为什么crossScalaVersion不是scalaVersion

Question

build.sbt

scalaVersion := "2.11.4"

项目/生成属性

sbt.version=0.13.7

然后

> show scalaVersion
[info] 2.11.4
> show crossScalaVersions
[info] List(2.10.4)
> inspect crossScalaVersions
[info] Setting: scala.collection.Seq[java.lang.String] = List(2.10.4)
[info] Description:
[info]  The versions of Scala used when cross-building.
[info] Provided by:
[info]  */*:crossScalaVersions
[info] Defined at:
[info]  (sbt.Defaults) Defaults.scala:237
[info] Delegates:
[info]  *:crossScalaVersions
[info]  {.}/*:crossScalaVersions
[info]  */*:crossScalaVersions
[info] Related:
[info]  */*:crossScalaVersions

似乎crossScalaVersions应该List(2.11.4).

看看SBT的源代码，这也是我的想法。

crossScalaVersions := Seq(scalaVersion.value)

为什么crossScalaVersions不符合scalaVersion？

Answer 1

scalaVersion.value是

上下文相关的。所以在Defaults.scala中，它与appConfiguration.value.provider.scalaProvider */*:scalaVersion.它是用于编译项目定义的版本，包括build.sbt文件（sbt 0.13.7使用 2.10.4 scala 编译器来编译项目定义）。并且，作为项目定义（包括scalaVersion）的唯一方法尚未编译，Defaults执行和定义crossScalaVersions。所以，*/*:crossScalaVersions取决于*/*:scalaVersion而不是proj/*:scalaVersion.

只需将Provided by与build.sbt中的显式scalaVersion := 2.11.4进行比较：

> inspect scalaVersion
[info] Setting: java.lang.String = 2.11.4
[info] Description:
[info]  The version of Scala used for building.
[info] Provided by:
[info]  {file:/Users/user/dev/proj/}proj/*:scalaVersion
[info] Defined at:
[info]  /Users/user/dev/proj/build.sbt:1
[info] Reverse dependencies (D=derives):
[info]    *:allDependencies
[info]  D *:scalaBinaryVersion
[info]    *:libraryDependencies
[info]    *:scalaInstance
[info]    *:crossScalaVersions
[info]    *:update
[info] Delegates:
[info]  *:scalaVersion
[info]  {.}/*:scalaVersion
[info]  */*:scalaVersion
[info] Related:
[info]  */*:scalaVersion

并且没有一个（只是空项目）：

> inspect scalaVersion
[info] Setting: java.lang.String = 2.10.4
[info] Description:
[info]  The version of Scala used for building.
[info] Provided by:
[info]  */*:scalaVersion
[info] Defined at:
[info]  (sbt.Defaults) Defaults.scala:232
[info] Reverse dependencies:
[info]  *:allDependencies
[info]  *:libraryDependencies
[info]  *:update
[info]  *:scalaInstance
[info] Delegates:
[info]  *:scalaVersion
[info]  {.}/*:scalaVersion
[info]  */*:scalaVersion
[info] Related:
[info]  */*:scalaVersion

因此，您只需要在build.sbt中重新定义*/*:scalaVersion：

scalaVersion in GlobalScope := "2.11.2"