[scribus-dev] scribus on arm linux (was: Re: Fw: Raspbian: building Scribus)

peter green plugwash at p10link.net
Wed Aug 21 00:12:06 UTC 2013

William Bell wrote:
> Hi Peter,
> Did you push the problem with Scribus back to the Scribus developers?
As a general rule I don't deal with upstreams directly unless it's for a 
program I use myself heavilly and/or am one of the debian matainers for. 
IMO the responsibility for knowing how best to deal with upstream and 
knowing what patches from debian they will and wont want lies with the 
maintainer of the debian packages.

In this case though given the lack of any action by the debian 
maintainer on the latest bug I filed I think it's best to keep upstream 
in the loop. I'm ccing them (and a few other places) on this mail.

Note that I do not personally use scribus.

 > It looks like Plugwash fixed the issue upstream:
 > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=659916
Afaict bug reports have been filed over issues with scribus on arm  on 
several occasions. All the ones I submitted were variants on the theme 
of "you need to be more careful about mixing qreal and double". From 
reading the debian changelog it looks like the maintainer pushed at 
least some of them upstream.

For anyone reading this who is not familiar with the issue the 
underlying problem is that qt developers chose to define qreal 
differently on arm from on other platforms. On most platforms qreal is 
defined as double but on arm platforms it is defined as float. I assume 
this was done to give better performance, especially on earlier arm 
hardware that did not have usable hardware floating point, whatever the 
original reason it seems to be a descision we are laregly stuck with*. 
Therefore qt application developers have to be careful about how they 
mix qreal and double if they want their code to work on arm.
>   The problem with double and float seems to be worse in 1.4.3.  There 
> are several references to QVector<double> and QList<double>.  The fix 
> is not as straightforward as hoped, since they have some overridden 
> functions with QVector<double> and QVector<float> inside Scribus.
I was able to get 1.4.2 to build with a patch that I posted at 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=707882 . However the 
patch was far more intrusive than previous patches I have prepared and I 
am not confident in it's correctness. It really needs someone who 
understands the code in question to check it before it is applied. The 
patch looks basically the same as the one the fedora guy posted.

This issue is blocking scribus 1.4.2 from reaching debian (and hence 
raspbian) jessie.

I have not looked at 1.4.3 partly because it's not in debian yet and 
partly because I only look at build failures when i'm bored or when they 
are blocking something I care about.

* Unless we want to break binary compatibility with upstream but I 
really do not think going down that road is a good idea.

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