Hello !

Based on a question about manually allocated structures with payload I found that a solution proposed seems to work when compiled with dmd but segfaults when compiled with gdc.

So my question is: Is this a bug on dmd, gdc or a bad idiom ?

---- code to see the problem
import std.stdio;
import core.stdc.stdlib;

void main()
{
	struct S
	{
		int size;
		char[0] _b;
		@property char[] buf() { return (_b.ptr)[0..size];}
	}
	
	int size = 12;
	S *s = cast(S*)malloc(S.sizeof + size);
	if(s !is null)
	{
		scope(exit) free(s);
		s.size = size;
		s.buf[0] = 'a';
		writeln(s.buf[0]);
	}
}

Domingo Alvarez Duarte:

> Based on a question about manually allocated structures with payload I found that a solution proposed seems to work when compiled with dmd but segfaults when compiled with gdc.
> ...
> 		int size;
> 		char[0] _b;
> 		@property char[] buf() { return (_b.ptr)[0..size];}
> 	}

I guess you are using different versions of the front-end. Zero-length arrays was null before, and it's not null in V. 2.066.

So probably there is no bug, just a little design change for the better.

Bye,
bearophile

On Monday, 28 July 2014 at 08:16:37 UTC, bearophile wrote:
> Domingo Alvarez Duarte:
>
>> Based on a question about manually allocated structures with payload I found that a solution proposed seems to work when compiled with dmd but segfaults when compiled with gdc.
>> ...
>> 		int size;
>> 		char[0] _b;
>> 		@property char[] buf() { return (_b.ptr)[0..size];}
>> 	}
>
> I guess you are using different versions of the front-end. Zero-length arrays was null before, and it's not null in V. 2.066.
>
> So probably there is no bug, just a little design change for the better.
>
> Bye,
> bearophile

Thanks ! You are right I'm using dmd 2.066 and gdc 4.8/4.9, Cheers !