[libcxx-commits] [PATCH] D132327: [libc++] Implement P2445R1 (`std::forward_like`)

[Hui via Phabricator via libcxx-commits]

huixie90 requested changes to this revision.
huixie90 added inline comments.
This revision now requires changes to proceed.


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Comment at: libcxx/include/__utility/forward_like.h:26-27
+template <class _Tp, class _Utp>
+[[nodiscard]] constexpr auto&& forward_like(_Utp&& __ux) noexcept {
+  static_assert(__can_reference<_Tp>, "std::forward_like's first template argument must be a referenceable type.");
+
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The standard spec has a trailing return type, meaning if the return type is ill formed, the function should be SFINAE out.
I think we should keep what is in the spec rather than hard error in the function body


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Comment at: libcxx/test/std/utilities/utility/forward_like/forward_like.msvc/test.compile.pass.cpp:72-82
+constexpr bool test() {
+  int val       = 1729;
+  auto&& result = forward_like<const double&>(val);
+  static_assert(is_same_v<decltype(result), const int&>);
+  assert(&result == &val);
+  return true;
+}
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I think it should also run the test at runtime and the `test()` should also test all different combinations. 


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  https://reviews.llvm.org/D132327/new/

https://reviews.llvm.org/D132327