Either the documentation is incorrect or the implementation is.

The documentation says:

"If the option has a parameter, that must be "stuck" to the option without any intervening space or "=": "

and

"Forms such as -t 5 and -timeout=5 will be not accepted. "

Does not appear to be true. The form -t 5 is accepted.

Example:

import std.stdio;
import std.getopt;

void main(string[] args)
{
	uint age;
	std.getopt.getopt(args, "a", &age);
	
	writeln("age = ", age);
	writeln("args = ", args);
}
C:\temp>dmd getopt.d && getopt -a 5000
age = 5000
args = ["getopt"]

Windows XP 32 bit. v2.065 

The implementation seems to work correctly as I regard it, unless there is a reason why it should be disallowed I think short options need not have thier parameter immediatly follow the option, and so the documentation should be adjusted.