Warnings due to `std::reverse_iterator` using the deprecated `std::iterator`

[JohelEGP]

In module 'cpp2.util' imported from /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:12:
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__iterator/reverse_iterator.h:53:14: warning: 'iterator<std::__1::random_access_iterator_tag, jegp::command>' is deprecated [-Wdeprecated-declarations]
   53 |     : public iterator<typename iterator_traits<_Iter>::iterator_category,
      |              ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:542:40: note: in instantiation of template class 'std::__1::reverse_iterator<jegp::command *>' requested here
  542 |     std::__allocator_destroy(__alloc_, std::reverse_iterator<_Iter>(__last_), std::reverse_iterator<_Iter>(__first_));
      |                                        ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__utility/exception_guard.h:86:7: note: in instantiation of member function 'std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>::operator()' requested here
   86 |       __rollback_();
      |       ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__utility/exception_guard.h:137:10: note: in instantiation of member function 'std::__exception_guard_exceptions<std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>>::~__exception_guard_exceptions' requested here
  137 |   return __exception_guard<_Rollback>(std::move(__rollback));
      |          ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:560:12: note: in instantiation of function template specialization 'std::__make_exception_guard<std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>>' requested here
  560 |       std::__make_exception_guard(_AllocatorDestroyRangeReverse<_Alloc, _Iter2>(__alloc, __destruct_first, __first2));
      |            ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:603:26: note: in instantiation of function template specialization 'std::__uninitialized_allocator_copy_impl<std::__1::allocator<jegp::command>, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>::__iterator<false>, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>::__iterator<false>, jegp::command *>' requested here
  603 |     auto __result = std::__uninitialized_allocator_copy_impl(__alloc, __unwrapped_range.first, __unwrapped_range.second, std::__unwrap_iter(__first2));
      |                          ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/vector:1145:22: note: (skipping 5 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all)
 1145 |   __tx.__pos_ = std::__uninitialized_allocator_copy(__alloc(), __first, __last, __tx.__pos_);
      |                      ^
/home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:57: note: in instantiation of function template specialization 'std::__1::ranges::to<std::__1::vector, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' requested here
  100 |     return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make));  }
      |                                                         ^
/home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:42: note: in instantiation of requirement here
  100 |     return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make));  }
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:373:72: note: expanded from macro 'CPP2_UFCS_QUALIFIED_TEMPLATE'
  373 | #define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...)          CPP2_UFCS_(&,QUALID,template,__VA_ARGS__)
      |                                                           ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:363:39: note: expanded from macro 'CPP2_UFCS_'
  363 |     requires CPP2_UFCS_CONSTRAINT_ARG(QUALID,TEMPKW,__VA_ARGS__) { \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:345:35: note: expanded from macro 'CPP2_UFCS_CONSTRAINT_ARG'
  345 | || requires { CPP2_UFCS_REMPARENS QUALID __VA_ARGS__(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); }
      |               ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:306:34: note: expanded from macro 'CPP2_UFCS_REMPARENS'
  306 | #define CPP2_UFCS_REMPARENS(...) __VA_ARGS__
      |                                  ^
/home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:12: note: while substituting template arguments into constraint expression here
  100 |     return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make));  }
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:373:59: note: expanded from macro 'CPP2_UFCS_QUALIFIED_TEMPLATE'
  373 | #define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...)          CPP2_UFCS_(&,QUALID,template,__VA_ARGS__)
      |                                                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:363:14: note: expanded from macro 'CPP2_UFCS_'
  363 |     requires CPP2_UFCS_CONSTRAINT_ARG(QUALID,TEMPKW,__VA_ARGS__) { \
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:345:4: note: expanded from macro 'CPP2_UFCS_CONSTRAINT_ARG'
  345 | || requires { CPP2_UFCS_REMPARENS QUALID __VA_ARGS__(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); }
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:73: note: while checking constraint satisfaction for template 'operator()<std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' required here
  100 |     return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make));  }
      |                                                                         ^
/home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:73: note: in instantiation of function template specialization 'jegp::command::range_from_array_arguments(std::vector<std::string>)::(anonymous class)::operator()<std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' requested here
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__iterator/iterator.h:24:29: note: 'iterator<std::__1::random_access_iterator_tag, jegp::command>' has been explicitly marked deprecated here
   24 | struct _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 iterator
      |                             ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__config:941:41: note: expanded from macro '_LIBCPP_DEPRECATED_IN_CXX17'
  941 | #    define _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_DEPRECATED
      |                                         ^
/home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__config:914:49: note: expanded from macro '_LIBCPP_DEPRECATED'
  914 | #      define _LIBCPP_DEPRECATED __attribute__((__deprecated__))
      |                                                 ^

[ravilpatel]

The warning you're seeing is related to the use of std::iterator in the std::reverse_iterator class, and it indicates that iterator <std::random_access_iterator_tag, jegp::command> is deprecated.

This warning is likely triggered by your use of the std::reverse_iterator in combination with certain algorithms or constructs in your code.

[JohelEGP]

Yes, a very indirect use, by using std::ranges::to<std::vector>.

[mordante]

@var-const has this been introduced by your ranges to patch?

[ldionne]

@JohelEGP Can you please share how and what you're building in a reproducer? Ideally a godbolt link would make it really easy for us to see what's wrong.

[JohelEGP]

I build Libc++ according to https://libcxx.llvm.org/Modules.html#using-in-external-projects.
Then building this simple program reproduces:

import std;

int main() {
  std::vector<int> v;
  v.reserve(0);
}

[ldionne]

This doesn't happen if we're not building with modules: https://godbolt.org/z/vxYPabq5h

@mordante Do you think you could have a first look?

[mordante]

As far as I can see we properly push and pop the deprecated diagnostic status. @cor3ntin could this be related to aafad2d?

