Add `scalaPBProtocPath` option to scalapblib (#714)

4 files changed, 26 insertions, 7 deletions

diff --git a/contrib/scalapblib/src/ScalaPBModule.scala b/contrib/scalapblib/src/ScalaPBModule.scala
index 00b977ce..4e663587 100644
--- a/contrib/scalapblib/src/ScalaPBModule.scala
+++ b/contrib/scalapblib/src/ScalaPBModule.scala
@@ -29,6 +29,8 @@ trait ScalaPBModule extends ScalaModule {
 
   def scalaPBSingleLineToProtoString: T[Boolean] = T { false }
 
+  def scalaPBProtocPath: T[Option[String]] = T { None }
+
   def scalaPBSources: Sources = T.sources {
     millSourcePath / 'protobuf
   }
@@ -63,6 +65,7 @@ trait ScalaPBModule extends ScalaModule {
     ScalaPBWorkerApi.scalaPBWorker
       .compile(
         scalaPBClasspath().map(_.path),
+        scalaPBProtocPath(),
         scalaPBSources().map(_.path),
         scalaPBOptions(),
         T.ctx().dest)
diff --git a/contrib/scalapblib/src/ScalaPBWorker.scala b/contrib/scalapblib/src/ScalaPBWorker.scala
index 125cd3fd..49c7492f 100644
--- a/contrib/scalapblib/src/ScalaPBWorker.scala
+++ b/contrib/scalapblib/src/ScalaPBWorker.scala
@@ -11,7 +11,7 @@ class ScalaPBWorker {
 
   private var scalaPBInstanceCache = Option.empty[(Long, ScalaPBWorkerApi)]
 
-  private def scalaPB(scalaPBClasspath: Agg[os.Path]) = {
+  private def scalaPB(scalaPBClasspath: Agg[os.Path], protocPath: Option[String]) = {
     val classloaderSig = scalaPBClasspath.map(p => p.toString().hashCode + os.mtime(p)).sum
     scalaPBInstanceCache match {
       case Some((sig, instance)) if sig == classloaderSig => instance
@@ -23,15 +23,13 @@ class ScalaPBWorker {
         val instance = new ScalaPBWorkerApi {
           override def compileScalaPB(source: File, scalaPBOptions: String, generatedDirectory: File) {
             val opts = if (scalaPBOptions.isEmpty) "" else scalaPBOptions + ":"
-            mainMethod.invoke(
-              null,
-              Array(
+            val args = protocPath.map(path => s"--protoc=$path").toList ++ List(
                 "--throw",
                 s"--scala_out=${opts}${generatedDirectory.getCanonicalPath}",
                 s"--proto_path=${source.getParentFile.getCanonicalPath}",
                 source.getCanonicalPath
               )
-            )
+            mainMethod.invoke(null, args.toArray)
           }
         }
         scalaPBInstanceCache = Some((classloaderSig, instance))
@@ -39,9 +37,9 @@ class ScalaPBWorker {
     }
   }
 
-  def compile(scalaPBClasspath: Agg[os.Path], scalaPBSources: Seq[os.Path], scalaPBOptions: String, dest: os.Path)
+  def compile(scalaPBClasspath: Agg[os.Path], protocPath: Option[String], scalaPBSources: Seq[os.Path], scalaPBOptions: String, dest: os.Path)
              (implicit ctx: mill.api.Ctx): mill.api.Result[PathRef] = {
-    val compiler = scalaPB(scalaPBClasspath)
+    val compiler = scalaPB(scalaPBClasspath, protocPath)
 
     def compileScalaPBDir(inputDir: os.Path) {
       // ls throws if the path doesn't exist
diff --git a/contrib/scalapblib/test/src/TutorialTests.scala b/contrib/scalapblib/test/src/TutorialTests.scala
index fe0ce8d5..35ad69e0 100644
--- a/contrib/scalapblib/test/src/TutorialTests.scala
+++ b/contrib/scalapblib/test/src/TutorialTests.scala
@@ -24,6 +24,12 @@ object TutorialTests extends TestSuite {
     }
   }
 
+  object TutorialWithProtoc extends TutorialBase {
+    object core extends TutorialModule {
+      override def scalaPBProtocPath = Some("/dev/null")
+    }
+  }
+
   val resourcePath: os.Path = os.pwd / 'contrib / 'scalapblib / 'test / 'protobuf / 'tutorial
 
   def protobufOutPath(eval: TestEvaluator): os.Path =
@@ -108,5 +114,15 @@ object TutorialTests extends TestSuite {
       //   assert(unchangedEvalCount == 0)
       // }
     }
+
+    'useExternalProtocCompiler - {
+      /* This ensure that the `scalaPBProtocPath` is properly used.
+       * As the given path is incorrect, the compilation should fail.
+       */
+      'calledWithWrongProtocFile - workspaceTest(TutorialWithProtoc) { eval =>
+        val result = eval.apply(TutorialWithProtoc.core.compileScalaPB)
+        assert(result.isLeft)
+      }
+    }
   }
 }
diff --git a/docs/pages/9 - Contrib Modules.md b/docs/pages/9 - Contrib Modules.md
index 40544d86..81607b71 100644
--- a/docs/pages/9 - Contrib Modules.md
+++ b/docs/pages/9 - Contrib Modules.md
@@ -564,6 +564,8 @@ example/
 
 * scalaPBSingleLineToProtoString - A `Boolean` option which determines whether the generated `.toString` methods should use a single line format.
 
+* scalaPBProtocPath - A `Option[Path]` option which determines the protoc compiler to use. If `None`, a java embedded protoc will be used, if set to `Some` path, the given binary is used.
+
 If you'd like to configure the options that are passed to the ScalaPB compiler directly, you can override the `scalaPBOptions` task, for example:
 
 ```scala