[core] Safeguard ICU UChar usage

1 files changed, 16 insertions, 0 deletions

diff --git a/include/mbgl/util/traits.hpp b/include/mbgl/util/traits.hpp
index 9d6f947cd2..5b9401aad7 100644
--- a/include/mbgl/util/traits.hpp
+++ b/include/mbgl/util/traits.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstdint>
 #include <type_traits>
 
 namespace mbgl {
@@ -9,4 +10,19 @@ constexpr auto underlying_type(T t) -> typename std::underlying_type_t<T> {
     return typename std::underlying_type_t<T>(t);
 }
 
+template <typename T> struct is_utf16char_like: std::false_type {};
+template <typename T> struct is_utf16char_like<const T>: is_utf16char_like<T> {};
+template <> struct is_utf16char_like<char16_t>: std::true_type {};
+template <> struct is_utf16char_like<wchar_t>: std::true_type {};
+template <> struct is_utf16char_like<uint16_t>: std::true_type {};
+
+template <typename T> using is_utf16char_like_pointer = std::integral_constant<bool, std::is_pointer<T>::value
+                                                                                     && is_utf16char_like<typename std::remove_pointer<T>::type>::value>;
+
+template <class OutPointer, class InChar>
+typename std::enable_if<is_utf16char_like<InChar>::value && is_utf16char_like_pointer<OutPointer>::value, OutPointer>::type utf16char_cast(InChar *in)
+{
+    return reinterpret_cast<OutPointer>(in);
+}
+
 } // namespace mbgl