Docx reader: Handle nested sdt tags.

Previously we had only unwrapped one level of sdt tags. Now we recurse
if we find them.

Closes: #4415

src/Text/Pandoc/Readers/Docx/Parse.hs

@@ -136,7 +136,7 @@ unwrapSDT :: NameSpaces -> Content -> [Content]
 unwrapSDT ns (Elem element)
   | isElem ns "w" "sdt" element
   , Just sdtContent <- findChildByName ns "w" "sdtContent" element
-  = map Elem $ elChildren sdtContent
+  = concatMap (unwrapSDT ns) $ map Elem $ elChildren sdtContent
 unwrapSDT _ content = [content]
 
 unwrapSDTchild :: NameSpaces -> Content -> Content

test/Tests/Readers/Docx.hs

@@ -178,6 +178,10 @@ tests = [ testGroup "inlines"
             "inlines inside of Structured Document Tags"
             "docx/sdt_elements.docx"
             "docx/sdt_elements.native"
+          , testCompare
+            "nested Structured Document Tags"
+            "docx/nested_sdt.docx"
+            "docx/nested_sdt.native"
           , testCompare
             "remove anchor spans with nothing pointing to them"
             "docx/unused_anchors.docx"

test/docx/nested_sdt.native

@@ -0,0 +1,3 @@
+[Para [Str "Test",Space,Str "Paragraph1"]
+,Para [Str "Test",Space,Str "Paragraph2"]
+,Para [Str "Test",Space,Str "Paragraph3"]]