Add -language:* as a possible repeatable compiler option

Author: Gedochao

modules/integration/src/test/scala/scala/cli/integration/SipScalaTests.scala

@@ -495,4 +495,23 @@ class SipScalaTests extends ScalaCliSuite {
       expect(res.exitCode == 0)
     }
   }
+
+  test("consecutive -language:* flags are not ignored") {
+    val sourceFileName = "example.scala"
+    TestInputs(os.rel / sourceFileName ->
+      """//> using scala 3.3.1
+        |//> using options -Yexplicit-nulls -language:fewerBraces -language:strictEquality
+        |def repro[A](as: List[A]): List[A] =
+        |  as match
+        |    case Nil => Nil
+        |    case _ => ???
+        |""".stripMargin).fromRoot { root =>
+      val res = os.proc(TestUtil.cli, "compile", sourceFileName)
+        .call(cwd = root, check = false, stderr = os.Pipe)
+      expect(res.exitCode == 1)
+      val expectedError =
+        "Values of types object scala.collection.immutable.Nil and List[A] cannot be compared with == or !="
+      expect(res.err.trim().contains(expectedError))
+    }
+  }
 }

modules/options/src/main/scala/scala/build/options/ScalacOpt.scala

@@ -15,7 +15,8 @@ final case class ScalacOpt(value: String) {
 object ScalacOpt {
   private val repeatingKeys = Set(
     "-Xplugin:",
-    "-P" // plugin options
+    "-P", // plugin options
+    "-language:"
   )
 
   implicit val hashedType: HashedType[ScalacOpt] = {