Re: QUESTION: strange behaviour of typedef enum and __attribute__((packed))using sh-hms-g++ 3.0.3

[Michael Svetlik <m dot svetlik at ssi-schaefer-peem dot com>]

Fabio Giovagnini wrote:

> Hi everybody,
> that's my problem:
> if I define
> typedef struct ms{
> 	unsigned long f1;
> 	unsigned long f2;
> 	unsigned char f3;
> 	} __attribute__((packed)) ms_t;
>
> unsigned char test;
>
> ...
> ...
> test = sizeof(ms_t);
> ...
> ...
>
> i see test == 9;
>
> if I delete attribure specifier, i see test = 12.
> This is the expected behaviour !!!!
>
> If I define
> typedef enum en {em_f1 = 0, em_f2, em_f3} __attribute__(((packed),aligned(1))) 
> em_t;
>
> compiling with sh-hms-g++ 3.0.3 I have an error: missing semicolon ....
> instead compiling with sh-hms-gcc 3.0.3 everything works fine and the size is 
> the expected size.
>
> If I define
> typedef enum en {em_f1 = 0, em_f2, em_f3} em_t 
> __attribute__(((packed),aligned(1)));
>
> no compiler error I see with sh-hms-g++ but the size is 4 that's unexpected 
> size for this enum type if we suppose the __attribute__ keyword has been 
> working.
I tried to compile the above statement with i686-linux-gnu gcc 2.95.3, 
with g++ 2.95.3 and with g++ 3.1 - each of them from gnu.org, and each 
of them returned an error - you have a tricky compiler.
What's the sense of packing a singular, scalar data type ? Do you want 
to zip it :-?
What does your HITACHI do, when accessing a data type, bigger than one 
byte, on an even address (aligned(1)) ?
You dont expect a size of 4 for your enum - what's the sizeof(int) on 
your machine ?

> So I dedice the __attribute__ working in thuis sintax is not working, as 
> someone said some time ago.
>
> Does anyone have some tips to understand and solve this problem?
>
> Regards.
>
>
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