T14059b.hs:24:1: warning: [GHC-62161] [-Wincomplete-patterns (in -Wextra)]
    Pattern match(es) are non-exhaustive
    In an equation for ‘wibble’:
        Patterns of type ‘Sing z’ not matched: SFalse

T14059b.hs:27:1: warning: [GHC-62161] [-Wincomplete-patterns (in -Wextra)]
    Pattern match(es) are non-exhaustive
    In an equation for ‘wobble’:
        Patterns of type ‘Sing z’ not matched: SFalse