Re: [9fans] the declaration of main()

["Douglas A. Gwyn" <gwyn@arl.army.mil>]

forsyth@caldo.demon.co.uk wrote:
> i realised later that i hadn't pointed out that regardless whether
> int main was a good choice for the C standard, it had further
> disadvantages in plan 9.

It needn't have.  Standard C of necessity provides a "lowest
common denominator" fit to existing target environments;
there are many systems (including Unix and VMS) that report
termination status as more than just success/failure, but
they do it in different ways.  Except for Plan 9's native
(non-APE) and some standalone environments, main() *does*
in fact return an int, even if many programmers believed
otherwise.  (On many platforms it is accidentally possible
to misdeclare main() and still get an executable that appears
to work.)  The C standard had to codify existing practice
(where there was already consensus), not try to change it.

> plan 9 does not use an integer for exit status: it uses a string.
> if it's considered desirable to return status from main, it would
> need to be char*, which is still different from the C standard.

No, there was an unhappy design decision.  Since there was
already a standard interface definition for the external
function name "main", Plan 9's startup entry point for user
code should have been given a different name, perhaps "start"
or "mains".  Then the Plan 9 library would provide a function:
	/* mains -- no need for APE since we conform to C99 */
	char *mains(int argc, char **argv) {
		exits(main(argc, argv) ? "FAILED" : "");
	}

> ...  void main was the better choice.

No, that choice pretty much forced the existence of an APE.
If the standard extern interfaces had been honored, Plan 9
C could support both the native Plan 9 way of doing things
*and* Standard C, without requiring any flags etc.

As a general design principle, whenever you find that two
similar but different approaches have been created, there
has been a lack of vision.  We see this in the two kinds
of "character" support in Standard C, for another example.