2012.01.23 17:50 "Re: [Tiff] update on tiff 4.x in debian", by Bob Friesenhahn
I will get to this as soon as I can, but I will probably want to get someone from the debian release team to look at it. Maybe Tom Lane can look at it too -- he probably has more experience with this than I do.
Sorry, I don't know much of anything about versioned symbols. My reaction TBH is that it's a big mistake to be changing 3.9.x's ABI at this late date, and that if this ships it will be a blocker to ever again updating libtiff 3.9 in existing RHEL branches.
The 3.9.x ABI would not change by default. If a distribution chooses to enable versioned symbols then it also needs to take responsibility to assure that all software is built consistently and that there is no way to introduce binaries which depend on the former ABI. This is most easily performed at beginning of a major baseline cycle, which typically occurs only every few years. Of course, the software could simply be updated to work with libtiff 4.0 instead.
Debian did previously jump through all these hoops in order to add versioned symbols to old IJG JPEG 6b so that it could introduce IJG JPEG 7 and IJG JPEG 8.
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/