Perplexing type error with unboxed tuples

The fast-digits package fails to build with 8.2.0-rc1,

[1 of 2] Compiling Data.FastDigits.Internal ( src/Data/FastDigits/Internal.hs, dist/build/Data/FastDigits/Internal.o )

src/Data/FastDigits/Internal.hs:42:34: error:
    • Couldn't match a lifted type with an unlifted type
      Expected type: Word# -> (# Word#, Word# #)
        Actual type: Word# -> (# Word#, Word# #)
    • In the expression: go pw2
      In a pattern binding: (# n, pw2n #) = go pw2
      In the expression:
        let (# n, pw2n #) = go pw2
        in
          case timesWord2# pw pw2n of
            (# 0##, pw2n1 #) -> (# n `timesWord#` 2## `plusWord#` 1##, pw2n1 #)
            _ -> (# n `timesWord#` 2##, pw2n #)
   |
42 |           -> let (# n, pw2n #) = go pw2 in
   |                                  ^^^^^^

src/Data/FastDigits/Internal.hs:43:33: error:
    • Couldn't match a lifted type with an unlifted type
      When matching the kind of ‘Word#’
    • In the second argument of ‘timesWord2#’, namely ‘pw2n’
      In the expression: timesWord2# pw pw2n
      In the expression:
        case timesWord2# pw pw2n of
          (# 0##, pw2n1 #) -> (# n `timesWord#` 2## `plusWord#` 1##, pw2n1 #)
          _ -> (# n `timesWord#` 2##, pw2n #)
   |
43 |             case timesWord2# pw pw2n of
   |                                 ^^^^

src/Data/FastDigits/Internal.hs:44:37: error:
    • Couldn't match a lifted type with an unlifted type
      When matching the kind of ‘Word#’
    • In the first argument of ‘timesWord#’, namely ‘n’
      In the first argument of ‘plusWord#’, namely ‘n `timesWord#` 2##’
      In the expression: n `timesWord#` 2## `plusWord#` 1##
   |
44 |               (# 0##, pw2n1 #) -> (#n `timesWord#` 2## `plusWord#` 1##, pw2n1 #)
   |                                     ^

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Compiler
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