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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Sounds reasonable to me. I believe expectations are set appropriately with the experimental namespace, and the extra, experimental library that needs to be linked in.<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> cfe-dev [mailto:cfe-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Marshall Clow via cfe-dev<br>
<b>Sent:</b> Monday, April 10, 2017 3:23 PM<br>
<b>To:</b> cfe-dev@lists.llvm.org; llvm-dev@lists.llvm.org<br>
<b>Subject:</b> [cfe-dev] RFC: Plan for removing components from namespace std::experimental<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">As part of the work on C++17, WG21 released a series of "Technical Specifications", (TS) which added proposed new features to the standard library. These were all defined in the namespace 'std::experimental' (and namespaces inside of that).
<o:p></o:p></p>
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<p class="MsoNormal">Then, much of these features were merged into the main standard, and became part of namespace 'std'. Libc++ now has two implementations of several of these, and they are diverging (because changes were made to the ones in the main standard,
but not to the ones in the TS.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In the long run, I would like to remove the TS versions of these features from libc++ - since there are "better" versions in the main standard now. However, since people are using these, I don't think yanking them w/o warning is the right
thing to do.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So, I'm proposing a new policy, and a timetable: <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">One year.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">One year after we ship a LLVM release that supports a new C++ standard, we will remove all the features that are in the 'experimental' namespace that are implemented in the new standard).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Applying this policy to C++17, we get:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">LLVM 5.0 will support C++17.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So, for LLVM 7.0, we will remove (at least) the following features from libc++<o:p></o:p></p>
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<p class="MsoNormal">* std::experimental::filesystem<o:p></o:p></p>
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<p class="MsoNormal">* std::experimental::optional<o:p></o:p></p>
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<p class="MsoNormal">* std::experimental::any<o:p></o:p></p>
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<p class="MsoNormal">* std::experimental::string_view<o:p></o:p></p>
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<p class="MsoNormal">* the searchers (std::experimental::boyer_moore, etc)<o:p></o:p></p>
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<p class="MsoNormal">* std::experimental::random_shuffle<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">and probably other things...<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Comments?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- Marshall<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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