ox: Correctly handle footnote section

* lisp/ox.el (org-export--collect-headline-numbering): Remove footnote
  section from TOC.
(org-export-collect-headlines): Do not count footnote section when
numbering a headline.
* testing/lisp/test-ox.el: Add tests.

lisp/ox.el

@@ -1795,10 +1795,12 @@ DATA is the parse tree.  OPTIONS is the plist holding export
 options.
 
 Return an alist whose key is an headline and value is its
-associated numbering \(in the shape of a list of numbers\)."
+associated numbering \(in the shape of a list of numbers\) or nil
+for a footnotes section."
   (let ((numbering (make-vector org-export-max-depth 0)))
     (org-element-map data 'headline
       (lambda (headline)
+	(unless (org-element-property :footnote-section-p headline)
 	  (let ((relative-level
 		 (1- (org-export-get-relative-level headline options))))
 	    (cons
@@ -1807,7 +1809,7 @@ associated numbering \(in the shape of a list of numbers\)."
 		   for idx from 0 to org-export-max-depth
 		   when (< idx relative-level) collect n
 		   when (= idx relative-level) collect (aset numbering idx (1+ n))
-		 when (> idx relative-level) do (aset numbering idx 0)))))
+		   when (> idx relative-level) do (aset numbering idx 0))))))
       options)))
 
 (defun org-export--populate-ignore-list (data options)
@@ -4434,13 +4436,15 @@ the table of contents.  Otherwise, it is set to the value of the
 last headline level.  See `org-export-headline-levels' for more
 information.
 
-Return a list of all exportable headlines as parsed elements."
+Return a list of all exportable headlines as parsed elements.
+Footnote sections, if any, will be ignored."
   (unless (wholenump n) (setq n (plist-get info :headline-levels)))
   (org-element-map (plist-get info :parse-tree) 'headline
     (lambda (headline)
+      (unless (org-element-property :footnote-section-p headline)
 	;; Strip contents from HEADLINE.
 	(let ((relative-level (org-export-get-relative-level headline info)))
-	(unless (> relative-level n) headline)))
+	  (unless (> relative-level n) headline))))
     info))
 
 (defun org-export-collect-elements (type info &optional predicate)

testing/lisp/test-ox.el

@@ -858,7 +858,22 @@ Paragraph[fn:1]"
     (should
      (org-test-with-parsed-data "[fn:1]"
        (org-export-get-footnote-definition
-	(org-element-map tree 'footnote-reference 'identity info t) info)))))
+	(org-element-map tree 'footnote-reference 'identity info t) info)))
+    ;; 7. Footnote section should be ignored in TOC and in headlines
+    ;;    numbering.
+    (should
+     (= 1 (let ((org-footnote-section "Footnotes"))
+	    (length (org-test-with-parsed-data "* H1\n* Footnotes\n"
+		      (org-export-collect-headlines info))))))
+    (should
+     (equal '(2)
+	    (let ((org-footnote-section "Footnotes"))
+	      (org-test-with-parsed-data "* H1\n* Footnotes\n* H2"
+		(org-element-map tree 'headline
+		  (lambda (hl)
+		    (when (equal (org-element-property :raw-value hl) "H2")
+		      (org-export-get-headline-number hl info)))
+		  info t)))))))