How to configure metals to work with a project that uses scala 2.12.11 and JDK 1.8?

[antonoal]

Hi
I've got a few legacy projects that can't be upgraded for the time being to the later versions of scala and JDK.
When I try to import such a project in vscode I get this error:

Stopped configuration of Scala SemanticDB in 2.12.15 projects: Error downloading org.scalameta:semanticdb-scalac_2.12.15:4.9.7 not found: /Users/alex/.ivy2/local/org.scalameta/semanticdb-scalac_2.12.15/4.9.7/ivys/ivy.xml not found: <company-maven-mirror-url>/maven-release/org/scalameta/semanticdb-scalac_2.12.15/4.9.7/semanticdb-scalac_2.12.15-4.9.7.pom After retry no existing semanticdb version found for scala version 2.12.15

This is what I get when I set java home to openjdk 17 before opening vscode. If I set it to jdk1.8 metals wouldn't start at all throwing this:

Metals version: 1.3.3
Using coursier located at /Users/alex/.metals/cs
Checking Java in JAVA_HOME, which points to /Users/alex/jdk/OpenJDK8U-jdk_x64_mac_hotspot_8u352b08
	openjdk version "1.8.0_352"
	OpenJDK Runtime Environment (Temurin)(build 1.8.0_352-b08)
	OpenJDK 64-Bit Server VM (Temurin)(build 25.352-b08, mixed mode)
Java version doesn't match the required one of 17

How do I configure metals to work with this project of mine?

Thanks
Alex

[kasiaMarek]

If I set it to jdk1.8 metals wouldn't start.

It should still start with JDK downloaded by coursier. You can set java home for your project in settings Metals: Java Home to point to Java 8. Here are docs on that: https://scalameta.org/metals/docs/editors/vscode#configure-java-version

[tgodzik]

For Java you just need to set metals.javaHome to the JDK you want to use and it should correctly compile with that version in mind.

As for semanticdb, this might be an issue on our side. I will take a look.

[antonoal]

I can't even make now work other projects that use scala 2.12.15 with metals. So I took that minimal project that I posted the pom of above and set it to use jdk17 and I'm getting the same errors in metals doctor as in the table above plus during import metals seems to be trying to pull a non-existent version of semanticsDb from maven:

2024.07.22 15:35:07 WARN  Stopped configuration of Scala SemanticDB in 2.12.15 projects: Error downloading org.scalameta:semanticdb-scalac_2.12.15:4.9.7
  not found: /Users/alex/.ivy2/local/org.scalameta/semanticdb-scalac_2.12.15/4.9.7/ivys/ivy.xml
  not found: https://internal-maven-mirror/maven-release/org/scalameta/semanticdb-scalac_2.12.15/4.9.7/semanticdb-scalac_2.12.15-4.9.7.pom
After retry no existing semanticdb version found for scala version 2.12.15

When I check public maven there's no version 4.9.7 for scala 2.12.15.

[tgodzik]

Och, I might know what is going on:

https://github.com/scalacenter/bloop/blob/main/frontend/src/main/scala/bloop/engine/caches/SemanticDBCache.scala#L76

This part might not be working with the proxy, we use coursier to find last supported plugin version for that specific Scala version. My guess is that it doesn't really work with a proxy.

A workaround for now would be to upgrade to newer 2.12.x version.

[antonoal]

I’m afraid upgrading scala version is not an option for me.

I could downgrade metals plugin version if that helps, or download by hand required semanticsDb dependency again if that can possibly help.

Just to clarify, I’ve got a coursier mirror defined.

Could any of those workarounds work?

[tgodzik]

I don't think any of those workaround aside from using older Metals version would work. I need to figure out how to fix it in Bloop itself.

[tgodzik]

I am also doing another fallback here scalacenter/bloop#2388