Read previousVersions for bincompat checking from a file (backport #3202)

build.sbt

@@ -17,6 +17,20 @@ ThisBuild / firtoolVersion := {
   }
 }
 
+// Previous versions are read from project/previous-versions.txt
+// If this file is empty or does not exist, no binary compatibility checking will be done
+// Add waivers to the directory defined by key `mimaFiltersDirectory` in files named: <since version>.backwards.excludes
+//   eg. unipublish/src/main/mima-filters/5.0.0.backwards.excludes
+val previousVersions = settingKey[Set[String]]("Previous versions for binary compatibility checking")
+ThisBuild / previousVersions := {
+  val file = new java.io.File("project", "previous-versions.txt")
+  if (file.isFile) {
+    scala.io.Source.fromFile(file).getLines.toSet
+  } else {
+    Set()
+  }
+}
+
 val emitVersion = taskKey[Unit]("Write the version to version.txt")
 emitVersion := {
   IO.write(new java.io.File("version.txt"), version.value)
@@ -193,8 +207,8 @@ lazy val plugin = (project in file("plugin"))
   )
   .settings(fatalWarningsSettings: _*)
   .settings(
-    mimaPreviousArtifacts := {
-      Set()
+    mimaPreviousArtifacts := previousVersions.value.map { version =>
+      (organization.value % name.value % version).cross(CrossVersion.full)
     }
   )
 
@@ -213,7 +227,11 @@ lazy val macros = (project in file("macros"))
   .settings(name := "chisel3-macros")
   .settings(commonSettings: _*)
   .settings(publishSettings: _*)
-  .settings(mimaPreviousArtifacts := Set())
+  .settings(
+    mimaPreviousArtifacts := previousVersions.value.map { version =>
+      organization.value %% name.value % version
+    }
+  )
 
 lazy val firrtlRef = ProjectRef(workspaceDirectory / "firrtl", "firrtl")
 
@@ -227,7 +245,11 @@ lazy val core = (project in file("core"))
     buildInfoKeys := Seq[BuildInfoKey](buildInfoPackage, version, scalaVersion, sbtVersion, firtoolVersion)
   )
   .settings(publishSettings: _*)
-  .settings(mimaPreviousArtifacts := Set())
+  .settings(
+    mimaPreviousArtifacts := previousVersions.value.map { version =>
+      organization.value %% name.value % version
+    }
+  )
   .settings(warningSuppression: _*)
   .settings(fatalWarningsSettings: _*)
   .settings(
@@ -263,7 +285,9 @@ lazy val chisel = (project in file("."))
   .settings(warningSuppression: _*)
   .settings(fatalWarningsSettings: _*)
   .settings(
-    mimaPreviousArtifacts := Set(),
+    mimaPreviousArtifacts := previousVersions.value.map { version =>
+      organization.value %% name.value % version
+    },
     Test / scalacOptions ++= Seq("-language:reflectiveCalls"),
     // Forward doc command to unidoc
     Compile / doc := (ScalaUnidoc / doc).value,

project/previous-versions.txt

@@ -0,0 +1 @@
+3.6.0