It looks like pushing and popping the diagnostics state for deprecated messages is not working properly when using modules.

[cor3ntin]

It appears we do not currently have a way to identify "system modules", amd all modules are considered user code, I think.
II have no idea how hard it would be to add that though. @ChuanqiXu9 ?

[llvmbot]

@llvm/issue-subscribers-clang-modules

Author: Johel Ernesto Guerrero Peña (JohelEGP)

```output In module 'cpp2.util' imported from /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:12: /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__iterator/reverse_iterator.h:53:14: warning: 'iterator<std::__1::random_access_iterator_tag, jegp::command>' is deprecated [-Wdeprecated-declarations] 53 | : public iterator<typename iterator_traits<_Iter>::iterator_category, | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:542:40: note: in instantiation of template class 'std::__1::reverse_iterator<jegp::command *>' requested here 542 | std::__allocator_destroy(__alloc_, std::reverse_iterator<_Iter>(__last_), std::reverse_iterator<_Iter>(__first_)); | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__utility/exception_guard.h:86:7: note: in instantiation of member function 'std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>::operator()' requested here 86 | __rollback_(); | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__utility/exception_guard.h:137:10: note: in instantiation of member function 'std::__exception_guard_exceptions<std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>>::~__exception_guard_exceptions' requested here 137 | return __exception_guard<_Rollback>(std::move(__rollback)); | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:560:12: note: in instantiation of function template specialization 'std::__make_exception_guard<std::_AllocatorDestroyRangeReverse<std::__1::allocator<jegp::command>, jegp::command *>>' requested here 560 | std::__make_exception_guard(_AllocatorDestroyRangeReverse<_Alloc, _Iter2>(__alloc, __destruct_first, __first2)); | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__memory/uninitialized_algorithms.h:603:26: note: in instantiation of function template specialization 'std::__uninitialized_allocator_copy_impl<std::__1::allocator<jegp::command>, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>::__iterator<false>, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>::__iterator<false>, jegp::command *>' requested here 603 | auto __result = std::__uninitialized_allocator_copy_impl(__alloc, __unwrapped_range.first, __unwrapped_range.second, std::__unwrap_iter(__first2)); | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/vector:1145:22: note: (skipping 5 contexts in backtrace; use -ftemplate-backtrace-limit=0 to see all) 1145 | __tx.__pos_ = std::__uninitialized_allocator_copy(__alloc(), __first, __last, __tx.__pos_); | ^ /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:57: note: in instantiation of function template specialization 'std::__1::ranges::to<std::__1::vector, std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' requested here 100 | return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make)); } | ^ /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:42: note: in instantiation of requirement here 100 | return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make)); } | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:373:72: note: expanded from macro 'CPP2_UFCS_QUALIFIED_TEMPLATE' 373 | #define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...) CPP2_UFCS_(&,QUALID,template,__VA_ARGS__) | ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:363:39: note: expanded from macro 'CPP2_UFCS_' 363 | requires CPP2_UFCS_CONSTRAINT_ARG(QUALID,TEMPKW,__VA_ARGS__) { \ | ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:345:35: note: expanded from macro 'CPP2_UFCS_CONSTRAINT_ARG' 345 | || requires { CPP2_UFCS_REMPARENS QUALID __VA_ARGS__(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } | ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:306:34: note: expanded from macro 'CPP2_UFCS_REMPARENS' 306 | #define CPP2_UFCS_REMPARENS(...) __VA_ARGS__ | ^ /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:12: note: while substituting template arguments into constraint expression here 100 | return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make)); } | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:373:59: note: expanded from macro 'CPP2_UFCS_QUALIFIED_TEMPLATE' 373 | #define CPP2_UFCS_QUALIFIED_TEMPLATE(QUALID,...) CPP2_UFCS_(&,QUALID,template,__VA_ARGS__) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:363:14: note: expanded from macro 'CPP2_UFCS_' 363 | requires CPP2_UFCS_CONSTRAINT_ARG(QUALID,TEMPKW,__VA_ARGS__) { \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/Documents/C++/Forks/hsutter/waarudo/include/cpp2util_pre.h:345:4: note: expanded from macro 'CPP2_UFCS_CONSTRAINT_ARG' 345 | || requires { CPP2_UFCS_REMPARENS QUALID __VA_ARGS__(CPP2_FORWARD(obj), CPP2_FORWARD(params)...); } | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:73: note: while checking constraint satisfaction for template 'operator()<std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' required here 100 | return CPP2_UFCS_QUALIFIED_TEMPLATE((std::ranges::),to<std::vector>)(CPP2_UFCS(std::views::transform)(std::move(v), command::make)); } | ^ /home/johel/build/Waarudo/ClangRelease/sources/jegp/algorithms/algorithms.cpp:100:73: note: in instantiation of function template specialization 'jegp::command::range_from_array_arguments(std::vector<std::string>)::(anonymous class)::operator()<std::__1::ranges::transform_view<std::__1::ranges::owning_view<std::__1::vector<std::__1::basic_string<char>>>, jegp::command (*)(std::__1::basic_string<char>)>>' requested here /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__iterator/iterator.h:24:29: note: 'iterator<std::__1::random_access_iterator_tag, jegp::command>' has been explicitly marked deprecated here 24 | struct _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 iterator | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__config:941:41: note: expanded from macro '_LIBCPP_DEPRECATED_IN_CXX17' 941 | # define _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_DEPRECATED | ^ /home/johel/Documents/C++/Forks/llvm/libcxx-std-modules/include/c++/v1/__config:914:49: note: expanded from macro '_LIBCPP_DEPRECATED' 914 | # define _LIBCPP_DEPRECATED __attribute__((__deprecated__)) | ^ ```