rewrite mill build scripts for chisel5.

This PR cleaned up the old build script, split it to common.sc and
builds.sc two files. common.sc is used for declare the dependencies and
project structual for each modules, which can be reused by other
projects for building from source. build.sc is used for build project in
tree.
This commit makes chisel3['2.13.10'] being able to compile.

build.sc

@@ -1,221 +1,148 @@
 import mill._
 import mill.scalalib._
+import mill.scalalib.TestModule._
 import mill.scalalib.publish._
 import mill.scalalib.scalafmt._
 import coursier.maven.MavenRepository
-import $ivy.`com.lihaoyi::mill-contrib-buildinfo:$MILL_VERSION`
-import mill.contrib.buildinfo.BuildInfo
-
-object chisel3 extends mill.Cross[chisel3CrossModule]("2.13.10", "2.12.17")
-
-// The following stanza is searched for and used when preparing releases.
-// Please retain it.
-// Provide a managed dependency on X if -DXVersion="" is supplied on the command line.
-val defaultVersions = Map(
-  "firrtl" -> "1.6-SNAPSHOT",
-)
-
-def getVersion(dep: String, org: String = "edu.berkeley.cs") = {
-  val version = sys.env.getOrElse(dep + "Version", defaultVersions(dep))
-  ivy"$org::$dep:$version"
-}
-// Do not remove the above logic, it is needed by the release automation
+import $file.common
 
 object v {
-  val firrtl = getVersion("firrtl")
-  val chiseltest = ivy"edu.berkeley.cs::chiseltest:0.6-SNAPSHOT"
-  val scalatest = ivy"org.scalatest::scalatest:3.2.15"
-  val scalacheck = ivy"org.scalatestplus::scalacheck-1-14:3.2.2.0"
+  val pluginScalaCrossVersions = Seq(
+    // scalamacros paradise version used is not published for 2.12.0 and 2.12.1
+    "2.12.2",
+    "2.12.3",
+    // 2.12.4 is broken in newer versions of Zinc: https://github.com/sbt/sbt/issues/6838
+    "2.12.5",
+    "2.12.6",
+    "2.12.7",
+    "2.12.8",
+    "2.12.9",
+    "2.12.10",
+    "2.12.11",
+    "2.12.12",
+    "2.12.13",
+    "2.12.14",
+    "2.12.15",
+    "2.12.16",
+    "2.12.17",
+    "2.13.0",
+    "2.13.1",
+    "2.13.2",
+    "2.13.3",
+    "2.13.4",
+    "2.13.5",
+    "2.13.6",
+    "2.13.7",
+    "2.13.8",
+    "2.13.9",
+    "2.13.10"
+  )
+  val scalaCrossVersions = Seq(
+    "2.12.17",
+    "2.13.10"
+  )
   val osLib = ivy"com.lihaoyi::os-lib:0.8.1"
   val upickle = ivy"com.lihaoyi::upickle:2.0.0"
   val macroParadise = ivy"org.scalamacros:::paradise:2.1.1"
-}
-
-// Since chisel contains submodule core and macros, a CommonModule is needed
-trait CommonModule extends CrossSbtModule with PublishModule with ScalafmtModule {
-  def firrtlModule: Option[PublishModule] = None
-
-  def firrtlIvyDeps = if (firrtlModule.isEmpty)
-    Agg(
-      v.firrtl
-    )
-  else Agg.empty[Dep]
-
-  def chiseltestModule: Option[PublishModule] = None
-
-  def chiseltestIvyDeps = if (chiseltestModule.isEmpty)
-    Agg(
-      v.chiseltest
-    )
-  else Agg.empty[Dep]
-
-  override def moduleDeps = super.moduleDeps ++ firrtlModule
-
-  override def ivyDeps = super.ivyDeps() ++ Agg(
-    v.osLib,
-    v.upickle
-  ) ++ firrtlIvyDeps
-
-  def publishVersion = "3.6-SNAPSHOT"
+  val scalatest = ivy"org.scalatest::scalatest:3.2.15"
+  val scalacheck = ivy"org.scalatestplus::scalacheck-1-14:3.2.2.0"
+  val json4s = ivy"org.json4s::json4s-native:4.0.6"
+  val dataclass = ivy"io.github.alexarchambault::data-class:0.2.5"
+  val commonText = ivy"org.apache.commons:commons-text:1.10.0"
+  val scopt = ivy"com.github.scopt::scopt:3.7.1"
 
