It's legal, (well, modulo envp, which is obsolete, and not a part of any
standard; use extern char **environ for POSIX.) but only because the
promoted types of int and char ** are int and char **.

The construct
	void foo(char);

	void foo(c)
		char c;
	{}

*IS NOT LEGAL NOW*.  It invokes undefined behavior, because foo is declared to
accept a char by the declaration, but an int by the definition, because the
old-style rule is that the standard promotions are applied to function
arguments.

My ideal solution is to declare that
	void foo(c)
		char c;
	{}
acts *EXACTLY* like
	void foo(char c);
in C9X programs.  Since the old-style declarations are obsolescent, any
code broken by this had it coming.  (Regardless, C9X is almost guaranteed
to have either the "prototype-equivalent" old-style definitions, or none
at all.)

People who need to use old code can do what they do now; use gcc -traditional.

-s