Fix plus Workaround for 13760

compiler/src/dotty/tools/MainGenericRunner.scala

@@ -81,6 +81,9 @@ case class Settings(
   def withSave: Settings =
     this.copy(save = true)
 
+  def noSave: Settings =
+    this.copy(save = false)
+
   def withModeShouldBePossibleRun: Settings =
     this.copy(modeShouldBePossibleRun = true)
 
@@ -135,6 +138,8 @@ object MainGenericRunner {
       )
     case "-save" :: tail =>
       process(tail, settings.withSave)
+    case "-nosave" :: tail =>
+      process(tail, settings.noSave)
     case "-with-compiler" :: tail =>
       process(tail, settings.withCompiler)
     case (o @ javaOption(striped)) :: tail =>
@@ -207,16 +212,18 @@ object MainGenericRunner {
       case ExecuteMode.Script =>
         val targetScript = Paths.get(settings.targetScript).toFile
         val targetJar = settings.targetScript.replaceAll("[.][^\\/]*$", "")+".jar"
-        val precompiledJar = Paths.get(targetJar).toFile
+        val precompiledJar = File(targetJar)
         val mainClass = if !precompiledJar.isFile then "" else Jar(targetJar).mainClass.getOrElse("")
-        val jarIsValid = mainClass.nonEmpty && precompiledJar.lastModified >= targetScript.lastModified
+        val jarIsValid = mainClass.nonEmpty && precompiledJar.lastModified >= targetScript.lastModified && settings.save
         if jarIsValid then
           // precompiledJar exists, is newer than targetScript, and manifest defines a mainClass
           sys.props("script.path") = targetScript.toPath.toAbsolutePath.normalize.toString
           val scalaClasspath = ClasspathFromClassloader(Thread.currentThread().getContextClassLoader).split(classpathSeparator)
           val newClasspath = (settings.classPath.flatMap(_.split(classpathSeparator).filter(_.nonEmpty)) ++ removeCompiler(scalaClasspath) :+ ".").map(File(_).toURI.toURL)
           if mainClass.nonEmpty then
-            ObjectRunner.runAndCatch(newClasspath :+ File(targetJar).toURI.toURL, mainClass, settings.scriptArgs)
+            ObjectRunner.runAndCatch(newClasspath :+ File(targetJar).toURI.toURL, mainClass, settings.scriptArgs).foreach { (t: Throwable) =>
+              t.printStackTrace()
+            }
           else
             Some(IllegalArgumentException(s"No main class defined in manifest in jar: $precompiledJar"))
         else

compiler/test-resources/scripting/sqlDateError.sc

@@ -0,0 +1,6 @@
+#!bin/scala -nosave
+
+def main(args: Array[String]): Unit = {
+  println(new java.sql.Date(100L))
+  System.err.println("SCALA_OPTS="+Option(System.getenv("SCALA_OPTS")).getOrElse(""))
+}

compiler/test/dotty/tools/scripting/BashScriptsTests.scala

@@ -188,3 +188,23 @@ class BashScriptsTests:
       if valid then printf(s"\n===> success: classpath begins with %s, as reported by [%s]\n", workingDirectory, scriptFile.getName)
       assert(valid, s"script ${scriptFile.absPath} did not report valid java.class.path first entry")
 
+  /*
+   * verify that individual scripts can override -save with -nosave (needed to address #13760).
+   */
+  @Test def sqlDateTest =
+    val scriptBase = "sqlDateError"
+    val scriptFile = testFiles.find(_.getName == s"$scriptBase.sc").get
+    val testJar = testFile(s"$scriptBase.jar") // jar should not be created when scriptFile runs
+    printf("===> verify '-save' is cancelled by '-nosave' in script hashbang.`\n")
+    val (validTest, exitCode, stdout, stderr) = bashCommand(s"SCALA_OPTS=-save ${scriptFile.absPath}")
+    printf("stdout: %s\n", stdout.mkString("\n","\n",""))
+    if verifyValid(validTest) then
+      // the script should print '1969-12-31' or '1970-01-01', depending on time zone
+      // stdout can be polluted with an ANSI color prefix, in some test environments
+      val valid = stdout.mkString("").matches(""".*\d{4}-\d{2}-\d{2}.*""")
+      if (!valid) then
+        stdout.foreach { printf("stdout[%s]\n", _) }
+        stderr.foreach { printf("stderr[%s]\n", _) }
+      if valid then printf(s"\n===> success: scripts can override -save via -nosave\n")
+      assert(valid, s"script ${scriptFile.absPath} reported unexpected value for java.sql.Date ${stdout.mkString("\n")}")
+      assert(!testJar.exists,s"unexpected, jar file [$testJar] was created")