If a project only includes a copy of the GPL, can it be relicensed under any version?

Question

There's a project that only includes a copy of the GNU GPLv2 accompanying it that I wish to combine with GPL-3.0-or-later code. Assume that simply including a license file applies it globally to the whole project. For clarity, there are no other notices besides the text of the GPLv2 itself in the LICENSE file.

GPLv2 § 9 states, "[i]f the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation." Does including the GPLv2 license text count as specifying a version number? That is, can I relicense it under GPL-3.0-or-later?

My hunch is that it's a "no," since, by providing the text of the GPLv2, the copyright holder is implicitly specifying you can use it under GPL-2.0, and, absent "or any later version," that means GPL-2.0-only. Would this be correct reasoning?

Answer 1

Your hunch of "no" seems correct to me. The GPL FAQ has this to say about standalone copies of the GPL without an explicit license grant:

Is it enough just to put a copy of the GNU GPL in my repository?

Just putting a copy of the GNU GPL in a file in your repository does not explicitly state that the code in the same repository may be used under the GNU GPL. Without such a statement, it's not entirely clear that the permissions in the license really apply to any particular source file. An explicit statement saying that eliminates all doubt.

A file containing just a license, without a statement that certain other files are covered by that license, resembles a file containing just a subroutine which is never called from anywhere else. The resemblance is not perfect: lawyers and courts might apply common sense and conclude that you must have put the copy of the GNU GPL there because you wanted to license the code that way. Or they might not. Why leave an uncertainty?

If the author failed to annotate that their code is under the GPL at all, but included a copy of the GPL then it seems to me there are only two possibilities:

1. The code is not actually under any version of the GPL, because there isn't a strong enough indication that the copy of the GPL terms included in the repository was intended to apply to the particular piece of code under consideration.

2. Conversely, there is sufficient evidence that the GPL license terms included in the repository do in fact apply to that piece of code, in which case those terms apply to the code. I cannot interpret this case as doing anything but exactly specifying which GPL version applies to the code.