The C11 Standard declares that:

5.1.2.2.1 Program startup

1. The function called at program startup is named main. The implementation declares no prototype for this function. It shall be defined with a return type of int and with no parameters:

   int main(void) { /* ... */ }
   

   or with two parameters (referred to here as argc and argv, though any names may be used, as they are local to the function in which they are declared):

   int main(int argc, char *argv[]) { /* ... */ }
   

   or equivalent; ¹⁰⁾, or in some other implementation-defined manner.

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¹⁰⁾ Thus, int can be replaced by a typedef name defined as int, or the type of argv can be written as char ** argv, and so on.

We will ignore this part: or in some other implementation-defined manner. since I'm interested only in definitions equivalent to the two above examples.

Would this be a valid definition for main since char* a[4] and char** are equivalent:

int main(int argc, char* argv[4]){/*...*/}

How about a VLA array, we are assuming printf will return a positive int value:

int main(int argc, char* argv[printf("Hello there!")]){/*...*/}