Update standalone deriving test, and add a failure test

testsuite/tests/ghc-regress/deriving/should_compile/drv014.hs

-{-# OPTIONS -fglasgow-exts #-}
+{-# LANGUAGE StandaloneDeriving, GeneralizedNewtypeDeriving #-}
 
 module ShouldCompile where
 
 data T a  = T1 a | T2
 newtype N = MkN Int
 
-derive instance Eq (T a)
-derive instance Num N
-derive instance Eq N
-derive instance Show N
+deriving instance Eq a => Eq (T a)
+deriving instance Num N
+deriving instance Eq N
+deriving instance Show N

testsuite/tests/ghc-regress/deriving/should_fail/all.T

@@ -9,3 +9,4 @@ test('drvfail007', normal, compile_fail, [''])
 test('drvfail008', reqlib('mtl'), compile_fail, [''])
 test('drvfail009', normal, compile_fail, [''])
 test('drvfail010', normal, compile_fail, [''])
+test('drvfail011', normal, compile_fail, [''])

testsuite/tests/ghc-regress/deriving/should_fail/drvfail011.hs

+{-# LANGUAGE StandaloneDeriving #-}
+
+module ShouldFail where
+
+data T a = T1 a | T2
+
+-- This fails as we need an (Eq a) context
+deriving instance Eq (T a)

testsuite/tests/ghc-regress/deriving/should_fail/drvfail011.stderr

+
+drvfail011.hs:5:5:
+    Could not deduce (Eq a) from the context (Eq (T a))
+      arising from a use of `==' at drvfail011.hs:5:5
+    Possible fix:
+      add (Eq a) to the context of the type signature for `=='
+    In the expression: ((a1 == b1))
+    In the definition of `==': == (T1 a1) (T1 b1) = ((a1 == b1))
+    In the definition for method `=='

testsuite/tests/ghc-regress/indexed-types/should_compile/Deriving.hs

@@ -18,7 +18,7 @@ instance Eq (T Char) where
 data family R a
 data instance R [a] = R
 
-derive instance Eq (R [a])
+deriving instance Eq (R [a])
 
 class C a where
   data S a