Andrew Black wrote:
Martin Sebor wrote:
This has been bugging me -- when someone checks out trunk, does a build and
sends
us build results, we have no way of telling that the build results are, in
fact, for trunk and
not for 4.2.0 (or the head of 4.2.x), because the value of _RWSTD_VER is the
same. I
think we should change it so that the value is unique for each branch, or at
least distinct
from any release.
Any suggestions for what would be a good value?
The following is my suggestion for a scheme for _RWSTD_VER:
Trunk: 0xFFFFFFFF
Trunk feature branch: 0xFFFFFFxx
Major branch: 0xMMFF0000
Maintenance branch: 0xMMmmFF00
Thanks, this is an interesting idea that I hadn't thought of.
At first I didn't think 0xFF made sense but I'm slowly starting
to warm up to it.
A trunk feature branch is a branch in subversion used for developing a
specific feature, which isn't ready for inclusion in trunk, but is major
enough that incremental testing is required. An example could be the
implementation of concepts. The placeholder 'xx' is a non-FF value,
unique to a feature branch. If the number of feature branches exceeds
255, it will be necessary to reuse numbers, but this isn't a likely
occurrence in the near term. These numbers should be issued in the
order the branches are created.
We'd have to find a way to avoid conflicts. I.e., How would one go
about finding the next available value of xx to grab for their new
feature branch? (It wouldn't be too hard to do today but if we had
as many feature branches as gcc, as unlikely as it is, it could be
a challenge.)
A major branch is a branch in subversion used for ongoing development of
a source compatible lineage. The placeholder MM represents the major
version. An example would be ongoing maintenance of the 4.x version of
stdcxx beyond 4.3, after the 5.0 release has been made. In the case of
a 4.x maintenance branch, the version would be 0x04FF0000
Makes sense.
Maintenance branches are an established concept, with the 4.2.x branch
being an example. The placeholder MM represents the major version, with
the placeholder mm representing the minor version. In the case of
4.2.x, the version would be 0x0402FF00.
Same here.
Justification:
My primary reason for using the 0xFF value as a placeholder (generally)
is because it is greater than any particular released version number.
This should allow checks which look for a specific version of the
library (either older or newer) to function correctly. If someone
wanted to exclude the trunk from these checks, it would be possible to
simply perform a bitwise negation, and if the value of that negation is
0, it means the token references a trunk version.
I think I like this idea quite a bit, actually Using a fixed value
also makes it easy to test for it in release scripts and catch
releases where the macro isn't set correctly (because the value
would either be 0xFF or fail to match the version in the name of
the tag).
Is everyone else happy with this scheme?
Martin
