Switch to the untracked version of getDirectoryFiles when scanning for GMP objects

See https://ghc.haskell.org/trac/ghc/ticket/15971.

This is work in progress: this commit does the right thing, but does not
yet fix the ticket.

2 files changed, 15 insertions, 6 deletions

diff --git a/hadrian/src/Rules/Gmp.hs b/hadrian/src/Rules/Gmp.hs
index 32265fe401..0194518d05 100644
--- a/hadrian/src/Rules/Gmp.hs
+++ b/hadrian/src/Rules/Gmp.hs
@@ -1,5 +1,5 @@
 module Rules.Gmp (
-    gmpRules, gmpBuildPath, gmpObjectsDir, gmpLibraryH
+    gmpRules, gmpBuildPath, gmpObjects, gmpLibraryH
     ) where
 
 import Base
@@ -9,6 +9,18 @@ import Packages
 import Target
 import Utilities
 
+-- | Build GMP library objects and return their paths.
+gmpObjects :: Action [FilePath]
+gmpObjects = do
+    gmpPath <- gmpBuildPath
+    need [gmpPath -/- gmpLibraryH]
+    -- We need to use the untracked version of 'getDirectoryFiles', because the
+    -- contents of 'gmpObjectsDir' is built by Hadrian (in 'gmpRules'). Using
+    -- the tracked version can lead to Shake Lint failure.
+    -- See: https://ghc.haskell.org/trac/ghc/ticket/15971.
+    map unifyPath <$>
+        liftIO (getDirectoryFilesIO "" [gmpPath -/- gmpObjectsDir -/- "*.o"])
+
 gmpBase :: FilePath
 gmpBase = pkgPath integerGmp -/- "gmp"
 
diff --git a/hadrian/src/Rules/Library.hs b/hadrian/src/Rules/Library.hs
index 122004084a..8bd7067202 100644
--- a/hadrian/src/Rules/Library.hs
+++ b/hadrian/src/Rules/Library.hs
@@ -103,11 +103,8 @@ cObjects context = do
 -- 'Context' is @integer-gmp@.
 extraObjects :: Context -> Action [FilePath]
 extraObjects context
-    | package context == integerGmp = do
-        gmpPath <- gmpBuildPath
-        need [gmpPath -/- gmpLibraryH]
-        map unifyPath <$> getDirectoryFiles "" [gmpPath -/- gmpObjectsDir -/- "*.o"]
-    | otherwise         = return []
+    | package context == integerGmp = gmpObjects
+    | otherwise                     = return []
 
 -- | Return all the object files to be put into the library we're building for
 -- the given 'Context'.