Merge pull request #4139 from retronym/ticket/7965

SI-7965 Support calls to MethodHandle.{invoke,invokeExact}

4 files changed, 23 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 6671183ff0..5719a9e358 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -3281,6 +3281,22 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
           }
           handleOverloaded
 
+        case _ if isPolymorphicSignature(fun.symbol) =>
+          // Mimic's Java's treatment of polymorphic signatures as described in
+          // https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.12.3
+          //
+          // One can think of these methods as being infinitely overloaded. We create
+          // a ficticious new cloned method symbol for each call site that takes on a signature
+          // governed by a) the argument types and b) the expected type
+          val args1 = typedArgs(args, forArgMode(fun, mode))
+          val pts = args1.map(_.tpe.deconst)
+          val clone = fun.symbol.cloneSymbol
+          val cloneParams = pts map (pt => clone.newValueParameter(currentUnit.freshTermName()).setInfo(pt))
+          val resultType = if (isFullyDefined(pt)) pt else ObjectTpe
+          clone.modifyInfo(mt => copyMethodType(mt, cloneParams, resultType))
+          val fun1 = fun.setSymbol(clone).setType(clone.info)
+          doTypedApply(tree, fun1, args1, mode, resultType).setType(resultType)
+
         case mt @ MethodType(params, _) =>
           val paramTypes = mt.paramTypes
           // repeat vararg as often as needed, remove by-name
diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 7e2d124486..4263bbccf3 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -514,6 +514,8 @@ trait Definitions extends api.StandardDefinitions {
     lazy val ScalaSignatureAnnotation = requiredClass[scala.reflect.ScalaSignature]
     lazy val ScalaLongSignatureAnnotation = requiredClass[scala.reflect.ScalaLongSignature]
 
+    lazy val MethodHandle = getClassIfDefined("java.lang.invoke.MethodHandle")
+
     // Option classes
     lazy val OptionClass: ClassSymbol   = requiredClass[Option[_]]
     lazy val OptionModule: ModuleSymbol = requiredModule[scala.Option.type]
@@ -1508,6 +1510,9 @@ trait Definitions extends api.StandardDefinitions {
 
       lazy val PartialManifestClass  = getTypeMember(ReflectPackage, tpnme.ClassManifest)
       lazy val ManifestSymbols = Set[Symbol](PartialManifestClass, FullManifestClass, OptManifestClass)
+
+      def isPolymorphicSignature(sym: Symbol) = PolySigMethods(sym)
+      private lazy val PolySigMethods: Set[Symbol] = Set[Symbol](MethodHandle.info.decl(sn.Invoke), MethodHandle.info.decl(sn.InvokeExact)).filter(_.exists)
     }
   }
 }
diff --git a/src/reflect/scala/reflect/internal/StdNames.scala b/src/reflect/scala/reflect/internal/StdNames.scala
index 667ff7c4b4..c94ee996e4 100644
--- a/src/reflect/scala/reflect/internal/StdNames.scala
+++ b/src/reflect/scala/reflect/internal/StdNames.scala
@@ -1147,6 +1147,7 @@ trait StdNames {
     final val GetClassLoader: TermName   = newTermName("getClassLoader")
     final val GetMethod: TermName        = newTermName("getMethod")
     final val Invoke: TermName           = newTermName("invoke")
+    final val InvokeExact: TermName      = newTermName("invokeExact")
 
     val Boxed = immutable.Map[TypeName, TypeName](
       tpnme.Boolean -> BoxedBoolean,
diff --git a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
index c87b810bdd..1c0aa7cf6d 100644
--- a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
+++ b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
@@ -310,6 +310,7 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     definitions.QuasiquoteClass_api_unapply
     definitions.ScalaSignatureAnnotation
     definitions.ScalaLongSignatureAnnotation
+    definitions.MethodHandle
     definitions.OptionClass
     definitions.OptionModule
     definitions.SomeClass