Treat u8 literals by their element type

Author: lucic71

cpp2rust/converter/converter_lib.cpp

@@ -259,7 +259,7 @@ bool IsStringLiteralExpr(const clang::Expr *expr) {
 
 bool IsCodeUnitStringLiteral(const clang::StringLiteral *expr) {
   return expr->getCharByteWidth() != 1 ||
-         expr->getKind() == clang::StringLiteralKind::UTF8;
+         expr->getType()->getArrayElementTypeNoTypeQual()->isChar8Type();
 }
 
 bool IsUserDefinedDecl(const clang::Decl *decl) {

tests/unit/char_signed.cpp

@@ -19,6 +19,9 @@ int main() {
   printf("%d %d\n", lit[0], ulit[0]);
   printf("%d\n", is_negative(lit));
 
+  const char *u8s = u8"\u00e9";
+  printf("%d %d\n", u8s[0], u8s[1]);
+
   const char *p = "\x80";
   printf("%d %d\n", p[0], (unsigned char)p[0]);