Re: CHECK_STRUCTS/dmpstruct.h mechanism is broken.

[Alan Mackenzie <acm@muc.de>]

Hello, Paul.

On Tue, Apr 09, 2019 at 15:47:17 -0700, Paul Eggert wrote:
> On 3/4/19 6:17 PM, Paul Eggert wrote:
> > On 2/28/19 12:59 PM, Alan Mackenzie wrote:
> >> is all this really needed?  Is pdumper.c really that fragile,
> >> that it can't cope with changes in certain structs?
> > No, it's not needed, and in my experience the mechanism's costs far
> > exceed any benefit.

> No further comment and the mechanism just bit me again, so I installed
> the attached patch to disable it.

Why?  Completely removing this mechanism seems very heavy handed.  All
that was needed to disable it was a single line change to set
CHECK_STRUCTS to zero.

You would have got further comment if you'd proposed a patch, rather
than just a vague idea that might or might not have been followed
through.  Discussing the merits of a patch is always best done before
committing it to master, not afterwards.

What does Daniel say?

> We can reenable it later if needed (which I hope won't happen....).

Funnily enough, it was of use to me recently when it reminded me to
amend dump_subr after extending struct subr.

My main problem with this mechanism was the vagueness of the error
messages it generated and of the comment in the code they pointed at,
which wasted lots of time.  Those defects have since been fixed.

> >>From 891e507d06c3bfcd9ac181de6bb0ff9c27dfa4aa Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Tue, 9 Apr 2019 15:42:10 -0700
> Subject: [PATCH] Remove dmpstruct.h
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
> 
> The hassles of updating the dmpstruct.h-using code bit me again.
> These updates are more trouble than they???re worth.  See:
> https://lists.gnu.org/r/emacs-devel/2019-03/msg00122.html
> As I???m the main person who???s made changes in this area since
> dmpstruct.h was introduced, I???m the most motivated to clean up
> the situation.
> * make-dist (possibly_non_vc_files): Remove src/dmpstruct.h.
> * src/Makefile.in (dmpstruct_headers, dmpstruct.h): Remove.
> (pdumper.o): Do not depend on dmpstruct.h.
> (mostlyclean): Do not remove dmpstruct.h.
> * src/dmpstruct.awk: Remove.
> * src/pdumper.c: Do not include dmpstruct.h.
> (CHECK_STRUCTS): Remove.  All uses removed.
> ---
>  .gitignore        |  1 -
>  make-dist         |  2 +-
>  src/Makefile.in   | 10 +-----
>  src/dmpstruct.awk | 45 ------------------------
>  src/pdumper.c     | 89 -----------------------------------------------
>  5 files changed, 2 insertions(+), 145 deletions(-)
>  delete mode 100755 src/dmpstruct.awk

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).