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

[Brandon Guttersohn <brandon@guttersohn.org>]

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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