3 files changed, 14 insertions, 31 deletions
diff --git a/src/CabalHelper/Compiletime/Cabal.hs b/src/CabalHelper/Compiletime/Cabal.hs
index 17f4d7f..85ab83c 100644
--- a/src/CabalHelper/Compiletime/Cabal.hs
+++ b/src/CabalHelper/Compiletime/Cabal.hs
@@ -43,7 +43,7 @@ import qualified Data.ByteString.Char8 as BS8
 
 import CabalHelper.Compiletime.Types
 import CabalHelper.Compiletime.Process
-import CabalHelper.Shared.Common (replace, parseVer, parseVerMay, parsePkgIdBS)
+import CabalHelper.Shared.Common (replace, parseVer, parseVerMay, parsePkgIdBS, panicIO)
 
 type UnpackedCabalVersion = CabalVersion' (CommitId, CabalSourceDir)
 type ResolvedCabalVersion = CabalVersion' CommitId
@@ -246,10 +246,14 @@ resolveCabalVersion (CabalHEAD ()) = do
   let commit = takeWhile isHexDigit out
   return $ CabalHEAD $ CommitId commit
 
-findCabalFile :: FilePath -> IO FilePath
+findCabalFile :: FilePath -> IO (Maybe FilePath)
 findCabalFile pkgdir = do
-    [cfile] <- filter isCabalFile <$> getDirectoryContents pkgdir
-    return $ pkgdir </> cfile
+    cfiles <- filter isCabalFile <$> getDirectoryContents pkgdir
+    case cfiles of
+      [] -> return Nothing
+      [cfile] -> return $ Just $ pkgdir </> cfile
+      _ -> panicIO $ "Multiple cabal-files found in directory '"
+             ++pkgdir++"': " ++ show cfiles
   where
     isCabalFile :: FilePath -> Bool
     isCabalFile f = takeExtension' f == ".cabal"
@@ -260,6 +264,11 @@ findCabalFile pkgdir = do
           then "" -- just ".cabal" is not a valid cabal file
           else takeExtension p
 
+complainIfNoCabalFile :: FilePath -> Maybe FilePath -> IO FilePath
+complainIfNoCabalFile _ (Just cabal_file) = return cabal_file
+complainIfNoCabalFile pkgdir Nothing =
+  panicIO $ "No cabal file found in package-dir: '"++pkgdir++"'"
+
 bultinCabalVersion :: Version
 bultinCabalVersion = parseVer VERSION_Cabal
 
diff --git a/src/CabalHelper/Compiletime/Compat/Directory.hs b/src/CabalHelper/Compiletime/Compat/Directory.hs
deleted file mode 100644
index 0a65164..0000000
--- a/src/CabalHelper/Compiletime/Compat/Directory.hs
+++ /dev/null
@@ -1,26 +0,0 @@
--- cabal-helper: Simple interface to Cabal's configuration state
--- Copyright (C) 2019  Daniel Gröber <cabal-helper@dxld.at>
---
--- This program is free software: you can redistribute it and/or modify
--- it under the terms of the GNU General Public License as published by
--- the Free Software Foundation, either version 3 of the License, or
--- (at your option) any later version.
---
--- This program is distributed in the hope that it will be useful,
--- but WITHOUT ANY WARRANTY; without even the implied warranty of
--- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--- GNU General Public License for more details.
---
--- You should have received a copy of the GNU General Public License
--- along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-{-# LANGUAGE CPP #-}
-module CabalHelper.Compiletime.Compat.Directory where
-
-import System.Directory (getDirectoryContents)
-
-#if !MIN_VERSION_directory(1,2,5)
-listDirectory :: FilePath -> IO [FilePath]
-listDirectory path =
-  filter (\f -> f /= "." && f /= "..") <$> getDirectoryContents path
-#endif
diff --git a/src/CabalHelper/Compiletime/Program/CabalInstall.hs b/src/CabalHelper/Compiletime/Program/CabalInstall.hs
index b1c661c..4411bc3 100644
--- a/src/CabalHelper/Compiletime/Program/CabalInstall.hs
+++ b/src/CabalHelper/Compiletime/Program/CabalInstall.hs
@@ -261,7 +261,7 @@ planUnits plan = do
       , uComps=comps
       , uPId=CP.PkgId pkg_name _
       } = do
-        cabal_file <- Cabal.findCabalFile pkgdir
+        cabal_file <- Cabal.complainIfNoCabalFile pkgdir =<< Cabal.findCabalFile pkgdir
         let comp_names = Map.keys comps
         let uiV2Components =
               map (Text.unpack . CP.dispCompNameTarget pkg_name) $ Map.keys comps