Previous bug: #992069
This is not fixed. The package libvkd3d-doc still is not installable alongside libvkd3d-dev, as it tries to overwrite files in /usr/share/doc/libvkd3d-dev folder.
This placement of files in /usr/share/doc/libvkd3d-dev folder seems counter intuitive to me, as libvkd3d-doc package is installable alone - Why "split" documents in these two folders. I am not sure if this is intended or just something strange that happens in the "rules" script, because aborting the build before override_dh_gencontrol: seems to NOT have the files in the wrong folder.
I added this below override_dh_gencontrol:
# Need to move html and .pdf to libvkd3d-doc
ifneq (,$(filter $(DEB_HOST_ARCH),amd64))
mv debian/libvkd3d-doc/usr/share/doc/libvkd3d-dev/* debian/libvkd3d-doc/usr/share/doc/libvkd3d-doc
rm -rf debian/libvkd3d-doc/usr/share/doc/libvkd3d-dev
Since this is a "all" package, i guess i386 will kinda drop the package (override_dh_gencontrol maybe not run? dunno), so i did this just for amd64, or it would fail building on launchpad PPA for Ubuntu on the i386 package (file not found)
The result of this is that ALL the files are placed in /usr/share/doc/libvkd3d-doc folder instead instead of split between /usr/share/doc/libvkd3d-dev and /usr/share/doc/libvkd3d-doc. I do not claim to say this is "correct" or even wanted... maybe it is your intent to have the html docs in /usr/share/doc/libvkd3d-dev folder anyway.. it just seems somewhat strange to me, unless you actually do a "depends libvkd3d-dev" on the package (After all.. most likely scenario is to install documentation alongside -dev package). This is not up to me... but the fact are that (as the original bug #992069 also said) the files ANNOUNCE.gz AUTHORS and README files being put in /usr/share/doc/libvkd3d-dev is causing a overwrite conflict when installing both the packages.
By all means - solve this more correct - just make sure that someone TEST install the package so that you can install BOTH libvkd3d-dev and libvkd3d-doc at the same time.