Possible fix for :includes header argument in org-babel C source blocks

Possible fix for :includes header argument in org-babel C source blocks

[Brandon Guttersohn]

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Hey all, I think I may have a small fix for executing C source blocks in 
org-babel. Or, possibly just a bad case of user error.

The issue (in emacs 27 with -q) is that it doesn't seem possible to 
specify non-system header files with the :includes header argument.

For example; while the following line:

     #+BEGIN_SRC C :includes <example.h>

...produces reasonable code...

     #include <example.h>

...all of the following lines...

     #+BEGIN_SRC C :includes example.h

     #+BEGIN_SRC C :includes "example.h"

     #+BEGIN_SRC C :includes "\"example.h\""

...just result in this...

     #include example.h

...rather than this...

     #include "example.h"

The attached patch will wrap filenames in quotes if they do not begin 
with "<", and works for me.

Is this a reasonable fix, or maybe I'm misusing the feature?


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From e16887fd17c24397b3f9709fcb81e522adab13ee Mon Sep 17 00:00:00 2001
From: Brandon Guttersohn <brandon@guttersohn.org>
Date: Tue, 28 Apr 2020 19:16:41 -0500
Subject: [PATCH] Fix support for non-system C include directives in org-babel

C source blocks in org-babel support an ":includes" header argument,
which can generate #include directives prior to execution. Without
this patch, only system header files (enclosed in < and >) seem to
work, as double quotes are neither added nor preserved.

With this patch, any include file name which does not begin with a <
character will be wrapped in double quotes.
---
 lisp/org/ob-C.el | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lisp/org/ob-C.el b/lisp/org/ob-C.el
index 3a26bc014b..00711cad12 100644
--- a/lisp/org/ob-C.el
+++ b/lisp/org/ob-C.el
@@ -232,7 +232,10 @@ org-babel-C-expand-C
 	       (list
 		;; includes
 		(mapconcat
-		 (lambda (inc) (format "#include %s" inc))
+		 (lambda (inc)
+           (if (string-prefix-p "<" inc)
+               (format "#include %s" inc)
+             (format "#include \"%s\"" inc)))
 		 includes "\n")
 		;; defines
 		(mapconcat
-- 
2.24.1

Possible fix for :includes header argument in org-babel C source blocks

[Ori]

Hi Brandon,

Some other interesting test results, the first of which makes me think that string un-escaping could be going too far and perhaps the problem lies elsewhere:

    :includes "example.h\""
results in:
    #includes example.h"

    :includes '("\"/some/path/to/example.h\"" "<example_2.h>")
results in:
    #include "/some/path/to/example.h"
    #include <example_2.h>

That works with just one sting in the list as well:
    :includes '("\"/some/path/to/example.h\"")
results in:
    #include "/some/path/to/example.h"


This is on Emacs 26 with org 9.3.4

Ori

Re: Possible fix for :includes header argument in org-babel C source blocks

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

How does a system do un-escaping?  With RECAPTCHA?

;-}

-- 
Dr Richard Stallman
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Re: Possible fix for :includes header argument in org-babel C source blocks

[Bastien]

Hi Brandon,

Brandon Guttersohn <brandon@guttersohn.org> writes:

> Hey all, I think I may have a small fix for executing C source blocks
> in org-babel. Or, possibly just a bad case of user error.
>
> The issue (in emacs 27 with -q) is that it doesn't seem possible to
> specify non-system header files with the :includes header argument.
>
> [...]
>
> The attached patch will wrap filenames in quotes if they do not begin
> with "<", and works for me.

Thanks for reporting this and for suggesting this patch, I think it is
good enough.  I have applied it to the master branch of Org:

https://code.orgmode.org/bzg/org-mode/commit/44cb98fdb6

Best,

-- 
 Bastien