Read tool args in test files

Author: dwijnand

compiler/test/dotty/tools/dotc/transform/PatmatExhaustivityTest.scala

@@ -10,9 +10,8 @@ import reporting.TestReporter
 import dotty.tools.io.Directory
 
 import java.io._
-import java.nio.file.{Files, Path => JPath}
+import java.nio.file.{Path => JPath}
 
-import scala.io.Source._
 import org.junit.Test
 
 class PatmatExhaustivityTest {
@@ -75,22 +74,4 @@ class PatmatExhaustivityTest {
 
     println(msg)
   }
-
-  // inspect given files for tool args of the form `tool: args`
-  // if args string ends in close comment, drop the `*` `/`
-  // if split, parse the args string as command line.
-  // (from scala.tools.partest.nest.Runner#toolArgsFor)
-  private def toolArgsFor(files: List[JPath]): List[String] = {
-    import scala.jdk.OptionConverters._
-    import config.CommandLineParser.tokenize
-    files.flatMap { path =>
-      val tag  = "scalac:"
-      val endc = "*" + "/"    // be forgiving of /* scalac: ... */
-      def stripped(s: String) = s.substring(s.indexOf(tag) + tag.length).stripSuffix(endc)
-      val args = scala.util.Using.resource(Files.lines(path, scala.io.Codec.UTF8.charSet))(
-        _.limit(10).filter(_.contains(tag)).map(stripped).findAny.toScala
-      )
-      args.map(tokenize).getOrElse(Nil)
-    }
-  }
 }

compiler/test/dotty/tools/utils.scala

@@ -2,8 +2,9 @@ package dotty.tools
 
 import java.io.File
 import java.nio.charset.StandardCharsets.UTF_8
+import java.nio.file.{Files, Path => JPath}
 
-import scala.io.Source
+import scala.io.{Codec, Source}
 import scala.reflect.ClassTag
 import scala.util.Using.resource
 import scala.util.chaining.given
@@ -39,3 +40,21 @@ def assertThrows[T <: Throwable: ClassTag](p: T => Boolean)(body: => Any): Unit
     case failed: T       => throw AssertionError(s"Exception failed check: $failed").tap(_.addSuppressed(failed))
     case NonFatal(other) => throw AssertionError(s"Wrong exception: expected ${implicitly[ClassTag[T]]} but was ${other.getClass.getName}").tap(_.addSuppressed(other))
 end assertThrows
+
+// inspect given files for tool args of the form `tool: args`
+// if args string ends in close comment, drop the `*` `/`
+// if split, parse the args string as command line.
+// (from scala.tools.partest.nest.Runner#toolArgsFor)
+def toolArgsFor(files: List[JPath])(implicit codec: Codec = Codec.UTF8): List[String] =
+  import scala.jdk.OptionConverters._
+  import dotc.config.CommandLineParser.tokenize
+  files.flatMap { path =>
+    val tag  = "scalac:"
+    val endc = "*" + "/"    // be forgiving of /* scalac: ... */
+    def stripped(s: String) = s.substring(s.indexOf(tag) + tag.length).stripSuffix(endc)
+    val args = scala.util.Using.resource(Files.lines(path, codec.charSet))(
+      _.limit(10).filter(_.contains(tag)).map(stripped).findAny.toScala
+    )
+    args.map(tokenize).getOrElse(Nil)
+  }
+end toolArgsFor

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -441,15 +441,17 @@ trait ParallelTesting extends RunnerOrchestration { self =>
           throw e
 
     protected def compile(files0: Array[JFile], flags0: TestFlags, suppressErrors: Boolean, targetDir: JFile): TestReporter = {
-      val flags = flags0.and("-d", targetDir.getPath)
-        .withClasspath(targetDir.getPath)
-
       def flattenFiles(f: JFile): Array[JFile] =
         if (f.isDirectory) f.listFiles.flatMap(flattenFiles)
         else Array(f)
 
       val files: Array[JFile] = files0.flatMap(flattenFiles)
 
+      val flags = flags0
+        .and(toolArgsFor(files.toList.map(_.toPath))(using getCodecFromEncodingOpt(flags0)): _*)
+        .and("-d", targetDir.getPath)
+        .withClasspath(targetDir.getPath)
+
       def compileWithJavac(fs: Array[String]) = if (fs.nonEmpty) {
         val fullArgs = Array(
           "javac",
@@ -1358,6 +1360,11 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     // Create a CompilationTest and let the user decide whether to execute a pos or a neg test
     new CompilationTest(targets)
   }
+
+  private def getCodecFromEncodingOpt(flags: TestFlags) =
+    flags.options.sliding(2).collectFirst {
+      case Array("-encoding", encoding) => scala.io.Codec(encoding)
+    }.getOrElse(scala.io.Codec.UTF8)
 }
 
 object ParallelTesting {