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TLDR; IntelliJ isn't highlighting any errors (syntax/type mismatch) in my Scala project. I've tried type-aware highlighting, setting highlighting level to "Inspections", and enabling "Experimental Features" according to StackOverflow answers, and reloading the project.

I have a Scala 2.13 project (sbt) that was working just fine in IntelliJ 2019.3. I made some changes after that (I did not check to see if it compiled, and it had several errors in it) and then I decided to port it to Dotty (and also updated IntelliJ to 2020.1 EAP). I created a new Dotty project, which obviously had no errors.

I then copied all my source files to this project and modified the build.sbt file. When I did this, I could see a few syntax errors highlighted, and the given keyword was not detected as a keyword, most likely because the plugin thought the language was supposed to be Scala 2, not Scala 3.

After that, I imported the project from sbt, and the wrong syntax errors disappeared, so I happily closed that file and started fixing the others. I'm not sure if error highlighting was working at first and then turned off, or if it never worked. After a while, I realized that unresolved references weren't highlighted - for example, when I mispelled a class name and tried to go to the declaration, it didn't do anything, although when I corrected it, it could resolve the reference, presumably because that was one of the files that had no errors. Then I saw that syntax errors weren't recognized either.

I have type-aware highlighting enabled, and the highlighting level is set to inspections. I am using IntelliJ 2020.1 EAP with Scala plugin build 2020.1.977 (EAP). The build.sbt contains scala version "0.23.0-RC1". IntelliJ wasn't running any other processes, and there weren't any resource-intensive programs on my computer at the time.

I got multiple error messages at the bottom right, such as

  • java.lang.AssertionError: assertion failed (A couple times)

  • com.intellij.psi.PsiInvalidElementAccessException: Element: class org.jetbrains.plugins.scala.lang.psi.impl.statements.params.ScTypeParamImpl #Scala because: different providers: org.jetbrains.plugins.scala.lang.psi.ScFileViewProvider{vFile=file:<The path>/Pattern.scala, content=VirtualFileContent{size=1716}, eventSystemEnabled=true}(a24437); org.jetbrains.plugins.scala.lang.psi.ScFileViewProvider{vFile=file:<Same path>/Pattern.scala, content=VirtualFileContent{size=1716}, eventSystemEnabled=true}(b39181a) invalidated at (This one came up several times)

I have a feeling this is just a bug with Dotty that will be resolved soon. The Scala Nightly plugin had similar behavior, which is why I switched to EAP and also created an entirely new project, which I assumed would be less buggy. Any suggestions would be really appreciated.

The same thing is happening with my old Scala 2 project also when I open it in IntelliJ 2020.1 EAP but not in 2019.3. It now seems it's not a Dotty-specific thing.

stefanobaghino
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user
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2 Answers2

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Dotty oficialy is not supported yet because its syntax is not frozen, a thing like optional braces is being changed now. The only place where everything works relatively fine is an official vscode, and it used by compiler devs. So, if you want to play with dotty, a vscode and all the env probably would be your choice: https://dotty.epfl.ch/docs/usage/ide-support.html

Iva Kam
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    Thanks, it's just that VSCode requires you to compile with sbt before loading the project, and my project isn't compiling. – user Apr 01 '20 at 13:24
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    Try to comment out most of the code then sbt run ide, and uncomment part by part to see which part of code is the cause of error. – Iva Kam Apr 01 '20 at 13:29
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As of IntelliJ Scala Plugin 2020.1 Scala 3/dotty is getting support

The Scala plugin now includes preliminary support for Scala 3: the new syntax, error highlighting, navigation, type info, and many other bread-and-butter IDE features.

Because both the language and the language support are still works in progress, we recommend using plugin nightly builds if you want to get new features and bug fixes as quickly as possible.

More details can be found in the IntelliJ Scala Plugin Blog

Community
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Muhammad Farag
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  • I read that, and I was using the nightly plugin with IntelliJ 2020.1. Whatever it was, it’s stopped happening now after I updated the plugin once, and everything is working fine, so I’m not going to update my plugin for a while lest it break again – user Apr 21 '20 at 13:12