Fix warning on 7.10

Ericson2314 · ezyang · commit c7cd985b9718 · 2017-03-16T23:55:58.000-07:00
diff --git a/Cabal/Distribution/Simple/PackageIndex.hs b/Cabal/Distribution/Simple/PackageIndex.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
 
 -----------------------------------------------------------------------------

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`{-# LANGUAGE DeriveGeneric #-}`
	`2`	`+{-# LANGUAGE FlexibleContexts #-}`
`2`	`3`	`{-# LANGUAGE FlexibleInstances #-}`
`3`	`4`
`4`	`5`	`-----------------------------------------------------------------------------`