I copied the code from outbuffer.d to a new file. It looks like this:
import outbuffer;
int main(){
    OutBuffer buf = new OutBuffer();

    //printf("buf = %p\n", buf);
    //printf("buf.offset = %x\n", buf.offset);
    assert(buf.offset == 0);
    buf.write("hello");
    buf.write(cast(byte)0x20);
    buf.write("world");
    buf.printf(" %d", 6);
    // printf("buf = '%.*s'\n", buf.toString());
    return 0;
}

If I run this code I code crash with this backtrace:
(gdb) run
Starting program: /home/frido/Arbeit/LM/D/src/bug_1
(no debugging symbols found)...[New Thread 16384 (LWP 5652)]
(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 5652)]
0x08049c3b in _D9outbuffer9OutBuffer6spreadFkkZv ()
(gdb) backtrace
#0  0x08049c3b in _D9outbuffer9OutBuffer6spreadFkkZv ()
#1  0x08048ffb in _Dmain ()
#2  0x080494c4 in main ()
#3  0x400abd04 in __libc_start_main () from /lib/libc.so.6


I do not think that this should happen.

I'm running DMD 0.69 on a Debian/unstable box Libc version 2.3.x


Another point. I wrote about a generic way for printing objects. Now it seems Outbuffer is the answer, unfortunatly there's not function for printing an Object. I wonder if this patch would work:
    void write(Object o){
        reserve(o.toString().size);
        write(o.toString());
}

Regards
Friedrich

Try deleting lines of code from it until the problem goes away, that way at least it's down to which line is the problem.

Walter wrote:
> Try deleting lines of code from it until the problem goes away, that way at
> least it's down to which line is the problem.
> 
> 
The bugs seems to be with printf:
This works:
import outbuffer;
int main(){
    OutBuffer buf = new OutBuffer();

    //printf("buf = %p\n", buf);
    //printf("buf.offset = %x\n", buf.offset);
    assert(buf.offset == 0);
    buf.write("hello");
    buf.write(cast(byte)0x20);
    //buf.write("world");
    // buf.printf(" %d", 6);
    printf("buf = '%.*s'\n", buf.toString());
    return 0;
}

this crashes:
import outbuffer;
int main(){
    OutBuffer buf = new OutBuffer();

    //printf("buf = %p\n", buf);
    //printf("buf.offset = %x\n", buf.offset);
    assert(buf.offset == 0);
    buf.write("hello");
    buf.write(cast(byte)0x20);
    //buf.write("world");
    buf.printf(" %d", 6);
    printf("buf = '%.*s'\n", buf.toString());
    return 0;
}

Regards
Friedrich