Actually, the ecpg pre-compiler resolves ESQL/C statements like
EXEC SQL SELECT ....
into a function call to the executer in the ecpglib as:
where __LINE__ is later substituted by the C-precompiler by the current
line number as an integer. The purpose is mostly for logging features
 [14.01.2020 12:05:18:433]: ECPGtrans on line 1108: action "rollback"; connection "sisis71"
i.e. to have the line number in the log statement
(btw: the date and timestamp is already a local modification we did to
bring the log line in sync with other logs our application is writing).
In a real world server application written in some hundreds foo.pgc
files (a generated application interface with the pgc files based on
the 400 tables in the database), it would be nice to have the call done
ECPGdo(__LINE__, __FILE__, ...)
and the resulting log line like this:
 [14.01.2020 12:05:18:433]: ECPGtrans on line 1108 in file D01buch.c: action "rollback"; connection "sisis71"
Before hacking this into the ecpglib code by my own, I wanted discuss this here
or even file somewhere a structured change request for further development.