PDF: Use / as path separators in latex input only

Fixes compile error on Windows for 5040f3e
Reverted back to canonical file separators </> in all places except for
arguments to the LaTeX builder and in TEXINPUTS

See #1151.

Note: Temporary directories still fail to be removed in Windows due to
call of ByteString.Lazy.readFile creating process ownership of the
compiled pdf file.

src/Text/Pandoc/PDF.hs

@@ -56,11 +56,11 @@ import Data.List (intercalate)
 #endif
 
 withTempDir :: String -> (FilePath -> IO a) -> IO a
-withTempDir f =
+withTempDir =
 #ifdef _WINDOWS
-  withTempDirectory "." (f . changePathSeparators)
+  withTempDirectory "."
 #else
-  withSystemTempDirectory f
+  withSystemTempDirectory
 #endif
 
 #ifdef _WINDOWS
@@ -99,8 +99,7 @@ handleImage' baseURL tmpdir (Image ils (src,tit)) = do
                 let ext = fromMaybe (takeExtension src) $
                           extensionFromMimeType mime
                 let basename = UTF8.toString $ B64.encode $ UTF8.fromString src
-                -- note:  we want / even on Windows, for TexLive:
-                let fname = tmpdir ++ "/" ++ basename <.> ext
+                let fname = tmpdir </> basename <.> ext
                 BS.writeFile fname contents
                 return $ Image ils (fname,tit)
               _ -> do
@@ -152,18 +151,22 @@ extractMsg log' = do
 runTeXProgram :: String -> Int -> FilePath -> String
               -> IO (ExitCode, ByteString, Maybe ByteString)
 runTeXProgram program runsLeft tmpDir source = do
-    let file = tmpDir ++ "/input.tex"
+    let file = tmpDir </> "input.tex"
     exists <- doesFileExist file
     unless exists $ UTF8.writeFile file source
-    let programArgs = ["-halt-on-error", "-interaction", "nonstopmode",
-         "-output-directory", tmpDir, file]
-    env' <- getEnvironment
 #ifdef _WINDOWS
-    let sep = ";"
+    -- note:  we want / even on Windows, for TexLive
+    let tmpDir' = changePathSeparators tmpDir
+    let file' = changePathSeparators file
 #else
-    let sep = ":"
+    let tmpDir' = tmpDir
+    let file' = file
 #endif
-    let texinputs = maybe (tmpDir ++ sep) ((tmpDir ++ sep) ++)
+    let programArgs = ["-halt-on-error", "-interaction", "nonstopmode",
+         "-output-directory", tmpDir', file']
+    env' <- getEnvironment
+    let sep = searchPathSeparator:[]
+    let texinputs = maybe (tmpDir' ++ sep) ((tmpDir' ++ sep) ++)
           $ lookup "TEXINPUTS" env'
     let env'' = ("TEXINPUTS", texinputs) :
                   [(k,v) | (k,v) <- env', k /= "TEXINPUTS"]