boost [math] excessive warnings via [lexical_cast] from [date_time] (and others) for clang 3.4?

From: Mike (mike.dev_at_[hidden])
Date: 2020-03-24 18:10:38

> Gesendet: Dienstag, 24. März 2020 um 18:41 Uhr
> Von: "John Maddock via Boost" <boost_at_[hidden]>
>
> 
> On 24/03/2020 17:32, Jeff Garland via Boost wrote:
> >>    Well it will be a real issue in a year from now when we being removing
> >> C++03 support - it may be that lexical_cast's dependencies have nothing
> >> that will actually break (but I would need to check that), or that as a
> >>
> > it's basically using it for floating point traits and functions like
> > changesign.
> >
> > lexical_cast/detail/if_nan.hpp
> > #include <boost/math/special_functions/sign.hpp>
> > #include <boost/math/special_functions/fpclassify.hpp>
> Nod.  And there's nothing in there that requires anything other than 
> C++03, so I could fix this up to not issue the warnings if that's really 
> required.
> 

There was talk / the suggestion to move some core parts to a separate 
library, also to avoid circular dependencies: 

https://github.com/boostorg/math/issues/151

That would also solve this problem as a side effect.