[libcxx][span] Implement P1976R2

This resolves the NB comment about the construction of a fixed-size span
from a dynamic range.

Differential Revision: https://reviews.llvm.org/D74577

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 6d2599e4f776d0cd88438cb82a00c4fc25cc3f67
diff --git a/include/version b/include/version
index c2e99cc..46b0d65 100644
--- a/include/version
+++ b/include/version
@@ -98,6 +98,7 @@
 __cpp_lib_shared_ptr_arrays                             201611L <memory>
 __cpp_lib_shared_ptr_weak_type                          201606L <memory>
 __cpp_lib_shared_timed_mutex                            201402L <shared_mutex>
+__cpp_lib_span                                          202002L <span>
 __cpp_lib_string_udls                                   201304L <string>
 __cpp_lib_string_view                                   201606L <string> <string_view>
 __cpp_lib_three_way_comparison                          201711L <compare>
@@ -234,8 +235,9 @@
 # endif
 # define __cpp_lib_list_remove_return_type              201806L
 // # define __cpp_lib_ranges                               201811L
-# define __cpp_lib_to_array                                201907L
+# define __cpp_lib_span                                 202002L
 // # define __cpp_lib_three_way_comparison                 201711L
+# define __cpp_lib_to_array                             201907L
 #endif
 
 #endif // _LIBCPP_VERSIONH