Bug#791485: symbols file: arch-bits=32|64 vs subst

[Mathieu Malaterre <malat@debian.org>]

Hi Lisandro,

On Tue, Sep 15, 2015 at 3:50 PM, Lisandro Damián Nicanor Pérez
<perezmeyer@gmail.com> wrote:
> tag 791485 wontfix
> thanks
>
> tl;dr: we still need to support qt4' qreal.
>
> On Tuesday 15 September 2015 15:13:29 Mathieu Malaterre wrote:
>> Hi,
>>
>> [For some reason I never received your -submitter@b.d.o email]
>
> Sometimes mails get lost, it also happens to me from time to time.
>
>> > For what I understand of your bug report arch-bits it's simply 32 or 64.
>> > The problem is that it's not as simple as that. There are differences
>> > between archs that use the same amount of bits.
>> :q!
>> Could you name a single example in Debian archs ?
>>
>> Thx much.
>
> Take a look at <https://wiki.debian.org/ArchitectureSpecificsMemo>, first
> table.

Good. I see that sizeof (void*) is either 4 or 8 (which is how I
understand `arch-bits` implementation)

> An example was s390 and s390x which share the size of some types, like size_t.
> While s390 is no longer a release arch it makes an example of something that
> might happen again. So yes, we can now say this is a storical reason, but was
> valid for quite some time.
>
> See the full table of conversions in:
>
>  pkg-kde-tools/perllib/Debian/PkgKde/SymbolsHelper/Substs/TypeSubst.pm

As per my original post, I never said I wanted `subst` behavior. I
said I wanted a merge mechanism based on `arch-bits`.

> Another offender is qreal for qt4 apps, which we still need to support, and so
> we need to keep this until we get rid of qt4... if we ever do.

That's KDE-specific. There is no such thing as qreal in C++.

> And if we do change this we would need to fix tons of packages...

Sorry failed to understand you.

> My suggestion is to really try to get a symbols generator directly in dpkg. I
> would keep the possibility of not depending just on the arch-bits because
> history has shown us that exceptions might happen. But that's up to the
> implementer... until a new arch arrives ;)

Ok. I've totally failed to follow you.

Here is a simple one liner from dpkg-gensymbols file. The man page states:

[...]
            The architecture-bits is either 32 or 64.

               (arch-bits=32)a_32bit_specific_symbol@Base 1.0
               (arch-bits=64)a_64bit_specific_symbol@Base 1.0
[...]

This is a strict *or*. As per my understanding one said arch is either
`arch-bits=32` or `arch-bits=32`.

So you are saying that for a said `arch-bits` (let's say 32) with a
particular said function, you are saying the symbols for this C or C++
function will be different on another `arch-bits=32` ? Could you
please take me by the hand and show me such function (C or C++, no KDE
typedef please) ?

Regards.