GHC < 7 is no longer supported.

574086ce · Mikhail Glushenkov · 70cc6971 · 574086ce
Commit 574086ce authored Apr 08, 2016 by Mikhail Glushenkov
--- a/Cabal/Cabal.cabal
+++ b/Cabal/Cabal.cabal
@@ -354,9 +354,6 @@ library
      Distribution.Compat.Binary.Generic

  default-language: Haskell98
-  -- starting with GHC 7.0, rely on {-# LANGUAGE CPP #-} instead
-  if !impl(ghc >= 7.0)
-    default-extensions: CPP

 -- Small, fast running tests.
 test-suite unit-tests