feat: add in ability to specify the output type

This allows the user to pass in `--output dump.lsif` or just `dump.lsif`
or another valid output type to output other types than the default scip
which was happening before. If used the same way as before with no
argument the behavior is the same.

Refs: sourcegraph/scip-java#482

build.sc

@@ -93,7 +93,13 @@ object itest extends MillIntegrationTestModule {
     T {
       Seq(
         PathRef(testBase / "minimal") -> Seq(
-          TestInvocation.Targets(Seq("generate"), noServer = true)
+          TestInvocation.Targets(Seq("generate"), noServer = true),
+          TestInvocation.Targets(Seq("lsif"), noServer = true),
+          TestInvocation.Targets(
+            Seq("fail"),
+            noServer = true,
+            expectedExitCode = 1
+          )
         )
       )
     }

itest/src/minimal/build.sc

@@ -35,3 +35,12 @@ def generate(ev: Evaluator) = T.command {
   // Then we ensure that the index.scip file was actually created
   assertEquals(os.exists(scipFile), true)
 }
+
+def lsif(ev: Evaluator) = T.command {
+  val scipFile = Scip.generate(ev, "dump.lsif")()
+  assertEquals(os.exists(scipFile), true)
+}
+
+def fail(ev: Evaluator) = T.command {
+  Scip.generate(ev, "wrong.format")
+}

plugin/src/io/kipp/mill/scip/Scip.scala

@@ -6,7 +6,9 @@ import com.sourcegraph.scip_semanticdb.ScipSemanticdb
 import com.sourcegraph.scip_semanticdb.ScipSemanticdbOptions
 import mill._
 import mill.api.Logger
+import mill.api.Result
 import mill.define.ExternalModule
+import mill.define.Task
 import mill.eval.Evaluator
 import mill.main.EvaluatorScopt
 import mill.scalalib.JavaModule
@@ -26,9 +28,12 @@ object Scip extends ExternalModule {
     * producing semanticDB. Once we fully have all the semanticDB we call
     * ScipSemanticdb to slurp it all up and create a SCIP index.
     */
-  def generate(ev: Evaluator) = T.command {
+  def generate(ev: Evaluator, output: String = "index.scip") = T.command {
+
     val log = T.ctx().log
 
+    val outputFormat = validateFormat(output)()
+
     val semanticdbVersion = ScipBuildInfo.semanticDBVersion
 
     val modules = computeModules(ev)
@@ -200,8 +205,33 @@ object Scip extends ExternalModule {
       }
       .map(_.path)
 
-    createScip(log, T.dest, T.workspace, projects)
-    T.dest / "index.scip"
+    createScip(log, T.dest, T.workspace, projects, output, outputFormat)
+    T.dest / output
+  }
+
+  /** Given an output string, determine that a ScipOutputFormat can be
+    * determined from it.
+    *
+    * @param output
+    *   the given output from the user
+    * @return
+    *   the parsed output format to be generated
+    */
+  private def validateFormat(output: String): Task[ScipOutputFormat] = T.task {
+    val format = ScipOutputFormat.fromFilename(output)
+    if (format == ScipOutputFormat.UNKNOWN) {
+      val msg =
+        s"""Detected an unknown output type. You'll want to use one of the following:
+                    |
+                    | - *.lsif
+                    | - *.lsif-protobuf
+                    | - *.scip
+                    | - *.scip.ndjson
+                    |""".stripMargin
+      Result.Failure(msg)
+    } else {
+      format
+    }
   }
 
   /** After all the semanticDB has been produced we can create the SCIP index
@@ -215,14 +245,21 @@ object Scip extends ExternalModule {
     *   The current workspace root
     * @param projects
     *   Full classpath of the project to be used for cross-project navigation.
+    * @param output
+    *   The name out of the output file
+    * @param outputFormat
+    *   The format of the output
     */
   private def createScip(
       log: Logger,
       dest: Path,
       workspace: Path,
-      projects: Seq[Path]
+      projects: Seq[Path],
+      output: String,
+      outputFormat: ScipOutputFormat
   ): Unit = {
-    val scipFile = dest / "index.scip"
+
+    val scipFile = dest / output
     val reporter = new ScipReporter(log)
     val toolInfo =
       LsifToolInfo
@@ -233,7 +270,7 @@ object Scip extends ExternalModule {
         .setVersion(ScipBuildInfo.semanticDBJavaVersion)
         .build()
 
-    log.info(s"Creating a index.scip in ${scipFile}")
+    log.info(s"Creating a ${output} in ${scipFile}")
 
     // So this is maybe a bit opinionated here, but we're only writing this to
     // disk for easier debugging. Normally scip-java can read this up to when
@@ -260,7 +297,7 @@ object Scip extends ExternalModule {
       reporter,
       toolInfo,
       "java",
-      ScipOutputFormat.TYPED_PROTOBUF,
+      outputFormat,
       true, // parallel -- this is fine
       classPathEntries
         .map(_.toPackageInformation)