From e713e6de0de187a4c3c4c26c6551033d66a84878 Mon Sep 17 00:00:00 2001
From: Luke Murphy <lukewm@riseup.net>
Date: Sat, 22 Oct 2016 13:37:58 +0200
Subject: [PATCH] Improve error message for missing Cabal file.

---
 src/Stack/Types/Package.hs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/Stack/Types/Package.hs b/src/Stack/Types/Package.hs
index 2e13362653..cb2f63eca0 100644
--- a/src/Stack/Types/Package.hs
+++ b/src/Stack/Types/Package.hs
@@ -66,9 +66,12 @@ instance Show PackageException where
             Just file -> ' ' : toFilePath file) ++
         ": " ++
         show err
-    show (PackageNoCabalFileFound dir) =
-        "No .cabal file found in directory " ++
-        toFilePath dir
+    show (PackageNoCabalFileFound dir) = concat
+        [ "Stack looks for packages in the directories configured in"
+        , " the 'packages' variable defined in your stack.yaml\n"
+        , "The current entry points to " ++ toFilePath dir ++
+          " but no .cabal file could be found there."
+        ]
     show (PackageMultipleCabalFilesFound dir files) =
         "Multiple .cabal files found in directory " ++
         toFilePath dir ++