@jorge: if we supply a list of regexps to find language constructs we want to remove from the language, can we get a list of addons that contain them, and maybe even statistics? Also, how would the deprecation-process work. I guess we'd start by adding warnings to the addon verifier?

(In reply to Till Schneidereit [:till] from comment #1) > @jorge: if we supply a list of regexps to find language constructs we want > to remove from the language, can we get a list of addons that contain them, > and maybe even statistics? We use the add-ons MXR (https://mxr.mozilla.org/addons/) to find this out. Depending on the complexity of the RE, the search could not work or generate too many false positives, so there are cases where we won't know how many add-ons are affected. That shouldn't stop us from making a change if necessary, though. > Also, how would the deprecation-process work. I guess we'd start by adding > warnings to the addon verifier? I need the bugs making these changes to be flagged with the addon-compat keyword, and to have the Target Milestone properly set. Before a release, I check all flagged bugs and create a compatibility report (like this one https://blog.mozilla.org/addons/2013/04/26/compatibility-for-firefox-21/) and file validation bugs and then run the bulk compatibility checks on AMO.

I also have about 4000 extracted add-ons and 12000 XPIs on my workstation that I can grep for a more complex expression if need be.

Legacy extensions are dead, and WebExtensions don't allow versioned JS, so this is no longer a concern.