No instance for (Text.Parser.Combinators.Parsing Parser) arising from a use of `unexpected'

[freeman42x]

How to reproduce:

checkout unexpected-bug-example branch from this fork: https://github.com/razvan-panda/parsers/tree/unexpected-bug-example

stack init
stack test

Causes following error:

[1 of 2] Compiling SemVer           ( tests/SemVer.hs, .stack-work/dist/x86_64-linux-nix/Cabal-2.0.1.0/build/quickcheck/quickcheck-tmp/SemVer.o )
            
/home/neo/Forks/parsers/tests/SemVer.hs:13:10: error:
    * No instance for (Text.Parser.Combinators.Parsing Parser)
        arising from a use of `unexpected'
    There are instances for similar types:
        instance Data.Attoparsec.Internal.Types.Chunk t =>
                Text.Parser.Combinators.Parsing
                (Data.Attoparsec.Internal.Types.Parser t)
        -- Defined in `Text.Parser.Combinators'
    * In the expression: unexpected "Leading Zeros"
    In a stmt of a 'do' block:
        if length digits > 1 && head digits == '0' then
            unexpected "Leading Zeros"
        else 
            return $ read digits
    In the expression:
        do digits <- some digit
        if length digits > 1 && head digits == '0' then
            unexpected "Leading Zeros"
        else
            return $ read digits
|         
13 |     then unexpected "Leading Zeros"
|

[RyanGlScott]

This is a Cabal issue, not a parsers issue. The advice in #73 (comment) contains a workaround.