Display all supported scalaVersions for ExplicitResultType (#1194)

Author: mlachkar

Diff for: build.sbt

@@ -74,7 +74,8 @@ lazy val rules = project
     buildInfoKeys ++= Seq[BuildInfoKey](
       "supportedScalaVersions" -> (scalaVersion.value +:
         testedPreviousScalaVersions
-          .getOrElse(scalaVersion.value, Nil))
+          .getOrElse(scalaVersion.value, Nil)),
+      "allSupportedScalaVersions" -> ((crossScalaVersions.value ++ testedPreviousScalaVersions.values.toSeq.flatten).sorted)
     ),
     buildInfoObject := "RulesBuildInfo",
     description := "Built-in Scalafix rules",

Diff for: scalafix-rules/src/main/scala/scalafix/internal/rule/ExplicitResultTypes.scala

@@ -18,14 +18,15 @@ final class ExplicitResultTypes(
 ) extends SemanticRule("ExplicitResultTypes") {
 
   def this() = this(ExplicitResultTypesConfig.default, LazyValue.now(None))
-  val supportedScalaVersions = RulesBuildInfo.supportedScalaVersions
-  val compilerScalaVersion = RulesBuildInfo.scalaVersion
+  val supportedScalaVersions: collection.Seq[String] =
+    RulesBuildInfo.supportedScalaVersions
+  val compilerScalaVersion: String = RulesBuildInfo.scalaVersion
 
   private def toBinaryVersion(v: String) = v.split('.').take(2).mkString(".")
 
   override def description: String =
     "Inserts type annotations for inferred public members. " +
-      s"Only compatible with Scala ${supportedScalaVersions.mkString(",")}."
+      s"Only compatible with Scala ${RulesBuildInfo.allSupportedScalaVersions.mkString(", ")}."
   override def isRewrite: Boolean = true
 
   override def afterComplete(): Unit = {