Bug#904302: Why outlawing vendor-specific patch series would be a bad idea

[Adrian Bunk <bunk@debian.org>]

On Sat, Aug 18, 2018 at 11:31:06AM -0700, Sean Whitton wrote:
> Hello,
> 
> On Fri 17 Aug 2018 at 07:36PM +0300, Adrian Bunk wrote:
> 
> > The main misconception is that there would always be *the* source.
> >
> > Steps you might have before the compilation starts:
> > 1. dpkg unpacks upstream sources
> > 2. dpkg applies patches
> > 3. debian/rules unpacks upstream tarballs as part of the build
> > 4. debian/rules applies patches based on distribution
> > 5. debian/rules applies patches based on release
> > 6. debian/rules applies patches based on architecture
> >
> > What is "the source running on their Ubuntu system" for src:gcc-8?
> >
> > This package skips steps 1 and 2, but does all of steps 3-6.
> 
> But all of steps 3--6 are part of the package build.
> 
> "The source" is what you get after steps 1 and 2.

Why is "The source" what you get after dpkg applied patches,
but before debian/rules applied patches?

For a user it doesn't make a difference which tool applies the patches.

Note that you were also arguing based on a different source
definition:

On Mon, Jul 23, 2018 at 09:22:17AM +0800, Sean Whitton wrote:
> For example, someone might want to use a Debian system to investigate a
> bug on an Ubuntu system.  They might begin by downloading some source
> packages from the Ubuntu mirrors.  Since they obtained them from Ubuntu,
> they will form the reasonable expectation that unpacking these source
> packages will get them the code running on the Ubuntu system they are
> debugging.

This would be useful for debugging problems.

But it is important to understand that in the general case there will 
always be cases where the code running on your system will depend on
the architecture of your system - after applying patches the sources
might be architecture-specific.

This implies that for these usecases you want to make possible dpkg 
would not require less conditional patching functionality - it would
actually require more conditional patching functionality so that
dpkg can give you the exact sources for the architecture you are
looking at.

Since we have established that conditional patching support is in any 
case required for your usecase, the vendor patching becomes less of
an issue since this will anyways require even more tooling support
for conditional patching.

> Sean Whitton

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed