For posterity, re: "reverting change" -- the XML ID is now part of the priv struct, so from the public API's perspective that commit has not been reverted.

@kgaillot I don't think the existing XSLT error handler sets config warning, FYI. If we want that, we'll want a wishlist task for it, because it looks like it's gonna require some rearranging of cib_upgrade_err() that might be tricky to avoid redundant logs.

In T898#14801, @kgaillot wrote:

Since the risk of corner cases is so high, and our time for 3.0.0 is limited, I think the best approach would be to log a warning if a CIB contains ACLs with xpaths and the upgrade adds or renames any element or attribute. (We could possibly check whether an xpath exists that refers to an attribute, to reduce the scope a bit.) Something like: "WARNING: CIB syntax changes may invalidate ACLs that use 'xpath'. It is strongly recommended to run 'cibadmin --upgrade' then go through the updated CIB carefully to ensure ACLs still match the desired intent."

In T898#14801, @kgaillot wrote:

Do you know what version of libxslt added support for dyn:evaluate? We only require 2.9.2 currently. I wouldn't mind using it to reduce the scope of the log further, but it's not necessary.

@kgaillot Can you weigh in when you have a chance? I know things are especially busy.
I figure it's unwise to work on the xpath case until we agree upon how we ought to address it -- if at all.

CLPR#3747 fixes the case of ACLs that refer to dropped elements, but it doesn't do anything special for replaced elements yet.

XSL has some mechanism for this, and we already have an appropriate logger in C.