[Pkg-pascal-devel] Bug#820708: Bug#820708: Bug#820708: castle-game-engine: hardcoded libpng12 dependency

[Paul Gevers]

Hi Michalis,

On 19-04-16 02:15, Michalis Kamburelis wrote:
> 
> 
>     > For Debian packaging, it may make sense to just simplify and say
>     > "let castle-game-engine recommend libpng". I'm just saying that it's
>     > not a strict dependency for upstream.
> 
>     Not sure if I fully agree. If I understand correctly the packages that
>     have a Build-Depends on cge need the Depends/Recommends on libpng (like
>     view3dscene).
> 
> 
> Sure, it's correct that view3dscene "Recommends" the libpng. Because
> opening a VRML/X3D file that uses a texture encoded in png is a very
> common case, it's reasonable for a user to assume that "just installing
> view3dscene" will make this possible.
> 
> And most games use png for textures/images, so they will want to
> "Depend" on libpng. Otherwise they could not read png textures. (Which
> doesn't need to cause a crash, a particular game may choose to turn it
> into a mere warning.)
> What I meant to say, in my earlier mail, is that: if you somehow make a
> game that doesn't use png (maybe it has no textures/images, or only in
> other formats like jpg or ppm or dds), then it does not need to depend
> on libpng. It will happily work on a system without libpng. So merely
> using CGE does not *always* imply that you also need to have libpng at
> runtime.

What you describe above was exactly what I meant/had in mind, so I
understood you very well. My point is that the binary packages in Debian
don't "use" CGE, they are build with CGE and thus (unfortunately in the
current Free Pascal stack) have CGE build in (instead of linked to a CGE
library. Therefore, it doesn't help one little bit that the binary
packages of CGE have Depends or Recommends on libpng*, as the build
binary packages of stuff build with CGE needs those. We currently lack
any automated way of getting that knowledge transfered.

In hind-sight to my changes yesterday to downgrade this bug I am not
sure if I don't consider this RC. Packages build with CGE that NEED png
support are soon broken in testing (the moment libpng12 is removed)
without a way to be fixed. And fixing this bug is not enough, those
packages need to be rebuild as well.

Just a thought, should all packages in the Free Pascal stack declare a
"Build-Using" relation¹?

Paul

¹
https://www.debian.org/doc/debian-policy/ch-relationships.html#s-built-using

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