bug#23264: 25.0.90; `C-h f' (`describe-function'): "This function has a compiler macro"

[Stefan Monnier]

>>   This function has a compiler macro.
[...]
> It doesn't seem very useful to me either, no -- it doesn't really convey
> much of interest to the user.  Eli, Stefan -- what do you think?  Should
> we just remove it?

I can see to benefits:

1- If it includes a link to the compiler macro.  Admittedly, compiler
   macros are supposed to be placed directly inside the `declare` of the
   function, so you can get there via the usual link to the function's
   definition, which makes this link's usefulness rather marginal.
   (except in theory for those rare exceptions where the compiler macro
   is not provided via `declare`, but to be honest, I can't think of any
   and `grep` couldn't find any either).
2- It warns that advice and (more generally) redefinitions of this
   function may not be obeys at all call sites.

Point 1 is quite weak.
Point 2 is a bit more interesting but then we should say so more
explicitly and (more importantly) we should also say so for those
functions which have the same property but for other reasons (e.g. they
have their own byte-code, or they have a `byte-compile` or
`byte-optimizer` property).

IOW, I agree but maybe it would be a good idea to replace it with
a better message that covers this and similar cases warning about
applicability of `advice`.


        Stefan