[Bug target/84829] -mieee-fp causes to link with -lieee but that is no longer available

[matz at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84829

--- Comment #9 from Michael Matz <matz at gcc dot gnu.org> ---
(In reply to Carlos O'Donell from comment #8)
> > It matters from the users' point of view.  I think it's better to give them
> > a build error when they use unsupported functionality, rather than giving
> > the wrong results at run time.  The overloaded nature of -mieee-fp makes
> > this difficult to achieve, though.
> 
> I agree.

Except, of course, that it isn't unsupported functionality.  On the contrary,
it now is the default in glibc.

Even worse: the non-libm aspect of -mieee-fp is also the default on linux.  So
giving -mieee-fp is a no-op on new glibc, while it is not one on old glibc
(adding libieee.a).  I don't see how the current link error can be avoided
in a sensible way from within gcc (sensible includes: "works with old and new
glibc").