Scala 3.5.2 artifacts seem to contain empty jars

[rubin55]

I downloaded both the zip and tar.gz versions of scala-3.5.2 on the releases page.

In the lib directory, there are only 3 .jar files, all of them only contain a manifest file. trying to run for example scalac gives:

Error: Could not find or load main class dotty.tools.MainGenericCompiler
Caused by: java.lang.ClassNotFoundException: dotty.tools.MainGenericCompiler

The actual eval line constructed by the scalac script in my case, is:

/usr/lib/jvm/java-21-jetbrains/bin/java" -Xmx768m -Xms768m -classpath "/usr/share/scala3/lib/scala.jar:/usr/share/scala3/lib/with_compiler.jar" -Dscala.expandjavacp=true -Dscala.usejavacp=true -Dscala.home="/usr/share/scala3" dotty.tools.MainGenericCompiler

[rubin55]

Huh. I figured out that, as opposed to LTS (3.3.4), the artifacts contain a maven2 directory, next to the usual bin and lib directory. That maven2 directory seems to contain all the jar archives that would normally end up in lib. The classpath constructed by the scripts look at lib, and don't seem to be maven2 directory-aware. This must be a artifact packaging mistake right?

[WojciechMazur]

maven2 directory was introduced in #20351 for me it seems the expected behaviour. It was part of integrating scala-cli as default runner.

@bishabosha @hamzaremmal @Gedochao opinions?

[bishabosha]

@rubin55 those three jars list the classpath for the commands in the manifest file "Class-Path" attribute - it's necessary for windows on Java 8 where cmd has a limit to the size of a command

[rubin55]

Ok sure, but the intention can't be that the other command line utilities fail to run right? I suppose the scripts need to be adjusted so they construct a valid classpath or somesuch? Because at least scalac doesn't work like this.

[Gedochao]

I downloaded both the zip and tar.gz versions of scala-3.5.2 on the releases page.

Alright, so right there, downloading the artifacts manually is not a recommended way of installation.
@rubin55 You should be able to make things work with power user knowledge, sure.
So perhaps we miss documentation for this case, even if it's not recommended. (cc @hamzaremmal)

However, first things first.
Please refer to https://www.scala-lang.org/download/ and let us know if the recommended ways of installation work for you.
If you run into any issues, please give us more context on your setup.

Ok sure, but the intention can't be that the other command line utilities fail to run right? I suppose the scripts need to be adjusted so they construct a valid classpath or somesuch? Because at least scalac doesn't work like this.

I am suspecting you need to put the jars in the right directories for the scripts to be able to find them. The installer would normally do it for you.

Other than that, is there any reason why you'd download the artifacts manually?

EDIT: I did a quick check, downloaded scala3-3.5.2.zip and unpacked it locally.
Both bin/scala and bin/scalac scripts seem to work as expected.
@rubin55 how exactly did you invoke them to get the ClassNotFoundException?

[hamzaremmal]

@rubin55 What's the structure of the /usr/share/scala3 folder ? The paths mentionned stored in the Class-Path attribute are relative and therefore sensible to the layout of the /usr/share/scala3 structure.

[rubin55]

@Gedochao

Second option recommended installation: "Download release from GitHub".

For your information, I've been running Scala like this for years. Also note that 3.3.4, the latest LTS release still works correctly (just have a look at the lib subdirectory of any 3.3.4 artifact to understand why).

[rubin55]

@hamzaremmal @Gedochao

It's working now. I was using the AUR package which recently updated from LTS to latest; in the PKGBUILD the directories that need to end up in the /usr/share/scala3 directory are explicitly specified and was missing the maven2 directory. Sorry for the noise. TL;DR; downloadable artifacts work, got confused by the empty MANIFEST-only jars in lib, root-cause was missing maven2 directory.

[Gedochao]

Second option recommended installation: "Download release from GitHub".

Right... we do not recommend it on https://www.scala-lang.org/download/, but we do under a specific release, my bad.
We should fix it at some point, installing via a package manager should be considered the default.

TL;DR; downloadable artifacts work, got confused by the empty MANIFEST-only jars in lib, root-cause was missing maven2 directory.

FYI, the changes were introduced in Scala 3.5.0. I'm glad it works.
Seems like there's nothing to do in the scope of this issue, closing this as invalid.