fixes #4070

compiler/lambdalifting.nim

@@ -716,6 +716,7 @@ proc liftCapturedVars(n: PNode; owner: PSym; d: DetectionPass;
         #localError(n.info, "internal error: closure to closure created")
         # now we know better, so patch it:
         n.sons[0] = x.sons[0]
+        n.sons[1] = x.sons[1]
   of nkLambdaKinds, nkIteratorDef:
     if n.typ != nil and n[namePos].kind == nkSym:
       let m = newSymNode(n[namePos].sym)

tests/closure/tdeeplynested.nim

@@ -0,0 +1,20 @@
+discard """
+  output: '''108'''
+"""
+
+# bug #4070
+
+proc id(f: (proc())): auto =
+  return f
+
+proc foo(myinteger: int): (iterator(): int) =
+  return iterator(): int {.closure.} =
+           proc bar() =
+             proc kk() =
+               echo "int: ", myinteger
+
+             kk()
+
+           id(bar)()
+
+discard foo(108)()