fix sbt-dotty doc on sbt 1.5

Author: adpi2

sbt-dotty/sbt-test/sbt-dotty/scaladoc/build.sbt

@@ -1,7 +1,15 @@
 scalaVersion := sys.props("plugin.scalaVersion")
 
-lazy val assertUsingScaladoc = taskKey[Unit]("")
-
-assertUsingScaladoc := {
+TaskKey[Unit]("assertUsingScaladoc") := {
   assert(useScaladoc.value)
 }
+
+TaskKey[Unit]("checkScaladocOptions") := {
+  val options = (Compile / doc / scalacOptions).value
+  assert(options.count(_ == "-project") == 1)
+}
+
+TaskKey[Unit]("checkHtmlFiles") := {
+  val helloHtml = (Compile / doc / target).value / "api" / "hello.html"
+  assert(helloHtml.exists)
+}

sbt-dotty/sbt-test/sbt-dotty/scaladoc/test

@@ -1,3 +1,4 @@
 > assertUsingScaladoc
+> checkScaladocOptions
 > doc
-
+> checkHtmlFiles

sbt-dotty/src/dotty/tools/sbtplugin/DottyPlugin.scala

@@ -464,7 +464,10 @@ object DottyPlugin extends AutoPlugin {
       else Def.task { originalSources }
     }.value,
     scalacOptions ++= {
-      if (isDotty.value) {
+      // From sbt 1.5 scaladoc is natively supported, and so the scalacOptions are already set.
+      val isSbt15 = VersionNumber(sbtVersion.value)
+        .matchesSemVer(SemanticSelector(">=1.5.0-M1"))
+      if (isDotty.value && !isSbt15) {
         val projectName =
           if (configuration.value == Compile)
             name.value