-  // 2.12.10 -> Array("2", "12", "10") -> "12" -> 12
-  protected def majorVersion = crossScalaVersion.split('.')(1).toInt
+  def scalaReflect(scalaVersion: String) = ivy"org.scala-lang:scala-reflect:$scalaVersion"
 
-  override def repositories = super.repositories ++ Seq(
-    MavenRepository("https://oss.sonatype.org/content/repositories/snapshots"),
-    MavenRepository("https://oss.sonatype.org/content/repositories/releases")
-  )
+  def scalaCompiler(scalaVersion: String) = ivy"org.scala-lang:scala-compiler:$scalaVersion"
 
-  override def scalacOptions = T {
-    super.scalacOptions() ++ Agg(
-      "-deprecation",
-      "-feature"
-    ) ++ (if (majorVersion == 13) Agg("-Ymacro-annotations") else Agg.empty[String])
-  }
-
-  override def compileIvyDeps = if (majorVersion == 13) super.compileIvyDeps else Agg(v.macroParadise)
-
-  override def scalacPluginIvyDeps = if (majorVersion == 13) super.compileIvyDeps else Agg(v.macroParadise)
-
-  def pomSettings = PomSettings(
-    description = artifactName(),
-    organization = "edu.berkeley.cs",
-    url = "https://www.chisel-lang.org",
-    licenses = Seq(License.`Apache-2.0`),
-    versionControl = VersionControl.github("freechipsproject", "chisel3"),
-    developers = Seq(
-      Developer("jackbackrack", "Jonathan Bachrach", "https://eecs.berkeley.edu/~jrb/")
-    )
-  )
+  def scalaLibrary(scalaVersion: String) = ivy"org.scala-lang:scala-library:$scalaVersion"
 }
+private def majorScalaVersion(scalaVersion: String) = scalaVersion.split('.')(1).toInt
 
-class chisel3CrossModule(val crossScalaVersion: String) extends CommonModule with BuildInfo {
-  m =>
-
-  /** Default behavior assumes `build.sc` in the upper path of `src`.
-    * This override makes `src` folder stay with `build.sc` in the same directory,
-    * If chisel3 is used as a sub-project, [[millSourcePath]] should be overridden to the folder where `src` located.
-    */
-  override def millSourcePath = super.millSourcePath / os.up
-
-  override def mainClass = T {
-    Some("chisel3.stage.ChiselMain")
-  }
-
-  override def moduleDeps = super.moduleDeps ++ Seq(macros, core)
-
-  override def scalacPluginClasspath = T {
-    super.scalacPluginClasspath() ++ Agg(
-      plugin.jar()
-    )
-  }
-
-  override def scalacOptions = T {
-    super.scalacOptions() ++ Agg(s"-Xplugin:${plugin.jar().path}")
-  }
+object firrtl extends mill.Cross[firrtl](v.scalaCrossVersions: _*)
 
-  object stdlib extends CommonModule {
-    override def moduleDeps = super.moduleDeps ++ Agg(m)
+class firrtl(val crossScalaVersion: String)
+  extends common.FirrtlModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  def macroParadiseIvy: Option[Dep] = if (majorScalaVersion(crossScalaVersion) < 13) Some(v.macroParadise) else None
 
-    override def millSourcePath = m.millSourcePath / "stdlib"
+  def osLibModuleIvy = v.osLib
 
-    override def crossScalaVersion = m.crossScalaVersion
+  def json4sIvy = v.json4s
 
-    override def scalacPluginClasspath = T { m.scalacPluginClasspath() }
-  }
+  def dataclassIvy = v.dataclass
 
-  object test extends Tests with TestModule.ScalaTest with ScalafmtModule {
-    override def scalacPluginClasspath = T { m.scalacPluginClasspath() }
+  def commonTextIvy = v.commonText
 
-    override def ivyDeps = m.ivyDeps() ++ Agg(
-      v.scalatest,
-      v.scalacheck
-    )
-
-    override def moduleDeps = super.moduleDeps
-  }
-
-  object `integration-tests` extends Tests with TestModule.ScalaTest with ScalafmtModule {
-    override def sources = T.sources(millSourcePath / "integration-tests" / "src" / "test" / "scala")
-    override def ivyDeps = m.ivyDeps() ++ Agg(
-      v.scalatest,
-      v.scalacheck
-    ) ++ m.chiseltestIvyDeps
+  def scoptIvy = v.scopt
+}
 
-    override def moduleDeps = super.moduleDeps ++ Seq(stdlib) ++ chiseltestModule
-  }
+object macros extends mill.Cross[macros](v.scalaCrossVersions: _*)
 
