Fix ghc 9.11 build.

[wavewave]

This fixes the following build error with GHC 9.11.20240512.

[49 of 67] Compiling TextShow.GHC.RTS.Flags ( src/TextShow/GHC/RTS/Flags.hs, /Users/ianwookim/repo/mercury/mwb-on-ghcHEAD/20240506/mwb-20240506/dist-newstyle/build/aarch64-osx/ghc-9.11.20240512/text-show-3.10.5/noopt/build/TextShow/GHC/RTS/Flags.dyn_o )
src/TextShow/GHC/RTS/Flags.hs:53:2: error: [GHC-39999]
    • No instance for ‘TextShow.Classes.TextShow IoManagerFlag’
        arising from a use of ‘TextShow.Classes.showbPrec’
    • In the first argument of ‘(<>)’, namely
        ‘TextShow.Classes.showbPrec 0 arg11_a1iZs’
      In the second argument of ‘(<>)’, namely
        ‘(TextShow.Classes.showbPrec 0 arg11_a1iZs
            <>
              (TextShow.Classes.showbCommaSpace
                 <>
                   (Data.Text.Internal.Builder.fromString "numIoWorkerThreads = "
                      <>
                        (TextShow.Classes.showbPrec 0 arg12_a1iZt
                           <> Data.Text.Internal.Builder.singleton '}'))))’
      In the second argument of ‘(<>)’, namely
        ‘(Data.Text.Internal.Builder.fromString "ioManager = "
            <>
              (TextShow.Classes.showbPrec 0 arg11_a1iZs
                 <>
                   (TextShow.Classes.showbCommaSpace
                      <>
                        (Data.Text.Internal.Builder.fromString "numIoWorkerThreads = "
                           <>
                             (TextShow.Classes.showbPrec 0 arg12_a1iZt
                                <> Data.Text.Internal.Builder.singleton '}')))))’
   |
53 | $(deriveTextShow ''MiscFlags)
   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Could you add this here or to head.hackage patch list, (as you prefer)? Thanks!

[RyanGlScott]

Thanks for the patch.

Given that this is targeting a pre-release version of GHC (and one that likely won't be released for quite a while), I'm somewhat reluctant to merge this in just yet. If it's alright with you, I'd prefer to add this to head.hackage for now as a stopgap measure.

[RyanGlScott]

I've submitted https://gitlab.haskell.org/ghc/head.hackage/-/merge_requests/369 to add this patch to head.hackage.

[RyanGlScott]

Superseded by #64.