[project @ 2001-11-02 09:54:42 by simonpj]

Test for record update failure

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

@@ -100,3 +100,4 @@ test "tcfail099" { vtcf("") }
 
 test "tcfail100" { vtcf("") }
 test "tcfail101" { vtcf("") }
+test "tcfail102" { vtcf("") }

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail102.hs

+module ShouldFail where
+
+import Ratio
+
+data Integral a => P a = P { p :: a }
+
+f :: Integral a => P (Ratio a) -> P (Ratio a)
+f x = x { p = p x }

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail102.stderr

+
+tcfail102.hs:8:
+    Could not deduce (Integral (Ratio a)) from the context (Integral a)
+    Probable fix:
+	Add (Integral (Ratio a)) to the type signature(s) for f
+	Or add an instance declaration for (Integral (Ratio a))
+    arising from a record update at tcfail102.hs:8
+    In the record update: x {p = p x}
+    In the definition of `f': x {p = p x}