Add a test for #16597

testsuite/tests/overloadedrecflds/should_compile/T16597.hs

+module T16597 where
+
+import T16597a (distinct)
+
+showDistinct = show . distinct

testsuite/tests/overloadedrecflds/should_compile/T16597a.hs

+{-# LANGUAGE DuplicateRecordFields #-}
+
+module T16597a where
+
+data Record = Record { distinct :: String }

testsuite/tests/overloadedrecflds/should_compile/all.T

 test('T11173', [], multimod_compile, ['T11173', '-v0'])
 test('T12609', normal, compile, [''])
+test('T16597', [], multimod_compile, ['T16597', '-v0'])