Add a deleted constructor from nullptr_t to string_view; closes #113

test/sv_nullptr_fail.cpp

@@ -0,0 +1,10 @@
+// Copyright 2022 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/string_view.hpp>
+
+int main()
+{
+    return boost::core::string_view( nullptr ).size() == 0;
+}