1 files changed, 35 insertions, 0 deletions
diff --git a/hadrian/src/Rules/Dependencies.hs b/hadrian/src/Rules/Dependencies.hs
new file mode 100644
index 0000000000..9589d12aa0
--- /dev/null
+++ b/hadrian/src/Rules/Dependencies.hs
@@ -0,0 +1,35 @@
+module Rules.Dependencies (buildPackageDependencies) where
+
+import Data.Bifunctor
+import Data.Function
+
+import Base
+import Context
+import Expression
+import Oracles.ModuleFiles
+import Rules.Generate
+import Target
+import Utilities
+
+buildPackageDependencies :: [(Resource, Int)] -> Context -> Rules ()
+buildPackageDependencies rs context@Context {..} = do
+    root <- buildRootRules
+    root -/- contextDir context -/- ".dependencies.mk" %> \mk -> do
+        srcs <- hsSources context
+        need srcs
+        orderOnly =<< interpretInContext context generatedDependencies
+        if null srcs
+        then writeFileChanged mk ""
+        else buildWithResources rs $
+            target context (Ghc FindHsDependencies stage) srcs [mk]
+        removeFile $ mk <.> "bak"
+
+    root -/- contextDir context -/- ".dependencies" %> \deps -> do
+        mkDeps <- readFile' (deps <.> "mk")
+        writeFileChanged deps . unlines
+                              . map (\(src, deps) -> unwords $ src : deps)
+                              . map (bimap unifyPath (map unifyPath))
+                              . map (bimap head concat . unzip)
+                              . groupBy ((==) `on` fst)
+                              . sortBy (compare `on` fst)
+                              $ parseMakefile mkDeps