C++ Logo


Advanced search

[std-proposals] operator mangled

From: Frederick Virchanza Gotham <cauldwell.thomas_at_[hidden]>
Date: Fri, 23 Feb 2024 13:02:44 +0000
Imagine if C++ had a new operator called '{mangled}', which sits just
above 'sizeof' on the operator precedence table, which must be
followed by a type in parentheses, for example:

    {mangled(std::mutex)} expands to St5mutex
    {"mangled(std::mutex)"} expands to "St5mutex"

The latter behaves exactly like a string literal, such that you can do:

    std::stringstream ss;
    char const *str = "_ZTV" {"mangled(decltype(ss))"};

and it's as if you wrote:

    std::stringstream ss;
    char const *str = "_ZTV"

which of course is the same as:

    std::stringstream ss;
    char const *str =

What would make it more interesting though is if we could use it with
'extern' as follows:

    #include <sstream>
    int main(void)
        std::stringstream ss;

        // On the next line, we declare the mangled name of the vtable
        extern void (*_ZTV{mangled(decltype(ss))})(void);

        // On the next line, we get the address of the vtable
        void (**vtable)(void*) = &_ZTV{mangled(decltype(ss))};

        vtable[0](&ss); // Invoke the destructor
        ::new(&ss) std::stringstream(); // Invoke the constructor

Received on 2024-02-23 13:02:57