std::invoke should use std::is_nothrow_callable (2807)

[ldionne]

Summary

Use std::is_nothrow_callable for std::invoke according to 2807.

[zoecarver]

@EricWF, @mclow.lists Friendly ping.

[ldionne]

Also, please update the signature of invoke at the top of test/std/utilities/function.objects/func.invoke/invoke.pass.cpp.

include/functional

14 ↗

(On Diff #186394)

Please add this to the synopsis (right now std::invoke is not mentioned):

template<class F, class... Args>
invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) // C++17
    noexcept(is_nothrow_invocable_v<_Fn, _Args...>);

[zoecarver]

Add synopsis comment.

[zoecarver]

Sorry for the delay, forgot about this one.

[ldionne]

Looks good with a few nitpicks.

[ldionne]

Nitpicks

libcxx/include/functional

template <class T> inline constexpr int is_placeholder_v
   = is_placeholder<T>::value; // C++17
 
 
 template<class Fn, class... BoundArgs>
   unspecified bind(Fn&&, BoundArgs&&...);
 template<class R, class Fn, class... BoundArgs>
   unspecified bind(Fn&&, BoundArgs&&...);
 
+template<class F, class... Args>
+ invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) // C++17
+    noexcept(is_nothrow_invocable_v<F, Args...>);
+
 namespace placeholders {
   // M is the implementation-defined number of placeholders
   extern unspecified _1;
   extern unspecified _2;
   .
   .
   .
   extern unspecified _Mp;
bind(_Fp&& __f, _BoundArgs&&... __bound_args)
     return type(_VSTD::forward<_Fp>(__f), _VSTD::forward<_BoundArgs>(__bound_args)...);
 }
 
 #endif  // _LIBCPP_CXX03_LANG
 
 #if _LIBCPP_STD_VER > 14
 
 template <class _Fn, class ..._Args>
-result_of_t<_Fn&&(_Args&&...)>
+invoke_result_t<_Fn, _Args...>
 invoke(_Fn&& __f, _Args&&... __args)
-    noexcept(noexcept(_VSTD::__invoke(_VSTD::forward<_Fn>(__f), _VSTD::forward<_Args>(__args)...)))
+    noexcept(is_nothrow_invocable_v<_Fn, _Args...>)
 {
     return _VSTD::__invoke(_VSTD::forward<_Fn>(__f), _VSTD::forward<_Args>(__args)...);
 }
 
 template <class _DecayFunc>
 class _LIBCPP_TEMPLATE_VIS __not_fn_imp {
   _DecayFunc __fd;
 

libcxx/test/std/utilities/function.objects/func.invoke/invoke.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14
 
 // <functional>
 
-// template <class F, class ...Args>
-// result_of_t<F&&(Args&&...)> invoke(F&&, Args&&...);
+// template<class F, class... Args>
+// invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) // C++17
+//     noexcept(is_nothrow_invocable_v<_Fn, _Args...>);
 
 /// C++14 [func.def] 20.9.0
 /// (1) The following definitions apply to this Clause:
 /// (2) A call signature is the name of a return type followed by a parenthesized
 ///     comma-separated list of zero or more argument types.
 /// (3) A callable type is a function object type (20.9) or a pointer to member.
 /// (4) A callable object is an object of a callable type.
 /// (5) A call wrapper type is a type that holds a callable object and supports

libcxx/www/cxx1z_status.html

<!--   <I>Note: "NAD" means that the issue was deemed "Not a defect"</I> -->
   <tr><td><a href="https://wg21.link/LWG2790">2790</a></td><td>Missing specification of istreambuf_iterator::operator-&gt;</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2794">2794</a></td><td>Missing requirements for allocator pointers</td><td>Kona</td><td><I>Nothing to do</I></td></tr>
   <tr><td><a href="https://wg21.link/LWG2795">2795</a></td><td>&sect;[global.functions] provides incorrect example of ADL use</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2796">2796</a></td><td>tuple should be a literal type</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2801">2801</a></td><td>Default-constructibility of unique_ptr</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2802">2802</a></td><td>shared_ptr constructor requirements for a deleter</td><td>Kona</td><td></td></tr>
   <tr><td><a href="https://wg21.link/LWG2804">2804</a></td><td>Unconditional constexpr default constructor for istream_iterator</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2806">2806</a></td><td>Base class of bad_optional_access</td><td>Kona</td><td>Complete</td></tr>
-  <tr><td><a href="https://wg21.link/LWG2807">2807</a></td><td>std::invoke should use std::is_nothrow_callable</td><td>Kona</td><td></td></tr>
+  <tr><td><a href="https://wg21.link/LWG2807">2807</a></td><td>std::invoke should use std::is_nothrow_callable</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2812">2812</a></td><td>Range access is available with &lt;string_view&gt;</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2824">2824</a></td><td>list::sort should say that the order of elements is unspecified if an exception is thrown</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2826">2826</a></td><td>string_view iterators use old wording</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2834">2834</a></td><td>Resolution LWG 2223 is missing wording about end iterators</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2835">2835</a></td><td>LWG 2536 seems to misspecify &lt;tgmath.h&gt;</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2837">2837</a></td><td>gcd and lcm should support a wider range of input values</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2838">2838</a></td><td>is_literal_type specification needs a little cleanup</td><td>Kona</td><td>Complete</td></tr>
   <tr><td><a href="https://wg21.link/LWG2842">2842</a></td><td>in_place_t check for optional::optional(U&amp;&amp;) should decay U</td><td>Kona</td><td>Complete</td></tr>