"MulipleResultsBug"

[jgm]

General summary/comments (optional)

I'm getting a MulipleResultsBug (sic) on stack builds in CI for pandoc.

Steps to reproduce

See https://github.com/jgm/pandoc/actions/runs/4038196626/jobs/6942025643 or any of the recent pandoc CI builds.

Expected

Expected project to build normally.

Actual

MulipleResultsBug
  (PackageName "z-pandoc-z-xml-light")
  [ DumpPackage
      { dpGhcPkgId = "pandoc-3.0.1-77ZLKePxhTaCRRSLZRG4Rc-xml-light"
      , dpPackageIdent =
          PackageIdentifier
            { pkgName = PackageName "z-pandoc-z-xml-light"
            , pkgVersion = mkVersion [ 3 , 0 , 1 ]
            }
      , dpParentLibIdent =
          Just
            PackageIdentifier
              { pkgName = PackageName "pandoc"
              , pkgVersion = mkVersion [ 3 , 0 , 1 ]
              }
      , dpLicense = Just (GPL (Just (mkVersion [ 2 , 0 ])))
      , dpLibDirs =
          [ "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\lib\\x86_64-windows-ghc-9.2.5\\pandoc-3.0.1-77ZLKePxhTaCRRSLZRG4Rc-xml-light"
          , "C:\\Users\\runneradmin\\AppData\\Local\\Programs\\stack\\x86_64-windows\\msys2-20221216\\mingw64\\lib"
          , "C:\\Users\\runneradmin\\AppData\\Local\\Programs\\stack\\x86_64-windows\\msys2-20221216\\mingw64\\bin"
          ]
      , dpLibraries =
          [ "HSpandoc-3.0.1-77ZLKePxhTaCRRSLZRG4Rc-xml-light" ]
      , dpHasExposedModules = True
      , dpExposedModules =
          fromList
            [ ModuleName "Text.Pandoc.XML.Light"
            , ModuleName "Text.Pandoc.XML.Light.Output"
            , ModuleName "Text.Pandoc.XML.Light.Proc"
            , ModuleName "Text.Pandoc.XML.Light.Types"
            ]
      , dpDepends =
          [ "base-4.16.4.0"
          , "containers-0.6.5.1"
          , "text-1.2.5.0"
          , "xml-1.3.14-KiW89sjmbIPAlN8B4nqhKb"
          , "xml-conduit-1.9.1.1-2pcaBXY4SmGGVoz4CdA3uA"
          , "xml-types-0.3.8-LZyzf9bLT8K9kdiyyQ9IUF"
          ]
      , dpHaddockInterfaces =
          [ "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\doc\\pandoc-3.0.1\\pandoc.haddock"
          ]
      , dpHaddockHtml =
          Just
            "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\doc\\pandoc-3.0.1"
      , dpIsExposed = False
      }
  , DumpPackage
      { dpGhcPkgId = "pandoc-3.0-HOHiVyu81CU8bKnUqaz1c5-xml-light"
      , dpPackageIdent =
          PackageIdentifier
            { pkgName = PackageName "z-pandoc-z-xml-light"
            , pkgVersion = mkVersion [ 3 , 0 ]
            }
      , dpParentLibIdent =
          Just
            PackageIdentifier
              { pkgName = PackageName "pandoc"
              , pkgVersion = mkVersion [ 3 , 0 ]
              }
      , dpLicense = Just (GPL (Just (mkVersion [ 2 , 0 ])))
      , dpLibDirs =
          [ "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\lib\\x86_64-windows-ghc-9.2.5\\pandoc-3.0-HOHiVyu81CU8bKnUqaz1c5-xml-light"
          , "C:\\Users\\runneradmin\\AppData\\Local\\Programs\\stack\\x86_64-windows\\msys2-20221216\\mingw64\\lib"
          , "C:\\Users\\runneradmin\\AppData\\Local\\Programs\\stack\\x86_64-windows\\msys2-20221216\\mingw64\\bin"
          ]
      , dpLibraries = [ "HSpandoc-3.0-HOHiVyu81CU8bKnUqaz1c5-xml-light" ]
      , dpHasExposedModules = True
      , dpExposedModules =
          fromList
            [ ModuleName "Text.Pandoc.XML.Light"
            , ModuleName "Text.Pandoc.XML.Light.Output"
            , ModuleName "Text.Pandoc.XML.Light.Proc"
            , ModuleName "Text.Pandoc.XML.Light.Types"
            ]
      , dpDepends =
          [ "base-4.16.4.0"
          , "containers-0.6.5.1"
          , "text-1.2.5.0"
          , "xml-1.3.14-KiW89sjmbIPAlN8B4nqhKb"
          , "xml-conduit-1.9.1.1-2pcaBXY4SmGGVoz4CdA3uA"
          , "xml-types-0.3.8-LZyzf9bLT8K9kdiyyQ9IUF"
          ]
      , dpHaddockInterfaces =
          [ "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\doc\\pandoc-3.0\\pandoc.haddock"
          ]
      , dpHaddockHtml =
          Just
            "D:\\a\\pandoc\\pandoc\\.stack-work\\install\\8b79c707\\doc\\pandoc-3.0"
      , dpIsExposed = False
      }
  ]

pandoc has an internal library xml-light, and it seems that the problem here is that stack is finding two copies, one cached from pandoc 3.0 and one from pandoc 3.0.1.

I would have thought stack would know to use the one from pandoc 3.0.1.

Stack version

2.9.3 installed on GitHub actions Windows 2019 CI VM.

Method of installation

CI

Platform

Windows 2019

[jgm]

I solved my own problem by deleting the cache and building again, but this still seems like non-optimal behavior.

[mpilgrem]

@jgm, thanks for reporting. I see that, at the very least, I need to fix how that bug is reported by Stack.

[mpilgrem]

I can reproduce this bug locally on Windows by:

1. Cloning the pandoc repository (currently pandoc-3.0.1)
2. stack test, after renaming the package to pandoc-3.0.0
3. stack test, after reverting the package name to pandoc-3.0.1

[mpilgrem]

Some notes for my own use:

stack exec -- ghc-pkg list -v has (extract):

C:\Users\mikep\Documents\Code\GitHub\pandoc\.stack-work\install\4ca13fc5\pkgdb
    pandoc-3.0.1 (pandoc-3.0.1-Dm0IhW6A8PTLZ0SLxb8qEw)
    (z-pandoc-z-xml-light-3.0.0 (pandoc-3.0.0-DFdhTdyCRzO7qwWvMULv7q-xml-light))
    (z-pandoc-z-xml-light-3.0.1 (pandoc-3.0.1-77ZLKePxhTaCRRSLZRG4Rc-xml-light))

Is the problem 'unregistering'? When local pandoc-3.0.1 is built, the existing pandoc-3.0.0 is unregistered, but z-pandoc-z-xml-light-3.0.0 (the munged package identifier for the internal library xml-light) is not unregistered.

[mpilgrem]

@jgm, I have proposed a pull request that I believe fixes this. My diagnosis was that something was amiss with the unregistering of a local package for a sub library of a parent package that was itself to be unregistered.

[jgm]

Great - I can't comment on the pull, as I don't know how stack works, but that seems plausible to me.
Feel free to close. I can't test this organically any more as I avoided the issue in another way.