Fails to index a newly generated (g8) project

[umatrangolo]

Hi,

I'm struggling with Metals on emacs/lsp-mode/eglot.

Starting from a simple project created with sbt new http4s/http4s.g8 --branch 1.0-scala3 and just updating the Scala version with:

diff --git a/build.sbt b/build.sbt
index 79b45fa..48d5529 100644
--- a/build.sbt
+++ b/build.sbt
@@ -8,7 +8,7 @@ lazy val root = (project in file("."))
     organization := "com.example",
     name := "quickstart",
     version := "0.0.1-SNAPSHOT",
-    scalaVersion := "3.1.0",
+    scalaVersion := "3.6.2",
     libraryDependencies ++= Seq(
       "org.http4s"      %% "http4s-ember-server" % Http4sVersion,
       "org.http4s"      %% "http4s-ember-client" % Http4sVersion,

I can't have metals working correctly in this project (using either eglot or lsp-mode) while it works perfectly in VS Code.

As soon I run emacs on the Main.scala file (never touched, auto generated by the g8 template) it fails to recognise all the imports:

Not found: cats - did you mean caps? [6]

The same source code gets compiled by both SBT and Bloop.

This is what I can see from metals.log:

2024.12.28 11:35:01 INFO  Started: Metals version 1.4.1 in folders '/Users/umatrangolo/Development/incubator/http4s/quickstart, /Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example, /Users/umatrangolo/Development/incubator/cats-effect-playground, /Users/umatrangolo/Development/incubator/http4s/quickstart/src/main/scala/com/example/quickstart' for client emacs GNU Emacs 30.0.93 (build 2, aarch64-apple-darwin24.2.0, NS appkit-2575.30 Version 15.2 (Build 24C101))
 of 2024-12-24.

2024.12.28 11:35:03 INFO  Connected to Build server: Bloop v2.0.5

2024.12.28 11:40:02 ERROR Running process '/opt/homebrew/Cellar/scala/3.5.2/libexec/bin/scala-cli.jar --cli-default-scala-version 3.5.2 --repository file:///opt/homebrew/Cellar/scala/3.5.2/libexec/maven2 --prog-name scala bsp --json-options /Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example/.scala-build/ide-options-v2.json --json-launcher-options /Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example/.scala-build/ide-launcher-options.json --envs-file /Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example/.scala-build/ide-envs.json /Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example' failed
java.io.IOException: Cannot run program "/opt/homebrew/Cellar/scala/3.5.2/libexec/bin/scala-cli.jar" (in directory "/Users/umatrangolo/Development/incubator/cats-effect-playground/src/main/scala/com/example"): error=2, No such file or directory
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1143)
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1073)
        at scala.meta.internal.process.SystemProcess$.run(SystemProcess.scala:48)
        at scala.meta.internal.bsp.BspServers.newConnection$1(BspServers.scala:118)
        at scala.meta.internal.bsp.BspServers.$anonfun$newServer$8(BspServers.scala:161)
        at scala.meta.internal.metals.BuildServerConnection$.setupServer$1(BuildServerConnection.scala:600)
        at scala.meta.internal.metals.BuildServerConnection$.fromSockets(BuildServerConnection.scala:668)
        at scala.meta.internal.metals.BuildServerConnection$$anonfun$fromSockets$17.applyOrElse(BuildServerConnection.scala:685)
        at scala.meta.internal.metals.BuildServerConnection$$anonfun$fromSockets$17.applyOrElse(BuildServerConnection.scala:682)
        at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:490)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.lang.Thread.run(Thread.java:840)
Caused by: java.io.IOException: error=2, No such file or directory
        at java.lang.ProcessImpl.forkAndExec(Native Method)
        at java.lang.ProcessImpl.<init>(ProcessImpl.java:314)
        at java.lang.ProcessImpl.start(ProcessImpl.java:244)
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1110)
        at java.lang.ProcessBuilder.start(ProcessBuilder.java:1073)
        at scala.meta.internal.process.SystemProcess$.run(SystemProcess.scala:48)
        at scala.meta.internal.bsp.BspServers.newConnection$1(BspServers.scala:118)
        at scala.meta.internal.bsp.BspServers.$anonfun$newServer$8(BspServers.scala:161)
        at scala.meta.internal.metals.BuildServerConnection$.setupServer$1(BuildServerConnection.scala:600)
        at scala.meta.internal.metals.BuildServerConnection$.fromSockets(BuildServerConnection.scala:668)
        at scala.meta.internal.metals.BuildServerConnection$$anonfun$fromSockets$17.applyOrElse(BuildServerConnection.scala:685)
        at scala.meta.internal.metals.BuildServerConnection$$anonfun$fromSockets$17.applyOrElse(BuildServerConnection.scala:682)
        at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:490)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.lang.Thread.run(Thread.java:840)

that ends up in:

2024.12.28 11:41:02 ERROR Timeout waiting for 'build/initialize' response
2024.12.28 11:41:02 ERROR Failed to connect with build server, no functionality will work.
java.util.concurrent.TimeoutException
        at java.util.concurrent.CompletableFuture.timedGet(CompletableFuture.java:1960)
        at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2095)
        at scala.meta.internal.metals.BuildServerConnection$.initialize(BuildServerConnection.scala:753)
        at scala.meta.internal.metals.BuildServerConnection$.$anonfun$fromSockets$1(BuildServerConnection.scala:626)
        at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:467)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.lang.Thread.run(Thread.java:840)

I have no scala 3.5.2 installed (currently I have installed 3.6.2) and I have no idea from where it comes from.

I believe that is some sort of misconfiguration that makes metals fail to work correctly with bloop/bsp but I can't pin point the source of it.

Wondering if anyone knows what is going on here :)

metals.log.zip

[tgodzik]

I think there are two issues:

• you are starting metals for a single file, which will not have a proper claspath
• we are detecting scala-cli jar, which is not actually runnable, to use for that single file
  We should fix the latter, but not sure how to start a workspace in emacs

[umatrangolo]

Answering myself for when I will stumble again into this pit.

The 'eglot' LSP client needs to know which files are part of the current project. To do so it uses the Emacs native backend that is going to look either for (i) an EDE setup or (ii) a GIT repository. Missing both of them, 'eglot' is blind and will just start a new LSP session for each visited folder resulting in odd errors like disappearing dependencies from a previously loaded class path (as per my issue).

To avoid these issues, remember to always create a proper GIT setup for any new Scala project.