From 13e4c20ced14c9d19782a6a5aa8ddbeb3788d3a0 Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Fri, 30 Oct 2009 18:01:14 +0000
Subject: [PATCH] Improve error message for malformed LANGUAGE pragma

---
 compiler/main/HeaderInfo.hs |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/main/HeaderInfo.hs b/compiler/main/HeaderInfo.hs
index 9262884..c3c78ae 100644
--- a/compiler/main/HeaderInfo.hs
+++ b/compiler/main/HeaderInfo.hs
@@ -237,13 +237,16 @@ languagePragParseError :: SrcSpan -> a
 languagePragParseError loc =
   throw $ mkSrcErr $ unitBag $
      (mkPlainErrMsg loc $
-       text "cannot parse LANGUAGE pragma: comma-separated list expected")
+       vcat [ text "Cannot parse LANGUAGE pragma"
+            , text "Expecting comma-separated list of language options,"
+            , text "each starting with a capital letter"
+            , nest 2 (text "E.g. {-# LANGUAGE RecordPuns, Generics #-}") ])
 
 unsupportedExtnError :: SrcSpan -> String -> a
 unsupportedExtnError loc unsup =
   throw $ mkSrcErr $ unitBag $
     mkPlainErrMsg loc $
-        text "unsupported extension: " <> text unsup
+        text "Unsupported extension: " <> text unsup
 
 
 optionsErrorMsgs :: [String] -> [Located String] -> FilePath -> Messages
-- 
1.7.10.4