Unhelpful error message about "hidden" packages

Anatoly Yakonenko reported: I am trying to build ParseP on the latest ghc, and I am getting this error:

 Text/ParserCombinators/ParseP/Interface.hs:26:17:
    Could not find module `Data.ByteString.Char8':
      it is a member of package bytestring-0.9.1.4, which is hidden

Ross Mellgren responded (correctly): I assume you're using cabal, which hides all packages by default. Add "bytestring" or "bytestring >= 0.9.*" or something along those lines to Build-Depends in your .cabal file.

Suggestion: improve GHC's error message.

Trac metadata

Trac field	Value
Version	6.10.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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Unhelpful error message about "hidden" packages