Fix string literals rendering

[Cherry-picked f039f7d]

Author: ghostbuster91

compiler/src/dotty/tools/dotc/transform/patmat/Space.scala

@@ -786,7 +786,8 @@ object SpaceEngine {
 
     def doShow(s: Space, flattenList: Boolean = false): String = s match {
       case Empty => "empty"
-      case Typ(c: ConstantType, _) => "" + c.value.value
+      case Typ(ConstantType(const : Constant), _) if const.tag == StringTag => "\"" + const.value + "\""
+      case Typ(ConstantType(const : Constant), _) => "" + const.value 
       case Typ(tp: TermRef, _) =>
         if (flattenList && tp <:< defn.NilType) ""
         else tp.symbol.showName

compiler/test/dotty/tools/dotc/reporting/CodeActionTest.scala

@@ -100,6 +100,25 @@ class CodeActionTest extends DottyTest:
          afterPhase = "patternMatcher"
       )
 
+  @Test def insertMissingCasesForUnionIntType =
+    checkCodeAction(
+      code =
+        """object Test:
+           |  def foo(text: 1 | 2) = text match {
+           |    case 2 => ???
+           |  }
+           |""".stripMargin,
+         title = "Insert missing cases (1)",
+      expected =
+        """object Test:
+           |  def foo(text: 1 | 2) = text match {
+           |    case 2 => ???
+           |    case 1 => ???
+           |  }
+           |""".stripMargin,
+         afterPhase = "patternMatcher"
+      )
+
   // Make sure we're not using the default reporter, which is the ConsoleReporter,
   // meaning they will get reported in the test run and that's it.
   private def newContext =