More for extra attributes from POM

cli/src/main/scala/coursier/cli/Coursier.scala

@@ -31,7 +31,8 @@ case class CommonOptions(
   @HelpMessage("Do not add default repositories (~/.ivy2/local, and Central)")
     noDefault: Boolean = false,
   @HelpMessage("Modify names in Maven repository paths for SBT plugins")
-    sbtPluginHack: Boolean = false,
+  @ValueDescription("Attribute prefix (typically \"e\")")
+    sbtPluginHack: String = "",
   @HelpMessage("Force module version")
   @ValueDescription("organization:name:forcedVersion")
   @ExtraName("V")

cli/src/main/scala/coursier/cli/Helper.scala

@@ -118,9 +118,9 @@ class Helper(
       repositories0.collect { case Right(r) => r }
 
   val repositories =
-    if (common.sbtPluginHack)
+    if (common.sbtPluginHack.nonEmpty)
       repositories1.map {
-        case m: MavenRepository => m.copy(sbtAttrStub = true)
+        case m: MavenRepository => m.copy(sbtAttrStub = Some(common.sbtPluginHack))
         case other => other
       }
     else

core/shared/src/main/scala/coursier/Fetch.scala

@@ -42,7 +42,7 @@ object Fetch {
     val task = lookups.foldLeft[F[Seq[String] \/ (Artifact.Source, Project)]](F.point(-\/(Nil))) {
       case (acc, (repo, eitherProjTask)) =>
         val looseModuleValidation = repo match {
-          case m: MavenRepository => m.sbtAttrStub // that sucks so much
+          case m: MavenRepository => m.sbtAttrStub.nonEmpty // that sucks so much
           case _ => false
         }
         val moduleCmp = if (looseModuleValidation) module.copy(attributes = Map.empty) else module
@@ -66,7 +66,7 @@ object Fetch {
     EitherT(F.map(task)(_.leftMap(_.reverse)))
       .map {case x @ (source, proj) =>
         val looseModuleValidation = source match {
-          case m: MavenSource => m.sbtAttrStub // omfg
+          case m: MavenSource => m.sbtAttrStub.nonEmpty // omfg
           case _ => false
         }
         val projModule =

core/shared/src/main/scala/coursier/maven/MavenRepository.scala

@@ -45,16 +45,24 @@ object MavenRepository {
     "test" -> Seq("runtime")
   )
 
-  def dirModuleName(module: Module, sbtAttrStub: Boolean): String =
-    if (sbtAttrStub) {
+  def dirModuleName(module: Module, sbtAttrStub: Option[String]): String =
+    sbtAttrStub.fold(module.name) { prefix =>
+      def attr(name: String) = {
+        val base = module.attributes.get(name)
+
+        if (prefix.isEmpty)
+          base
+        else
+          base.orElse(module.attributes.get(s"$prefix:$name"))
+      }
+
       var name = module.name
-      for (scalaVersion <- module.attributes.get("scalaVersion"))
+      for (scalaVersion <- attr("scalaVersion"))
         name = name + "_" + scalaVersion
-      for (sbtVersion <- module.attributes.get("sbtVersion"))
+      for (sbtVersion <- attr("sbtVersion"))
         name = name + "_" + sbtVersion
       name
-    } else
-      module.name
+    }
 
 }
 
@@ -63,7 +71,7 @@ case class MavenRepository(
   ivyLike: Boolean = false,
   changing: Option[Boolean] = None,
   /** Hackish hack for sbt plugins mainly - what this does really sucks */
-  sbtAttrStub: Boolean = false
+  sbtAttrStub: Option[String] = None
 ) extends Repository {
 
   import Repository._

core/shared/src/main/scala/coursier/maven/MavenSource.scala

@@ -7,7 +7,7 @@ case class MavenSource(
   ivyLike: Boolean,
   changing: Option[Boolean] = None,
   /** See doc on MavenRepository */
-  sbtAttrStub: Boolean
+  sbtAttrStub: Option[String] = None
 ) extends Artifact.Source {
 
   import Repository._

plugin/src/main/scala/coursier/FromSbt.scala

@@ -119,7 +119,7 @@ object FromSbt {
       case sbt.MavenRepository(_, root) =>
         if (root.startsWith("http://") || root.startsWith("https://")) {
           val root0 = if (root.endsWith("/")) root else root + "/"
-          Some(MavenRepository(root0, sbtAttrStub = true))
+          Some(MavenRepository(root0, sbtAttrStub = Some("e")))
         } else {
           Console.err.println(s"Warning: unrecognized Maven repository protocol in $root, ignoring it")
           None