SI-7779 Account for class name compactification in reflection

We have to assume that the classes we are reflecting on were
compiled with the default value for -Xmax-classfile-name (255).

With this assumption, we can apply the same name compactification
as done in the regular compiler.

The REPL is particularly prone to generating long class names
with the '$iw' prefixes, so this is an important fix for runtime
reflection.

Also adds support for getting the runtime class of `O.type` if
`O` is a module.

2 files changed, 15 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/StdNames.scala b/src/reflect/scala/reflect/internal/StdNames.scala
index de7af4340d..c3b7f24a9d 100644
--- a/src/reflect/scala/reflect/internal/StdNames.scala
+++ b/src/reflect/scala/reflect/internal/StdNames.scala
@@ -44,6 +44,7 @@ trait StdNames {
     }
   }
 
+  private[reflect] def compactifyName(orig: String): String = compactify(orig)
   private final object compactify extends (String => String) {
     val md5 = MessageDigest.getInstance("MD5")
 
diff --git a/src/reflect/scala/reflect/runtime/JavaMirrors.scala b/src/reflect/scala/reflect/runtime/JavaMirrors.scala
index 22fe7f098c..6fdb238462 100644
--- a/src/reflect/scala/reflect/runtime/JavaMirrors.scala
+++ b/src/reflect/scala/reflect/runtime/JavaMirrors.scala
@@ -1178,6 +1178,17 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
         var fullNameOfJavaClass = ownerClazz.getName
         if (childOfClass || childOfTopLevel) fullNameOfJavaClass += "$"
         fullNameOfJavaClass += clazz.name
+
+        // compactify (see SI-7779)
+        fullNameOfJavaClass = fullNameOfJavaClass match {
+          case PackageAndClassPattern(pack, clazzName) =>
+            // in a package
+            pack + compactifyName(clazzName)
+          case _ =>
+            // in the empty package
+            compactifyName(fullNameOfJavaClass)
+        }
+
         if (clazz.isModuleClass) fullNameOfJavaClass += "$"
 
         // println(s"ownerChildren = ${ownerChildren.toList}")
@@ -1187,6 +1198,8 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
         noClass
     }
 
+    private val PackageAndClassPattern = """(.*\.)(.*)$""".r
+
     private def expandedName(sym: Symbol): String =
       if (sym.isPrivate) nme.expandedName(sym.name.toTermName, sym.owner).toString
       else sym.name.toString
@@ -1241,6 +1254,7 @@ private[reflect] trait JavaMirrors extends internal.SymbolTable with api.JavaUni
       case TypeRef(_, ArrayClass, List(elemtpe)) => jArrayClass(typeToJavaClass(elemtpe))
       case TypeRef(_, sym: ClassSymbol, _) => classToJava(sym.asClass)
       case tpe @ TypeRef(_, sym: AliasTypeSymbol, _) => typeToJavaClass(tpe.dealias)
+      case SingleType(_, sym: ModuleSymbol) => classToJava(sym.moduleClass.asClass)
       case _ => throw new NoClassDefFoundError("no Java class corresponding to "+tpe+" found")
     }
   }