[pca] patchdiag.xref feature request for Don

[Martin Paul]

Thomas,

> I wonder if this feature could be integrated into We Sun Solve website,
> as from the patchdiag.xref archive, I could generate a patchdiag.xref with
> latest revision as base and then add older revision of patches into it by looking at
> patchdiag.xref archive.

Yes, you're right. Theoretically one should be able to build a master xref file 
by joining the old copies, which could then be used to show patch dependencies 
for older revisions as well.

One problem is that a simple "cat */patchdiag.xref | sort | uniq" won't be 
enough. One would have to take care of the R/S/O flags on past patch revisions. 
and it would be very hard (or, impossible) to verify whether the result is 
actually consistent.

As far as PCA is concerned, there's another problem - its data structures assume 
that there is only one revision per patch (the main array is indexed by patch-ID 
only). Changing this would require a re-write of big parts of the code.

Martin.