Re: [RFC PATCH v1 0/8] qapi: add generator for Golang interface

[Daniel P . Berrangé]

On Tue, May 10, 2022 at 11:06:39AM +0200, Victor Toso wrote:
> Hi,
> 
> On Tue, May 10, 2022 at 09:53:05AM +0100, Daniel P. Berrangé wrote:
> > > > * License
> > > >
> > > > While the generator (golang.py in this series) is GPL v2, the
> > > 
> > > I'd make it v2+, just to express my displeasure with the decision to
> > > make the initial QAPI generator v2 only for no good reason at all.
> > 
> > Our policy is that all new code should be v2+ anyway, unless it
> > was clearly derived from some pre-existing v2-only code. Upto
> > Victor to say whether the golang.py is considered clean, or was
> > copy+paste in any parts from existin v2-only code
> 
> Should be fine to consider it v2+, the generator.
> 
> > > > generated code needs to be compatible with other Golang projects,
> > > > such as the ones mentioned above. My intention is to keep a Go
> > > > module with a MIT license.
> > >
> > > Meh.  Can't be helped, I guess.
> > 
> > This does make me wonder though whether the license of the QAPI
> > input files has a bearing on the Go (or other $LANGUAGE) ouput
> > files. eg is the Go code to be considered a derived work of the
> > QAPI JSON files.
> 
> GPL does not enforce that the generated code to be GPL [0] unless
> the generator copies GPL code to the output. My only concern has
> been the fact that I am copying the documentation of QAPI
> specification to the Go package in order to have data structures,
> commands, etc. with the information provided by the
> specification.
> 
> [0] https://www.gnu.org/licenses/old-licenses/gpl-2.0-faq.html#GPLOutput
>
> > I'm not finding a clearly articulated POV on this question so
> > far.
> 
> I don't find it trivial either but I've accepted that the Go data
> structures are fine based on [0] and the documentation can be
> split from the Go module (sadly!) if someone finds it to be a
> legal issue.

Ah well that link above is actually reasonably clear:

  "More generally, when a program translates its input into 
   some other form, the copyright status of the output inherits
   that of the input it was generated from. "

In our case the input is the QAPI JSON, and we're translating that
into  Golang. That could be read as meaning our Golang code has to
be GPLv2+ licensed just as with the QAPI, not merely the docs.

With regards,
Daniel
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