1 files changed, 31 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_compile/tc187.hs b/testsuite/tests/typecheck/should_compile/tc187.hs
new file mode 100644
index 0000000000..15946f8a50
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+++ b/testsuite/tests/typecheck/should_compile/tc187.hs
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+{-# LANGUAGE UndecidableInstances, FlexibleInstances,
+             MultiParamTypeClasses, FunctionalDependencies #-}
+-- UndecidableInstances now needed because the Coverage Condition fails
+
+-- Hugs failed this functional-dependency test
+-- Reported by Iavor Diatchki Feb 05
+
+module ShouldCompile where
+
+data N0
+newtype Succ n    = Succ n
+
+class Plus a b c | a b -> c
+instance Plus N0 n n
+instance Plus a b c => Plus (Succ a) b (Succ c)
+
+( # )              :: Plus x y z => x -> y -> z
+( # )               = undefined
+
+class BitRep t n | t -> n where
+  toBits         :: t -> n
+
+instance BitRep Bool (Succ N0) where
+  toBits = error "urk"
+
+instance BitRep (Bool,Bool,Bool) (Succ (Succ (Succ N0))) where
+  toBits (x,y,z) = toBits x # toBits y # toBits z
+
+-- Hugs complains that it cannot solve the constraint:
+-- Plus (Succ N0) (Succ N0) (Succ (Succ N0))
+