We'd generally like to remove [array] from xpconnect. See bug 1509981.

The replacement is the Array type. So for example, an API like getSubjects() in nsIActivity.idl would change from:

  void getSubjects(out unsigned long length, [retval, array,
                   size_is(length)] out nsIVariant aSubjects);

to

  Array<nsIVariant> getSubjects();

C++ callers would need to change to use nsTArray for the array. JS callers can mostly not change much; in this specific case the aCount argument and setting its .value can go away in nsActivity.js, and JS callers can stop passing the {} argument they ignore.

It looks like there are a few uses in mail/, a bunch in mailnews/, and a bunch in calendar/. I don't know whether those need separate bugs.

Oh, one other heads-up: you can't do Array<string> or Array<wstring>. Generally you would do Array<ACString>, Array<AUTF8String>, or Array<AString> depending on the semantics you want.

Thanks for the heads-up. We'll deal with it in the 69 cycle.

I guess we're looking at all these:
https://searchfox.org/comm-central/search?q=retval%2C+array%2C+size_is&case=false&regexp=false&path=

All those, yes but also, for example, these: https://searchfox.org/comm-central/search?q=array%2C+size_is%28aCount%29%2C+retval&path= (the annotations are in a different order).

And also the non-retvals: https://searchfox.org/comm-central/search?q=%5Barray%2C+size_is(aCount)%5D&case=false&regexp=false&path= (plus maybe other names for the size).

What I've been querying for on the m-c side are lines in .idl files that contain both "array" and '['. I've also considered just instrumenting the xpidl parser to spit out the list of things involved; if that would be useful I can probably post a patch for that.

Aceman or Ben, can I get you interested in this. Otherwise Magnus needs to assign someone before this ends up in big bustage.

I'm looking at the ldap ones now then I'll move onto the other C++ ones.
(can look into the JS ones too after that if needed)

This is now done!

Right. Strangely M-C aren't done yet. If you click on the links in comment #2 and comment #3, you'll see four IDL files in M-C which still use the old syntax.