Add regression test for issue 18726 (#20318)

Closes #18726

[test_windows_full]

Author: tgodzik

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -287,7 +287,6 @@ object Completion:
     if denot.isType then denot.symbol.showFullName
     else denot.info.widenTermRefExpr.show
 
-
   def isInNewContext(untpdPath: List[untpd.Tree]): Boolean =
     untpdPath match
       case _ :: untpd.New(selectOrIdent: (untpd.Select | untpd.Ident)) :: _ => true

presentation-compiler/src/main/dotty/tools/pc/ScalaPresentationCompiler.scala

@@ -60,7 +60,7 @@ case class ScalaPresentationCompiler(
   val scalaVersion = BuildInfo.scalaVersion
 
   private val forbiddenOptions = Set("-print-lines", "-print-tasty")
-  private val forbiddenDoubleOptions = Set("-release")
+  private val forbiddenDoubleOptions = Set.empty[String]
 
   given ReportContext =
     folderPath

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionRelease11Suite.scala

@@ -0,0 +1,32 @@
+package dotty.tools.pc.tests.completion
+
+import dotty.tools.pc.base.BaseCompletionSuite
+
+import org.junit.Test
+import org.junit.Before
+import java.nio.file.Path
+import dotty.tools.pc.utils.JRE
+
+class CompletionRelease11Suite extends BaseCompletionSuite:
+
+  override protected def scalacOptions(classpath: Seq[Path]): Seq[String] =
+    "-release:11" +: super.scalacOptions(classpath)
+
+  @Before
+  def beforeMethod(): Unit =
+    org.junit.Assume.assumeTrue(JRE.getJavaMajorVersion >= 11)
+
+  @Test def java11Symbols =
+    check(
+      """
+        |object A {
+        |  "".repea@@
+        |}""".stripMargin,
+      """repeat(x$0: Int): String
+        |replaceAll(x$0: String, x$1: String): String
+        |prependedAll[B >: A](prefix: IterableOnce[B]): IndexedSeq[B]
+        |prependedAll(prefix: String): String
+        |prependedAll[B >: Char](prefix: IterableOnce[B]): IndexedSeq[B]
+        |replaceAllLiterally(literal: String, replacement: String): String
+        |""".stripMargin
+    )

presentation-compiler/test/dotty/tools/pc/tests/completion/CompletionRelease8Suite.scala

@@ -0,0 +1,31 @@
+package dotty.tools.pc.tests.completion
+
+import dotty.tools.pc.base.BaseCompletionSuite
+
+import org.junit.Test
+import org.junit.Before
+import java.nio.file.Path
+import dotty.tools.pc.utils.JRE
+
+class CompletionRelease8Suite extends BaseCompletionSuite:
+
+  override protected def scalacOptions(classpath: Seq[Path]): Seq[String] =
+    "-release:8" +: super.scalacOptions(classpath)
+
+  @Before
+  def beforeMethod(): Unit =
+    org.junit.Assume.assumeTrue(JRE.getJavaMajorVersion >= 8)
+
+  @Test def noJvm11Symbols =
+    check(
+      """
+        |object A {
+        |  "".repea@@
+        |}""".stripMargin,
+      """replaceAll(x$0: String, x$1: String): String
+        |prependedAll[B >: A](prefix: IterableOnce[B]): IndexedSeq[B]
+        |prependedAll(prefix: String): String
+        |prependedAll[B >: Char](prefix: IterableOnce[B]): IndexedSeq[B]
+        |replaceAllLiterally(literal: String, replacement: String): String
+        |""".stripMargin
+    )

presentation-compiler/test/dotty/tools/pc/utils/JRE.scala

@@ -0,0 +1,13 @@
+package dotty.tools.pc.utils
+
+object JRE:
+
+  def getJavaMajorVersion: Int =
+    val javaVersion = sys.env.get("java.specification.version").filter(!_.isEmpty())
+
+    javaVersion match
+      case Some(version) if version.startsWith("1.8") => 8
+      case Some(version) => version.toInt // it is better to crash during tests than to run incorrect suite
+      case None => 8
+
+