SI-6215 Fix compiler crash on private method in value class

Fixes the problem with private defs in value classes by moving the $extension after the name proper rather than before. The previous scheme did not commute with makeNonPrivate:

I.e. if -ext-> is "generate extension name" and -mnp-> is "make not private" we did get for
method foo in value class Foo:

  foo -ext-> extension$foo -mnp-> Foo$$extension$foo

but

  foo -mnp-> Foo$$foo -ext-> extension$Foo$$foo

With the change both variations give the same name:

  foo -ext-> foo$extension -mnp-> Foo$$foo$extension

but

  foo -mnp-> Foo$$foo -ext-> Foo$$foo$extension

3 files changed, 13 insertions, 12 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala b/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
index 8a9d0e58ec..6dd937c0ad 100644
--- a/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExtensionMethods.scala
@@ -56,11 +56,11 @@ abstract class ExtensionMethods extends Transform with TypingTransformers {
       case OverloadedType(_, alts) =>
         val index = alts indexOf imeth
         assert(index >= 0, alts+" does not contain "+imeth)
-        def altName(index: Int) = newTermName("extension"+index+"$"+imeth.name)
+        def altName(index: Int) = newTermName(imeth.name+"$extension"+index)
         altName(index) #:: ((0 until alts.length).toStream filter (index != _) map altName)
       case tpe =>
         assert(tpe != NoType, imeth.name+" not found in "+imeth.owner+"'s decls: "+imeth.owner.info.decls)
-        Stream(newTermName("extension$"+imeth.name))
+        Stream(newTermName(imeth.name+"$extension"))
     }
   }
 
@@ -68,10 +68,10 @@ abstract class ExtensionMethods extends Transform with TypingTransformers {
    */
   def extensionMethod(imeth: Symbol): Symbol = atPhase(currentRun.refchecksPhase) {
     val companionInfo = imeth.owner.companionModule.info
-    val candidates = extensionNames(imeth) map (companionInfo.decl(_))
+    val candidates = extensionNames(imeth) map (companionInfo.decl(_)) filter (_.exists)
     val matching = candidates filter (alt => normalize(alt.tpe, imeth.owner) matches imeth.tpe)
     assert(matching.nonEmpty,
-      s"no extension method found for $imeth:${imeth.tpe}+among ${candidates map (c => c.name+":"+c.tpe)} / ${extensionNames(imeth)}")
+      s"no extension method found for $imeth:${imeth.tpe} among ${candidates map (c => c.name+":"+c.tpe)} / ${extensionNames(imeth)}")
     matching.head
   }
 
diff --git a/test/files/pos/t6215.scala b/test/files/pos/t6215.scala
new file mode 100644
index 0000000000..2f66892b69
--- /dev/null
+++ b/test/files/pos/t6215.scala
@@ -0,0 +1 @@
+class Foo(val v: String) extends AnyVal { private def len = v.length ; def f = len }
diff --git a/test/files/run/t6344.check b/test/files/run/t6344.check
index 5ac04d0320..8d9adac849 100644
--- a/test/files/run/t6344.check
+++ b/test/files/run/t6344.check
@@ -101,14 +101,14 @@ public int ValueInt.x()
 public int ValueInt.x()
 public java.lang.Object ValueInt.x()
 public java.lang.Object ValueInt.x()
-public static Gen ValueInt.extension$plus(int,Gen,Gen)
-public static Gen<java.lang.Object> ValueInt.extension$plus(int,Gen<java.lang.Object>,Gen<java.lang.Object>)
-public static boolean ValueInt.extension$equals(int,java.lang.Object)
-public static boolean ValueInt.extension$equals(int,java.lang.Object)
-public static int ValueInt.extension$hashCode(int)
-public static int ValueInt.extension$hashCode(int)
-public static int ValueInt.extension$iplus(int,int,int)
-public static int ValueInt.extension$iplus(int,int,int)
+public static Gen ValueInt.plus$extension(int,Gen,Gen)
+public static Gen<java.lang.Object> ValueInt.plus$extension(int,Gen<java.lang.Object>,Gen<java.lang.Object>)
+public static boolean ValueInt.equals$extension(int,java.lang.Object)
+public static boolean ValueInt.equals$extension(int,java.lang.Object)
+public static int ValueInt.hashCode$extension(int)
+public static int ValueInt.hashCode$extension(int)
+public static int ValueInt.iplus$extension(int,int,int)
+public static int ValueInt.iplus$extension(int,int,int)
 
 RefInt
 public Gen RefInt.plus(Gen,Gen)