Make sure that toFunctionType deos not have a method type as return type

Without this change we got types like `Int => (n: Int): Int`, now we get `Int => Int => Int`.
The first type happened to work fine but is not consistent.

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -1442,9 +1442,13 @@ object Types {
         val formals1 = if (dropLast == 0) mt.paramInfos else mt.paramInfos dropRight dropLast
         val isImplicit = mt.isImplicitMethod && !ctx.erasedTypes
         val isErased = mt.isErasedMethod && !ctx.erasedTypes
+        val result1 = mt.nonDependentResultApprox match {
+          case res: MethodType => res.toFunctionType()
+          case res => res
+        }
         val funType = defn.FunctionOf(
           formals1 mapConserve (_.underlyingIfRepeated(mt.isJavaMethod)),
-          mt.nonDependentResultApprox, isImplicit, isErased)
+          result1, isImplicit, isErased)
         if (mt.isResultDependent) RefinedType(funType, nme.apply, mt)
         else funType
     }

compiler/src/dotty/tools/dotc/tastyreflect/QuotedOpsImpl.scala

@@ -6,7 +6,7 @@ import dotty.tools.dotc.core.Flags._
 import dotty.tools.dotc.core.Symbols.defn
 import dotty.tools.dotc.core.StdNames.nme
 import dotty.tools.dotc.core.quoted.PickledQuotes
-import dotty.tools.dotc.core.Types.MethodType
+import dotty.tools.dotc.core.Types
 
 trait QuotedOpsImpl extends scala.tasty.reflect.QuotedOps with CoreImpl {
 
@@ -25,12 +25,12 @@ trait QuotedOpsImpl extends scala.tasty.reflect.QuotedOps with CoreImpl {
       val expectedType = QuotedTypeDeco(implicitly[scala.quoted.Type[T]]).unseal.tpe
 
       def etaExpand(term: Term): Term = term.tpe.widen match {
-        case mtpe: MethodType =>
+        case mtpe: Types.MethodType if !mtpe.isParamDependent =>
           val closureResType = mtpe.resType match {
-            case t: MethodType => t.toFunctionType()
+            case t: Types.MethodType => t.toFunctionType()
             case t => t
           }
-          val closureTpe = MethodType(mtpe.paramNames, mtpe.paramInfos, closureResType)
+          val closureTpe = Types.MethodType(mtpe.paramNames, mtpe.paramInfos, closureResType)
           val closureMethod = ctx.newSymbol(ctx.owner, nme.ANON_FUN, Synthetic | Method, closureTpe)
           tpd.Closure(closureMethod, tss => etaExpand(new tpd.TreeOps(term).appliedToArgs(tss.head)))
         case _ => term

tests/run/tasty-seal-method/quoted_2.scala

@@ -9,13 +9,17 @@ object Test {
     assert(zeroLastArgs(f1(2)) == 1)
     assert(zeroLastArgs(f2(2, 3)) == 2)
     assert(zeroLastArgs(f3(2)(4, 5)) == 5)
+    assert(zeroLastArgs(f4(2, 3)(4, 5)) == 9)
+    assert(zeroLastArgs(f6(2, 3)(4, 5)(6, 7)) == 20)
 
     assert(zeroAllArgs(-1) == -1)
     assert(zeroAllArgs(f) == 41)
     assert(zeroAllArgs(f0()) == 42)
     assert(zeroAllArgs(f1(2)) == 1)
     assert(zeroAllArgs(f2(2, 3)) == 2)
     assert(zeroAllArgs(f3(2)(4, 5)) == 3)
+    assert(zeroAllArgs(f4(2, 3)(4, 5)) == 4)
+    assert(zeroAllArgs(f6(2, 3)(4, 5)(6, 7)) == 6)
   }
 
   def f: Int = 41
@@ -24,5 +28,6 @@ object Test {
   def f2(i: Int, j: Int): Int = 2 + i + j
   def f3(i: Int)(j: Int, k: Int): Int = 3 + i + j
   def f4(i: Int, j: Int)(k: Int, l: Int): Int = 4 + i + j + k + l
+  def f6(i: Int, j: Int)(k: Int, l: Int)(m: Int, n: Int): Int = 6 + i + j + k + l + m + n
 
 }