[project @ 2001-08-24 15:17:29 by simonmar]

These two tests collectively used to be rnfail014.  tcfail097 works,
tcfail098 currently fails.

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

@@ -88,3 +88,5 @@ test "tcfail093" { vtcf("") }
 test "tcfail094" { vtcf("") }
 test "tcfail095" { vtcf("") }
 test "tcfail096" { vtcf("") }
+test "tcfail097" { vtcf("") }
+test "tcfail098" { vtcf("") }

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail097.hs

+module ShouldFail where
+
+-- !!! Ambiguous constraint in type signature
+
+f :: Eq a => Int -> Int
+f x = x

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail097.stderr

+
+tcfail097.hs:5:
+    Ambiguous constraint `Eq a'
+	At least one of the forall'd type variables mentioned by the constraint
+	must be reachable from the type after the =>
+    In the type: forall a. (Eq a) => Int -> Int
+    While checking the type signature for `f'

testsuite/tests/ghc-regress/typecheck/should_fail/tcfail098.hs

+module ShouldFail where
+
+-- !!! ambiguous constraint in the context of an instance declaration
+class Bar a
+instance Bar a => Bar Bool
+
+-- !!! constraining the type variable in a class head is illegal
+class Foo a where
+  op :: Eq a => a -> a