SPARK-17424: Fix unsound substitution bug in ScalaReflection.

rdblue · rdblue · commit 931f156450da · 2016-09-12T10:25:10.000-07:00
Substitution fails when the actual type args are empty because they are
still unknown. Instead, when there are no resolved types to subsitute,
return the formal type args with unresovled type parameters.
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/ScalaReflection.scala
@@ -785,8 +785,16 @@ trait ScalaReflection {
   def getConstructorParameters(tpe: Type): Seq[(String, Type)] = {
     val formalTypeArgs = tpe.typeSymbol.asClass.typeParams
     val TypeRef(_, _, actualTypeArgs) = tpe
-    constructParams(tpe).map { p =>
-      p.name.toString -> p.typeSignature.substituteTypes(formalTypeArgs, actualTypeArgs)
+    val params = constructParams(tpe)
+    // if there are type variables to fill in, do the substitution (SomeClass[T] -> SomeClass[Int])
+    if (actualTypeArgs.nonEmpty) {
+      params.map { p =>
+        p.name.toString -> p.typeSignature.substituteTypes(formalTypeArgs, actualTypeArgs)
+      }
+    } else {
+      params.map { p =>
+        p.name.toString -> p.typeSignature
+      }
     }
   }
 
