I was trying to remake some generic containers from c++’s STL but in C.
For instance, this std::pair implementation works in C23:

#define Pair(T1, T2) 
    struct Pair_##T1##_##T2 { 
        T1 first; 
        T2 second; 
    }

But in older versions i get struct redefinition error if Pair is used more than once.
I came up with a simple solution:

#define Pair_define(T1, T2) 
    struct Pair_##T1##_##T2 { 
        T1 first; 
        T2 second; 
    }

#define Pair(T1, T2) struct Pair_##T1##_##T2

Where Pair_define is designed to be used once as a definition.
However it produces the same error when used more than once.

I would like to keep the C++ – like syntax but make it more foolproof

//C++
std::pair<int, char> p1 = std::make_pair(4, 'c');

//C
Pair(int, char) p2 = Pair_make(4, 'c');

Tried adding Pair_define macro, but i can’t protect it against multiple use.