Error: cannot return non-void from void function

[Daniel Kozak via Digitalmars-d-learn]

On Thursday, 27 November 2014 at 17:22:36 UTC, Suliman wrote:
>
>> ah, that's it! as spec says, D determines function return 
>> value from
>> the first 'return' statement it seen. in your case this is 
>> `return;`,
>> so function return type is determined to be `void`.
>>
>> if you doing `auto` functions, try to arrange your code so the 
>> first
>> `return` returning the actual value.
>>
>> besides, your code is wrong anyway, 'cause you can't have 
>> function that
>> returns both "nothing" and "something". your first `return;` 
>> should
>> either return something, or must be changed to throwing some 
>> exception.
>
> How I can terminate program? First return I used to terminate 
> app if config file is exists.

You can use this:

auto parseConfig()
{
	string txtlinks = buildPath(getcwd,"notexist");
	if(exists(txtlinks))
	{
		auto lines = File(txtlinks, "r").byLine;
		return lines;
	}
	writeln("Can't find input file with list of links.");
	return typeof(return)();
}

it works somehow, but it is not good way how to do it.

Other way is use exit

         if(!exists(txtlinks))
	{
		import core.runtime;
		import std.c.process;
		writeln("Can't find input file with list of links.");
		Runtime.terminate();
		exit(1);
	}
But best way is use throw exception

         if(!exists(txtlinks))
	{
	    throw new Exception("Can't find input file with list of 
links.");
	}
and catch it somewhere from calling side