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dhall-lang / dhall-haskell

Maintainable configuration files
https://dhall-lang.org/
BSD 3-Clause "New" or "Revised" License
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Build failure on GHC 9.8.1: 'Illegal invisible type variable binder' #2567

Open Vekhir opened 7 months ago

Vekhir commented 7 months ago

Hi, when building dhall 1.42.1 on Arch Linux with GHC 9.8.1 and template-haskell 2.21.0.0, the following error occurs while building the tests:

tests/Dhall/Test/TH.hs:111:1: error: [GHC-58589]
    Illegal invisible type variable binder: @b0
    Suggested fix: Perhaps you intended to use TypeAbstractions
    |
111 | Dhall.TH.makeHaskellTypesWith (Dhall.TH.defaultGenerateOptions
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

The same error occurs 4 times (see Appendix). The error itself suggests to use TypeAbstractions to fix the issue.\ The offending line is dhall/tests/Dhall/Test/TH.hs#L111, and the issue doesn't seem fixed on main.

template-haskell from 2.21 onwards supports Invisible binders in type declarations, see also the migration guide and GHC proposal #425.\ dhall 1.42.1 advertises support for template-haskell 2.21 and GHC 9.8 - not sure what's going on there.

-- Vekhir

Appendix

[ 5 of 21] Compiling Dhall.Test.TH    ( tests/Dhall/Test/TH.hs, dist/build/tasty/tasty-tmp/Dhall/Test/TH.dyn_o )

tests/Dhall/Test/TH.hs:111:1: error: [GHC-58589]
    Illegal invisible type variable binder: @a0
    Suggested fix: Perhaps you intended to use TypeAbstractions
    |
111 | Dhall.TH.makeHaskellTypesWith (Dhall.TH.defaultGenerateOptions
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

tests/Dhall/Test/TH.hs:111:1: error: [GHC-58589]
    Illegal invisible type variable binder: @a1
    Suggested fix: Perhaps you intended to use TypeAbstractions
    |
111 | Dhall.TH.makeHaskellTypesWith (Dhall.TH.defaultGenerateOptions
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

tests/Dhall/Test/TH.hs:111:1: error: [GHC-58589]
    Illegal invisible type variable binder: @b0
    Suggested fix: Perhaps you intended to use TypeAbstractions
    |
111 | Dhall.TH.makeHaskellTypesWith (Dhall.TH.defaultGenerateOptions
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

tests/Dhall/Test/TH.hs:111:1: error: [GHC-58589]
    Illegal invisible type variable binder: @a0
    Suggested fix: Perhaps you intended to use TypeAbstractions
    |
111 | Dhall.TH.makeHaskellTypesWith (Dhall.TH.defaultGenerateOptions
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...