Add -Wnoncanonical-{monad,monoid}-instances to standardWarnings

-------------------------
Metric Decrease:
   T12425
Metric Increase:
   T17516
-------------------------

6 files changed, 9 insertions, 14 deletions

diff --git a/testsuite/tests/simplCore/prog002/Simpl009Help.hs b/testsuite/tests/simplCore/prog002/Simpl009Help.hs
index b64639ec8a..b1e2a080e2 100644
--- a/testsuite/tests/simplCore/prog002/Simpl009Help.hs
+++ b/testsuite/tests/simplCore/prog002/Simpl009Help.hs
@@ -3,7 +3,7 @@
 -- Helper for simpl009.hs (see comments there)
 
 module Simpl009Help where
-  
+
 import Control.Applicative (Applicative(..), Alternative(empty, (<|>)))
 import Control.Monad
 
@@ -19,12 +19,12 @@ instance Functor (Parser s) where
     fmap = liftM
 
 instance Applicative (Parser s) where
-    pure = return
+    pure a = Parser (\fut -> fut a)
     (<*>) = ap
 
 instance Monad (Parser s) where
-  return a = Parser (\fut -> fut a)
-  
+
+
   Parser f >>= k =
     Parser (\fut -> f (\a -> let Parser g = k a in g fut))
 
diff --git a/testsuite/tests/simplCore/should_compile/EvalTest.hs b/testsuite/tests/simplCore/should_compile/EvalTest.hs
index dbaba0515d..2795c0421e 100644
--- a/testsuite/tests/simplCore/should_compile/EvalTest.hs
+++ b/testsuite/tests/simplCore/should_compile/EvalTest.hs
@@ -20,11 +20,10 @@ instance Functor Eval where
     fmap = liftM
 
 instance Applicative Eval where
-    pure = return
+    pure = Done
     (<*>) = ap
 
 instance Monad Eval where
-  return x = Done x
   Done x >>= k = k x   -- Note: pattern 'Done x' makes '>>=' strict
 
 rpar :: a -> Eval a
diff --git a/testsuite/tests/simplCore/should_compile/T10176.hs b/testsuite/tests/simplCore/should_compile/T10176.hs
index e91ccda4e9..c4d738db09 100644
--- a/testsuite/tests/simplCore/should_compile/T10176.hs
+++ b/testsuite/tests/simplCore/should_compile/T10176.hs
@@ -13,11 +13,10 @@ instance Functor (ReaderT r) where
 instance Applicative (ReaderT r) where
     pure    = liftReaderT . pure
     f <*> v = undefined
+    m *> k  = ReaderT $ \r -> do runReaderT m r; runReaderT k r
 
 instance Monad (ReaderT r) where
-    return   = liftReaderT . return
     m >>= k  = undefined
-    m >> k  = ReaderT $ \r -> do runReaderT m r; runReaderT k r
 
 liftReaderT :: IO a -> ReaderT r a
 liftReaderT m = ReaderT (const m)
diff --git a/testsuite/tests/simplCore/should_compile/T3831.hs b/testsuite/tests/simplCore/should_compile/T3831.hs
index 554e786cf2..22689002e5 100644
--- a/testsuite/tests/simplCore/should_compile/T3831.hs
+++ b/testsuite/tests/simplCore/should_compile/T3831.hs
@@ -1,7 +1,7 @@
 {-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
 {-# LANGUAGE ScopedTypeVariables, FlexibleInstances  #-}
 
--- This test has a deep nest of join points, which led to 
+-- This test has a deep nest of join points, which led to
 -- an exponential blow-up in GHC.Core.Opt.SpecConstr
 
 module T3831(setAttributes)  where
@@ -24,11 +24,10 @@ instance Functor Capability where
     fmap = liftM
 
 instance Applicative Capability where
-    pure = return
+    pure = Capability . const . return . Just
     (<*>) = ap
 
 instance Monad Capability where
-    return = Capability . const . return . Just
     Capability f >>= g = Capability $ \t -> do
         mx <- f t
         case mx of
diff --git a/testsuite/tests/simplCore/should_compile/T4203.hs b/testsuite/tests/simplCore/should_compile/T4203.hs
index 3bf9259544..62e1957529 100644
--- a/testsuite/tests/simplCore/should_compile/T4203.hs
+++ b/testsuite/tests/simplCore/should_compile/T4203.hs
@@ -32,11 +32,10 @@ instance Functor Gen where
     fmap = liftM
 
 instance Applicative Gen where
-    pure = return
+    pure = Gen
     (<*>) = ap
 
 instance Monad Gen where
-  return a    = Gen a
   Gen m >>= k = Gen (let Gen m' = k m in m')
 
 class Arbitrary a where
diff --git a/testsuite/tests/simplCore/should_compile/T8331.hs b/testsuite/tests/simplCore/should_compile/T8331.hs
index a7dc318826..3ad183e293 100644
--- a/testsuite/tests/simplCore/should_compile/T8331.hs
+++ b/testsuite/tests/simplCore/should_compile/T8331.hs
@@ -19,7 +19,6 @@ instance (Functor m) => Functor (ReaderT r m) where
     fmap f  = mapReaderT (fmap f)
 
 instance (Monad m) => Monad (ReaderT r m) where
-    return x  = ReaderT (\_ -> return x)
     m >>= k  = ReaderT $ \ r -> do
         a <- runReaderT m r
         runReaderT (k a) r