cabal-install: call Cabal in-library

This commit modifies the SetupWrapper mechanism, adding a new way of
building a package: directly calling Cabal library functions (e.g.
'build', 'configure' etc).

This currently requires a bit of GADT trickery to accomodate the fact
that configure returns a LocalBuildInfo which must then be passed to
subsequent phases, while with the old Setup interface everything returns
IO () and communication is done through the filesystem
(the local build info file).

To handle 'build-type: Hooks', this commit introduces the hooks-exe
package, which contains:

  - the hooks-exe library, used to compile a set of SetupHooks into an
    external executable,
  - the hooks-cli library, which is used by cabal-install to communicate
    with an external hooks executable.

This package depends on the new `CommunicationHandle` functionality from
haskell/process#308.

Author: sheaf

Cabal/src/Distribution/Simple.hs

@@ -172,6 +172,15 @@ defaultMainWithSetupHooksArgs setupHooks verbHandles =
       , hscolourHook = setup_hscolourHook
       }
   where
+    preBuildHook =
+      case SetupHooks.preBuildComponentRules (SetupHooks.buildHooks setupHooks) of
+        Nothing -> const $ return []
+        Just pbcRules -> \pbci -> runPreBuildHooks verbHandles pbci pbcRules
+    postBuildHook =
+      case SetupHooks.postBuildComponentHook (SetupHooks.buildHooks setupHooks) of
+        Nothing -> const $ return ()
+        Just hk -> hk
+
     setup_confHook
       :: (GenericPackageDescription, HookedBuildInfo)
       -> ConfigFlags
@@ -189,13 +198,14 @@ defaultMainWithSetupHooksArgs setupHooks verbHandles =
       -> BuildFlags
       -> IO ()
     setup_buildHook pkg_descr lbi hooks flags =
-      build_setupHooks
-        (SetupHooks.buildHooks setupHooks)
-        verbHandles
-        pkg_descr
-        lbi
-        flags
-        (allSuffixHandlers hooks)
+      void $
+        build_setupHooks
+          (preBuildHook, postBuildHook)
+          verbHandles
+          pkg_descr
+          lbi
+          flags
+          (allSuffixHandlers hooks)
 
     setup_copyHook
       :: PackageDescription
@@ -230,14 +240,15 @@ defaultMainWithSetupHooksArgs setupHooks verbHandles =
       -> [String]
       -> IO ()
     setup_replHook pkg_descr lbi hooks flags args =
-      repl_setupHooks
-        (SetupHooks.buildHooks setupHooks)
-        verbHandles
-        pkg_descr
-        lbi
-        flags
-        (allSuffixHandlers hooks)
-        args
+      void $
+        repl_setupHooks
+          preBuildHook
+          verbHandles
+          pkg_descr
+          lbi
+          flags
+          (allSuffixHandlers hooks)
+          args
 
     setup_haddockHook
       :: PackageDescription
@@ -246,13 +257,14 @@ defaultMainWithSetupHooksArgs setupHooks verbHandles =
       -> HaddockFlags
       -> IO ()
     setup_haddockHook pkg_descr lbi hooks flags =
-      haddock_setupHooks
-        (SetupHooks.buildHooks setupHooks)
-        verbHandles
-        pkg_descr
-        lbi
-        (allSuffixHandlers hooks)
-        flags
+      void $
+        haddock_setupHooks
+          preBuildHook
+          verbHandles
+          pkg_descr
+          lbi
+          (allSuffixHandlers hooks)
+          flags
 
     setup_hscolourHook
       :: PackageDescription
@@ -261,13 +273,14 @@ defaultMainWithSetupHooksArgs setupHooks verbHandles =
       -> HscolourFlags
       -> IO ()
     setup_hscolourHook pkg_descr lbi hooks flags =
-      hscolour_setupHooks
-        (SetupHooks.buildHooks setupHooks)
-        verbHandles
-        pkg_descr
-        lbi
-        (allSuffixHandlers hooks)
-        flags
+      void $
+        hscolour_setupHooks
+          preBuildHook
+          verbHandles
+          pkg_descr
+          lbi
+          (allSuffixHandlers hooks)
+          flags
 
 -- | A customizable version of 'defaultMain'.
 defaultMainWithHooks :: UserHooks -> IO ()
@@ -931,12 +944,13 @@ simpleUserHooksWithHandles verbHandles =
     , testHook = defaultTestHook verbHandles
     , benchHook = defaultBenchHook verbHandles
     , cleanHook = \p _ _ f -> clean verbHandles p f
-    , hscolourHook = \p l h f -> hscolour_setupHooks SetupHooks.noBuildHooks verbHandles p l (allSuffixHandlers h) f
-    , haddockHook = \p l h f -> haddock_setupHooks SetupHooks.noBuildHooks verbHandles p l (allSuffixHandlers h) f
+    , hscolourHook = \p l h f -> void $ hscolour_setupHooks noBuildHooks verbHandles p l (allSuffixHandlers h) f
+    , haddockHook = \p l h f -> void $ haddock_setupHooks noBuildHooks verbHandles p l (allSuffixHandlers h) f
     , regHook = defaultRegHook verbHandles
     , unregHook = \p l _ f -> unregisterWithHandles verbHandles p l f
     }
   where
+    noBuildHooks = const (pure [])
     finalChecks _args flags pkg_descr lbi =
       checkForeignDeps pkg_descr lbi (modifyVerbosityFlags lessVerbose verbosity)
       where
@@ -1156,13 +1170,14 @@ defaultBuildHook
   -> BuildFlags
   -> IO ()
 defaultBuildHook verbHandles pkg_descr localbuildinfo hooks flags =
-  build_setupHooks
-    SetupHooks.noBuildHooks
-    verbHandles
-    pkg_descr
-    localbuildinfo
-    flags
-    (allSuffixHandlers hooks)
+  void $
+    build_setupHooks
+      (const $ return [], const $ pure ())
+      verbHandles
+      pkg_descr
+      localbuildinfo
+      flags
+      (allSuffixHandlers hooks)
 
 defaultReplHook
   :: VerbosityHandles
@@ -1173,14 +1188,15 @@ defaultReplHook
   -> [String]
   -> IO ()
 defaultReplHook verbHandles pkg_descr localbuildinfo hooks flags args =
-  repl_setupHooks
-    SetupHooks.noBuildHooks
-    verbHandles
-    pkg_descr
-    localbuildinfo
-    flags
-    (allSuffixHandlers hooks)
-    args
+  void $
+    repl_setupHooks
+      (const $ return [])
+      verbHandles
+      pkg_descr
+      localbuildinfo
+      flags
+      (allSuffixHandlers hooks)
+      args
 
 defaultRegHook
   :: VerbosityHandles