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
