Having something that works with any 3rd-party project is difficult, I thought you were talking about your own projects. Since no one but you has ever asked for this, as far as I can recall, evidently the rest of the world is not in dire need of this feature. It's been a problem since day one of automake, so presumably everyone who cares has already dealt with it.
>From what I can easily see, other packages handle this by getting the files they want in their bootstrap script and not using --add-missing (usually), or replacing the files it installs (gettext). Looking at the code for --add-missing in automake, it seems far from simple to me. I see no good way to make (yet another) special case for texinfo.tex. I continue to dislike the idea of looking for 20 or so new environment variables like AUTOMAKE_ADD_MISSING_TEXINFO_TEX, AUTOMAKE_ADD_MISSING_ABOUT_GNU, etc., which is apparently the only acceptable solution for you. The next step would be that people want certain envvars to apply to more than one file, since they're generally going to be in the same place. Or be able to check multiple places. Etc. Anyway, it's not something I'm going to work on. If you feel like preparing a patch for the code and doc, I'll look at it. --best, karl.
