Add support for hpack (see commercialhaskell#1679)

src/Stack/Build/Source.hs

@@ -227,7 +227,7 @@ getLocalPackageViews :: (MonadThrow m, MonadIO m, MonadReader env m, HasEnvConfi
 getLocalPackageViews = do
     econfig <- asks getEnvConfig
     locals <- forM (Map.toList $ envConfigPackages econfig) $ \(dir, validWanted) -> do
-        cabalfp <- getCabalFileName dir
+        cabalfp <- findOrGenerateCabalFile dir
         (warnings,gpkg) <- readPackageUnresolved cabalfp
         mapM_ (printCabalFileWarning cabalfp) warnings
         let cabalID = package $ packageDescription gpkg

src/Stack/Ghci.hs

@@ -299,7 +299,7 @@ ghciSetup GhciOpts{..} = do
     directlyWanted <-
         forMaybeM (M.toList (envConfigPackages econfig)) $
         \(dir,validWanted) ->
-             do cabalfp <- getCabalFileName dir
+             do cabalfp <- findOrGenerateCabalFile dir
                 name <- parsePackageNameFromFilePath cabalfp
                 if validWanted
                     then case M.lookup name targets of

src/Stack/Package.hs

@@ -20,7 +20,7 @@ module Stack.Package
   ,readPackageUnresolved
   ,readPackageUnresolvedBS
   ,resolvePackage
-  ,getCabalFileName
+  ,findOrGenerateCabalFile
   ,Package(..)
   ,GetPackageFiles(..)
   ,GetPackageOpts(..)
@@ -93,6 +93,8 @@ import qualified System.Directory as D
 import           System.FilePath (splitExtensions, replaceExtension)
 import qualified System.FilePath as FilePath
 import           System.IO.Error
+import qualified Hpack
+import qualified Hpack.Config as Hpack
 
 packageIdentifier :: Package -> Stack.Types.PackageIdentifier.PackageIdentifier
 packageIdentifier pkg =
@@ -149,7 +151,7 @@ readPackageDescriptionDir :: (MonadLogger m, MonadIO m, MonadThrow m, MonadCatch
   -> Path Abs Dir
   -> m (GenericPackageDescription, PackageDescription)
 readPackageDescriptionDir config pkgDir = do
-    cabalfp <- getCabalFileName pkgDir
+    cabalfp <- findOrGenerateCabalFile pkgDir
     gdesc   <- liftM snd (readPackageUnresolved cabalfp)
     return (gdesc, resolvePackageDescription config gdesc)
 
@@ -1057,11 +1059,15 @@ logPossibilities dirs mn = do
 --
 -- If no .cabal file is present, or more than one is present, an exception is
 -- thrown via 'throwM'.
-getCabalFileName
+--
+-- If the directory contains a file named package.yaml, hpack is used to
+-- generate a .cabal file from it.
+findOrGenerateCabalFile
     :: (MonadThrow m, MonadIO m)
     => Path Abs Dir -- ^ package directory
     -> m (Path Abs File)
-getCabalFileName pkgDir = do
+findOrGenerateCabalFile pkgDir = do
+    liftIO $ hpack pkgDir
     files <- liftIO $ findFiles
         pkgDir
         (flip hasExtension "cabal" . FL.toFilePath)
@@ -1072,6 +1078,13 @@ getCabalFileName pkgDir = do
         _:_ -> throwM $ PackageMultipleCabalFilesFound pkgDir files
   where hasExtension fp x = FilePath.takeExtension fp == "." ++ x
 
+-- | Generate .cabal file from package.yaml, if necessary.
+hpack :: Path Abs Dir -> IO ()
+hpack pkgDir = do
+    exists <- doesFileExist (pkgDir </> $(mkRelFile Hpack.packageConfig))
+    when exists $ do
+        Hpack.hpack (toFilePath pkgDir) True
+
 -- | Path for the package's build log.
 buildLogPath :: (MonadReader env m, HasBuildConfig env, MonadThrow m)
              => Package -> Maybe String -> m (Path Abs File)

src/Stack/SDist.hs

@@ -174,7 +174,7 @@ gtraverseT f =
 -- use-cases.
 readLocalPackage :: M env m => Path Abs Dir -> m LocalPackage
 readLocalPackage pkgDir = do
-    cabalfp <- getCabalFileName pkgDir
+    cabalfp <- findOrGenerateCabalFile pkgDir
     name    <- parsePackageNameFromFilePath cabalfp
     config  <- getPackageConfig defaultBuildOpts name
     (warnings,package) <- readPackage config cabalfp
@@ -267,7 +267,7 @@ checkSDistTarball tarball = withTempTarGzContents tarball $ \pkgDir' -> do
     pkgDir  <- (pkgDir' </>) `liftM`
         (parseRelDir . FP.takeBaseName . FP.takeBaseName . toFilePath $ tarball)
     --               ^ drop ".tar"     ^ drop ".gz"
-    cabalfp <- getCabalFileName pkgDir
+    cabalfp <- findOrGenerateCabalFile pkgDir
     name    <- parsePackageNameFromFilePath cabalfp
     config  <- getPackageConfig defaultBuildOpts name
     (gdesc, pkgDesc) <- readPackageDescriptionDir config pkgDir

src/main/Main.hs

@@ -75,7 +75,7 @@ import qualified Stack.Image as Image
 import           Stack.Init
 import           Stack.New
 import           Stack.Options
-import           Stack.Package (getCabalFileName)
+import           Stack.Package (findOrGenerateCabalFile)
 import qualified Stack.PackageIndex
 import           Stack.SDist (getSDistTarball, checkSDistTarball, checkSDistTarball')
 import           Stack.Setup
@@ -1063,7 +1063,7 @@ packagesCmd () go@GlobalOpts{..} =
          locals <-
              forM (M.toList (envConfigPackages econfig)) $
              \(dir,_) ->
-                  do cabalfp <- getCabalFileName dir
+                  do cabalfp <- findOrGenerateCabalFile dir
                      parsePackageNameFromFilePath cabalfp
          forM_ locals (liftIO . putStrLn . packageNameString)
 

stack-7.8.yaml

@@ -23,3 +23,5 @@ extra-deps:
 - hpc-0.6.0.2
 - process-1.2.1.0
 - time-1.5.0.1
+- base-compat-0.9.0
+- hpack-0.9.0

stack.cabal

@@ -207,6 +207,7 @@ library
                    , project-template >= 0.2
                    , uuid
                    , zip-archive
+                   , hpack >= 0.9.0
   if os(windows)
     cpp-options:     -DWINDOWS
     build-depends:   Win32

stack.yaml

@@ -11,3 +11,4 @@ nix:
     - zlib
 extra-deps:
 - path-io-0.3.1
+- hpack-0.9.0