Prepare for ICU's switch to char16_t

src/runtime/runtime-i18n.cc

Index: src/runtime/runtime-i18n.cc
diff --git a/src/runtime/runtime-i18n.cc b/src/runtime/runtime-i18n.cc
index 0b45381914641a824e36e99eaa0d315bf96252aa..4ea7e1d31e444648e72d3dff0596a3ea85c26c57 100644
--- a/src/runtime/runtime-i18n.cc
+++ b/src/runtime/runtime-i18n.cc
@@ -43,6 +43,8 @@
 #include "unicode/uloc.h"
 #include "unicode/unistr.h"
 #include "unicode/unum.h"
+#include "unicode/ustring.h"
+#include "unicode/uvernum.h"
 #include "unicode/uversion.h"
 
 
@@ -609,8 +611,15 @@ RUNTIME_FUNCTION(Runtime_InternalCompare) {
     String::FlatContent flat2 = string2->GetFlatContent();
     std::unique_ptr<uc16[]> sap1;
     std::unique_ptr<uc16[]> sap2;
+#if U_ICU_VERSION_MAJOR_NUM < 59
     const UChar* string_val1 = GetUCharBufferFromFlat(flat1, &sap1, length1);
     const UChar* string_val2 = GetUCharBufferFromFlat(flat2, &sap2, length2);
+#else
+    const char16_t* string_val1 = reinterpret_cast<const char16_t*>(
+        GetUCharBufferFromFlat(flat1, &sap1, length1));
+    const char16_t* string_val2 = reinterpret_cast<const char16_t*>(
+        GetUCharBufferFromFlat(flat2, &sap2, length2));

[jungshik at Google, 2017/03/08 22:56:53]

Markus, can you change (or add an overload to) icu::Collator::compare to take
Char16Ptr instead of char16_t?  Then, I can get rid of this reinterpret_cast
(with an undefined behavior when the spec is interpreted strictly. ubsan may
catch this as well)?  

+#endif
     result =
         collator->compare(string_val1, length1, string_val2, length2, status);
   }