support repeated native plugins with different options

build.sbt

@@ -15,7 +15,7 @@ scalaVersion := "2.12.13"
 addSbtPlugin("org.portable-scala" % "sbt-platform-deps" % "1.0.0")
 
 libraryDependencies ++= Seq(
-  "com.thesamet.scalapb" %% "protoc-bridge" % "0.9.1"
+  "com.thesamet.scalapb" %% "protoc-bridge" % "0.9.1+4-8a125376-SNAPSHOT"
 )
 
 enablePlugins(SbtPlugin)

src/main/scala/sbtprotoc/ProtocPlugin.scala

@@ -14,7 +14,7 @@ import org.portablescala.sbtplatformdeps.PlatformDepsPlugin.autoImport.platformD
 import java.net.URLClassLoader
 import sbt.librarymanagement.DependencyResolution
 import protocbridge.{Artifact => BridgeArtifact}
-import protocbridge.{SystemDetector => BridgeSystemDetector, FileCache}
+import protocbridge.{SystemDetector => BridgeSystemDetector, FileCache, PluginGenerator}
 import scala.concurrent.{Future, blocking}
 import scala.concurrent.ExecutionContext.Implicits.global
 
@@ -503,9 +503,9 @@ object ProtocPlugin extends AutoPlugin {
       // Ensure all plugins are executable
       nativePlugins.foreach { dep => dep.data.setExecutable(true) }
 
-      val nativePluginsArgs = nativePlugins.map { a =>
+      val nativePluginsArgs = nativePlugins.flatMap { a =>
         val dep = a.get(artifact.key).get
-        val pluginPath =
+        val pluginPath = {
           maybeNixDynamicLinker.filterNot(_ => a.data.getName.endsWith(".sh")) match {
             case None => a.data.absolutePath
             case Some(linker) =>
@@ -516,7 +516,13 @@ object ProtocPlugin extends AutoPlugin {
                 f.getAbsolutePath()
               }
           }
-        s"--plugin=${dep.name}=${pluginPath}"
+        }
+        val targetCount = PB.targets.value.count {
+          case Target(PluginGenerator(name, _, _), _, _) => s"protoc-gen-$name" == dep.name
+          case _                                         => false
+        }
+        if (targetCount == 1) Seq(s"--plugin=${dep.name}=${pluginPath}")
+        else Seq.range(0, targetCount).map(i => s"--plugin=${dep.name}_$i=${pluginPath}")
       }
 
       val classLoader: BridgeArtifact => ClassLoader =

src/sbt-test/settings/native/build.sbt

@@ -0,0 +1,24 @@
+Compile / PB.targets := Seq(
+  (
+    PB.gens.plugin("scala"),
+    Seq()
+  ) -> (Compile / sourceManaged).value,
+  (
+    PB.gens.plugin("scala"),
+    Seq("flat_package")
+  ) -> (Compile / sourceManaged).value
+)
+
+val scalapbcClassifier =
+  if (protocbridge.SystemDetector.detectedClassifier().startsWith("windows")) "windows"
+  else "unix"
+
+libraryDependencies += "com.thesamet.scalapb" %% "scalapb-runtime"  % "0.10.10"
+libraryDependencies += "com.thesamet.scalapb"  % "protoc-gen-scala" % "0.10.10" % "protobuf" artifacts (
+  Artifact(
+    "protoc-gen-scala",
+    PB.ProtocPlugin,
+    "sh",
+    scalapbcClassifier
+  )
+)

src/sbt-test/settings/native/project/plugins.sbt

@@ -0,0 +1,7 @@
+{
+  val pluginVersion = System.getProperty("plugin.version")
+  if(pluginVersion == null)
+    throw new RuntimeException("""|The system property 'plugin.version' is not defined.
+                                  |Specify this property using the scriptedLaunchOpts -D.""".stripMargin)
+  else addSbtPlugin("com.thesamet" % "sbt-protoc" % pluginVersion)
+}

src/sbt-test/settings/native/src/main/protobuf/test1.proto

@@ -0,0 +1,7 @@
+syntax = "proto3";
+
+package test;
+
+message msg {
+  int32 thing = 1;
+}

src/sbt-test/settings/native/test

@@ -0,0 +1,6 @@
+> compile
+
+$ exists target/scala-2.12/src_managed/main/test/test1/Test1Proto.scala
+$ exists target/scala-2.12/src_managed/main/test/test1/msg.scala
+$ exists target/scala-2.12/src_managed/main/test/Test1Proto.scala
+$ exists target/scala-2.12/src_managed/main/test/msg.scala