sbt 0.12.4 -有x个特性警告；详细信息请与-feature一起重新运行

Question

我得到一个错误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
[info] Set current project to sbt-android (in build file:/home/alex/Documents/projects/my_app123/)

> compile -feature
[error] Expected end of input.
[error] compile -feature
[error]        ^

> sbt-version
[info] 0.12.4

> compile 
[warn] Credentials file /home/alex/.ivy2/.credentials does not exist
[info] Compiling 20 Scala sources to /home/alex/Documents/projects/my_app123/target/scala-2.10/sbt-0.12/classes...
[error] there were 15 feature warning(s); re-run with -feature for details
[error] one error found
[error] (compile:compile) Compilation failed
[error] Total time: 27 s, completed 01 12, 15 1:20:12 PM

在build.sbt

scalaVersion := "2.10.4"

我找不出这个错误是什么，因为它没有这么说，即使我以$ /usr/local/sbt/bin/sbt -feature的形式运行sbt。

$ /usr/local/sbt/bin/sbt -feature
[info] Loading project definition from /home/alex/Documents/projects/my_app123/project
[info] Set current project to sbt-android (in build file:/home/alex/Documents/projects/my_app123/)
$

是JDK 1.7

错误是什么?我如何修复它？

更新

build.sbt

scalacOptions in ThisBuild ++= Seq("-unchecked", "-deprecation")

或在sbt本身：

> set scalacOptions in ThisBuild ++= Seq("-unchecked", "-deprecation")

错误保持不变。

Answer 1

我没有机会每天使用sbt，所以这只是为了确认链接答案中的建议：

$ sbt
[info] Set current project to Compiler options (in build file:/home/apm/tmp/sbtwarn/)
> compile
[info] Compiling 1 Scala source to /home/apm/tmp/sbtwarn/target/scala-2.11/classes...
[warn] there was one feature warning; re-run with -feature for details
[warn] one warning found
[success] Total time: 4 s, completed Jan 12, 2015 9:45:17 AM
> set scalacOptions in ThisBuild ++= Seq("-feature")
[info] Defining {.}/*:scalacOptions
[info] The new value will be used by compile:scalacOptions
[info] Reapplying settings...
[info] Set current project to Compiler options (in build file:/home/apm/tmp/sbtwarn/)
> compile
[info] Compiling 1 Scala source to /home/apm/tmp/sbtwarn/target/scala-2.11/classes...
[warn] /home/apm/tmp/sbtwarn/src/main/scala/Sample.scala:6: postfix operator head should be enabled
[warn] by making the implicit value scala.language.postfixOps visible.
[warn] This can be achieved by adding the import clause 'import scala.language.postfixOps'
[warn] or by setting the compiler option -language:postfixOps.
[warn] See the Scala docs for value scala.language.postfixOps for a discussion
[warn] why the feature should be explicitly enabled.
[warn]   Console println (List(1,2,3) head)
[warn]                                ^
[warn] one warning found
[success] Total time: 1 s, completed Jan 12, 2015 9:45:46 AM

嘿，成功了！

Answer 2

你应该加上

scalacOptions += "-feature"

如果您的sbt控制台正在运行(或重新启动)，则执行build.sbt。

或者，如果您只想为单个会话设置它，而在sbt控制台中，您可以编写set scalacOptions += "-feature"，此设置将立即应用，不需要重新加载或重新启动sbt控制台。

Re-run with -feature for details