Add test for infix type constructor

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

@@ -158,4 +158,5 @@ test('tcfail169', normal, compile_fail, [''])
 test('tcfail170', normal, compile_fail, [''])
 test('tcfail171', normal, compile_fail, [''])
 test('tcfail172', normal, compile_fail, [''])
+test('tcfail173', normal, compile_fail, [''])
 

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail173.hs

+{-# OPTIONS -fglasgow-exts #-}
+
+module ShouldFail where
+
+newtype (f <.> g) a = Compose (f (g a))

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail173.stderr

+
+tcfail173.hs:5:9: Malformed head of type or class declaration