[temp] Following RC's way to build Chisel from source or Maven [ci skip]

.sbtopts

@@ -1,2 +1,2 @@
 -Dsbt.sourcemode=true
--Dsbt.workspace=$PWD
+-Dsbt.workspace=$PWD/tools

build.sbt

@@ -78,7 +78,15 @@ def isolateAllTests(tests: Seq[TestDefinition]) = tests map { test =>
 
 // Subproject definitions begin
 
-lazy val chisel  = (project in file("tools/chisel3"))
+// This needs to stay in sync with the chisel3 and firrtl git submodules
+val chiselVersion = "3.4.0"
+
+lazy val chiselRef = ProjectRef(workspaceDirectory / "chisel3", "chisel")
+lazy val chiselLib = "edu.berkeley.cs" %% "chisel3" % chiselVersion
+// While not built from source, *must* be in sync with the chisel3 git submodule
+// Building from source requires extending sbt-sriracha or a similar plugin and
+//   keeping scalaVersion in sync with chisel3 to the minor version
+lazy val chiselPluginLib = "edu.berkeley.cs" % "chisel3-plugin" % chiselVersion cross CrossVersion.full
 
 lazy val firrtl_interpreter = (project in file("tools/firrtl-interpreter"))
   .settings(commonSettings)
@@ -87,7 +95,9 @@ lazy val treadle = (project in file("tools/treadle"))
   .settings(commonSettings)
 
 lazy val chisel_testers = (project in file("tools/chisel-testers"))
-  .dependsOn(chisel, firrtl_interpreter, treadle)
+  .sourceDependency(chiselRef, chiselLib)
+  .dependsOn(firrtl_interpreter, treadle)
+  .settings(addCompilerPlugin(chiselPluginLib))
   .settings(
       commonSettings,
       libraryDependencies ++= Seq(
@@ -113,15 +123,18 @@ lazy val rocketConfig = (project in rocketChipDir / "api-config-chipsalliance/bu
   .settings(commonSettings)
 
 lazy val rocketchip = freshProject("rocketchip", rocketChipDir)
+  .sourceDependency(chiselRef, chiselLib)
+  .dependsOn(hardfloat, rocketMacros, rocketConfig)
+  .settings(addCompilerPlugin(chiselPluginLib))
   .settings(commonSettings)
-  .dependsOn(chisel, hardfloat, rocketMacros, rocketConfig)
 
 lazy val testchipip = (project in file("generators/testchipip"))
   .dependsOn(rocketchip, sifive_blocks)
   .settings(commonSettings)
 
 lazy val iocell = (project in file("./tools/barstools/iocell/"))
-  .dependsOn(chisel)
+  .sourceDependency(chiselRef, chiselLib)
+  .settings(addCompilerPlugin(chiselPluginLib))
   .settings(commonSettings)
 
 lazy val chipyard = conditionalDependsOn(project in file("generators/chipyard"))
@@ -184,7 +197,9 @@ lazy val barstoolsMacros = (project in file("./tools/barstools/macros/"))
   .settings(commonSettings)
 
 lazy val dsptools = freshProject("dsptools", file("./tools/dsptools"))
-  .dependsOn(chisel, chisel_testers)
+  .sourceDependency(chiselRef, chiselLib)
+  .dependsOn(chisel_testers)
+  .settings(addCompilerPlugin(chiselPluginLib))
   .settings(
       commonSettings,
       libraryDependencies ++= Seq(