Bug#939950: hkl: fails to build with gtk-doc 1.32

[Andreas Henriksson]

Source: hkl
Severity: important
Control: block 939500 by -1

Hello,

Your package seems to fail to build from source with the new gtk-doc-tools 1.32 (currently in experimental).
The issue seems to be that your sgml files include a file that's no longer being generated when there's no content to put in it.

https://gitlab.gnome.org/GNOME/gtk-doc/commit/97541700fe55bf5ba1522773dd242a4598cac187

"... As a notable change we don't output empty tree_index files
anymore."


The build failure snippet looks something similar to this:

warning: failed to load external entity "../xml/tree_index.sgml"
../foobar.sgml:63: element include: XInclude error : could not load ../xml/tree_index.sgml, and no fallback was found

Possible solutions could be:
- remove the lines referencing the non-existant (and previously empty) tree_index.sgml file.
- extend the include of tree_index.sgml with additional <xi:fallback/> tags.

For an example of the first alternative see:
https://salsa.debian.org/gnome-team/brasero/blob/f38e3a5838157432799c0ee29cebcca334af8f5a/debian/patches/0002-Stop-referencing-empty-Object-Hierarchy.patch

Regards,
Andreas Henriksson