[BUG] org-babel: Binding a cons in var header arg yields error [9.4.5 (9.4.5-g914fe8 @ /home/yantar92/.emacs.d/straight/build/org/)]

[Ihor Radchenko]

With the following org file on master:

#+name: gen
#+begin_src emacs-lisp
(cons 1 2)
#+end_src

#+header: :var inp=gen()
#+begin_src emacs-lisp
inp
#+end_src

C-c C-c on the second code block yields:
executing Emacs-Lisp code block (gen)...
(1 . 2)
org-babel-disassemble-tables: Wrong type argument: listp, 2

The fix is attached.

Best,
Ihor

>From 761c6227e82c6e9f4d6ee701eaa0b532ac9c7916 Mon Sep 17 00:00:00 2001
Message-Id: 
<761c6227e82c6e9f4d6ee701eaa0b532ac9c7916.1621508858.git.yantar92@gmail.com>
From: Ihor Radchenko <yantar92@gmail.com>
Date: Thu, 20 May 2021 19:01:06 +0800
Subject: [PATCH] Allow :var header args to be assigned to cons cells

* lisp/ob-core.el (org-babel-disassemble-tables,
org-babel-gnuplot-process-vars): Use `proper-list-p' check instead of
`listp'.
(org-babel-disassemble-tables): Check list length before trying to
remove hline from a table assignment.
* testing/lisp/test-ob.el (test-ob/cons-cell-as-variable): Add the
test.
---
 lisp/ob-core.el         |  5 +++--
 lisp/ob-gnuplot.el      |  2 +-
 testing/lisp/test-ob.el | 16 ++++++++++++++++
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index 857e03e55..c04bec9ae 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -1684,9 +1684,10 @@ (defun org-babel-disassemble-tables (vars hlines 
colnames rownames)
     (list
      (mapcar
       (lambda (var)
-        (when (listp (cdr var))
+        (when (proper-list-p (cdr var))
           (when (and (not (equal colnames "no"))
-                     (or colnames (and (eq (nth 1 (cdr var)) 'hline)
+                     (or colnames (and (length> (cdr var) 1)
+                                       (eq (nth 1 (cdr var)) 'hline)
                                        (not (member 'hline (cddr (cdr 
var)))))))
             (let ((both (org-babel-get-colnames (cdr var))))
               (setq cnames (cons (cons (car var) (cdr both))
diff --git a/lisp/ob-gnuplot.el b/lisp/ob-gnuplot.el
index a9b8e65e5..ea7d29c4e 100644
--- a/lisp/ob-gnuplot.el
+++ b/lisp/ob-gnuplot.el
@@ -87,7 +87,7 @@ (defun org-babel-gnuplot-process-vars (params)
        (cons
        (car pair) ;; variable name
        (let* ((val (cdr pair)) ;; variable value
-              (lp  (listp val)))
+              (lp  (proper-list-p val)))
          (if lp
              (org-babel-gnuplot-table-to-data
               (let* ((first  (car val))
diff --git a/testing/lisp/test-ob.el b/testing/lisp/test-ob.el
index 88ecb62b5..a5ae8e389 100644
--- a/testing/lisp/test-ob.el
+++ b/testing/lisp/test-ob.el
@@ -178,6 +178,22 @@ (ert-deftest test-ob/simple-variable-resolution ()
                            (point-at-bol)
                            (point-at-eol))))))
 
+(ert-deftest test-ob/cons-cell-as-variable ()
+  "Test that cons cell can be assigned as variable."
+  (org-test-with-temp-text "
+
+#+name: cons
+#+begin_src emacs-lisp
+  (cons 1 2)
+#+end_src
+
+#+begin_src emacs-lisp :var x=cons
+  x
+#+end_src"
+
+    (org-babel-next-src-block 2)
+    (should (equal (cons 1 2) (org-babel-execute-src-block)))))
+
 (ert-deftest test-ob/multi-line-header-arguments ()
   "Test that multi-line header arguments and can be read."
   (org-test-with-temp-text-in-file "
-- 
2.26.3