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

[Philipp Stephani <p.stephani2@gmail.com>]

[-- Attachment #1.1: Type: text/plain, Size: 684 bytes --]

Paul Eggert <eggert@cs.ucla.edu> schrieb am Mo., 7. Dez. 2015 um 20:14 Uhr:

> On 12/07/2015 11:00 AM, Philipp Stephani wrote:
> > this would be a rather big change.
>
> I suppose that depends on what one means by "big". To me it feels like a
> fairly small improvement. We've already made some progress along these
> lines in emacs-25 by removing emacs-build-system from the result of the
> emacs-version function; we just need to make more improvements like that.
>
> It should be in 'master', though, not in 'emacs-25', as it's not fixing
> a bug.
>

OK, here's a first patch that replaces system-name with a constant during
dumping. That eliminates one source  of nondeterminism.

[-- Attachment #1.2: Type: text/html, Size: 1029 bytes --]

[-- Attachment #2: 0001-Remove-build-system-name-from-dump.patch --]
[-- Type: application/octet-stream, Size: 2013 bytes --]

From 7f9df3f7f311f82efaec2330b0c46094d1a04d39 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Sun, 20 Dec 2015 01:57:34 +0100
Subject: [PATCH] Remove build system name from dump.

* sysdep.c (init_system_name): Use a constant if we might dump.
* version.el (emacs-build-time): Add a comment to remove the
variable.
(emacs-build-system): Make variable obsolete, replace its value
with a constant.
---
 lisp/version.el | 9 ++++++---
 src/sysdep.c    | 7 +++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/lisp/version.el b/lisp/version.el
index 43103fd..d755874 100644
--- a/lisp/version.el
+++ b/lisp/version.el
@@ -38,13 +38,16 @@ emacs-minor-version
   "Minor version number of this version of Emacs.
 This variable first existed in version 19.23.")
 
+;; FIXME: The next variable should also be a constant.
 (defconst emacs-build-time (current-time)
   "Time at which Emacs was dumped out.")
 
-;; I think this should be obsoleted/removed.  It's just one more meaningless
-;; difference between different builds.  It's usually not even an fqdn.
-(defconst emacs-build-system (system-name)
+;; This was the actual system name before, but that made the dump
+;; non-deterministic, so now it's just a constant.
+(defconst emacs-build-system "unknown"
   "Name of the system on which Emacs was built.")
+(make-obsolete-variable 'emacs-build-system
+                        "this information is no longer available." "25.2")
 
 (defvar motif-version-string)
 (defvar gtk-version-string)
diff --git a/src/sysdep.c b/src/sysdep.c
index 1af323e..5bed2f9 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -1399,6 +1399,13 @@ setup_pty (int fd)
 void
 init_system_name (void)
 {
+  if (might_dump)
+    {
+      /* If we're dumping, set the hostname to a literal so that the
+         dump is deterministic.  */
+      Vsystem_name = build_pure_c_string ("unknown");
+      return;
+    }
   char *hostname_alloc = NULL;
   char *hostname;
 #ifndef HAVE_GETHOSTNAME
-- 
2.6.4