fixes #6732 (#11255)

tests/generics/tprevent_double_bind.nim

@@ -0,0 +1,21 @@
+discard """
+  errormsg: "type mismatch: got <TT[seq[string]], proc (v: int){.gcsafe, locks: 0.}>"
+  line: 20
+"""
+
+# bug #6732
+import typetraits
+
+type
+  TT[T] = ref object of RootObj
+    val: T
+  CB[T] = proc (v: T)
+
+proc testGeneric[T](val: TT[T], cb: CB[T]) =
+  echo val.type.name
+  echo $val.val
+
+var tt = new(TT[seq[string]])
+echo tt.type.name
+tt.testGeneric( proc (v: int) =
+    echo $v )