multiple-libs-2.cabal:17:3: The field "visibility" is available only since the Cabal specification version 3.0. This field will be ignored. cabal-version: 2.0 name: multiple-libs version: 0 synopsis: visible flag only since 3.0 build-type: Simple library exposed-modules: ElseIf default-language: Haskell2010 build-depends: base -any library public exposed-modules: ElseIf2 default-language: Haskell2010 build-depends: base -any