[libcxx] deprecates/removes `std::raw_storage_iterator`

[cjdb]

Summary

C++17 deprecates std::raw_storage_iterator and C++20 removes it.

Implements part of:

• P0174R2 'Deprecating Vestigial Library Parts in C++17'
• P0619R4 'Reviewing Deprecated Facilities of C++17 for C++20'

[• Quuxplusone]

LGTM % comments.

libcxx/include/__memory/raw_storage_iterator.h

28

Insert a blank line between lines 28 and 29. (Or, remove line 55; but I think for a chunk of code this long, "insert" is the right answer.)

libcxx/test/std/utilities/memory/storage.iterator/deprecated.verify.cpp

10

REQUIRES: c++17

18–29

I don't even think you use struct A?
Replace these 12 lines with one line:

std::raw_storage_iterator<int*, int> it; // expected-warning {{deprecated}}

libcxx/test/std/utilities/memory/storage.iterator/raw_storage_iterator.pass.cpp

13–14

#define _LIBCPP_DISABLE_DEPRECATION_WARNINGS

[cjdb]

applies @Quuxplusone feedback

[cjdb]

libcxx/test/std/utilities/memory/storage.iterator/deprecated.verify.cpp

10

Thanks. Is there a way to say REQUIRES: <less-than-std>? It'd be sucky if we needed to add c++2c, c++2d, ....

[• Quuxplusone]

Looks like you need to git grep -i p0619 libcxx/ and update at least one of those comments.
Also git grep -i p0174, although maybe nothing needs changing there? I'm assuming this doesn't finish p0174. (But you should check and see.)

libcxx/test/std/utilities/memory/storage.iterator/deprecated.verify.cpp

10

IIUC, you're asking about this syntax, which is indeed supported.

// REQUIRES: c++03 || c++11 || c++14

Look at the auto_ptr tests for some examples of that.

libcxx/test/std/utilities/memory/storage.iterator/raw_storage_iterator.base.pass.cpp

9

// REQUIRES: c++03 || c++11 || c++14 || c++17

[ldionne]

We should also amend the <memory> synopsis with // deprecated in C++17, removed in C++20.

LGTM with my and Arthur's suggestions.

Note that if that were a more widely used type, I'd request that we add an escape hatch for users to get the type back in C++20. I hate those, but sometimes they are a necessity if we want to be able to ship the library to users. In this case I think it won't be necessary.

libcxx/test/std/utilities/memory/storage.iterator/deprecated.verify.cpp

16

This include is not needed.

[cjdb]

applies all of @Quuxplusone's feedback

[cjdb]

Feedback addressed.

libcxx/include/__memory/raw_storage_iterator.h

 #pragma GCC system_header
 #endif
 
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if _LIBCPP_STD_VER <= 17
+
 template <class _OutputIterator, class _Tp>
-class _LIBCPP_TEMPLATE_VIS raw_storage_iterator
+class _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 raw_storage_iterator
     : public iterator<output_iterator_tag,
                       _Tp,                                         // purposefully not C++03
                       ptrdiff_t,                                   // purposefully not C++03
                       _Tp*,                                        // purposefully not C++03
                       raw_storage_iterator<_OutputIterator, _Tp>&> // purposefully not C++03
 {
 private:
     _OutputIterator __x_;
#endif
     _LIBCPP_INLINE_VISIBILITY raw_storage_iterator& operator++() {++__x_; return *this;}
     _LIBCPP_INLINE_VISIBILITY raw_storage_iterator  operator++(int)
         {raw_storage_iterator __t(*this); ++__x_; return __t;}
 #if _LIBCPP_STD_VER >= 14
     _LIBCPP_INLINE_VISIBILITY _OutputIterator base() const { return __x_; }
 #endif
 };
 
+#endif // _LIBCPP_STD_VER <= 17
+
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
 #endif // _LIBCPP___MEMORY_RAW_STORAGE_ITERATOR_H

libcxx/test/std/utilities/memory/storage.iterator/deprecated.verify.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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: c++17
+
+// std::raw_storage_iterator
+
+#include <memory>
+
+std::raw_storage_iterator<int*, int> it(nullptr);
+// expected-warning@-1{{'raw_storage_iterator<int *, int>' is deprecated}}

libcxx/test/std/utilities/memory/storage.iterator/raw_storage_iterator.base.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
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++03 || c++11 || c++14 || c++17
+
 // raw_storage_iterator
 
+#define _LIBCPP_DISABLE_DEPRECATION_WARNINGS
+
 #include <memory>
 #include <type_traits>
 #include <cassert>
 
 #include "test_macros.h"
 
 #if TEST_STD_VER >= 11
 #define DELETE_FUNCTION = delete

libcxx/test/std/utilities/memory/storage.iterator/raw_storage_iterator.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
 //
 //===----------------------------------------------------------------------===//
 
+// REQUIRES: c++03 || c++11 || c++14 || c++17
+
 // raw_storage_iterator
 
+#define _LIBCPP_DISABLE_DEPRECATION_WARNINGS
+
 #include <memory>
 #include <type_traits>
 #include <cassert>
 
 #include "test_macros.h"
 #include <MoveOnly.h>
 
 #if TEST_STD_VER >= 11