halt-on-error

[Karl Berry]

Hi Jean-Francois - back on this mail from July:

    https://tug.org/pipermail/tex-live/2024-July/050741.html
    
    >    With option -halt-on-error, the \errhelp contents is not displayed.
    >    Could there be an option showing it first, then stopping?

I made this change in tex.ch (in the |error| procedure) to do this
(r73008 and 73009).  Hope it doesn't crash anything. (Andreas, sorry, I
bet the formatting is screwed up.)

My test file was this, both with and without the \errhelp line.
\nonstopmode
\catcode`\{=1 \catcode`\}=2 % run with initex
\errhelp{myhelp}\errmessage{myerr}
\xerro
\end

karl

P.S. Not that it's relevant to help messages, but let me mention that I
redirect from </dev/null instead of using -halt-on-error, which has a
similar result but is even more general.

--- tex.ch	(revision 73007)
+++ tex.ch	(working copy)
@@ -881,6 +881,15 @@
    here; just give up in that case. If files are truncated, too bad.}
   if (halting_on_error_p) then do_final_end; {quit immediately}
   halting_on_error_p:=true;
+
+  {This module is executed at the end of the |error| procedure in
+   \.{tex.web}, but we'll never get there when |halt_on_error_p|, so the
+   error help shouldn't get duplicated. It's potentially useful to see,
+   especially if \.{\\errhelp} is being used. See thread at:
+   \.{https://tug.org/pipermail/tex-live/2024-July/050741.html}.}
+  @<Put help message on the transcript file@>;
+
+  {Proceed with normal exit.}
   history:=fatal_error_stop;
   jump_out;
 end;