Yes, I've used 'bear' before (in fact I asked you, remember?).
But -- great as it is -- it's still basically a hack which requires actually compiling the code to learn _how_ it would be compiled. That's not always practical, perhaps not even always possible depending on the toolchain to use.
So it's a needless hindrance and, afair, not perfectly accurate (you had some non-trivial ad-hoc tweak script as I recall).
I don't see a fundamental technical reason not to generate this simple file from our own configuration script, which is the source of truth for this information after all. In all Cmake projects I work with, it's a matter of setting a simple variable. I wonder if the automake world doesn't have something similar. If it doesn't, how hard can it be to add one?
We should lower that bar so that every Emacs C hacker (including Eli and other long timers) can benefit from LSP (with Eglot, of course ;) ). This will be beneficial to Emacs C code and to Eglot itself of course.
And with that, it seems I have done all the lobbying myself :)
João