Markdown writer: match indents in definition items

Previously, the first line of a definition details item always used a
colon and three spaces instead of respecting the tab-stop setting, which
could lead to round-tripping issues.

Likewise, the indentation of continuation paragraphs in definition lists
now matches the two-characters leader of the first line for Markua
output.

Fixes: #10890

3 files changed, 30 insertions, 14 deletions

diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 39abed8fa..cd3e4ab91 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -857,17 +857,18 @@ definitionListItemToMarkdown opts (label, defs) = do
        let tabStop = writerTabStop opts
        variant <- asks envVariant
        let leader  = case variant of
-                        PlainText -> "   "
-                        Markua -> ":"
-                        _ -> ":  "
-       let sps = case writerTabStop opts - 3 of
-                      n | n > 0   -> literal $ T.replicate n " "
-                      _ -> literal " "
+                        PlainText -> " "
+                        _ -> ":"
+       let leadingChars = case tabStop of
+                            -- Always use two leading characters for Markua
+                            n | n >= 2 && variant /= Markua -> n
+                            _ -> 2
+       let sps = literal $ T.replicate (leadingChars - 1) " "
        let isTight = case defs of
                         ((Plain _ : _): _) -> True
                         _                  -> False
        let contents = (if isTight then vcat else vsep) $ map
-                       (\d -> hang tabStop (leader <> sps) $ vcat d)
+                       (\d -> hang leadingChars (leader <> sps) $ vcat d)
                        defs'
        return $ blankline <> nowrap labelText $$
                 (if isTight then empty else blankline) <> contents <> blankline
diff --git a/test/command/10890.md b/test/command/10890.md
new file mode 100644
index 000000000..508a9a3d2
--- /dev/null
+++ b/test/command/10890.md
@@ -0,0 +1,15 @@
+```
+% pandoc --tab-stop=2 --from=native --to=markdown
+[ DefinitionList
+    [ ( [ Str "apple" ]
+      , [ [ Para [ Str "pomaceous" ] , Para [ Str "fruit" ] ] ]
+      )
+    ]
+]
+^D
+apple
+
+: pomaceous
+
+  fruit
+```
diff --git a/test/writer.markua b/test/writer.markua
index a7032dc27..c1ca713d9 100644
--- a/test/writer.markua
+++ b/test/writer.markua
@@ -317,17 +317,17 @@ Multiple blocks with italics:
 
 : red fruit
 
-    contains seeds, crisp, pleasant to taste
+  contains seeds, crisp, pleasant to taste
 
 *orange*
 
 : orange fruit
 
-    ```
-    { orange code block }
-    ```
+  ```
+  { orange code block }
+  ```
 
-    > orange block quote
+  > orange block quote
 
 Multiple definitions, tight:
 
@@ -365,8 +365,8 @@ orange
 
 : orange fruit
 
-    1. sublist
-    2. sublist
+  1. sublist
+  2. sublist
 
 {id: html-blocks}
 # HTML Blocks