[libc++] Make the constraints as intended.

[philnik]

Please add tests for this under libcxx/test/std/iterators/iterator.requirements/iterator.cust/iterator.cust.move/.

[cjdb]

Can you please provide a descriptive subject line about what has changed for the commit? It should also be prefixed with [libcxx] or [libc++].

[K1ZeKaTo]

The constraints do not work while rvalue.

[K1ZeKaTo]

Modify to pass tests.

[K1ZeKaTo]

Try to fix CI.

[K1ZeKaTo]

Try to fix CI.

[cjdb]

I'm still not quite sure what problem this patch aims to solve. Would you please be able to provide a commit description that describes the problem that's being solved in some detail?

[cjdb]

The changes in the header seem correct to me, but we can't move forward till the commit message has been fixed.

libcxx/test/std/iterators/iterator.requirements/iterator.cust/iterator.cust.move/iter_move_rvalue.compile.pass.cpp

1 ↗

(On Diff #547466)

I'd prefer that this be a runtime test, since it's something that needs to work in both cases. As such, we'll need to rework this test so it handles runtime too.

libcxx/include/__iterator/iter_move.h

requires (_Tp&& __t) {
     // NOLINTNEXTLINE(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
     iter_move(std::forward<_Tp>(__t));
   };
 
 template<class _Tp>
 concept __move_deref =
   !__unqualified_iter_move<_Tp> &&
   requires (_Tp&& __t) {
-    *__t;
-    requires is_lvalue_reference_v<decltype(*__t)>;
+    *std::forward<_Tp>(__t);
+    requires is_lvalue_reference_v<decltype(*std::forward<_Tp>(__t))>;
   };
 
 template<class _Tp>
 concept __just_deref =
   !__unqualified_iter_move<_Tp> &&
   !__move_deref<_Tp> &&
   requires (_Tp&& __t) {
-    *__t;
-    requires (!is_lvalue_reference_v<decltype(*__t)>);
+    *std::forward<_Tp>(__t);
+    requires (!is_lvalue_reference_v<decltype(*std::forward<_Tp>(__t))>);
   };
 
 // [iterator.cust.move]
 
 struct __fn {
   // NOLINTBEGIN(libcpp-robust-against-adl) iter_move ADL calls should only be made through ranges::iter_move
   template<class _Ip>
     requires __unqualified_iter_move<_Ip>