Number `Listing' (source code block) captions in pandoc export.

Overrides the exporter for source code blocks to add the org-mode
standard numbered label ("Listing %d:") before any caption text. As with
the Table and Figure caption labels, this is passed through org-mode's
standard language translators to convert the label to the local language.

ox-pandoc.el

@@ -217,7 +217,8 @@
  (link . org-pandoc-link)
  (table . org-pandoc-table)
  (template . org-pandoc-template)
- (paragraph . org-pandoc-paragraph))
+ (paragraph . org-pandoc-paragraph)
+ (src-block . org-pandoc-src-block))
  ;; :export-block "PANDOC"
  :menu-entry
  `(?p "export via pandoc"
@@ -1411,6 +1412,15 @@ the plist used as a communication channel."
  ;; preserves #+ATTR_* tags in the output.
  (org-export-expand paragraph contents t))
 
+(defun org-pandoc-src-block (src-block contents info)
+ "Transcode a SRC-BLOCK element from Org to Pandoc.
+CONTENTS is the contents of the table. INFO is a plist holding
+contextual information."
+ (org-pandoc-set-caption-title src-block info "Listing %d:"
+ #'org-pandoc--has-caption-p)
+ ;; Export the src-block with it's modified caption
+ (org-export-expand src-block contents t))
+
 (defun org-pandoc-identity (blob contents _info)
  "Transcode BLOB element or object back into Org syntax.
 CONTENTS is its contents, as a string or nil. INFO is ignored.