Re: meaning of "Automatic date update in version.in" commits

[Mikhail Terekhov <Mikhail dot Terekhov at dell dot com>]

On 09/20/17 14:14, Matthias Klose wrote:
> On 20.09.2017 19:23, Petr Ovtchenkov wrote:
> > On Wed, 20 Sep 2017 18:16:45 +0200
> > Andreas Schwab <schwab@linux-m68k.org> wrote:
> >
> > > On Sep 20 2017, Petr Ovtchenkov <ptr@void-ptr.info> wrote:
> > >
> > > > What is the meaning of "Automatic date update in version.in" commits?
> > > > I mean commits like f625a739e5.
> > > It is used to name the shared libbfd and libopcodes, since there is no
> > > stable ABI.
> > >
> > > > This commits litter commits tree and create problems for  	
> > > > deterministic, bit-identical and/or verifiable builds.
> > > Why is that a problem?  The version is fixed for a particular source
> > > snapshot.
> > It's looks as a problem indeed:
> >     - garbage in commits
> >     - disorientation, when date present in SONAME
> >         0x000000000000000e (SONAME)             Library soname: [libbfd-2.29.0.20170729.so]
> this is correct, and it's usually set to not include the date for a releases, an
> exception being the 2.29.1 release, but things happen.
>
> > You see:
> >
> > git show 3110f4be18a2
> >    commit 3110f4be18a2f3b9fcd9663ed1dd141bbd6ed14f
> >    Author: GDB Administrator <gdbadmin@sourceware.org>
> >    Date:   Wed Sep 20 00:01:01 2017 +0000
> >
> >        Automatic date update in version.in
> >
> >    diff --git a/bfd/version.h b/bfd/version.h
> >    index 3405e42..955269f 100644
> >    --- a/bfd/version.h
> >    +++ b/bfd/version.h
> >    @@ -1,4 +1,4 @@
> >    -#define BFD_VERSION_DATE 20170919
> >    +#define BFD_VERSION_DATE 20170920
> >     #define BFD_VERSION @bfd_version@
> >     #define BFD_VERSION_STRING  @bfd_version_package@ @bfd_version_string@
> >     #define REPORT_BUGS_TO @report_bugs_to@
> >
> > git show f625a739
> >    commit f625a739e567f0110b2675539b7a0e5d5f67c5dc
> >    Author: GDB Administrator <gdbadmin@sourceware.org>
> >    Date:   Wed Sep 20 00:01:22 2017 +0000
> >
> >        Automatic date update in version.in
> >
> >    diff --git a/bfd/version.h b/bfd/version.h
> >    index 3405e42..955269f 100644
> >    --- a/bfd/version.h
> >    +++ b/bfd/version.h
> >    @@ -1,4 +1,4 @@
> >    -#define BFD_VERSION_DATE 20170919
> >    +#define BFD_VERSION_DATE 20170920
> >     #define BFD_VERSION @bfd_version@
> >     #define BFD_VERSION_STRING  @bfd_version_package@ @bfd_version_string@
> >     #define REPORT_BUGS_TO @report_bugs_to@
> >
> > git diff 3110f4be18a2 f625a739
> > ...
> > Ooops....
> >
> > This approch produce ambiguity, but try to conceal it.
> Feel free to limit the bumps to exactly one after another commit.
What if build scripts obtain date of last commit automatically i.e. 
something like this:

    ~/tmp/gdb/binutils-gdb (master)>git log -1 --format=%cd 
--date=format:%Y%m%d
    20170920

Then there is no need for additional commit.

Regards,
Mikhail