Add a test for the WARNING pragma

testsuite/tests/ghc-regress/rename/should_compile/Rn066_A.hs

+module Rn066_A where
+
+{-# WARNING C "Are you sure you want to do that?" #-}
+{-# WARNING op "Is that really a good idea?" #-}
+
+data T = C | D
+
+class Foo a where
+  op :: a -> a
+  bop :: a -> a

testsuite/tests/ghc-regress/rename/should_compile/all.T

@@ -104,6 +104,10 @@ test('rn065',
      multimod_compile,
      ['rn065', '-v0'])
 
+test('rn066',
+     extra_clean(['Rn066_A.hi', 'Rn066_A.o']),
+     multimod_compile, ['rn066', '-v0'])
+
 test('T1972', if_compiler_lt('ghc', '6.9', expect_fail), compile, [''])
 test('T2205', normal, compile, [''])
 

testsuite/tests/ghc-regress/rename/should_compile/rn066.hs

+{-# OPTIONS_GHC -fwarn-warnings-deprecations #-}
+
+-- Test warnings on constructors and class ops
+
+module ShouldCompile where
+
+import Rn066_A
+
+instance Foo T where
+  op x  = x
+  bop y = y
+
+foo = op C

testsuite/tests/ghc-regress/rename/should_compile/rn066.stderr

+
+rn066.hs:7:0:
+    Warning: In the use of data constructor `C'
+             (imported from Rn066_A):
+             "Are you sure you want to do that?"
+
+rn066.hs:7:0:
+    Warning: In the use of `op'
+             (imported from Rn066_A):
+             "Is that really a good idea?"