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From: Mark Wielaard <mjw-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Arnaldo Carvalho de Melo <acme-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: Nicolas <nikos42-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	dwarves-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Brain fart alert
Date: Mon, 20 Aug 2012 00:16:36 +0200
Message-ID: <20120819221636.GC19422@toonder.wildebeest.org> (raw)
In-Reply-To: <20120816195224.GC10277-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

On Thu, Aug 16, 2012 at 04:52:24PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Aug 15, 2012 at 02:56:47PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Sat, Jul 21, 2012 at 08:22:33PM +0200, Nicolas escreveu:
> So the problem is that 'in' is (from the .cpp file):
> 
> static const _Ios_Openmode in = _S_in;
> 
>  <2><82>: Abbrev Number: 10 (DW_TAG_member)
>     <83>   DW_AT_name        : in       
>     <86>   DW_AT_decl_file   : 1        
>     <87>   DW_AT_decl_line   : 15       
>     <88>   DW_AT_type        : <0x9b>   
>     <8c>   DW_AT_external    : 1        
>     <8d>   DW_AT_declaration : 1        
>     <8e>   DW_AT_const_value : 8

Although I cannot find it said explicitly in the DWARF spec I think
you can assume that any member with a const_value (and without a
data_member_location) doesn't occupy space.

> I need to capture the fact that it is a static const, and investigate
> the C++ structure encoding rules, why is that it takes 1 byte when it
> has no per instance members?

That is by definition in C++, in C it is a GNU extension to allow empty
structs. Depending on whether you compile an empty struct with gcc or g++
it will have a size on zero or one.
http://gcc.gnu.org/onlinedocs/gcc/Empty-Structures.html

Cheers,

Mark
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  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-21 18:22 Nicolas
     [not found] ` <CACHCVZ6oDyFwGbC4EwF_wsR9tCkoych5N6buLhRRLcyaL6iifw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-08-15 17:56   ` Arnaldo Carvalho de Melo
     [not found]     ` <20120815175647.GK2370-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2012-08-16 19:52       ` Arnaldo Carvalho de Melo
     [not found]         ` <20120816195224.GC10277-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2012-08-19 22:16           ` Mark Wielaard [this message]
2012-08-20 13:45         ` Dodji Seketeli
     [not found]           ` <m3obm5fzhs.fsf-fIDRvF7C5exg9hUCZPvPmw@public.gmane.org>
2012-08-20 17:35             ` Arnaldo Carvalho de Melo
2012-08-20 18:02   ` Arnaldo Carvalho de Melo
     [not found]     ` <20120820180216.GE3046-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2012-08-20 18:28       ` Arnaldo Carvalho de Melo
2012-08-30 16:35       ` Nicolas
     [not found]         ` <CACHCVZ5EJadxOTJ0T4phSfAcm1FK7wfeDTp9QcSa1V1JCpa8SA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-09-03 12:22           ` Mark Wielaard
     [not found]             ` <1346674948.3090.40.camel-OO0OHOuVXW89n/EXqpbZ8ns8WZQLr0HW@public.gmane.org>
2012-09-24 22:19               ` Nicolas
     [not found]                 ` <5060DC56.4080609-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-02-26  1:50                   ` Nicolas
     [not found]                     ` <CACHCVZ6uvDW1CpyxXio3P17EL6bE=FKGDNm11RNZTceR-dWLjg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-02-26 10:56                       ` Mark Wielaard
     [not found]                         ` <1361876163.4930.4.camel-Et2QWsRS+g7yukXOleVwRPp4M6BF03vq@public.gmane.org>
2013-03-20 13:37                           ` Arnaldo Carvalho de Melo
2015-11-11 18:26 David Sterba
     [not found] ` <20151111182618.GF6445-AlSwsSmVLrQ@public.gmane.org>
2015-11-11 20:11   ` Arnaldo Carvalho de Melo
     [not found]     ` <20151111201151.GA6712-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-11-11 21:05       ` David Sterba
     [not found]         ` <20151111210519.GG6445-AlSwsSmVLrQ@public.gmane.org>
2015-11-11 22:13           ` Arnaldo Carvalho de Melo
     [not found]             ` <20151111221340.GB12579-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-11-11 22:17               ` Arnaldo Carvalho de Melo
     [not found]                 ` <20151111221747.GC12579-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2015-11-11 22:48                   ` Arnaldo Carvalho de Melo

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