Question

the only way I’ve found to have maven compile scala sources on the command line using mvn is to add the executions explicitly in the scala-maven-plugin.

  <plugin>
    <groupId>net.alchim31.maven</groupId>
    <artifactId>scala-maven-plugin</artifactId>
    <version>3.0.1</version>
    <executions>
      <execution>
        <goals>
          <goal>compile</goal>
          <goal>testCompile</goal>
        </goals>
      </execution>
    </executions>
    <configuration>
      <args>
        <arg>-deprecation</arg>
        <arg>-unchecked</arg>
      </args>
      <jvmArgs>
        <jvmArg>-Xms128m</jvmArg>
        <jvmArg>-Xmx1024m</jvmArg>
      </jvmArgs>
    </configuration>
  </plugin>

However, Eclipse does not like these executions and gives the following errors.

Plugin execution not covered by lifecycle configuration: net.alchim31.maven:scala-maven-plugin:3.0.1:compile (execution: default, phase: compile)

Plugin execution not covered by lifecycle configuration: net.alchim31.maven:scala-maven-plugin:3.0.1:testCompile (execution: default, phase: test-compile)

Eclipse suggests permanently marking the goals as ignored, but this means a lot of ugly garbage is added to my pom. I mean, XML is already hard to look at. Is there a better way to configure my project to compile the sources with mvn? Following is what Eclipse adds.

<pluginManagement>
        <plugins>
            <!--This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself.-->
            <plugin>
                <groupId>org.eclipse.m2e</groupId>
                <artifactId>lifecycle-mapping</artifactId>
                <version>1.0.0</version>
                <configuration>
                    <lifecycleMappingMetadata>
                        <pluginExecutions>
                            <pluginExecution>
                                <pluginExecutionFilter>
                                    <groupId>
                                        net.alchim31.maven
                                    </groupId>
                                    <artifactId>
                                        scala-maven-plugin
                                    </artifactId>
                                    <versionRange>
                                        [3.0.1,)
                                    </versionRange>
                                    <goals>
                                        <goal>testCompile</goal>
                                        <goal>compile</goal>
                                    </goals>
                                </pluginExecutionFilter>
                                <action>
                                    <ignore></ignore>
                                </action>
                            </pluginExecution>
                        </pluginExecutions>
                    </lifecycleMappingMetadata>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>

Answer 1

m2e requires you install specific m2e plugins.
The one for scala-maven-plugin is m2e-scala: https://github.com/sonatype/m2eclipse-scala

Remove the pluginManagement that disables scala-maven-plugin, and install m2e-scala
http://alchim31.free.fr/m2e-scala/update-site

BTW, latest scala-maven-plugin is 3.1.0, not 3.0.1.

Cheers,

Stéphane