Ensure that automatically set variables ...

`pandoc-version`, `outputfile`, `title-prefix`, `epub-cover-image`,
`curdir`, `dzslides-core` can be overridden by `--variable` on the
command line.

Previously they would create lists in the template Context,
which is not desirable.

4 files changed, 10 insertions, 8 deletions

diff --git a/src/Text/Pandoc/App/CommandLineOptions.hs b/src/Text/Pandoc/App/CommandLineOptions.hs
index fc636e438..b54279e02 100644
--- a/src/Text/Pandoc/App/CommandLineOptions.hs
+++ b/src/Text/Pandoc/App/CommandLineOptions.hs
@@ -1062,7 +1062,8 @@ deprecatedOption o msg = do
        Right () -> return ()
        Left e   -> optError e
 
--- | Set text value in text context.
+-- | Set text value in text context.  Create list if it has a value already,
+-- or add to a list value.
 setVariable :: Text -> Text -> Context Text -> Context Text
 setVariable key val (Context ctx) = Context $ M.alter go key ctx
   where go Nothing             = Just $ toVal val
diff --git a/src/Text/Pandoc/App/OutputSettings.hs b/src/Text/Pandoc/App/OutputSettings.hs
index 4fd30ff66..17df09e9d 100644
--- a/src/Text/Pandoc/App/OutputSettings.hs
+++ b/src/Text/Pandoc/App/OutputSettings.hs
@@ -38,7 +38,7 @@ import System.IO (stdout)
 import Text.Pandoc
 import Text.Pandoc.App.FormatHeuristics (formatFromFilePaths)
 import Text.Pandoc.App.Opt (Opt (..))
-import Text.Pandoc.App.CommandLineOptions (engines, setVariable)
+import Text.Pandoc.App.CommandLineOptions (engines)
 import qualified Text.Pandoc.Format as Format
 import Text.Pandoc.Highlighting (lookupHighlightingStyle)
 import Text.Pandoc.Scripting (ScriptingEngine (engineLoadCustom),
@@ -163,8 +163,6 @@ optToOutputSettings scriptingEngine opts = do
   hlStyle <- traverse (lookupHighlightingStyle . T.unpack) $
                optHighlightStyle opts
 
-  let setVariableM k v = return . setVariable k v
-
   let setListVariableM _ [] ctx = return ctx
       setListVariableM k vs ctx = do
         let ctxMap = unContext ctx
@@ -263,6 +261,13 @@ optToOutputSettings scriptingEngine opts = do
     , outputPdfProgram = maybePdfProg
     }
 
+-- | Set text value in text context unless it is already set.
+setVariableM :: Monad m
+             => T.Text -> T.Text -> Context T.Text -> m (Context T.Text)
+setVariableM key val (Context ctx) = return $ Context $ M.alter go key ctx
+  where go Nothing             = Just $ toVal val
+        go (Just x)            = Just x
+
 baseWriterName :: T.Text -> T.Text
 baseWriterName = T.takeWhile (\c -> c /= '+' && c /= '-')
 
diff --git a/test/writer.man b/test/writer.man
index fb21c9f60..bee7f7178 100644
--- a/test/writer.man
+++ b/test/writer.man
@@ -1,5 +1,3 @@
-.\" Automatically generated by Pandoc 3.0
-.\"
 .\" Define V font for inline verbatim, using C font in formats
 .\" that render this, and otherwise B font.
 .ie "\f[CB]x\f[]"x" \{\
diff --git a/test/writer.ms b/test/writer.ms
index ec7d5d6b1..32d7c1670 100644
--- a/test/writer.ms
+++ b/test/writer.ms
@@ -1,5 +1,3 @@
-.\" Automatically generated by Pandoc 3.0
-.\"
 .\" **** Custom macro definitions *********************************
 .\" * Super/subscript
 .\" (https://lists.gnu.org/archive/html/groff/2012-07/msg00046.html)