1 files changed, 71 insertions, 0 deletions
diff --git a/thirdparty/icu4c/common/unicode/char16ptr.h b/thirdparty/icu4c/common/unicode/char16ptr.h
index de8182c7ad..daf35cd43b 100644
--- a/thirdparty/icu4c/common/unicode/char16ptr.h
+++ b/thirdparty/icu4c/common/unicode/char16ptr.h
@@ -12,6 +12,7 @@
 #if U_SHOW_CPLUSPLUS_API
 
 #include <cstddef>
+#include <string_view>
 
 /**
  * \file
@@ -306,6 +307,76 @@ inline OldUChar *toOldUCharPtr(char16_t *p) {
     return reinterpret_cast<OldUChar *>(p);
 }
 
+#ifndef U_FORCE_HIDE_INTERNAL_API
+/**
+ * Is T convertible to a std::u16string_view or some other 16-bit string view?
+ * @internal
+ */
+template<typename T>
+constexpr bool ConvertibleToU16StringView =
+    std::is_convertible_v<T, std::u16string_view>
+#if !U_CHAR16_IS_TYPEDEF && (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION < 180000)
+    || std::is_convertible_v<T, std::basic_string_view<uint16_t>>
+#endif
+#if U_SIZEOF_WCHAR_T==2
+    || std::is_convertible_v<T, std::wstring_view>
+#endif
+    ;
+
+namespace internal {
+/**
+ * Pass-through overload.
+ * @internal
+ */
+inline std::u16string_view toU16StringView(std::u16string_view sv) { return sv; }
+
+#if !U_CHAR16_IS_TYPEDEF && (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION < 180000)
+/**
+ * Basically undefined behavior but sometimes necessary conversion
+ * from std::basic_string_view<uint16_t> to std::u16string_view.
+ * @internal
+ */
+inline std::u16string_view toU16StringView(std::basic_string_view<uint16_t> sv) {
+    return { ConstChar16Ptr(sv.data()), sv.length() };
+}
+#endif
+
+#if U_SIZEOF_WCHAR_T==2
+/**
+ * Basically undefined behavior but sometimes necessary conversion
+ * from std::wstring_view to std::u16string_view.
+ * @internal
+ */
+inline std::u16string_view toU16StringView(std::wstring_view sv) {
+    return { ConstChar16Ptr(sv.data()), sv.length() };
+}
+#endif
+
+/**
+ * Pass-through overload.
+ * @internal
+ */
+template <typename T,
+          typename = typename std::enable_if_t<!std::is_pointer_v<std::remove_reference_t<T>>>>
+inline std::u16string_view toU16StringViewNullable(const T& text) {
+    return toU16StringView(text);
+}
+
+/**
+ * In case of nullptr, return an empty view.
+ * @internal
+ */
+template <typename T,
+          typename = typename std::enable_if_t<std::is_pointer_v<std::remove_reference_t<T>>>,
+          typename = void>
+inline std::u16string_view toU16StringViewNullable(const T& text) {
+    if (text == nullptr) return {};  // For backward compatibility.
+    return toU16StringView(text);
+}
+
+}  // internal
+#endif  // U_FORCE_HIDE_INTERNAL_API
+
 U_NAMESPACE_END
 
 #endif /* U_SHOW_CPLUSPLUS_API */