[gardaani]

This C++ code actually compiles with clang++. Incredible!

    int main(int argc, char *argv<::>)
    <%
        if (argc not_eq 1 and argc not_eq 2) <% return 1; %>
        return 0;
    %>

https://en.wikipedia.org/wiki/Digraphs_and_trigraphs#C

[bregma]

Digraphs are still a part of the language. I would be more surprised if a conformant piece of code did not compile with a conformant compiler.