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[PATCH] bfd/version.h: Add rationale for BFD_VERSION_DATE (Re: meaning of "Automatic date update in version.in" commits)
On 09/22/2017 12:59 AM, Alan Modra wrote:
> On Thu, Sep 21, 2017 at 08:38:57PM +0300, Petr Ovtchenkov wrote:
>> 1. Explicit "Automatic date update in version.in" commits litter commits tree,
>> but useless. All required info already present in git.
>> [Thanks for Ian Lance Taylor for the background!]
> It isn't useless. People build binutils from a variety of sources,
> git, tarballs, distro sources, then report bugs. We want something
> that can easily identify the source they used. The bfd version plus
> date is usually good enough for that purpose.
>> Let's remove this "Automatic date update in version.in" commits.
> No. That won't happen unless we have something equivalent. And it
> must work *without* git.
>> 2. I see a lot of suggestions "Let's push date to SONAME, the date we
>> will take from ....".
>> I trying to prevent such "solutions". Because it's not a solution, but
>> origin of another problems.
> The date is in the soname because people naturally expect shared
> libraries with the same soname to have compatible ABIs. During
> development, we could bump the bfd version on every ABI change, but
> that's just another thing contributors and maintainers would need to
> remember. It's much easier for all if the soname contains the date.
> Again, it's not perfect but is good enough.
> None of this is going to change just because you don't like a date
> stamp in the source. You do realize that a bisect uses a binary
> search, don't you? So doubling the number of commits just needs one
> extra build/test step on average.
> Yes, it would be nice if the automatic date stamp update didn't happen
> when the most recent commit was a date update..
I like this summary. How about we put something like that in bfd/version.h ?
I assume that the bot is just replacing the line with
BFD_VERSION_DATE instead of regenerating the whole file from
scratch, but that's just guessing. (I don't have sourceware
shell access; I have no idea how the auto updater is implemented.)
>From 08c8f26323a978608256cd574321d9f39658cc51 Mon Sep 17 00:00:00 2001
From: Pedro Alves <email@example.com>
Date: Fri, 22 Sep 2017 10:17:03 +0100
Subject: [PATCH] bfd/version.h: Add rationale for BFD_VERSION_DATE
yyyy-mm-dd Pedro Alves <firstname.lastname@example.org>
Alan Modra <email@example.com>
* version.h: Add comment.
bfd/version.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/bfd/version.h b/bfd/version.h
index 955269f..7d9151a 100644
@@ -1,3 +1,21 @@
+/* The date below is automatically updated every day by a bot. During
+ development, we include the date in the tools' version strings
+ (visible in 'ld -v' etc.) because people build binutils from a
+ variety of sources - git, tarballs, distro sources - and we want
+ something that can easily identify the source they used when they
+ report bugs. The bfd version plus date is usually good enough for
+ that purpose.
+ During development, this date ends up in libbfd and libopcodes
+ sonames because people naturally expect shared libraries with the
+ same soname to have compatible ABIs. We could bump the bfd version
+ on every ABI change, but that's just another thing contributors and
+ maintainers would need to remember. Instead, it's much easier for
+ all if the soname contains the date. This is not perfect but is
+ good enough.
+ In releases, the date is not included in either version strings or
+ sonames. */
#define BFD_VERSION_DATE 20170920
#define BFD_VERSION @bfd_version@
#define BFD_VERSION_STRING @bfd_version_package@ @bfd_version_string@