Re: Supporting C++17

[Chris Vine <chris cvine freeserve co uk>]

On Tue, 4 Apr 2017 22:56:22 +0100
Chris Vine <chris cvine freeserve co uk> wrote:
> On Tue, 04 Apr 2017 18:13:46 +0200
> Murray Cumming <murrayc murrayc com> wrote:
> > On Tue, 2017-04-04 at 15:09 +0100, Jonathan Wakely wrote:  
> > > On 4 April 2017 at 14:52, Murray Cumming wrote:    
> > > > Any ideas about how we should support C++17 in gtkmm-3.0 without
> > > > losing
> > > > C++11/14 compatibility and without breaking ABI?    
> > >
> > > Replace all dynamic exception specifications with noexcept(false)
> > > (or just no exception specification). That's not an ABI
> > > change.    
> >
> > That's great to know. I'll take care of that then.  
>
> I would check that.  It didn't affect ABI in C++11/14, but I am not so
> sure about C++17.  According to
> http://en.cppreference.com/w/cpp/language/noexcept_spec,
> in C++17 "The noexcept-specification is a part of the function type
> and may appear as part of any function declarator."  If it is part of
> the type then it might feature in name mangling, so this is worth
> checking with the compiler writers.

On second thoughts, noexcept(true) might possibly change ABI in C++17,
but it seems inconceivable that noexcept(false) would.  It also seems
weird that merely applying -std=c++17 to your code should break its
ABI.  The more I think about it, the less clear I am what making the
noexcept specification part of the function type in C++17 actually
involves compiler-wise, or what it achieves.