Hi, Jordi,
I am glad you know what I said completely.
Just one thing...the suggestion you made...exists.
The Fedora way was introduced by early openSUSE go maintainers, I just
renamed it to "-source" to better reflect what this sub-package really
is.
And I myself usually don't add that macro to my specfile. Because I
don't like souce codes shipped to the end users. (traditionally, they
recommends/requires the -source sub-package for the main package, so a
user may have accidentally installed many source codes.)
I must admit that I didn't realize the real purpose of -source sub-packages.