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  • Andrei Borzenkov's avatar
    Fix printing of promoted MkSolo datacon (#22785) · 14b5982a
    Andrei Borzenkov authored and Marge Bot's avatar Marge Bot committed
    Problem: In 2463df2f, the Solo data constructor was renamed to MkSolo,
    and Solo was turned into a pattern synonym for backwards compatibility.
    Since pattern synonyms can not be promoted, the old code that pretty-printed
    promoted single-element tuples started producing ill-typed code:
       t :: Proxy ('Solo Int)
    This fails with "Pattern synonym ‘Solo’ used as a type"
    
    The solution is to track the distinction between type constructors and data
    constructors more carefully when printing single-element tuples.
    14b5982a