__attribute__((packed)) behavior with gcc and g++ [gcc version 3.2 20020903]

__attribute__((packed)) behavior with gcc and g++ [gcc version 3.2 20020903]

[Milind Changire]

Following peice of code compiles under gcc and reports the size of
struct as 11, as expected.  However g++ just does not like the code
and reports an error 'semicolon missing after enum declaration'
g++ 3.4.1 reports a 'warning: `packed' attribute ignored' and I get
the size of struct as 14.
I'd like to pack structures and cause enums to use mininum possible
space, mostly a single byte, under gcc 3.2.
Arch: i686
------
#include <stdio.h>

#pragma pack(1)
typedef enum {
	Red,
	Green,
	Blue
} __attribute__((packed)) MYENUM;

struct pragma_struct_t {
	char	ch;
	int	val;
	char	ch2;
	long	len;
	MYENUM	color;
};
#pragma pack(0)

int main()
{
	printf("sizeof(struct pragma_struct_t)= %d\n",
	sizeof(struct pragma_struct_t));
	return 0;
}
------

How do I get this to work under g++ 3.2?
Any patches or suggestions?

-Milind

__attribute__((packed)) behavior with gcc and g++ [gcc version 3.2 20020903]

[Milind Changire]

Following peice of code compiles under gcc and reports the size of
struct as 11, as expected.  However g++ just does not like the code
and reports an error 'semicolon missing after enum declaration'
g++ 3.4.1 reports a 'warning: `packed' attribute ignored' and I get
the size of struct as 14.
I'd like to pack structures and cause enums to use mininum possible
space, mostly a single byte, under gcc 3.2.
Arch: i686
------
#include <stdio.h>

#pragma pack(1)
typedef enum {
	Red,
	Green,
	Blue
} __attribute__((packed)) MYENUM;

struct pragma_struct_t {
	char	ch;
	int	val;
	char	ch2;
	long	len;
	MYENUM	color;
};
#pragma pack(0)

int main()
{
	printf("sizeof(struct pragma_struct_t)= %d\n",
	sizeof(struct pragma_struct_t));
	return 0;
}
------

How do I get this to work under g++ 3.2?
Any patches or suggestions?

-Milind

__attribute__((packed)) behavior with gcc and g++ [gcc version 3.2 20020903]

[Milind Changire]

Following peice of code compiles under gcc and reports the size of
struct as 11, as expected.  However g++ just does not like the code
and reports an error 'semicolon missing after enum declaration'
g++ 3.4.1 reports a 'warning: `packed' attribute ignored' and I get
the size of struct as 14.
I'd like to pack structures and cause enums to use mininum possible
space, mostly a single byte, under gcc 3.2.
Arch: i686
------
#include <stdio.h>

#pragma pack(1)
typedef enum {
	Red,
	Green,
	Blue
} __attribute__((packed)) MYENUM;

struct pragma_struct_t {
	char	ch;
	int	val;
	char	ch2;
	long	len;
	MYENUM	color;
};
#pragma pack(0)

int main()
{
	printf("sizeof(struct pragma_struct_t)= %d\n",
	sizeof(struct pragma_struct_t));
	return 0;
}
------

How do I get this to work under g++ 3.2?
Any patches or suggestions?

-Milind

Re: __attribute__((packed)) behavior with gcc and g++ [gcc version 3.2 20020903]

[Paweł Sikora]

[-- Attachment #1: Type: text/plain, Size: 372 bytes --]

On Wednesday 04 of August 2004 17:48, Milind Changire wrote:

> Any patches or suggestions?

# g++ --version; g++ packed.cpp -o packed && ./packed

g++ (GCC) 3.4.2 20040730 (prerelease) (PLD Linux)
(...)

sizeof(...)= 14

arch == pentium3.


-- 
/* Copyright (C) 2003, SCO, Inc. This is valuable Intellectual Property. */

                           #define say(x) lie(x)

[-- Attachment #2: packed.cpp --]
[-- Type: text/x-c++src, Size: 466 bytes --]

#include <stdio.h>

typedef enum {
	Red,
	Green,
	Blue
} MYENUM;	// enum == int

struct pragma_struct_t {
	char	ch	__attribute__((packed));	// 1 byte
	int	val	__attribute__((packed));	// 4 bytes
	char	ch2	__attribute__((packed));	// 1 byte
	long	len	__attribute__((packed));	// 4 bytes
	MYENUM	color	__attribute__((packed));	// 4 bytes
							// ========
							// 14 bytes
};

int main()
{
	printf("sizeof(...)= %d\n", sizeof(struct pragma_struct_t));
	return 0;
}