set line number / input file name in psql

Heyho!

I'm writing a little toy project, part of it involves scripts that pre-
process sql and then feed it to psql.

Is it possible to set the input filename / line number in psql?

(Similar to how cpp includes this information so that the compiler can
report the filename/line number of the C file and not the preprocessed
file.)

If it's not possible: would it be realistic that PostgreSQL would accept a
patch, if I were to implement it? Either (without changing the syntax)
using \set a special variable, or (for those who'd like to use cpp)
extending the lexer and accepting the cpp syntax. (Perhaps conditionally on
a --cpp-processed cmdline option.)

cheers
-- vbi

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Kallisti!