$ERROR ENABLE
$ERROR EXIT std::exit( 2 )
$MESSAGE Fatal
@ code int
|fatal error {$code}, giving up

void FatalError( int code, std::locale const &loc );
void FatalError( int code );

The function writes the text to std::cerr — imbued with loc for the duration, in the locale overload — and then runs the EXIT statement. The statement is copied into the function body as it is, so it can be anything: std::exit( 2 ), std::abort( ), throw 42, even nothing that leaves ((void) 0) — the function is not declared [[noreturn]] for that reason.

No newline is added: end the text with one (a |bar line does).

The source includes <cstdlib> and <iostream> for it.