Add prepare command

1 files changed, 15 insertions, 0 deletions

diff --git a/Distribution/Helper.hs b/Distribution/Helper.hs
index 3544d2e..ca189a3 100644
--- a/Distribution/Helper.hs
+++ b/Distribution/Helper.hs
@@ -50,6 +50,7 @@ module Distribution.Helper (
   , Distribution.Helper.getSandboxPkgDb
 
   -- * Managing @dist/@
+  , prepare
   , reconfigure
   , writeAutogenFiles
 
@@ -261,6 +262,20 @@ getSomeConfigState = ask >>= \(QueryEnv readProc progs projdir distdir) -> do
   return $ SomeLocalBuildInfo
     pkgDbs eps srcDirs ghcOpts ghcSrcOpts ghcPkgOpts ghcMergedPkgOpts ghcLangOpts
 
+-- | Make sure the appropriate helper executable for the given project is
+-- installed and ready to run queries.
+prepare :: MonadIO m
+        => (FilePath -> [String] -> String -> IO String)
+        -> FilePath
+        -- ^ Path to project directory, i.e. the one containing the
+        -- @project.cabal@ file
+        -> FilePath
+        -- ^ Path to the @dist/@ directory
+        -> m ()
+prepare readProc projdir distdir = liftIO $ do
+  exe  <- findLibexecExe "cabal-helper-wrapper"
+  void $ readProc exe [projdir, distdir] ""
+
 -- | Create @cabal_macros.h@ and @Paths_\<pkg\>@ possibly other generated files
 -- in the usual place.
 writeAutogenFiles :: MonadIO m