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diff --git a/testsuite/tests/indexed-types/should_compile/T2448.hs b/testsuite/tests/indexed-types/should_compile/T2448.hs
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+{-# LANGUAGE TypeFamilies, UndecidableInstances #-}
+
+module T2448 where
+
+-- Demonstrates a bug in propagating type equality constraints
+
+class VectorSpace v where
+  type Scalar v :: *
+
+class VectorSpace v => InnerSpace v
+
+instance (VectorSpace u,VectorSpace v, Scalar u ~ Scalar v) => 
+  VectorSpace (u,v) 
+  where
+  type Scalar (u,v) = Scalar u
+
+instance (InnerSpace u,InnerSpace v, Scalar u ~ Scalar v) => InnerSpace (u,v)