Added test for #7667.

testsuite/tests/th/T7667.hs

+{-# LANGUAGE TemplateHaskell, TypeOperators #-}
+
+module T7667 where
+
+import Language.Haskell.TH
+
+$( return [ TySynD (mkName "+") [PlainTV (mkName "a"), PlainTV (mkName "b")]
+                   (AppT (AppT (ConT ''Either) (VarT $ mkName "a")) (VarT $ mkName "b")) ] )
\ No newline at end of file

testsuite/tests/th/all.T

@@ -300,3 +300,4 @@ test('T4128', normal, compile, ['-v0'])
 test('T6062', normal, compile, ['-v0'])
 test('T4364', normal, compile, ['-v0'])
 test('T8412', normal, compile_fail, ['-v0'])
+test('T7667', normal, compile, ['-v0'])
\ No newline at end of file