haskell.packages.ghc881.alex: apply temporary patch for ghc881

pkgs/development/haskell-modules/configuration-common.nix

@@ -1005,7 +1005,7 @@ self: super: {
   spdx = dontCheck super.spdx;
 
   # The test suite does not know how to find the 'alex' binary.
-  alex = overrideCabal super.alex (drv: {
+  alex = overrideCabal (appendPatch super.alex ./patches/alex-3.2.4-ghc8.8.x.patch) (drv: {
     testSystemDepends = (drv.testSystemDepends or []) ++ [pkgs.which];
     preCheck = ''export PATH="$PWD/dist/build/alex:$PATH"'';
   });

pkgs/development/haskell-modules/patches/alex-3.2.4-ghc8.8.x.patch

@@ -0,0 +1,27 @@
+From deaae6eddef5186bfd0e42e2c3ced39e26afa4d6 Mon Sep 17 00:00:00 2001
+From: "Joseph C. Sible" <josephcsible@users.noreply.github.com>
+Date: Sat, 31 Aug 2019 21:19:37 -0400
+Subject: [PATCH] Remove fail from default_typeclass test
+
+This was added when we copied in StateT from MTL, but we don't actually
+use it. Since the MonadFail Proposal was finished in GHC 8.8.1, it now
+breaks compiling, so remove it.
+---
+ tests/default_typeclass.x | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/tests/default_typeclass.x b/tests/default_typeclass.x
+index fb06684..5491e28 100644
+--- a/tests/default_typeclass.x
++++ b/tests/default_typeclass.x
+@@ -285,7 +285,6 @@ instance (Monad m) => Monad (StateT s m) where
+     m >>= k  = StateT $ \s -> do
+         (a, s') <- runStateT m s
+         runStateT (k a) s'
+-    fail str = StateT $ \_ -> fail str
+ 
+ -- | Fetch the current value of the state within the monad.
+ get' :: (Monad m) => StateT s m s
+-- 
+2.16.1
+