haskell-singletons: fix tests for darwin

pkgs/development/libraries/haskell/singletons/default.nix

@@ -9,6 +9,7 @@ cabal.mkDerivation (self: {
   buildDepends = [ mtl thDesugar ];
   testDepends = [ Cabal constraints filepath tasty tastyGolden ];
   noHaddock = true;
+  patches = self.stdenv.lib.optional self.stdenv.isDarwin ./test.patch;
   meta = {
     homepage = "http://www.cis.upenn.edu/~eir/packages/singletons";
     description = "A framework for generating singleton types";

pkgs/development/libraries/haskell/singletons/test.patch

@@ -0,0 +1,12 @@
+--- a/tests/SingletonsTestSuiteUtils.hs
++++ b/tests/SingletonsTestSuiteUtils.hs
+@@ -201,7 +201,7 @@ testCompileAndDumpGroup testDir tests =
+ filterWithSed :: FilePath -> IO ()
+ filterWithSed file = runProcessWithOpts CreatePipe "sed"
+ #ifdef darwin_HOST_OS
+-  [ "-i", "''"
++  [ "-i"
+ #else
+   [ "-i"
+ #endif
+