[PATCH 2/3] Provide a C++ version of issignaling that does not use __MATH_TG

[Joseph Myers]

On Tue, 15 Aug 2017, Gabriel F. T. Gomes wrote:

> The macro __MATH_TG contains the logic to select between long double and
> _Float128, when these types are ABI-distinct.  This logic relies on
> __builtin_types_compatible_p, which is not available in C++ mode.
> 
> On the other hand, C++ function overloading provides the means to
> distinguish between the floating-point types.  The overloading
> resolution will match the correct parameter regardless of type
> qualifiers, i.e.: const and volatile.

I think this should include a C++ testcase for issignaling (cf. 
test-math-iszero.cc, but the issignaling test should cover float128 when 
supported).

-- 
Joseph S. Myers
joseph@codesourcery.com