Warn for Safe Haskell when -XOverlappingInstances or

-XIncoherentInstances turned on.

9 files changed, 50 insertions, 4 deletions

diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.hs b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.hs
index 2df65765aa..b3e7f34586 100644
--- a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.hs
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.hs
@@ -1,6 +1,6 @@
 {-# OPTIONS_GHC -fwarn-unsafe -Werror #-}
 {-# LANGUAGE FlexibleInstances #-}
-module UnsafeInfered15 where
+module UnsafeInfered16 where
 
 class C a where
   f :: a -> String
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.stderr b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.stderr
index 21674c407b..5ac27d3d82 100644
--- a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.stderr
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered16.stderr
@@ -1,6 +1,6 @@
 
 UnsafeInfered16.hs:1:16: Warning:
-    ‘UnsafeInfered15’ has been inferred as unsafe!
+    ‘UnsafeInfered16’ has been inferred as unsafe!
     Reason:
         UnsafeInfered16.hs:8:30:
             [overlapping] overlap mode isn't allowed in Safe Haskell
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.hs b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.hs
index 04591b5f77..7f17a136ff 100644
--- a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.hs
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.hs
@@ -1,6 +1,6 @@
 {-# OPTIONS_GHC -fwarn-unsafe -Werror #-}
 {-# LANGUAGE FlexibleInstances #-}
-module UnsafeInfered15 where
+module UnsafeInfered17 where
 
 class C a where
   f :: a -> String
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.stderr b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.stderr
index 415e9a1f37..aa43fbeeed 100644
--- a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.stderr
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered17.stderr
@@ -1,6 +1,6 @@
 
 UnsafeInfered17.hs:1:16: Warning:
-    ‘UnsafeInfered15’ has been inferred as unsafe!
+    ‘UnsafeInfered17’ has been inferred as unsafe!
     Reason:
         UnsafeInfered17.hs:8:29:
             [incoherent] overlap mode isn't allowed in Safe Haskell
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.hs b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.hs
new file mode 100644
index 0000000000..a6dbfe1745
--- /dev/null
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.hs
@@ -0,0 +1,11 @@
+{-# OPTIONS_GHC -fwarn-unsafe #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE OverlappingInstances #-}
+module UnsafeInfered18 where
+
+class C a where
+  f :: a -> String
+
+instance C a where
+  f _ = "a"
+
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.stderr b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.stderr
new file mode 100644
index 0000000000..0896ec500f
--- /dev/null
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered18.stderr
@@ -0,0 +1,11 @@
+
+UnsafeInfered18.hs:3:14: Warning:
+    -XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS
+
+UnsafeInfered18.hs:1:16: Warning:
+    ‘UnsafeInfered18’ has been inferred as unsafe!
+    Reason:
+        UnsafeInfered18.hs:3:14:
+            -XOverlappingInstances is not allowed in Safe Haskell
+        UnsafeInfered18.hs:9:10:
+            [overlap ok] overlap mode isn't allowed in Safe Haskell
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.hs b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.hs
new file mode 100644
index 0000000000..587bc4edbf
--- /dev/null
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.hs
@@ -0,0 +1,11 @@
+{-# OPTIONS_GHC -fwarn-unsafe -Werror #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE IncoherentInstances #-}
+module UnsafeInfered19 where
+
+class C a where
+  f :: a -> String
+
+instance C a where
+  f _ = "a"
+
diff --git a/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.stderr b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.stderr
new file mode 100644
index 0000000000..002c950930
--- /dev/null
+++ b/testsuite/tests/safeHaskell/safeInfered/UnsafeInfered19.stderr
@@ -0,0 +1,11 @@
+
+UnsafeInfered19.hs:1:16: Warning:
+    ‘UnsafeInfered19’ has been inferred as unsafe!
+    Reason:
+        UnsafeInfered19.hs:3:14:
+            -XIncoherentInstances is not allowed in Safe Haskell
+        UnsafeInfered19.hs:9:10:
+            [incoherent] overlap mode isn't allowed in Safe Haskell
+
+<no location info>: 
+Failing due to -Werror.
diff --git a/testsuite/tests/safeHaskell/safeInfered/all.T b/testsuite/tests/safeHaskell/safeInfered/all.T
index 4fc9fcecb8..c2222a3549 100644
--- a/testsuite/tests/safeHaskell/safeInfered/all.T
+++ b/testsuite/tests/safeHaskell/safeInfered/all.T
@@ -65,6 +65,8 @@ test('UnsafeInfered14', normal, compile_fail, [''])
 test('UnsafeInfered15', normal, compile_fail, [''])
 test('UnsafeInfered16', normal, compile_fail, [''])
 test('UnsafeInfered17', normal, compile_fail, [''])
+test('UnsafeInfered18', normal, compile, [''])
+test('UnsafeInfered19', normal, compile_fail, [''])
 
 # Mixed tests
 test('Mixed01', normal, compile_fail, [''])