commit 9d1c0d4d971a060e581abc46da1d368c06ffb847
author Joe Loser <joeloser93@gmail.com> Thu Oct 14 11:53:43 2021 -0400
committer Copybara-Service <copybara-worker@google.com> Thu Oct 14 09:05:20 2021 -0700
tree 604efc5ac41ca6031aa411c154961b14478972f9
parent 4af4c2f15d7e7adbd2bcd69a6a4cfb1b61a1491f

[libc++] LWG3480: make (recursive_)directory_iterator C++20 ranges

Implement LWG3480 which enables `directory_iterator` and
`recursive_directory_iterator` to be both a `borrowed_range` and a
`view`.

Reviewed By: ldionne, #libc

Differential Revision: https://reviews.llvm.org/D111644

NOKEYCHECK=True
GitOrigin-RevId: 1fa27f2a10e8eec15387aba7eeff65d7d332b9af

include/filesystem

diff --git a/include/filesystem b/include/filesystem
index a11d2a4..1fd77af 100644
--- a/include/filesystem
+++ b/include/filesystem
@@ -11,7 +11,7 @@
 /*
     filesystem synopsis
 
-    namespace std { namespace filesystem {
+    namespace std::filesystem {
 
     class path;
 
@@ -48,13 +48,13 @@
 
     // enable directory_iterator range-based for statements
     directory_iterator begin(directory_iterator iter) noexcept;
-    directory_iterator end(const directory_iterator&) noexcept;
+    directory_iterator end(directory_iterator) noexcept;
 
     class recursive_directory_iterator;
 
     // enable recursive_directory_iterator range-based for statements
     recursive_directory_iterator begin(recursive_directory_iterator iter) noexcept;
-    recursive_directory_iterator end(const recursive_directory_iterator&) noexcept;
+    recursive_directory_iterator end(recursive_directory_iterator) noexcept;
 
     class file_status;
 
@@ -224,14 +224,25 @@
     path weakly_canonical(path const& p);
     path weakly_canonical(path const& p, error_code& ec);
 
+} // namespace std::filesystem
 
-} }  // namespaces std::filesystem
+template <>
+inline constexpr bool std::ranges::enable_borrowed_range<std::filesystem::directory_iterator> = true;
+template <>
+inline constexpr bool std::ranges::enable_borrowed_range<std::filesystem::recursive_directory_iterator> = true;
+
+template <>
+inline constexpr bool std::ranges::enable_view<std::filesystem::directory_iterator> = true;
+template <>
+inline constexpr bool std::ranges::enable_view<std::filesystem::recursive_directory_iterator> = true;
 
 */
 
 #include <__availability>
 #include <__config>
 #include <__debug>
+#include <__ranges/enable_borrowed_range.h>
+#include <__ranges/enable_view.h>
 #include <__utility/forward.h>
 #include <chrono>
 #include <compare>
@@ -2869,7 +2880,7 @@
 }
 
 inline _LIBCPP_INLINE_VISIBILITY directory_iterator
-end(const directory_iterator&) noexcept {
+end(directory_iterator) noexcept {
   return directory_iterator();
 }
 
@@ -3001,7 +3012,7 @@
 }
 
 inline _LIBCPP_INLINE_VISIBILITY recursive_directory_iterator
-end(const recursive_directory_iterator&) noexcept {
+end(recursive_directory_iterator) noexcept {
   return recursive_directory_iterator();
 }
 
@@ -3009,6 +3020,18 @@
 
 _LIBCPP_END_NAMESPACE_FILESYSTEM
 
+#if !defined(_LIBCPP_HAS_NO_RANGES)
+template <>
+inline constexpr bool _VSTD::ranges::enable_borrowed_range<_VSTD_FS::directory_iterator> = true;
+template <>
+inline constexpr bool _VSTD::ranges::enable_borrowed_range<_VSTD_FS::recursive_directory_iterator> = true;
+
+template <>
+inline constexpr bool _VSTD::ranges::enable_view<_VSTD_FS::directory_iterator> = true;
+template <>
+inline constexpr bool _VSTD::ranges::enable_view<_VSTD_FS::recursive_directory_iterator> = true;
+#endif
+
 #endif // !_LIBCPP_CXX03_LANG
 
 _LIBCPP_POP_MACROS