Re: GPL carve-out missing for barrier

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Tue, 6 Sept 2022 at 11:29, Tom James <tom.james@cd-adapco.com> wrote:
>
> Hi,
>
> I'm working on a closed-source c++ project that compiles with gcc 11.2.  We
> need to ship the GNU 11.2 run-time alongside our product, and it looks like
> the std::barrier header is missing the GPL3 carve-out for shipping
> run-times.

Ouch, I'm pretty sure that's unintentional. I'll go back through my
email to confirm that.


> For the purposes of comparison, let's look at algorithm:
> https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/std/algorithm
>
> Lines 16-18 read as follows:
>   // Under Section 7 of GPL version 3, you are granted additional
>   // permissions described in the GCC Runtime Library Exception, version
>   // 3.1, as published by the Free Software Foundation.
>
> These lines are necessary to prevent the GPL infecting our closed-source
> code.

What exactly are you shipping? There is no code from <barrier> in
libstdc++.so so unless your own code is including the <barrier> header
and odr-using the inline functions and templates in that header, I
think your compiled code will not be affected by the license of
<barrier>. If you are including that header in the works you
propagate, or shipping it to customers for compiling their own works
which they will propagate, then the license exception matters.

> The barrier header appears to be missing these lines:
> https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/std/barrier
>
>
> Would it be possible to please make the following changes?
> 1.  Add these lines to the master branch,
> 2.  Backport these lines to gnu 11.2 (which is the most recent version
> supported by our toolchain).

No, we can't backport anything to 11.2 because that's already been released.

I'll add it to the master, gcc-12, and gcc-11 branches, which will
mean it's present for 11.4, 12.3 and 13.1 (and all releases that
follow them).

If you are producing a combined work that includes the <barrier> code,
then unless/until you're able to wait for 11.4 and use that, you could
copy the fixed header into your own GCC 11.2 that you distribute.