vendor/llvm-project/llvmorg-18-init-16595-g7c00a5be5cde

1 files changed, 18 insertions, 0 deletions

diff --git a/libcxx/include/span b/libcxx/include/span
index 7dd53110ac29..007a32597f96 100644
--- a/libcxx/include/span
+++ b/libcxx/include/span
@@ -92,6 +92,7 @@ public:
 
     // [span.elem], span element access
     constexpr reference operator[](size_type idx) const;
+    constexpr reference at(size_type idx) const; // since C++26
     constexpr reference front() const;
     constexpr reference back() const;
     constexpr pointer data() const noexcept;
@@ -146,6 +147,7 @@ template<class R>
 #include <__utility/forward.h>
 #include <array>   // for array
 #include <cstddef> // for byte
+#include <stdexcept>
 #include <version>
 
 // standard-mandated includes
@@ -321,6 +323,14 @@ public:
     return __data_[__idx];
   }
 
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI constexpr reference at(size_type __index) const {
+    if (__index >= size())
+      std::__throw_out_of_range("span");
+    return __data_[__index];
+  }
+#  endif
+
   _LIBCPP_HIDE_FROM_ABI constexpr reference front() const noexcept {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T, N>::front() on empty span");
     return __data_[0];
@@ -469,6 +479,14 @@ public:
     return __data_[__idx];
   }
 
+#  if _LIBCPP_STD_VER >= 26
+  _LIBCPP_HIDE_FROM_ABI constexpr reference at(size_type __index) const {
+    if (__index >= size())
+      std::__throw_out_of_range("span");
+    return __data_[__index];
+  }
+#  endif
+
   _LIBCPP_HIDE_FROM_ABI constexpr reference front() const noexcept {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "span<T>::front() on empty span");
     return __data_[0];