bug#44014: 28.0.50; Incorrect compilter warning that function is called with 2 arguments

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Thu, 15 Oct 2020 18:34:10 +0200
> Cc: 44014@debbugs.gnu.org
> 
> Jean Louis <bugs@gnu.support> writes:
> 
> > Thanks. Compiler warning shows different line number, is that normal?
> 
> Here's a minimal case to reproduce the bug:
> 
> (defun bar (a)
>   a)
> 
> (defun foo ()
>   (bar 1)
>   (bar 1 2)
>   (bar 1))
> 
> It'll say that the error is on the final call to bar, not the preceding
> line.  If I remove the first call to bar, then it puts the error on the
> correct line.
> 
> Anybody know what could be causing this bug?

The byte compiler doesn't really track source lines, only sexps.  It's
a known issue.  There was a long discussion a year or so ago, and Alan
Mackenzie proposed a concept of a solution, but it turned out to slow
down compilation, so I don't think people were very enthusiastic.