Here is an example of a problem with the parsing of C++ default template parameters that implies operators <<, <, > and >>:

----------------------------------------------------------------
#include <iostream>
#include <type_traits>

template <class Type, class = typename std::enable_if<!std::is_void<decltype(std::declval<std::ostream&>()<<std::declval<Type>())>::value>::type>
bool print(std::ostream& stream, const Type& value)
{
    return stream<<value;
}

int main(int argc, char* argv[])
{
    print(std::cout, 42);
    return 0;
}
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It seems that these operators are interpreted as template delimiters causing a parsing problem.