javap -c TestMatch$

  public java.lang.String foo(scala.Option<java.lang.String>);
    Code:
       0: aload_1       
       1: astore_2      
       2: aload_2       
       3: instanceof    #16                 // class scala/Some
       6: ifeq          34
       9: aload_2       
      10: checkcast     #16                 // class scala/Some
      13: astore_3      
      14: aload_3       
      15: ifnull        34
      18: aload_3       
      19: invokevirtual #20                 // Method scala/Some.x:()Ljava/lang/Object;
      22: checkcast     #22                 // class java/lang/String
      25: astore        4
      27: aload         4
      29: astore        5
      31: goto          68
      34: getstatic     #27                 // Field scala/None$.MODULE$:Lscala/None$;
      37: aload_2       
      38: astore        6
      40: dup           
      41: ifnonnull     53
      44: pop           
      45: aload         6
      47: ifnull        61
      50: goto          71
      53: aload         6
      55: invokevirtual #31                 // Method java/lang/Object.equals:(Ljava/lang/Object;)Z
      58: ifeq          71
      61: aload_2       
      62: astore        7
      64: ldc           #33                 // String 
      66: astore        5
      68: aload         5
      70: areturn       
      71: new           #35                 // class scala/MatchError
      74: dup           
      75: aload_2       
      76: invokespecial #38                 // Method scala/MatchError."<init>":(Ljava/lang/Object;)V
      79: athrow        

testMatch.scala

object TestMatch {
  def foo(x: Option[String]): String = {
    x match {
      case Some(y) => y
      case None => ""
    }
  }
}