Org mode elisp in :var in header-args causing max-specpdl-size error

Question

In org mode, :var header arg definitions can actually call other SRC blocks, which is very nice! However I've run into a problem exemplified by the following org file:

#+NAME: add3
#+BEGIN_SRC elisp :var num=0
(+ 3 num)
#+END_SRC

* Use function drawer header arg
:PROPERTIES:
:header-args: :var n=add3(5)
:END:

#+NAME: whatIsN
#+BEGIN_SRC sh
echo $n
#+END_SRC

#+RESULTS: whatIsN
: 8

#+BEGIN_SRC sh :var a=whatIsN
echo $a
#+END_SRC

# !!!!ERROR!!!!: "variable binding depth exceeds max-specpdl-size"

This exact same example works fine if the :var for n is defined inline (instead of in the :PROPERTIES: drawer), like:

#+NAME: whatIsN
#+BEGIN_SRC sh :var n=add3(5)
echo $n
#+END_SRC

Anyone know what's causing org mode to stumble when the :var is defined in the :PROPERTIES: section?

org-version 9.1.11

Answer 1

The problem is located in org-babel-get-src-block-info.

The function org-babel-params-from-properties is used there. Its doc-string is:

Retrieve parameters specified as properties. Return a list of association lists of source block params specified in the properties of the current outline entry.

But they do not say what the current outline entry is. In org-babel-get-src-block-info they assumed that the current outline entry would be that one at point but org-babel-params-from-properties uses also org-babel-current-src-block-location to retrieve parameters from there.

Even if (point) is 1 for the first source block add3 the variable org-babel-current-src-block-location in org-babel-params-from-properties points to the source block whatIsN.

So not the header-args for add3 are collected by org-babel-params-from-properties but those of whatIsN.

The consequence is that add3 gets the header arg n=add3(5) from the drawer. Naturally, that leads to infinite recursion.

The funny thing is that they already tried to make sure that org-babel-params-from-properties gets the right header args from the location of datum. I cite a small section of org-babel-get-src-block-info:

           ;; If DATUM is provided, make sure we get node
           ;; properties applicable to its location within
           ;; the document.
           (org-with-point-at (org-element-property :begin datum)
             (org-babel-params-from-properties lang))

You can avoid the error if you additionally let-bind org-babel-current-src-block-location to the location of datum:

           ;; If DATUM is provided, make sure we get node
           ;; properties applicable to its location within
           ;; the document.
           (let ((org-babel-current-src-block-location (org-element-property :begin datum)))
             (org-with-point-at org-babel-current-src-block-location
               (org-babel-params-from-properties lang)))

I am not sure about the full consequences of that change through.

Note that I sent a bug-report to [email protected].

---

EDIT: I already got a response on [email protected] from Charles Berry. He wrote that he could not reproduce the problem on Orgmode 9.1.14.

I had a quick look at the current master of the orgmode repository. They fixed the bug by substituting the reference to org-babel-current-src-block-location with (point) in org-babel-params-from-properties.

Nevertheless, the problem is still present in the current maint branch of orgmode.

The problematic reference of org-babel-current-src-block-location within org-babel-params-from-properties is even present in the release_9.14 branch of orgmode. In spite of what Charles said.