fixes #25167; fixes deref type (#25195)

fixes #25167

Author: ringabout

compiler/transf.nim

@@ -834,7 +834,9 @@ proc transformFor(c: PTransf, n: PNode): PNode =
         var temp = newTemp(c, arg[0].typ, formal.info)
         addVar(v, temp)
         stmtList.add(newAsgnStmt(c, nkFastAsgn, temp, arg[0], true))
-        newC.mapping[formal.itemId] = newDeref(temp)
+        let newD = newDeref(temp)
+        newD.typ() = t
+        newC.mapping[formal.itemId] = newD
       else:
         # generate a temporary and produce an assignment statement:
         var temp = newTemp(c, t, formal.info)

tests/iter/titer_issues.nim

@@ -424,3 +424,11 @@ block: # bug #25121
   for _ in k():
     (proc() = (; let _ = block: 0))()
 
+let aaa = new array[1000, byte]
+block:
+  for _ in cast[typeof(aaa)](aaa)[]:
+    discard
+block:
+  let x = cast[typeof(aaa)](aaa)   # not even var
+  for _ in x[]:
+    discard