From https://github.com/jgoerzen/configfile/pull/12
From: Rodney Lorrimar <dev@rodney.id.au>
Date: Wed, 24 May 2023 09:36:44 +0800
Subject: [PATCH 01/13] Add compatibility with mtl>=2.3

The module Control.Monad.Error is no longer exported by mtl>=2.3.

Replace these imports with Control.Monad.Error.Class.

Also remove the Error instance of CPError, due to this deprecated
typeclass having been removed.
--- a/src/Data/ConfigFile.hs
+++ b/src/Data/ConfigFile.hs
@@ -106,7 +106,7 @@ import qualified Data.Map as Map
 import Data.List
 import System.IO(Handle)
 import Data.Char
-import Control.Monad.Error
+import Control.Monad.Error.Class
 
 -- For interpolatingAccess
 import Text.ParserCombinators.Parsec.Error (errorMessages, Message(..))
@@ -797,7 +797,7 @@ Error\/IO monad.  That is, you will get an IO result back.  Here is a full
 standalone example of doing that:
 
 >import Data.ConfigFile
->import Control.Monad.Error
+>import Control.Monad.Error.Class
 >
 >main = do
 >          rv <- runErrorT $
--- a/src/Data/ConfigFile/Monadic.hs
+++ b/src/Data/ConfigFile/Monadic.hs
@@ -10,7 +10,7 @@ module Data.ConfigFile.Monadic (
   set, setshow, remove_option, add_section, remove_section
 ) where
 
-import Control.Monad.Error
+import Control.Monad.Error.Class
 import System.IO(Handle)
 import Data.ConfigFile as Reexporting (SectionSpec, OptionSpec, ConfigParser(..),
                                   CPErrorData, CPError, emptyCP, Get_C(..), sections, merge, to_string)
--- a/src/Data/ConfigFile/Parser.hs
+++ b/src/Data/ConfigFile/Parser.hs
@@ -33,7 +33,7 @@ module Data.ConfigFile.Parser
        --main
 ) where
 import Text.ParserCombinators.Parsec
-import Control.Monad.Error(throwError, MonadError)
+import Control.Monad.Error.Class(MonadError(..))
 import Data.String.Utils
 import Data.ConfigFile.Lexer
 import System.IO(Handle, hGetContents)
--- a/src/Data/ConfigFile/Types.hs
+++ b/src/Data/ConfigFile/Types.hs
@@ -36,7 +36,7 @@ module Data.ConfigFile.Types (
                                    ) where
 import qualified Data.Map as Map
 import Data.Char
-import Control.Monad.Error
+import Control.Monad.Error.Class
 
 {- | Internal output from parser -}
 type ParseOutput = [(String, [(String, String)])]
@@ -73,10 +73,6 @@ data CPErrorData = ParseError String        -- ^ Parse error
 of the error. -}
 type CPError = (CPErrorData, String)
 
-instance Error CPError where
-    noMsg = (OtherProblem "", "")
-    strMsg x = (OtherProblem x, "")
-
 {- Removed due to Hugs incompatibility.
 
 | Basic ConfigParser error handling.  The Left value indicates

From 46991193f730b4d60422c2e0324ce99ba135ed53 Mon Sep 17 00:00:00 2001
From: Rodney Lorrimar <dev@rodney.id.au>
Date: Wed, 24 May 2023 11:17:45 +0800
Subject: [PATCH 11/13] Remove Makefile

With the .cabal file changes, it probably won't work any more.
--- a/ConfigFile.cabal
+++ b/ConfigFile.cabal
@@ -6,7 +6,6 @@ Author: John Goerzen
 Copyright: Copyright (c) 2004-2014 John Goerzen
 license-file: COPYRIGHT
 extra-source-files: README,
-                    Makefile,
                     COPYRIGHT, LGPL-2.1, BSD3,
                     testsrc/ConfigParser/test.cfg
 Category: Parsing
--- a/Makefile
+++ /dev/null
@@ -1,36 +0,0 @@
-all: setup
-	@echo "Please use Cabal to build this package; not make."
-	./setup configure
-	./setup build
-
-setup: Setup.hs
-	ghc --make -package Cabal -o setup Setup.hs
-
-install: setup
-	./setup install
-
-clean:
-	-runghc Setup.hs clean
-	-rm -rf html `find . -name "*.o"` `find . -name "*.hi" | grep -v debian` \
-		`find . -name "*~" | grep -v debian` *.a setup dist testsrc/runtests \
-		local-pkg doctmp
-	-rm -rf testtmp/* testtmp*
-
-.PHONY: test
-test: test-ghc test-hugs
-	@echo ""
-	@echo "All tests pass."
-
-test-hugs: setup
-	@echo " ****** Running hugs tests"
-	./setup configure -f buildtests --hugs --extra-include-dirs=/usr/lib/hugs/include
-	./setup build
-	runhugs -98 +o -P$(PWD)/dist/scratch:$(PWD)/dist/scratch/programs/runtests: \
-		dist/scratch/programs/runtests/Main.hs
-
-test-ghc: setup
-	@echo " ****** Building GHC tests"
-	./setup configure -f buildtests
-	./setup build
-	@echo " ****** Running GHC tests"
-	./dist/build/runtests/runtests