GPL license is ambiguous

[merkys]

To date, there are three versions of GNU GPL license, each differing from the other. It would be great to see GPL version number in the license of the code to unambiguously know what are the permissions for (re)use.

[levitte]

Not sure why you're talking about a GPL license, as it's not used here (as far as I can tell at least).

The license can be found here: https://github.com/dot-asm/cryptogams/blob/master/LICENSE

[merkys]

I mean the following lines of the same LICENSE file:

cryptogams/LICENSE

Lines 21 to 24 in 097e2c7

	ALTERNATIVELY, provided that this notice is retained in full, this
	product may be distributed under the terms of the GNU General Public
	License (GPL), in which case the provisions of the GPL apply INSTEAD OF
	those given above.

[noloader]

I mean the following lines of the same LICENSE file...

I believe that clause is present because the Linux kernel uses some of Andy's routines. Andy had to supply a compatible license for the kernel.

In the context of the kernel, it will be GPL v2.0. Also see https://www.kernel.org/doc/html/v4.16/process/license-rules.html .