bash -i -c // check from bashrc if within startup or execution

[Tycho Kirchner]

Hi,
When bash is invoked with bash -i -c ':' it sources ~/.bashrc before the 
processing of the BASH_EXECUTION_STRING begins.
I kindly wanted to ask for a robust way to discriminate the sourcing of 
~/.bashrc performed during initialization from a potential sourcing 
during the actual command execution. More specifically, how to tell from 
bashrc whether it was sourced using

bash -i -c ':'

or

bash --rcfile /dev/null -i -c 'source ~/.bashrc'


Thanks in advance
Kind regards
Tycho Kirchner