2 files changed, 53 insertions, 6 deletions
diff --git a/testsuite/tests/wcompat-warnings/Template.hs b/testsuite/tests/wcompat-warnings/Template.hs
index 2a9a11b0c4..86c1449c64 100644
--- a/testsuite/tests/wcompat-warnings/Template.hs
+++ b/testsuite/tests/wcompat-warnings/Template.hs
@@ -13,3 +13,18 @@ instance Semi.Semigroup S where
 instance Monoid S where
   S a `mappend` S b = S (a+b)
   mempty = S 0
+
+newtype M a = M a
+
+instance Functor M where
+  fmap = undefined
+
+instance Applicative M where
+  liftA2 = undefined
+  pure = return
+  (*>) = (>>)
+
+instance Monad M where
+  return = undefined
+  (>>=) = undefined
+  (>>) = undefined
diff --git a/testsuite/tests/wcompat-warnings/WCompatWarningsOn.stderr b/testsuite/tests/wcompat-warnings/WCompatWarningsOn.stderr
index aaf0772b41..75df49fd36 100644
--- a/testsuite/tests/wcompat-warnings/WCompatWarningsOn.stderr
+++ b/testsuite/tests/wcompat-warnings/WCompatWarningsOn.stderr
@@ -3,15 +3,47 @@ Template.hs:5:1: warning: [-Wsemigroup (in -Wcompat)]
     Local definition of ‘<>’ clashes with a future Prelude name.
     This will become an error in a future release.
 
-Template.hs:11:3: warning: [-Wnoncanonical-monoid-instances (in -Wdefault, -Wcompat)]
+Template.hs:11:3: warning: [GHC-50928] [-Wnoncanonical-monoid-instances (in -Wdefault, -Wcompat)]
     Noncanonical ‘(<>) = mappend’ definition detected
     in the instance declaration for ‘Semigroup S’.
-    Move definition from ‘mappend’ to ‘(<>)’
-    See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
+    Suggested fix:
+      Move definition from ‘mappend’ to ‘(<>)’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
 
-Template.hs:14:3: warning: [-Wnoncanonical-monoid-instances (in -Wdefault, -Wcompat)]
+Template.hs:14:3: warning: [GHC-50928] [-Wnoncanonical-monoid-instances (in -Wdefault, -Wcompat)]
     Noncanonical ‘mappend’ definition detected
     in the instance declaration for ‘Monoid S’.
     ‘mappend’ will eventually be removed in favour of ‘(<>)’
-    Either remove definition for ‘mappend’ (recommended) or define as ‘mappend = (<>)’
-    See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
+    Suggested fix:
+      Either remove definition for ‘mappend’ (recommended) or define as ‘mappend = (<>)’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
+
+Template.hs:24:3: warning: [GHC-22705] [-Wnoncanonical-monad-instances (in -Wdefault, -Wcompat)]
+    Noncanonical ‘pure = return’ definition detected
+    in the instance declaration for ‘Applicative M’.
+    Suggested fix:
+      Move definition from ‘return’ to ‘pure’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return
+
+Template.hs:25:3: warning: [GHC-22705] [-Wnoncanonical-monad-instances (in -Wdefault, -Wcompat)]
+    Noncanonical ‘(*>) = (>>)’ definition detected
+    in the instance declaration for ‘Applicative M’.
+    Suggested fix:
+      Move definition from ‘(>>)’ to ‘(*>)’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return
+
+Template.hs:28:3: warning: [GHC-22705] [-Wnoncanonical-monad-instances (in -Wdefault, -Wcompat)]
+    Noncanonical ‘return’ definition detected
+    in the instance declaration for ‘Monad M’.
+    ‘return’ will eventually be removed in favour of ‘pure’
+    Suggested fix:
+      Either remove definition for ‘return’ (recommended) or define as ‘return = pure’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return
+
+Template.hs:30:3: warning: [GHC-22705] [-Wnoncanonical-monad-instances (in -Wdefault, -Wcompat)]
+    Noncanonical ‘(>>)’ definition detected
+    in the instance declaration for ‘Monad M’.
+    ‘(>>)’ will eventually be removed in favour of ‘(*>)’
+    Suggested fix:
+      Either remove definition for ‘(>>)’ (recommended) or define as ‘(>>) = (*>)’
+      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return