ox: Make `org-export-table-cell-width' more robust

* lisp/ox.el (org-export-table-cell-width): Make
  `org-export-table-cell-width' robust against malformed tables.

Reported-by: michael <m.schoenwaelder@posteo.de>
<http://lists.gnu.org/r/emacs-orgmode/2019-05/msg00215.html>

lisp/ox.el

@@ -4916,26 +4916,32 @@ same column as TABLE-CELL, or nil."
 		      (plist-put info :table-cell-width-cache table)
 		      table)))
 	 (width-vector (or (gethash table cache)
-			   (puthash table (make-vector columns 'empty) cache)))
+			   (puthash table (make-vector columns 'empty) cache))))
-	 (value (aref width-vector column)))
+    ;; Table may not have the same number of rows.  Extend
-    (if (not (eq value 'empty)) value
+    ;; WIDTH-VECTOR appropriately if we encounter a row larger than
-      (let (cookie-width)
+    ;; expected.
-	(dolist (row (org-element-contents table)
+    (when (>= column (length width-vector))
-		     (aset width-vector column cookie-width))
+      (setq width-vector
+	    (vconcat width-vector
+		     (make-list (- (1+ column) (length width-vector))
+				'empty)))
+      (puthash table width-vector cache))
+    (pcase (aref width-vector column)
+      (`empty
+       (catch 'found
+	 (dolist (row (org-element-contents table))
 	   (when (org-export-table-row-is-special-p row info)
-	    ;; In a special row, try to find a width cookie at COLUMN.
+	     ;; In a special row, try to find a width cookie at
-	    (let* ((value (org-element-contents
+	     ;; COLUMN.  The following checks avoid expanding
-			   (elt (org-element-contents row) column)))
+	     ;; unnecessarily the cell with `org-export-data'.
-		   (cookie (car value)))
+	     (pcase (org-element-contents
-	      ;; The following checks avoid expanding unnecessarily
+		     (elt (org-element-contents row) column))
-	      ;; the cell with `org-export-data'.
+	       (`(,(and (pred stringp) cookie))
-	      (when (and value
+		(when (string-match "\\`<[lrc]?\\([0-9]+\\)>\\'" cookie)
-			 (not (cdr value))
+		  (let ((w (string-to-number (match-string 1 cookie))))
-			 (stringp cookie)
+		    (throw 'found (aset width-vector column w))))))))
-			 (string-match "\\`<[lrc]?\\([0-9]+\\)?>\\'" cookie)
+	 (aset width-vector column nil)))
-			 (match-string 1 cookie))
+      (value value))))
-		(setq cookie-width
-		      (string-to-number (match-string 1 cookie)))))))))))
 
 (defun org-export-table-cell-alignment (table-cell info)
   "Return TABLE-CELL contents alignment.

testing/lisp/test-ox.el

@@ -4148,33 +4148,28 @@ Another text. (ref:text)
 
 (ert-deftest test-org-export/table-cell-width ()
   "Test `org-export-table-cell-width' specifications."
-  ;; 1. Width is primarily determined by width cookies.  If no cookie
+  ;; Width is primarily determined by width cookies.  If no cookie is
-  ;;    is found, cell's width is nil.
+  ;; found, cell's width is nil.
+  (should
+   (equal '(nil 6 7)
 	  (org-test-with-parsed-data "
 | / | <l> | <6> | <l7> |
 |   |  a  |  b  |  c   |"
-    (should
-     (equal
-      '(nil 6 7)
 	    (mapcar (lambda (cell) (org-export-table-cell-width cell info))
 		    (org-element-map tree 'table-cell 'identity info)))))
-  ;; 2. The last width cookie has precedence.
+  ;; Valid width cookies must have a specific row.
-  (org-test-with-parsed-data "
-| <6> |
-| <7> |
-|  a  |"
   (should
-     (equal
+   (equal '(nil nil)
-      '(7)
-      (mapcar (lambda (cell) (org-export-table-cell-width cell info))
-	      (org-element-map tree 'table-cell 'identity info)))))
-  ;; 3. Valid width cookies must have a specific row.
 	  (org-test-with-parsed-data "| <6> | cell |"
-    (should
-     (equal
-      '(nil nil)
 	    (mapcar (lambda (cell) (org-export-table-cell-width cell info))
-	      (org-element-map tree 'table-cell 'identity))))))
+		    (org-element-map tree 'table-cell 'identity)))))
+  ;; Do not error on malformed tables.
+  (should
+   (org-test-with-parsed-data "
+| a |
+| b | c |"
+     (mapcar (lambda (cell) (org-export-table-cell-width cell info))
+	     (org-element-map tree 'table-cell 'identity info)))))
 
 (ert-deftest test-org-export/table-cell-alignment ()
   "Test `org-export-table-cell-alignment' specifications."