Hi. I'm having trouble calling a C function passing a structure by value, printing a member and getting it back in D but I must be doing something wrong.

I have a C file called native.c that defines a function called 'filter' taking a buf_t structure, I compile it using GCC to native.o. From D, I use extern(C) to access the 'filter' function defined in native.o.

##Makefile

app: native.o
	dmd -ofbin/app app.d native.o
	chmod +x bin/app
	bin/./app

native.o: native.c
	gcc -c native.c -o native.o

##app.d

import std.stdio;

extern(C) struct buf_t {
    void* base;
    size_t len;
  }

extern(C) buf_t filter(const buf_t value);

void main() {
  buf_t buf;
  buf.len = 10;
  auto r = filter(buf);
  writefln("D: len %d", r.len);
}

***native.c***

#include <sys/types.h>
#include <stdio.h>

typedef struct {
  void* base;
  size_t len;
} buf_t;

buf_t filter(buf_t value) {
  printf("C: len: %zu\n", value.len);
  return value;
}


***The output***

C: len: 140734905718328
D: len 0


"len" should be 10 in both cases. What am I doing wrong?

I'm using:
OS: Mac OSX Lion, 64bits.
D compiler: DMD64 D Compiler v2.058
C compiler: gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.1.00)

Thanks,
Johan

On Wed, 25 Apr 2012 09:57:39 +0200, Johan Hernandez <thepumpkin1979@gmail.com> wrote:

> Hi. I'm having trouble calling a C function passing a structure by value, printing a member and getting it back in D but I must be doing something wrong.

Could be this one: http://d.puremagic.com/issues/show_bug.cgi?id=5570

On Wednesday, 25 April 2012 at 08:38:02 UTC, simendsjo wrote:
> Could be this one: http://d.puremagic.com/issues/show_bug.cgi?id=5570

Thank you for your response.

It's a huge issue :(

On Wed, 25 Apr 2012 20:36:31 +0200, Johan Hernandez <thepumpkin1979@gmail.com> wrote:

> On Wednesday, 25 April 2012 at 08:38:02 UTC, simendsjo wrote:
>> Could be this one: http://d.puremagic.com/issues/show_bug.cgi?id=5570
>
> Thank you for your response.
>
> It's a huge issue :(

I agree. Let's hope it gets fixed now that it's confirmed on OSX too.
You could use the voting system in bugzilla to give the issue more focus.

On 2012-04-25 20:36, Johan Hernandez wrote:
> On Wednesday, 25 April 2012 at 08:38:02 UTC, simendsjo wrote:
>> Could be this one: http://d.puremagic.com/issues/show_bug.cgi?id=5570
>
> Thank you for your response.
>
> It's a huge issue :(

Compile as a 32bit binary. For DMD add "-m32" do the flags. For gcc add "-arch i386".

-- 
/Jacob Carlborg

On Wednesday, 25 April 2012 at 19:43:27 UTC, Jacob Carlborg wrote:

> Compile as a 32bit binary. For DMD add "-m32" do the flags. For gcc add "-arch i386".

Thanks Jacob, that worked!!!

simendsjo:

I upvoted and commented the same day bro.