[xml/sgml-pkgs] Bug#1073508: Bug#1074338: src:libxml2: fails to migrate to testing for too long: unresolved RC issue

[Paul Gevers]

Hi,

[Disclaimer: I'm not the most experienced person on transitions in the 
team, so I'd like for Graham, Emilio and/or Sebastian to check if they 
agree with me.]

Thanks for working on this.

On 17-08-2024 05:58, Aron Xu wrote:
> After some research, I prefer making a t64-like transition for libxml2
> for the following reasons:

I'm a bit curious in how far you think this looks like a t64-like 
transition as apposed to a regular c-library transition. Is it because 
the libraries will not be co-installable, you don't bump SONAME and just 
rename the binary package name? Even with all the work that went into 
the t64 transition, we're starting to see hidden bugs [0] (although I 
think this can happen with any transition).

>   - Upstream is not prepared to bump the SONAME to something like
> libxml3. Given the long history of this function library, determining
> which APIs should be public and which should be private is
> challenging.

That's why earlier I proposed a Debian specific SONAME, "in between" 2 
and 3. Upstream (I think) even suggested that [1].

>   - The potential for breaking locally built software is minimal.
> Although abi-compliance-checker raises many issues, most of them are
> not used in the real world.

Isn't the fact that we *caught* an issue in Debian the proof that it's 
not just academic?

>   - This approach is significantly easier and safer.

I'm hesitant because we have well established procedures to handle ABI 
breakage with SONAME bumps and how to handle them in Debian. Can you 
elaborate on the easier and safer parts? Because I mostly see risks to 
deviate from established paths as the corner cases on them are less known.

> I've prepared a preliminary debdiff and tested locally. What do you think?

Also just curious, why the letter n?

Paul

[0] https://lists.debian.org/msgid-search/Zr57AYhXiL3oi8_d@per
[1] https://gitlab.gnome.org/GNOME/libxml2/-/issues/751#note_2157870 
(second to last paragraph)
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