Prepare Stack for Cabal's changing approach to hooks

[mpilgrem]

Motivation:

• https://github.com/well-typed/hooks-build-type
• RFC: Replacing the Cabal Custom build-type haskellfoundation/tech-proposals#60
• Haddock documentation for Cabal-3.11.0.0

Currently:

• Stack itself has build type Custom, which makes use of generateBuildModule; and
• Stack uses replHook in StackSetupShim.hs to cause Cabal to create the autogenerated files for every configured component, without building everything, before Stack uses ghc --interactive.

Related question: haskellfoundation/tech-proposals#60 (comment)

[mpilgrem]

Currently:

Stack has:

stackReplHook :: PackageDescription -> LocalBuildInfo -> UserHooks -> ReplFlags -> [String] -> IO ()
stackReplHook pkg_descr lbi hooks flags args = do
    let distPref = fromFlag (replDistPref flags)
        verbosity = fromFlag (replVerbosity flags)
    case args of
        ("stack-initial-build-steps":rest)
            | null rest -> initialBuildSteps distPref pkg_descr lbi verbosity
            | otherwise ->
                fail "Misuse of running Setup.hs with stack-initial-build-steps, expected no arguments"
        _ -> replHook simpleUserHooks pkg_descr lbi hooks flags args

Cabal-3.10.3.0 has:

-- | Runs 'componentInitialBuildSteps' on every configured component.
initialBuildSteps ::
     FilePath -- ^"dist" prefix
  -> PackageDescription  -- ^mostly information from the .cabal file
  -> LocalBuildInfo -- ^Configuration information
  -> Verbosity -- ^The verbosity to use
  -> IO ()
initialBuildSteps distPref pkg_descr lbi verbosity =
  withAllComponentsInBuildOrder pkg_descr lbi $ \_comp clbi ->
    componentInitialBuildSteps distPref pkg_descr lbi clbi verbosity

-- | Creates the autogenerated files for a particular configured component.
componentInitialBuildSteps :: 
     FilePath -- ^"dist" prefix
  -> PackageDescription  -- ^mostly information from the .cabal file
  -> LocalBuildInfo -- ^Configuration information
  -> ComponentLocalBuildInfo
  -> Verbosity -- ^The verbosity to use
  -> IO ()
componentInitialBuildSteps _distPref pkg_descr lbi clbi verbosity = do
  createDirectoryIfMissingVerbose verbosity True (componentBuildDir lbi clbi)
  writeAutogenFiles verbosity pkg_descr lbi clbi

-- Field of UserHooks
replHook :: PackageDescription -> LocalBuildInfo -> UserHooks -> ReplFlags -> [String] -> IO ()

and, for stack --verbose ghci for a simple one-package project boo (extract, reformatted):

[info] boo> configure (lib + exe)
[debug] Run process within ...\boo\:
C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_9p6GVs8J_3.10.1.0_ghc-9.6.4.exe 
--verbose=1 
--builddir=.stack-work\dist\ab060f89
configure 
--with-ghc=...\x86_64-windows\ghc-9.6.4\bin\ghc-9.6.4.exe 
--with-ghc-pkg=...\x86_64-windows\ghc-9.6.4\bin\ghc-pkg-9.6.4.exe
--user 
--package-db=clear 
--package-db=global 
--package-db=C:\sr\snapshots\d672ac94\pkgdb 
--package-db=...\boo\.stack-work\install\fd78de5f\pkgdb 
--libdir=...\boo\.stack-work\install\fd78de5f\lib 
--bindir=...\boo\.stack-work\install\fd78de5f\bin 
--datadir=...\boo\.stack-work\install\fd78de5f\share 
--libexecdir=...\boo\.stack-work\install\fd78de5f\libexec 
--sysconfdir=...\boo\.stack-work\install\fd78de5f\etc 
--docdir=...\boo\.stack-work\install\fd78de5f\doc\boo-0.1.0.0 
--htmldir=...\boo\.stack-work\install\fd78de5f\doc\boo-0.1.0.0 
--haddockdir=...\boo\.stack-work\install\fd78de5f\doc\boo-0.1.0.0 
--dependency=base=base-4.18.2.0 
--ghc-options -haddock 
--extra-include-dirs=...\x86_64-windows\msys2-20230526\mingw64\include 
--extra-lib-dirs=...\x86_64-windows\msys2-20230526\mingw64\lib 
--extra-lib-dirs=...\x86_64-windows\msys2-20230526\mingw64\bin 
--exact-configuration 
--ghc-option=-fhide-source-paths
...
[info] boo> initial-build-steps (lib + exe)
[debug] Run process within ...\boo\: 
C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_9p6GVs8J_3.10.1.0_ghc-9.6.4.exe 
--verbose=1 
--builddir=.stack-work\dist\ab060f89 
repl 
stack-initial-build-steps <<<< This is what triggers the use of `initialBuildSteps`

[mpilgrem]

An alternative to the replHook 'trick' would be for the 'setup' executable to get the information that initialBuildSteps needs. Proof of concept:

module Main (main) where

import Data.List ( stripPrefix )
import Distribution.Parsec ( eitherParsec )
import Distribution.Simple.Build ( initialBuildSteps )
import Distribution.Simple.Configure ( getPersistBuildConfig )
import Distribution.Simple.PackageDescription ( readGenericPackageDescription )
import Distribution.Simple.Utils ( findPackageDesc )
import Distribution.Types.GenericPackageDescription
         ( GenericPackageDescription (..) )
import System.Environment ( getArgs )

main :: IO ()
main = do
  args <- getArgs
  case args of
    [] -> putStrLn "Expected Cabal verbosity as first argument and builddir \
                    \as second argument."
    arg1:arg2:[] -> do
      eFp <- findPackageDesc ""
      case eFp of
        Left msg1 -> putStrLn msg1
        Right fp -> do
          let mRawVerbosity = stripPrefix "--verbose=" arg1
              mRawBuildDir = stripPrefix "--builddir=" arg2
          case (mRawVerbosity, mRawBuildDir) of
            (Nothing, _) ->
              putStrLn "Expected first argument to start --verbose="
            (_, Nothing) ->
              putStrLn "Expected second argument to start --builddir="
            (Just rawVerbosity, Just rawBuildDir) -> do
              case eitherParsec rawVerbosity of
                Left msg2 -> putStrLn msg2
                Right verbosity -> do
                  gpd <- readGenericPackageDescription verbosity fp
                  let pd = packageDescription gpd
                  lbi <- getPersistBuildConfig rawBuildDir
                  initialBuildSteps rawBuildDir pd lbi verbosity
    _ -> putStrLn "Expected only Cabal verbosity as first argument and \
                  \builddir as second argument."

[sheaf]

I believe this is incorrect for a package with Custom build-type in which the custom Setup creates autogenerated modules. Is there a reason you cannot call Setup repl here?