bug#49326: haskell-build-tool: specifying a haskell version breaks some builds

bug#49326: haskell-build-tool: specifying a haskell version breaks some builds

[Philip Munksgaard]

[-- Attachment #1: Type: text/plain, Size: 397 bytes --]

The attached versions.scm has been generated using `guix import hackage versions` and specifying that I want to build it with `#:haskell ,ghc-8.8`. Upon building, I get the error posted here: http://paste.debian.net/1203119/

I'm not entirely sure what the problem is, but it seems like when another version of ghc has been specified, dependencies built with another version of ghc no longer work.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: versions.scm --]
[-- Type: text/x-scheme; name="versions.scm", Size: 2139 bytes --]

(use-modules (guix packages))
(use-modules (guix download))
(use-modules (guix build-system haskell))
(use-modules (guix licenses))
(use-modules (gnu packages))
(use-modules (gnu packages haskell))
(use-modules (gnu packages haskell-xyz))
(use-modules (gnu packages haskell-crypto))
(use-modules (gnu packages haskell-check))

(define-public ghc-versions
  (package
    (name "ghc-versions")
    (version "5.0.0")
    (source
      (origin
        (method url-fetch)
        (uri (string-append
               "https://hackage.haskell.org/package/versions/versions-"
               version
               ".tar.gz"))
        (sha256
          (base32
            "1rfxjivdsaqc6w7dfqdycy3a81rsajvpfyi5si9ssc0w3ljfsbzr"))))
    (build-system haskell-build-system)
    (arguments `(#:haskell ,ghc-8.8))
    (inputs
      `(("ghc-megaparsec" ,ghc-megaparsec)
        ("ghc-hashable" ,ghc-hashable)
        ("ghc-parser-combinators"
         ,ghc-parser-combinators)))
    (native-inputs
      `(("ghc-microlens" ,ghc-microlens)
        ("ghc-quickcheck" ,ghc-quickcheck)
        ("ghc-tasty" ,ghc-tasty)
        ("ghc-tasty-hunit" ,ghc-tasty-hunit)
        ("ghc-tasty-quickcheck" ,ghc-tasty-quickcheck)))
    (home-page
      "https://github.com/fosskers/versions")
    (synopsis
      "Types and parsers for software version numbers.")
    (description
      "A library for parsing and comparing software version numbers. We like to give version numbers to our software in a myriad of ways. Some ways follow strict guidelines for incrementing and comparison. Some follow conventional wisdom and are generally self-consistent. Some are just plain asinine. This library provides a means of parsing and comparing /any/ style of versioning, be it a nice Semantic Version like this: . > 1.2.3-r1+git123 . ...or a monstrosity like this: . > 2:10.2+0.0093r3+1-1 . Please switch to <http://semver.org Semantic Versioning> if you aren't currently using it. It provides consistency in version incrementing and has the best constraints on comparisons. . This library implements version @2.0.0@ of the SemVer spec.")
    (license bsd-3)))

ghc-versions