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Section: 23.15.2 [meta.type.synop], 23.15.6 [meta.rel] Status: Resolved Submitter: United States Opened: 2017-02-03 Last modified: 2017-05-31
Priority: Not Prioritized
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Discussion:Addresses US 85
The trick of encoding a functor and argument types as a function signature for is_callable and result_of loses cv information on argument types, fails for non-decayed function types, and is confusing. E.g.,
typedef int MyClass::*mp; result_of_t<mp(const MyClass)>; // should be const, but isn't typedef int F(double); is_callable<F(float)>; // ill-formed
Replace is_callable<Fn(ArgTypes...)> with is_callable<Fn, ArgTypes...> and replace is_callable<Fn(ArgTypes...), R> with is_callable_r<R, Fn, ArgTypes...>. Do the same for is_nothrow_callable.
All of the above, plus deprecate result_of<Fn(ArgTypes...)> and replace it with result_of_invoke<Fn, ArgTypes...>
See also LWG 2895.
[2017-02-22, Daniel comments]
LWG 2895 provides now wording for this issue and for LWG 2928 as well.
[2017-02-24, Daniel comments]
I suggest to apply the paper d0604r0 instead, available on the Kona LWG wiki.
Resolved by p0604r0.