Re: [PATCH PING] Honor 'SOURCE_DATE_EPOCH' when generating autoloads.

[Paul Eggert <eggert@cs.ucla.edu>]

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Eli Zaretskii wrote:
>> >What sort of error?
> "Wrong type argument: char-or-string-p, nil".  See the attached image,

Although you applied the patch to emacs-25, the patch was intended for master. 
emacs-25 and master disagree here because of emacs-25 commit 
2dd3581b78a5fe15e0562b1cc2daa6e3afeeec4a dated December 25 "Restore info about 
the build host in bug reports". This explains why I did not observe the problem 
on master, whereas you observed it on emacs-25.

I just now installed into emacs-25 the attached, which should future-proof the 
Dec. 25 change whenever it happens to be merged into master.

> the reproducible build is not (yet) the standard
> build, it's more like an anomaly at this time, so I thought we should
> have the string explain itself.  And nil cannot explain anything.

That is what documentation is for, no? :-)

Having now had some experience with using the deterministic-build API in code, I 
far prefer using (if FOO ...) to something like (if (string-equal FOO "(elided 
due to deterministic builds)") ...). Not only would the the latter be longer and 
harder to read, it would mean I need to go to the documentation and see how the 
magic-cookie string is spelled and would be likely to make a typo there, which 
means we would need to give the magic cookie a name like 
‘deterministic-build-system-name’ to catch typos so that the code will instead 
be (if (string-equal FOO deterministic-build-system-name) ...), and then we 
would need to give similar names to the magic cookies used for other things like 
emacs-build-time that are elided. This would all be complete overkill. It is 
much simpler to use nil to represent missing information; this is easier to 
remember and read and document and it fits squarely within the Emacs Lisp tradition.

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From 691092c904cc293d84e16f2239f51cbb8ff1cbcd Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 28 Dec 2015 18:43:09 -0800
Subject: [PATCH] Port report-emacs-bug to deterministic builds

* lisp/mail/emacsbug.el (report-emacs-bug): Future-proof the
recent "built on" change to deterministic builds where
emacs-build-system will be nil.  See:
http://lists.gnu.org/archive/html/emacs-devel/2015-12/msg01369.html
---
 lisp/mail/emacsbug.el | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lisp/mail/emacsbug.el b/lisp/mail/emacsbug.el
index ae0e711..ef5e86a 100644
--- a/lisp/mail/emacsbug.el
+++ b/lisp/mail/emacsbug.el
@@ -242,7 +242,11 @@ report-emacs-bug
     (let ((txt (delete-and-extract-region (1+ user-point) (point))))
       (insert (propertize "\n" 'display txt)))
 
-    (insert "\n\nIn " (emacs-version) " built on " emacs-build-system "\n")
+    (insert "\n\nIn " (emacs-version))
+    (if emacs-build-system
+        (insert " built on " emacs-build-system))
+    (insert "\n")
+
     (if (stringp emacs-repository-version)
 	(insert "Repository revision: " emacs-repository-version "\n"))
     (if (fboundp 'x-server-vendor)
-- 
2.5.0