou]

Just remove the src/main/scala/hello/out directory, which is obviously not part of your sources.

[lefou]

PR #1878 fixes this.