Why default return value of main is 0 and not EXIT_SUCCESS?

Question

The ISO 1998 c++ standard specifies that not explicitly using a return statement in the main is equivalent to use return 0. But what if an implementation has a different standard "no error" code, for example -1?

Why not use the standard macro EXIT_SUCCESS that would be replaced either by 0 or -1 or any other value depending on the implementation?

C++ seems to force the semantic of the program, which is not the role of a language which should only describe how the program behaves. Moreover the situation is different for the "error" return value: only EXIT_FAILURE is a standard "error" termination flag, with no explicit value, like "1" for example.

What are the reasons of these choices?

Answer 1

Returning zero from main() does essentially the same as what you're asking. Returning zero from main() does not have to return zero to the host environment.

From the C90/C99/C++98 standard document:

If the value of status is zero or EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned.

Answer 2

Actually, return 0 won't necessarily return 0! I'm quoting the C standard here, because it's what I know best.

About return in main():

5.1.2.2.3 Program termination

If the return type of the main function is a type compatible with int, a return from the initial call to the main function is equivalent to calling the exit function with the value returned by the main function as its argument;

About exit():

7.20.4.3 The exit function
Synopsis

#include <stdlib.h> void exit(int status); 

[...]
Finally, control is returned to the host environment. If the value of status is zero or EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned.