Hi, everyone.
TL;DR: I'd like to propose adding metadata/spdx-license.conf using
the following format:
<spdx-expr> = <ebuild-expr>
where <spdx-expr> is a SPDX-2.0 license identifier, optionally followed
by "+", optionally followed by "WITH" and an exception identifier,
and <ebuild-expr> is the corresponding ebuild-style LICENSE field value.
This has been proposed in bug 706472 [1], as an effort to aid converting
from the more commonly used SPDX-2.0 identifiers (used e.g. by Cargo) to
Gentoo licenses. Right now an inline mapping for them is used e.g. by cargo-ebuild [2].
Besides maintaining a basic mapping of licenses, there are two main
challenges to be overcome here:
1. SPDX-2.0 using "WITH" operator to combine licenses with exceptions,
whereas Gentoo uses combined files for that, e.g. "Apache-2.0 WITH LLVM- exception" corresponds to Gentoo "Apache-2.0-with-LLVM-exceptions").
2. SPDX-2.0 using "+" operator to indicate "or later" for most of
the licenses (except for GNU licenses, that have explicit "*-or-later"
variant, whereas Gentoo only features "or later" variants of specific
licenses.
I think the best approach here is to include both "+" and "WITH ..."
explicitly in the key, and to allow the RHS to specify an arbitrary
Gentoo license expression. Therefore, e.g. the file would specify:
Apache-1.1 = Apache-1.1
Apache-2.0 = Apache-2.0
Apache-2.0 WITH LLVM-exception = Apache-2.0-with-LLVM-exceptions
Apache-1.1+ = || ( Apache-1.1 Apache-2.0 )
Then, SPDX (sub)expressions would be mapped the following way:
a. plain "Apache-x.y" would be mapped to "Apache-x.y"
b. "Apache-2.0 WITH LLVM-exception" would be mapped to the appropriate
license
c. "Apache-2.0 WITH ..." any other exception would remain unmatched
d. "Apache-1.1+" would map to the OR-expression for all matching
licenses
e. "Apache-2.0+" would not be listed explicitly, the tool could fall
back to "Apache-2.0" then (assuming we don't have any later version)
WDYT?
[1]
https://bugs.gentoo.org/706472
[2]
https://github.com/gentoo/cargo-ebuild/blob/master/src/license.rs#L3
--
Best regards,
Michał Górny
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