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.gitignore

@@ -21,3 +21,4 @@ module-name-conflicts.txt
 /inclusive
 *.stackage
 /haddock/
+/build-summary/

Stackage/Build.hs

@@ -100,6 +100,7 @@ build settings' bp = do
                  : "--build-log=logs/$pkg.log"
                  : "--max-backjumps=-1"
                  : "--reorder-goals"
+                 : "--build-summary=build-summary/$pkgid.report"
                  : packageList
         hPutStrLn handle ("cabal " ++ unwords (map (\s -> "'" ++ s ++ "'") args))
         runCabal args handle