Add test cases for #13821

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13821

Differential Revision: https://phabricator.haskell.org/D3642

testsuite/tests/typecheck/should_fail/Makefile

@@ -6,3 +6,7 @@ include $(TOP)/mk/test.mk
 
 foo:
 	echo hello
+
+T13821A:
+	$(RM) -f T13821A.hi-boot T13821A.o-boot
+	!('$(TEST_HC)' $(TEST_HC_OPTS) -c T13821A.hs-boot)

testsuite/tests/typecheck/should_fail/T13821A.hs-boot

+{-# LANGUAGE MagicHash #-}
+module T13821A where
+
+import GHC.Prim
+
+x :: Int#

testsuite/tests/typecheck/should_fail/T13821B.bkp

+{-# LANGUAGE MagicHash #-}
+unit T13821B where
+  signature A where
+    import GHC.Prim
+
+    x :: Int#
\ No newline at end of file

testsuite/tests/typecheck/should_fail/all.T

@@ -442,3 +442,5 @@ test('T13611', expect_broken(13611), compile_fail, [''])
 test('T13320', normal, compile_fail, [''])
 test('T13640', normal, compile_fail, [''])
 test('T13677', normal, compile_fail, [''])
+test('T13821A', expect_broken(13821), run_command, ['$MAKE -s --no-print-directory T13821A'])
+test('T13821B', expect_broken(13821), backpack_typecheck_fail, [''])