This is cursed: https://github.com/es3n1n/defendnot/blob/master/defendnot-lo... If you're curious what's actually going on there: https://github.com/es3n1n/defendnot/blob/master/cxx-shared/s...
TL;DR, not AI
The code defers a function call until the point in time that an object goes out of scope. The implementation uses C macros to create a more succinct syntax that omits parts of the necessary C lambda/unnamed function definition and to create a unique variable name for managing the deferred function call. However, the resulting syntax eschews the common convention of using UPPER CASE to denote C macros, and instead appears similar at first glance to a function call from an object pointer.
This can cause confusion if one is not familiar with this pattern and expects macros to be communicated differently. Some commenters say this is common enough, or useful enough to them, to be considered almost idiomatic in some contexts.
For technical explanation, https://news.ycombinator.com/item?id=43959403#43960905 provides a useful breakdown of how the macro works.