From: Oz Ben-Ami <ozzieba@gmail.com>
To: Thierry Banel <tbanelwebmin@free.fr>
Cc: emacs-orgmode@gnu.org
Subject: Re: org-babel C math.h issue
Date: Fri, 11 Mar 2016 14:14:21 -0500 [thread overview]
Message-ID: <CABYMxKxaExgmjbbv3tCVDWHNJgtT4hw0tg1rU1o-huMmi3ibGg@mail.gmail.com> (raw)
In-Reply-To: <56E313E9.4010703@free.fr>
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Thanks for the response.
On my machine, I get the undefined references even with GCC 5 (gcc version
5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)), if I put -lm before the source
file name.
As far as a patch, I can try but this would be my first time really playing
with org-mode code. As far as I can see, I would need to add the following
lines in ob-C.el:
L133: (libs (cdr (assoc :libs params)))
(libs (mapconcat 'identity
(if (listp libs) libs (list libs)) " "))
L142: (format "%s -o %s %s %s %s" ;; (added %s)
L147: libs
Am I missing anything?
Oz
On Fri, Mar 11, 2016 at 1:52 PM, Thierry Banel <tbanelwebmin@free.fr> wrote:
> To summarize this thread:
> It seems there was an issue long ago.
> Version 5 of GCC magically fixed it.
> But it is still here for older compilers.
>
> -------------------------
>
> To debug, execute the following piece of lisp code:
>
> (defadvice org-babel-eval (before xxx (cmd body))
> ""
> (message "org-babel-eval : %s" cmd))
> (ad-activate 'org-babel-eval)
>
> The actual compilation command will be displayed in the *Messages* buffer.
>
> With your example, we get
>
> gcc -o /tmp/babel-8412zIw/C-bin-8412IZR -lm
> /tmp/babel-8412zIw/C-src-84127OL.c
>
> --------------------------
>
> You are right, Oz, this can be fixed in line 147.
> But :flags is intended for flags like -g or -O, which need to appear
> before the source file.
>
> Probably we are missing an additional flag, which could be named :libs
> Then your example would be:
>
> #+BEGIN_SRC C :includes '(<math.h> <stdio.h>) :libs -lm
> int i=9;
> printf("%d\n",(int)sqrt(i));
> #+END_SRC
>
> --------------------------
>
> Oz, do you think you would be able to provide a patch?
> The way to contribute is documented here:
> http://orgmode.org/worg/org-contribute.html#orgheadline1
>
> Thanks for reporting.
> Thierry
>
>
> Le 06/03/2016 23:44, Oz Ben-Ami a écrit :
> > Hi,
> >
> > I'm a new org user, and I'm sorry if I'm missing something obvious.
> > When executing a C code snippet with org-babel, that contains a math
> > function, I get the famous "undefined reference" errors. I tried
> > adding ":flags -lm", but that doesn't help. Looking at the code, it
> > seems the -lm flag is inserted in the wrong place, before the source
> > file. An easy change would be in line 147 of ob-C.el version
> > 8.3.4-634, moving "flags" to after the source file. This seems to
> > work, but I don't know if it would break anything else.
> >
> > A minimal working example, attached, includes the following snippet:
> >
> > #+BEGIN_SRC C :includes '(<math.h> <stdio.h>) :flags -lm
> > int i=9;
> > printf("%d\n",(int)sqrt(i));
> > #+END_SRC
> >
> > Note the issue disappears if constants are directly used rather than
> > variables, presumably because the function call is optimized away
> > entirely.
> >
> > Any thoughts are appreciated.
> >
> > Oz
>
>
>
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next prev parent reply other threads:[~2016-03-11 19:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-06 22:44 org-babel C math.h issue Oz Ben-Ami
2016-03-10 9:43 ` Nicolas Goaziou
2016-03-10 14:06 ` Anssi Saari
2016-03-10 15:20 ` John Kitchin
2016-03-10 21:19 ` Nick Dokos
2016-03-11 6:44 ` Anssi Saari
2016-03-11 15:36 ` Nick Dokos
2016-03-11 18:52 ` Thierry Banel
2016-03-11 19:14 ` Oz Ben-Ami [this message]
2016-03-11 23:14 ` Thierry Banel
2016-03-20 14:03 ` [PATCH] " Thierry Banel
2016-03-25 23:42 ` Nicolas Goaziou
2016-03-26 17:08 ` Thierry Banel
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