Re: [boost] [config] What Feature is this??

Subject: Re: [boost] [config] What Feature is this??
From: Edward Diener (eldiener_at_[hidden])
Date: 2017-07-24 11:37:30

On 7/23/2017 2:50 PM, John Maddock via Boost wrote:
> Folks, I think I'm looking to add a new C++11 defect macro, but don't 
> know what the feature is called, nor can I see a way of detecting it 
> with clang's __has_feature function.
> 
> The code I want to enable involves function overloading based on a 
> decltype return type as in:

I never realized that function overloading could occur based on any 
return type. I always thought it had to be based on the parameter types. 
Is this part of the C+11 standard ? Where in the standard is this 
specified ?

> 
> 
> auto integrate(args...) -> decltype(expression1);
> 
> auto integrate(args...) -> decltype(expression2);
> 
> 
> where expression1 and expression2 are two mutually exclusive options 
> (the conceptual requirements of args means that only one of these 2 will 
> ever be satisfied).
> 
> This works fine in msvc-14 and later and gcc-4.8 and later, but I don't 
> see any current config macros which cover this case, nor can I figure 
> out what this trick should be called.
> 
> Alternatively, if anyone has a better way of differentiating between 
> unary and binary functions I'm happy to hear about it ;)
> 
> 
> Thanks, John.
> 
> 
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