testsuite: Add test for #14965

testsuite/tests/simplCore/should_run/T14965.hs

+module Main (main) where
+
+import T14965_Sep
+
+main :: IO ()
+main = print $ cc bb
+
+bb :: Sep
+bb = catSep b1 b2
+
+b1 :: Sep
+b1 = Sep [] ["foo"] []
+
+b2 :: Sep
+b2 = Sep [] ["bar"] []

testsuite/tests/simplCore/should_run/T14965.stdout

+True

testsuite/tests/simplCore/should_run/T14965_Sep.hs

+module T14965_Sep where
+
+data Sep = Sep
+  { bugVanishesWithoutThis :: [()]
+  , middle :: [String]
+  , orThis :: [()]
+  }
+
+catSep :: Sep -> Sep -> Sep
+catSep (Sep a b c) (Sep x y z) = Sep (a ++ x) (b ++ y) (c ++ z)
+
+cc :: Sep -> Bool
+cc boost = elem "foo" $ middle boost

testsuite/tests/simplCore/should_run/all.T

@@ -83,3 +83,4 @@ test('T14868',
      [when((arch('powerpc64') or arch('powerpc64le')), expect_broken(11261))],
      compile_and_run, [''])
 test('T14894', normal, compile_and_run, [''])
+test('T14965', normal, compile_and_run, [''])