ref6 example from StaticPointers documentation doesn't type check

The documentation for StaticPointers contains the following example.

ref6 y = let x = 1 in static x

but this doesn't get accepted by the type checker.

sp.hs:27:23: error:
    • ‘x’ is used in a static form but it is not closed because it
      has a non-closed type because it contains the
      type variables: ‘p_a7KP’
    • In the expression: static x
      In the expression: let x = 1 in static x
      In an equation for ‘ref6’: ref6 y = let x = 1 in static x
   |
27 | ref6 y = let x = 1 in static x
   |                       ^^^^^^^

I tested on 8.6.1, 8.4.3, 8.2.2, 8.02, 7.10.3 and all fail.

Trac metadata

Trac field	Value
Version	8.4.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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