bug#67711: Org Babel gives incomplete result when writing multi-thread code

[Eli Zaretskii]

> From: ". shynur" <one.last.kiss@outlook.com>
> Date: Fri, 8 Dec 2023 14:31:37 +0000
> msip_labels: 
> 
> (I use Emacs v29.1.90 for MS-Windows; gcc 10.3.0)
> Here's an Org file:
> 
>     #+BEGIN_SRC C
>     #include <stdio.h>
>     #include <omp.h>
>     int main() {
>     #pragma omp parallel num_threads(3)
>         printf("0"), printf("1");
>     }
>     #+END_SRC
> 
>     # Local Variables:
>     # eval: (require 'ob-C)
>     # org-babel-C-compiler: "gcc.exe  \
>     #                         -std=c17 -Wall -O0  \
>     #                         -fopenmp "
>     # org-confirm-babel-evaluate: nil
>     # End:
> 
> Executing the C code block usually outputs:
> 
>     #+RESULTS:
>     : 10101
> 
>     #+RESULTS:
>     : 1101
> 
> This output was unexpected, so I personally ran the temporary EXE file 
> generated by Org-Babel:
> 
>     Windows Terminal
>     PS D:/Tmp/babel-Xyz123> ./C-bin-Xyz123.exe
>     010101
> 
> As you can see, this program should output 6 characters.

The above invocation is AFAIU not an accurate reproduction of what
happens when this program is invoked from Emacs on MS-Windows.  Emacs
on Windows communicates with subprocesses via pipes, so a more
accurate reproduction would be something like

   C-bin-Xyz123.exe | more

IOW, you need to invoke the program with its output redirected to a
pipe.

In any case, please report this to the Org developers first, and only
if their analysis shows this is a core Emacs problem, come here.

Thanks.