Build failure with ghc 8.10.3 and 8.10.4

[carlocab]

I'm updating Homebrew's version of ghc from 8.10.3 to 8.10.4 here: Homebrew/homebrew-core#70817

Homebrew CI tests all packages that depend on ghc, and this revealed a build failure for cryptol (on macOS 10.14, 10.15, and 11.2), with the following message:

src/Cryptol/Backend/FloatHelpers.hs:194:40: error:
    • Couldn't match expected type ‘Word’ with actual type ‘Int’
    • In the first argument of ‘precBits’, namely ‘(p' + 1)’
      In the first argument of ‘(<>)’, namely ‘precBits (p' + 1)’
      In the second argument of ‘(<>)’, namely
        ‘precBits (p' + 1) <> allowSubnormal’
    |
194 |   opts       = expBits e' <> precBits (p' + 1) <> allowSubnormal
    |                                        ^^^^^^

Upon testing, it seems I get this same build error with 8.10.3 as well, though I'm not sure what's changed since then. Assistance on this would be appreciated.

Build logs available at https://github.com/Homebrew/homebrew-core/actions/runs/571177255 (ignore the 11-arm failure, since ghc does not build on Apple M1)

On 11.2, the crpytol build starts at https://github.com/Homebrew/homebrew-core/runs/1909553886?check_suite_focus=true#step:7:166

[yav]

This is probably because cryptol didn't have an upper bound on its dependency of libBF and libBF had an update which is not compatible with the previous one. To make it work you'd need to use libBF-0.5.1

I'll leave this open because we still don't have an upper bound on libBF and we should add one to avoid this sort of thing in the future.

[carlocab]

Thanks; that does seem to work: https://github.com/Homebrew/homebrew-core/actions/runs/575623369

At least, it worked on macOS 10.14. Still waiting on 10.15 and 11.2.

I noticed that the libBF dependency is declared differently on master:

cryptol/cryptol.cabal

Line 60 in 5f3ff5b

libBF >= 0.6 && < 0.7,

I take it pinning this dependency should no longer be needed in the next version?

[robdockins]

Correct, the next release should no longer require pinning to libBF=0.5.1

[robdockins]

I believe the new release should have resolved this issue.