SI-6138 Centralize and refine detection of `getClass` calls

`getClass` is special cased in the compiler; this is described
in in the comments on `Definitions.Any_getClass`.

Part of this happens in `Typer#stabilize`. This was trying to determine
if an Ident or Select node was a call to `getClass` by merits of the name
of the tree's symbol and by checking that the its type (if it was a
MethodType or PolyType) had no parameters in the primary parameter list.

Overloaded user defined `getClass` methods confused this check. In the
enclosed test case, the tree `definitions.this.getClass` had an
`OverloadedType`, and such types always report an empty list of `params`.

This commit:

  - changes `stabilize` to use `isGetClass`, rather than the
    homebrew check
  - changes `isGetClass` to consider a `Set[Symbol]` containing all
    `getClass` variants. This moves some similar code from `Erasure`
    to `Definitions`
  - keeps a fast negative path in `isGetClass` based on the symbol's name

2 files changed, 1 insertions, 7 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Erasure.scala b/src/compiler/scala/tools/nsc/transform/Erasure.scala
index ead6ef288c..76249974ac 100644
--- a/src/compiler/scala/tools/nsc/transform/Erasure.scala
+++ b/src/compiler/scala/tools/nsc/transform/Erasure.scala
@@ -341,11 +341,6 @@ abstract class Erasure extends AddInterfaces
     }
   }
   
-  // Each primitive value class has its own getClass for ultra-precise class object typing.
-  private lazy val primitiveGetClassMethods = Set[Symbol](Any_getClass, AnyVal_getClass) ++ (
-    ScalaValueClasses map (_.tpe member nme.getClass_)
-  )
-  
   // ## requires a little translation
   private lazy val poundPoundMethods = Set[Symbol](Any_##, Object_##)
   
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index c59ef4ebda..29cd3d4bfa 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -656,8 +656,7 @@ trait Typers extends Modes with Adaptations with Tags {
         // To fully benefit from special casing the return type of
         // getClass, we have to catch it immediately so expressions
         // like x.getClass().newInstance() are typed with the type of x.
-        else if (  tree.symbol.name == nme.getClass_
-                && tree.tpe.params.isEmpty
+        else if (  isGetClass(tree.symbol)
                 // TODO: If the type of the qualifier is inaccessible, we can cause private types
                 // to escape scope here, e.g. pos/t1107.  I'm not sure how to properly handle this
                 // so for now it requires the type symbol be public.