-  override def buildInfoPackageName = Some("chisel3")
+class macros(val crossScalaVersion: String)
+  extends common.MacrosModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  def scalaReflectIvy = v.scalaReflect(crossScalaVersion)
 
-  override def buildInfoMembers = T {
-    Map(
-      "buildInfoPackage" -> artifactName(),
-      "version" -> publishVersion(),
-      "scalaVersion" -> scalaVersion()
-    )
-  }
+  def macroParadiseIvy: Option[Dep] = if (majorScalaVersion(crossScalaVersion) < 13) Some(v.macroParadise) else None
+}
 
-  object macros extends CommonModule {
+object core extends mill.Cross[core](v.scalaCrossVersions: _*)
 
-    /** millOuterCtx.segment.pathSegments didn't detect error here. */
-    override def millSourcePath = m.millSourcePath / "macros"
+class core(val crossScalaVersion: String)
+  extends common.CoreModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  def firrtlModule = firrtl(crossScalaVersion)
 
-    override def crossScalaVersion = m.crossScalaVersion
+  def macrosModule = macros(crossScalaVersion)
 
-    override def firrtlModule = m.firrtlModule
-  }
+  def macroParadiseIvy: Option[Dep] = if (majorScalaVersion(crossScalaVersion) < 13) Some(v.macroParadise) else None
 
-  object core extends CommonModule {
+  def osLibModuleIvy = v.osLib
 
-    /** millOuterCtx.segment.pathSegments didn't detect error here. */
-    override def millSourcePath = m.millSourcePath / "core"
+  def upickleModuleIvy = v.upickle
+}
 
-    override def crossScalaVersion = m.crossScalaVersion
+object plugin extends mill.Cross[plugin](v.pluginScalaCrossVersions: _*)
 
-    override def moduleDeps = super.moduleDeps ++ Seq(macros)
+class plugin(val crossScalaVersion: String)
+  extends common.PluginModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  def scalaLibraryIvy = v.scalaLibrary(crossScalaVersion)
 
-    override def firrtlModule = m.firrtlModule
+  def scalaReflectIvy = v.scalaReflect(crossScalaVersion)
 
-    def scalacOptions = T {
-      super.scalacOptions() ++ Seq(
-        "-deprecation",
-        "-explaintypes",
-        "-feature",
-        "-language:reflectiveCalls",
-        "-unchecked",
-        "-Xcheckinit",
-        "-Xlint:infer-any"
-      )
-    }
+  def scalaCompilerIvy: Dep = v.scalaCompiler(crossScalaVersion)
+}
 
-    override def generatedSources = T {
-      Seq(generatedBuildInfo()._2)
-    }
-  }
+object chisel extends mill.Cross[chisel](v.scalaCrossVersions: _*)
 
-  object plugin extends CommonModule {
+class chisel(val crossScalaVersion: String)
+  extends common.ChiselModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  override def millSourcePath = super.millSourcePath / os.up
 
-    /** millOuterCtx.segment.pathSegments didn't detect error here. */
-    override def millSourcePath = m.millSourcePath / "plugin"
+  def macrosModule = macros(crossScalaVersion)
 
-    override def crossScalaVersion = m.crossScalaVersion
+  def coreModule = core(crossScalaVersion)
 
-    override def firrtlModule = m.firrtlModule
+  def pluginModule = plugin(crossScalaVersion)
 
-    override def ivyDeps = Agg(
-      ivy"${scalaOrganization()}:scala-library:$crossScalaVersion"
-    ) ++ (if (majorVersion == 13) Agg(ivy"${scalaOrganization()}:scala-compiler:$crossScalaVersion")
-          else Agg.empty[Dep])
+  def macroParadiseIvy = if (majorScalaVersion(crossScalaVersion) < 13) Some(v.macroParadise) else None
+}
 
-    def scalacOptions = T {
-      Seq(
-        "-Xfatal-warnings"
-      )
-    }
+object stdlib extends mill.Cross[stdlib](v.scalaCrossVersions: _*)
 
-    override def artifactName = "chisel3-plugin"
-  }
+class stdlib(val crossScalaVersion: String)
+  extends common.StdLibModule
+    with CrossSbtModule
+    with ScalafmtModule {
+  def chiselModule = chisel(crossScalaVersion)
 
-  // make mill publish sbt compatible package
-  override def artifactName = "chisel3"
+  def pluginModule = plugin(crossScalaVersion)
 }