scala - Intellij Idea 12 Ultimate 无法为 Scala 项目正确导入 pom

Question

我有一个项目我已经在 Idea 中使用了数周，没有任何问题。我添加了一个新的 maven 依赖项，即使使用 maven 重新导入运行、使缓存无效等，它也无法找到其中的类。所以，我通过重新导入 pom 重新开始 - 但现在它找不到任何Scala 符号，甚至是自动导入的 Scala 符号。我已经尝试了多次，结果相同。这是有问题的pom（更改了一些细节）：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.aa</groupId>
    <artifactId>test-project</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <!-- Explicitly declaring the source encoding eliminates the following message: -->
        <!-- [WARNING] Using platform encoding (UTF-8 actually) to copy filtered
            resources, i.e. build is platform dependent! -->
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

        <compiler.plugin.version>2.3.1</compiler.plugin.version>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
    </properties>

    <dependencies>
        <!-- Scala -->
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.10.1</version>
        </dependency>
        <dependency>
            <groupId>org.scalatest</groupId>
            <artifactId>scalatest_2.10.0</artifactId>
            <version>2.0.M5</version>
        </dependency>

        <!-- Akka -->
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-actor_2.10</artifactId>
            <version>2.1.2</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-remote_2.10</artifactId>
            <version>2.1.2</version>
        </dependency>
        <dependency>
            <groupId>com.typesafe.akka</groupId>
            <artifactId>akka-kernel_2.10</artifactId>
            <version>2.1.2</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.scala-tools</groupId>
                <artifactId>maven-scala-plugin</artifactId>
                <executions>
                    <execution>
                        <id>compile</id>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                        <phase>compile</phase>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                        <phase>test-compile</phase>
                    </execution>
                    <execution>
                        <phase>process-resources</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.scalastyle</groupId>
                <artifactId>scalastyle-maven-plugin</artifactId>
                <version>0.2.0</version>
                <configuration>
                    <verbose>false</verbose>
                    <failOnViolation>true</failOnViolation>
                    <includeTestSourceDirectory>true</includeTestSourceDirectory>
                    <failOnWarning>false</failOnWarning>
                    <sourceDirectory>${basedir}/src/main/scala</sourceDirectory>
                    <testSourceDirectory>${basedir}/src/test/scala</testSourceDirectory>
                    <configLocation>${basedir}/src/main/resources/scalastyle_config.xml</configLocation>
                    <outputFile>${project.basedir}/scalastyle-output.xml</outputFile>
                    <outputEncoding>UTF-8</outputEncoding>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>check</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${compiler.plugin.version}</version>
                <configuration>
                    <source>${maven.compiler.source}</source>
                    <target>${maven.compiler.target}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

我已经为此奋斗了一个小时，现在我已经束手无策了。它从命令行构建得很好。但是，再一次，Idea 中没有构建任何东西——它甚至看不到 scala.predef 等中的符号。

为模块启用 Scala 方面也没有任何区别。

我没有发现任何类似问题的报告，所以也许我真的错过了一些东西。