如何修复idea IDE中关于sbt的错误？

Question

在sbt的idea IDE中遇到一个奇怪的错误，合并策略如下，

mergeStrategy in assembly <<= (mergeStrategy in assembly) { (old) =>
  {
    case m if m.toLowerCase.endsWith("manifest.mf") => MergeStrategy.discard
    case m if m.startsWith("META-INF") => MergeStrategy.discard
    case PathList("javax", "servlet", xs @ _*) => MergeStrategy.first
    case PathList("org", "apache", xs @ _*) => MergeStrategy.first
    case PathList("org", "jboss", xs @ _*) => MergeStrategy.first
    case "about.html"  => MergeStrategy.rename
    case "reference.conf" => MergeStrategy.concat
    case _ => MergeStrategy.first
  }
}

看起来不错，但不幸的是，IDE 报错了一个错误，它是

Cannot resolve reference <<= with such signature
Type mismatch,expected:Def.Initialize[(String) => Plugin.MergeStrategy],  
actual:Def.Initialize[Any].

任何人都可以向我解释这一点以及如何解决这个问题？

Answer 1

不推荐使用mergeStrategy （和<<=运算符）。 使用assemblyMergeStrategy代替：

assemblyMergeStrategy in assembly := {
  case m if m.toLowerCase.endsWith("manifest.mf") => MergeStrategy.discard
  case m if m.startsWith("META-INF") => MergeStrategy.discard
  case PathList("javax", "servlet", xs@_*) => MergeStrategy.first
  case PathList("org", "apache", xs@_*) => MergeStrategy.first
  case PathList("org", "jboss", xs@_*) => MergeStrategy.first
  case "about.html" => MergeStrategy.rename
  case "reference.conf" => MergeStrategy.concat
  case s => MergeStrategy.defaultMergeStrategy(s)
}