Manually allocated structs

[Domingo Alvarez Duarte via Digitalmars-d-learn]

Hello again !

Anyone knows how to compile with gdc for different versions I 
could not find how gdc implements it if it does ?

The proposed usage of "@property char[] buf()" although seems to 
work when compiled with dmd, segfaults when compiled with gdc:

----Code to test

import std.stdio;
import core.stdc.stdlib;

//version(c_style) {
	struct lua_char_buffer_st0 {
	    size_t size, used;
		char[1] buf;
	};
//}

//version(d_style) {
	struct lua_char_buffer_st2 {
	    size_t size, used;
		@property char[] buf() {
			return (_buf.ptr)[0 .. size];
		}
		private char[0] _buf;
	};
//}

//alias lua_char_buffer_st = lua_char_buffer_st0;
alias lua_char_buffer_st = lua_char_buffer_st2;
	
private enum MIN_ALLOC_SIZE = 2048;
private size_t NEW_SIZE(size_t sz) {return 
(((sz/MIN_ALLOC_SIZE)+1)*MIN_ALLOC_SIZE);}

lua_char_buffer_st *lua_realloc_char_buffer(lua_char_buffer_st 
*old, size_t size){
	lua_char_buffer_st *b = old;
	size_t n = NEW_SIZE(size);
	b = cast(lua_char_buffer_st*)realloc(old, 
lua_char_buffer_st.sizeof + n);
	if(b is null) return null;
	b.size = n;
	if(old is null) b.used = 0;
	return b;
}

int lua_char_buffer_add_char(lua_char_buffer_st **b, char c){
     lua_char_buffer_st *tmp = *b;
     if(tmp.used+1 >= tmp.size){
         tmp = lua_realloc_char_buffer(tmp, tmp.used+1);
         if(tmp is null){
             return 0;
         }
         *b = tmp;
     }
     //printf("lua_char_buffer_add_char %p : %p : %d : %d", 
&tmp.buf, tmp.buf.ptr, tmp.size, tmp.used);
     //fflush(stdout);
     //version(c_style)
     //*(&tmp.buf + tmp.used++) = c;
     //version(d_style)
     tmp.buf[tmp.used++] = c;
     return 1;
}

void main()
{
	lua_char_buffer_st *b = lua_realloc_char_buffer(null, 
MIN_ALLOC_SIZE);
	lua_char_buffer_add_char(&b, 'a');
	free(b);
	writeln("Hello !");
}