Prevent errors due to infinite recursion in self-referential macros

[martis42]

Fixes: #72

Patch based on work of @MatthewShao
Test created by stripping down the reproducing example in above issue.

[ned14]

Thanks for the PR

[ymsdad]

Hi @ned14,

Thanks for maintaining pcpp.

I ran into the recursion issue fixed in this PR while using the latest PyPI release (1.30), and can confirm this patch resolves it in practice.

Since PyPI hasn’t had a release since 2021, would you be open to merging this and possibly cutting a new release? It would unblock downstream users who currently have to depend on forks.

Thanks for your time.

[ned14]

You're kind to say I'm maintaining this project. If so, I've been doing a lousy job for years now.

Clearing all bugs and doing a release has been on my priority queue for a while now. It's currently at number thirteen in the priority queue. I'll be blunt, this bug which I recognise affects others hasn't affected me, so for me personally the urgency is low and there are bigger showstopper bugs in my other open source. Like, right now one of my Boost libraries the code doesn't compile at all on older compilers at all due to changes merged before Christmas.

That said, if WG14 greenlight the two reference libraries I have coming for the C standing library in the WG14 meeting next month, that will raise this project's priority as those use pcpp to turn the reference libraries into mergeable libraries for implementations. Sorry about my tardiness. I have limited free time.