Re: Jam: which licence is this?

[Leo Famulari <leo@famulari.name>]

On Sun, May 02, 2021 at 12:53:07AM -0400, Mark H Weaver wrote:
> My understanding is that the 'license' field of a package in Guix has
> _always_ been meant to summarize the license restrictions associated
> with the package source (the output of "guix build --source"), and
> *not* merely the package outputs.

My understanding is that the license field describes the license that
the package is redistributed under, which is typically a single license,
but could be a dual (or multiple) license if that is the case.

The manual section "package Reference" says:

The license of the package; a value from (guix licenses), or a list of
such values.

It's the license of the package, overall. Not of every single file in
the source code.

> Really?  Can you give some examples of this from our core packages?

The 'hello' package is not core, but it is a typical Autotools-based
package, and the core packages will be similar.

It is, overall, GPL3 or later. However, the component source files bear
these other licenses too:

aclocal.m4: An unnamed permissive license
AUTHORS: An unnamed permissive license
configure: An unnamed permissive license
configure.ac: An unnamed permissive license
INSTALL: An unnamed permissive license
maint.mk: An unnamed permissive license
Makefile.am, Makefile.in: An unnamed permissive license
README, README-dev: An unnamed permissive license
THANKS: An unnamed permissive license

build-aux/compile: GPL2+
build-aux/config.rpath: An unnamed permissive license
build-aux/depcomp: GPL2+
build-aux/install-sh: Expat license
build-aux/mdate-sh: GPL2+
build-aux/missing: GPL2+
build-aux/test-driver: GPL2+

doc: Some files bear the GFDL

m4: Maybe unnamed permissive licenses (I'm getting tired)

po/Makefile.in.in: The "GPL" with no version mentioned. I assume GPL1.
po/POTFILES.in: An unnamed permissive license

tests/*: An unnamed permissive license

Some of those unnamed permissive licenses are the same as each other,
some are different.

It would be unhelpful if the package definition's license field said
"gpl3+ gpl2+ gpl1 non-copyleft expat gfdl". Nobody would be able to
answer the question "What is the license of the 'hello' package?"

> The 'license' field can only mean one of these two things, and I think
> it's fairly clear which one it should be.  Moreover, I think that this
> is what it has always meant in Guix.  If not, that's a problem.

My survey of the "hello" package shows that the license field in Guix is
about the overall license of the program, not an exhaustive list of the
many licenses used for various components of the source code.

I don't think it's a problem to not mention those licenses in the
package definition. When the user acquires the source code, they still
get the benefits of the freely licensed components. Nothing is being
hidden.

The suggestion that our package definitions' license field should
mention every license contain in the source code has no precedent in
Guix, at least since I joined. I don't there is a demonstrated benefit
to making that change.