How can I find all of the flags for the latest scalac version? After googling for hours I have found only outdated docs. (for example, they don't even mention "-feature" flag). Is there any way to...

Currently, the dotty compiler released its first Release Candidate and will be released in the next few months. I updated the IntelliJ scala plugin to EarlyAccess to make it working with Scala 3.0,...

I want to be able to use -Xfatal-warnings and -Ywarn-unused-import, the problem is that the compiler is triggering an error on the file which contains the play routes for my application: [error] /...

I have been stuck on this issue for a week and don't seem to be getting anywhere. I am trying to copy some methods and fields from one class to another. I have two phases that are involved in this....

So I have a jar file that contains scala as the source code and I have lost the original code. Is there a way to convert the class files in the jar to scala functions and classes instead of the jav...

Assuming that A class called 'summoner' was defined, that is capable of summoning implicit views from the scope: case class Summoner[R]() { def summon[T](v: T)(implicit ev: T => R): R = ev(v)...

I have a custom class, A, and I have defined some operations within the class as follows: def +(that: A) = ... def -(that: A) = ... def *(that: A) = ... def +(that: Double) = ... def -(that: Doub...

I'm trying to use the java jcommander library from Scala. The java JCommander class has multiple constructors: public JCommander(Object object) public JCommander(Object object, ResourceBundle ...

I want to sharpen my picture of the phases of scala compilation. I know that certain things have to happen in the compiler, but don't really know the order in which they happen and how the order sh...

Running w/ a simple SBT project w/ Java 7 (details below) and invoking sbt run at the command line (no IntelliJ or anything) source import scala.tools.nsc.{ Global, Settings } object Playground ...

Consider the following class: package test class Test { def main(args: Array[String]): Unit = { val i: Int = 0 println(i) } } The bytecode of main is: public main([Ljava/lang/String;)V // ...

I'm new to Scala, and I've never written or compiled a program in it before. I'm trying to simply run the following Hello World example, which I have saved in a file name scalaApp.scala object sca...

I get an error there were 15 feature warning(s); re-run with -feature for details : $ /usr/local/sbt/bin/sbt [info] Loading project definition from /home/alex/Documents/projects/my_app123/project...

I've got a project that isn't a crazy number of lines of code, but its compilation time is really long on a clean compile. I have the feeling there are some hotspots, but I don't know how to find t...

I am trying to call sbt assembly from the command line passing it a scalac compiler flag to elides (elide-below 1). I have managed to get the flag working in the build.sbt by adding this line to t...

I have written some implicit code as shown below, and I am wondering why the i2d function implicit conversation isn't invoked. object Test { implicit def i2d(x: Int): Double = { println("foo") ...

I was reading this question and saw: scalac includes an 8-bit simulator of a fully armed and operational battle station, viewable using the magic key combination CTRL-ALT-F12 during the GenICode...

I am trying to add a library dependency through an sbt plugin. The dependency should be added to each sub-project per its binary scala version, so I iterate through each subproject. private def i...

Does the scala compiler optimize for memory usage by removing refs to vals used only once within a block? Imagine an object holding in aggregate some huge data - reaching a size where cloning dat...

When I'm doing sbt compile -feature on my Scala project I get a mysterious warnings: The `-` command is deprecated in favor of `onFailure` and will be removed in 0.14.0 I have no clue what that ...

I am in the process of upgrading a large project to 2.10.4 to 2.11.4. I have gotten a compiler crash, is there anyway to display the name of source file that is causing the crash? I am able to get ...

I would like to extract from a given Scala project, the call graph of all methods which are part of the project's own source. As I understand, the presentation compiler doesn't enable that, and it...

When decompiling Scala files to Java code, one often comes across classes that are annotated with the ScalaSignatures. These seem to only have one annotation value, a somewhat encoded String. Why d...

WartRemover is a scalac plugin. Typically it is configured via an sbt plugin. I'd like to be able to run WartRemover on my sbt project as a separate configuration or task without affecting the usu...

I recently noticed Scala compiler warnings that maven was generating that looked like this: [WARNING] warning: there were 4 deprecation warning(s); re-run with -deprecation for details [WARNING] ...