From a9628d0745784f6f99edfca008d64dcffeb74bc8 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Sun, 12 Apr 2015 21:18:21 -0700
Subject: [PATCH] Text.Pandoc.PDF: more comprehensible errors on image
 conversion.

Closes #2067.
EPS can't be supported without shelling out to something like
ImageMagick, but at least we can avoid mysterious error messages.

We now get:

    pandoc: Unable to convert `circle.eps' for use with pdflatex.
    ! Package pdftex.def Error: File `circle-eps-converted-to.pdf' not found.

which seems more straightforward.
---
 src/Text/Pandoc/PDF.hs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/Text/Pandoc/PDF.hs b/src/Text/Pandoc/PDF.hs
index 59a6ebede..8d9e69ee1 100644
--- a/src/Text/Pandoc/PDF.hs
+++ b/src/Text/Pandoc/PDF.hs
@@ -108,8 +108,7 @@ convertImages tmpdir (Image ils (src, tit)) = do
   img <- convertImage tmpdir src
   newPath <-
     case img of
-      Left e -> src <$
-                 warn ("Unable to convert image `" ++ src ++ "':\n" ++ e)
+      Left e -> src <$ warn e
       Right fp -> return fp
   return (Image ils (newPath, tit))
 convertImages _ x = return x
@@ -123,7 +122,8 @@ convertImage tmpdir fname =
     Just "application/pdf" -> doNothing
     _ -> JP.readImage fname >>= \res ->
           case res of
-               Left msg  -> return $ Left msg
+               Left msg  -> return $ Left $ "Unable to convert `" ++
+                               fname ++ "' for use with pdflatex."
                Right img ->
                  E.catch (Right fileOut <$ JP.savePngImage fileOut img) $
                      \(e :: E.SomeException) -> return (Left (show e))