3 files changed, 34 insertions, 0 deletions
diff --git a/libraries/base/tests/T22816.hs b/libraries/base/tests/T22816.hs
new file mode 100644
index 0000000000..0105a18c9d
--- /dev/null
+++ b/libraries/base/tests/T22816.hs
@@ -0,0 +1,31 @@
+module Main (main) where
+
+import Data.Functor.Classes
+import Data.Functor.Compose
+import Text.ParserCombinators.ReadP as P
+import Text.ParserCombinators.ReadPrec (ReadPrec, lift, minPrec, readPrec_to_S)
+
+readEither' :: ReadPrec a -> String -> Either String a
+readEither' rp s =
+  case [ x | (x,"") <- readPrec_to_S read' minPrec s ] of
+    [x] -> Right x
+    []  -> Left "read1: no parse"
+    _   -> Left "read1: ambiguous parse"
+ where
+  read' =
+    do x <- rp
+       lift P.skipSpaces
+       return x
+
+-- | Like 'read', but tailored to 'Read1'.
+read1 :: (Read1 f, Read a) => String -> f a
+read1 s = either errorWithoutStackTrace id (readEither' readPrec1 s)
+
+exRead, exRead1 :: Compose Maybe Maybe Int
+exRead  = read  "Compose Nothing"
+exRead1 = read1 "Compose Nothing"
+
+main :: IO ()
+main = do
+  putStrLn $ showsPrec  0 exRead  ""
+  putStrLn $ showsPrec1 0 exRead1 ""
diff --git a/libraries/base/tests/T22816.stdout b/libraries/base/tests/T22816.stdout
new file mode 100644
index 0000000000..1957c7edf8
--- /dev/null
+++ b/libraries/base/tests/T22816.stdout
@@ -0,0 +1,2 @@
+Compose Nothing
+Compose Nothing
diff --git a/libraries/base/tests/all.T b/libraries/base/tests/all.T
index 2b253ceca8..73e6059d7c 100644
--- a/libraries/base/tests/all.T
+++ b/libraries/base/tests/all.T
@@ -286,6 +286,7 @@ test('T18642',
 test('T19288', exit_code(1), compile_and_run, [''])
 test('T19719', normal, compile_and_run, [''])
 test('T20107', extra_run_opts('+RTS -M50M'), compile_and_run, ['-package bytestring'])
+test('T22816', normal, compile_and_run, [''])
 test('trace', normal, compile_and_run, [''])
 test('listThreads', js_broken(22261), compile_and_run, [''])
 test('inits1tails1', normal, compile_and_run, [''])