The first line of an entry is still exactly file:line:col: message, because
that is the GNU format compilation-mode already parses and the whole of the
editor story. Everything under it is indented, which compilation-mode
ignores, so the underline is free. A note gets an entry of its own rather
than being folded into the error's block — that is what makes the second
place somewhere next-error can go, and is the reason notes carry locations.
Every part of it degrades to the bare first line: a location the checker
invented has line 0, the prelude and the REPL have names that are not paths,
and a file can change under us between being read and being blamed. An error
printer that can raise is worse than one that prints less.
Joseph Ferano
2f1d20dfc3