Test for Trac #1806

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

@@ -175,3 +175,4 @@ test('tcfail185', normal, compile_fail, [''])
 test('tcfail186',
      extra_clean(['Tcfail186_Help.hi', 'Tcfail186_Help.o']),
      multimod_compile_fail, ['tcfail186', '-v0'])
+test('tcfail187', normal, compile_fail, [''])

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail187.hs

+-- Trac #1806
+
+module ShouldFail where
+
+data Foo = (:::)
+
+foo (x ::: y) = ()

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail187.stderr

+
+tcfail187.hs:7:7:
+    Constructor `:::' should have no arguments, but has been given 2
+    In the pattern: x ::: y
+    In the definition of `foo': foo (x ::: y) = ()