Deprecate sdist user hooks

Cabal/Distribution/Simple/UserHooks.hs

@@ -165,6 +165,9 @@ data UserHooks = UserHooks {
   }
 
 {-# DEPRECATED runTests "Please use the new testing interface instead!" #-}
+{-# DEPRECATED preSDist  "SDist hooks violate the invariants of new-sdist." #-}
+{-# DEPRECATED sDistHook "SDist hooks violate the invariants of new-sdist." #-}
+{-# DEPRECATED postSDist "SDist hooks violate the invariants of new-sdist." #-}
 
 -- |Empty 'UserHooks' which do nothing.
 emptyUserHooks :: UserHooks

Cabal/doc/nix-local-build.rst

@@ -497,6 +497,12 @@ and two archives of the same format built from the same source will hash to the
 - ``--output-dir``: Sets the output dir, if a non-default one is desired. The default is
   ``dist-newstyle/sdist/``.
 
+``new-sdist`` is inherently incompatible with sdist hooks, not due to implementation but due
+to fundamental core invariants (same source code should result in the same tarball, byte for
+byte) that must be satisfied for it to function correctly in the larger new-build ecosystem.
+``autogen-modules`` is able to replace uses of the hooks to add generated modules, along with
+the custom publishing of Haddock documentation to Hackage.
+
 Unsupported commands
 --------------------
 

cabal-install/Distribution/Client/CmdSdist.hs

@@ -60,7 +60,7 @@ import Control.Exception
     ( throwIO )
 import Control.Monad
     ( when, forM, forM_ )
-import Control.Monad.IO.Class
+import Control.Monad.Trans
     ( liftIO )
 import Control.Monad.State.Lazy
     ( StateT, modify, gets, evalStateT )