rsyslog-impcap cannot be installed from Adiscon ubuntu stable repository

[frikilax]

Description

When adding Adiscon's ubuntu stable repository to ubuntu and trying to install rsyslog-impcap, package cannot be installed due to missing/unresolved dependency :

root@8bde8114be4e:/# apt install rsyslog rsyslog-impcap
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 rsyslog-impcap : Depends: libpcap but it is not installable
E: Unable to correct problems, you have held broken packages.

How to reproduce

• sudo add-apt-repository ppa:adiscon/v8-stable
• sudo apt-get update
• sudo apt-get install rsyslog rsyslog-impcap

was tested on (docker) ubuntu 18.04 and (docker) ubuntu 20.04 (with additional installation of software-properties-common to add adiscon repo)

The bug

rsyslog-impcap is compiled using libpcap-dev, which is the transitional package for current libpcap0.8-dev.
It depends on libpcap which doesn't exist, dependency should be libpcap0.8 instead (agreed, this could be more a libpcap packaging problem, as they provide a transitional package for development package, but not for the library one)

this symptom should be the same on at least xenial, bionic and focal releases of ubuntu, as libpcap packages are the same on all those releases