GCC pre-releases and venerable traditions

Debian uses a tilde for version numbers that should reliability sort before, rather than after, an upcoming version. You'll see this with the "backports" section (i.e. versions from testing adapted to be installed on the stable release of Debian)

E.g. there's foo-1.8 in stable, foo-2.0~bp1 in backports, and foo-2.0 in testing. When the next stable release of Debian happens, foo-2.0 will be considered a "newer" version than foo-2.0~bp1 and installed preferentially.

Typically, the last backports version is identical with the new stable version except for being compiled against (and declaring dependencies on) the older libraries available in stable.

Conceptually, it's like having a patch version number of "-1" which naturally sorts earlier than a patch version of "0" (i.e. foo-2.0~bp1 sorts like 2 point 0 point -1 point (bp)1 < 2 point 0 point 0)

I like the semantics of this approach, but it does require that whatever is sorting version numbers understands what the tilde means and isn't really a widespread enough idiom for that be be something one can assume in general.