From: "ICE (Instrumentacion y Control Electr.)" <ice AT inti DOT edu DOT ar>
To: djgpp AT delorie DOT com
Subject: Patch for __attribute__ ((packed))
Date: Wed, 3 Apr 1996 16:47:20 +0300 (GMT)
Message-ID:  <9604031647.aa24779@ailin.inti.edu.ar>

Hi everybody:

  My name is Salvador Eduardo Tropea (SET), i'm from Argentina (South America).
  Sorry for my english.

  Robert Hoehne autor of RHIDE says in your READMETV.SRC:

*******NOT*******NOT*********
Do N O T compile the library with GCC V.2.7.1 or GCC 2.7.2, because
there is a bug in cc1plus, which dosn't handle correct packed
structures, which are used by the File-classes (struct ffblk).
I have compiled the library with GCC V.2.7.0. If you have no
access to this version and you want it, see my on my TV-Homepage.
*******NOT******NOT**********

  I sent the following message to Robert:

>
> 2) I succesfully remake RHIDE (and libtv ofcourse) with gcc 2.7.2 !!!!
>  I know about the bug in gcc, i'm one of the people (hundreds i guess) that
> report this bug to GNU, but on april 2 A. Appleyard (from england)
> wrote the following message to the djgpp list:
>
> > One problem might be that you declare structs with packed fields and use
> > the size of struct modeinfo in one of the variants (but not in the
> > other).  GCC 2.7.2 has a known bug in its C++ compiler: it doesn't pack
> > structs even if you use __attribute__((packed)), so you might use a wrong
> > struct layout and size.
>
> > To make GCC pack the structures, surround the code with these (I hope I
> > get this right; to be sure, search the DJGPP mailing archives for
> > `pragma' as keyword):
>
> > #ifdef __cplusplus
> > #pragma pack(1)
>
> !!> put here the code that declares packed structures
>
> >#pragma pack()
> >#endif
>
>  I made the following:
>
> a) I created a header file called 'pack.h':
>
> #ifndef __pack_bug_fixer
> #define __pack_bug_fixer
>
> #define Pack_ON  #pragma pack(1)
> #define Pack_OFF #pragma pack()
>
> #endif
>
> b) I enclosed the declarations in dos.h and dir.h which use
> __attribute__ ((packed)), with Pack_ON and Pack_OFF (including the header
> pack.h very close to the declaration).
>
> c) I made the same in 'file.cc' of RHIDE.
>
>  This procedure seems to work fine.
>

  Now i propose this procedure to make a patch for gcc 2.7.2.

Note: I don't know nothing about diff and related tools, and i supose that
Delorie must put this patch in SimTel.

Greetings SET.


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