Fix Cabal version selection for Stack (esp. build-type:Custom)

Previously we would pick up Stack's Cabal version with ghc-pkg on the
global package-db. This however ignores that Stack also supports custom
Setup.hs with the Cabal version from the snapshot instead.

2 files changed, 17 insertions, 8 deletions

diff --git a/src/CabalHelper/Compiletime/Cabal.hs b/src/CabalHelper/Compiletime/Cabal.hs
index b565152..88e53a7 100644
--- a/src/CabalHelper/Compiletime/Cabal.hs
+++ b/src/CabalHelper/Compiletime/Cabal.hs
@@ -268,9 +268,18 @@ complainIfNoCabalFile pkgdir Nothing =
 bultinCabalVersion :: Version
 bultinCabalVersion = parseVer VERSION_Cabal
 
-readSetupConfigHeader :: FilePath -> IO (Maybe UnitHeader)
+readSetupConfigHeader :: FilePath -> IO UnitHeader
 readSetupConfigHeader file = bracket (openFile file ReadMode) hClose $ \h -> do
-  parseSetupHeader <$> BS.hGetLine h
+  mhdr <- parseSetupHeader <$> BS.hGetLine h
+  case mhdr of
+    Just hdr@(UnitHeader _PkgId ("Cabal", _hdrCabalVersion) _compId) -> do
+      return hdr
+    Just UnitHeader {uhSetupId=(setup_name, _)} -> panicIO $
+      printf "Unknown Setup package-id in setup-config header '%s': '%s'"
+        (BS8.unpack setup_name) file
+    Nothing -> panicIO $
+      printf "Could not read '%s' header" file
+
 
 parseSetupHeader :: BS.ByteString -> Maybe UnitHeader
 parseSetupHeader header = case BS8.words header of
diff --git a/src/CabalHelper/Compiletime/Compile.hs b/src/CabalHelper/Compiletime/Compile.hs
index d2886e8..a55ee93 100644
--- a/src/CabalHelper/Compiletime/Compile.hs
+++ b/src/CabalHelper/Compiletime/Compile.hs
@@ -90,7 +90,7 @@ data CompilationProductScope = CPSGlobal | CPSProject
 type CompHelperEnv = CompHelperEnv' CabalVersion
 data CompHelperEnv' cv = CompHelperEnv
   { cheCabalVer :: !cv
-  , chePkgDb    :: !(Maybe PackageDbDir)
+  , chePkgDb    :: ![PackageDbDir]
   -- ^ A package-db where we are guaranteed to find Cabal-`cheCabalVer`.
   , cheProjDir  :: !FilePath
   , chePlanJson :: !(Maybe PlanJson)
@@ -119,7 +119,7 @@ compileHelper' CompHelperEnv {..} = do
     CabalVersion cabalVerPlain -> do
       runMaybeT $ msum $ map (\f -> f ghcVer cabalVerPlain) $
         case chePkgDb of
-          Nothing ->
+          [] ->
             [ compileWithCabalV2Inplace
             , compileWithCabalV2GhcEnv
             , compileCabalSource
@@ -127,8 +127,8 @@ compileHelper' CompHelperEnv {..} = do
             , compileGlobal
             , compileWithCabalInPrivatePkgDb
             ]
-          Just db ->
-            [ ((.).(.)) liftIO (compilePkgDb db)
+          dbs ->
+            [ ((.).(.)) liftIO (compilePkgDbs dbs)
             ]
   appdir <- appCacheDir
   let cp@CompPaths {compExePath} = compPaths appdir cheProjLocalCacheDir comp
@@ -148,11 +148,11 @@ compileHelper' CompHelperEnv {..} = do
 
 -- for relaxed deps: find (sameMajorVersionAs cheCabalVer) . reverse . sort
 
-   compilePkgDb db _ghcVer cabalVer  = return $
+   compilePkgDbs dbs _ghcVer cabalVer = return $
        (,)
          (pure ())
          CompileWithCabalPackage
-           { compPackageSource = GPSPackageDBs [db]
+           { compPackageSource = GPSPackageDBs dbs
            , compCabalVersion  = CabalVersion cabalVer
            , compProductTarget = CPSProject
            }