threads / discuss / 51454

Problem with git diff

Subject: Problem with git diff

## tl;dr

5 messages between Jul 9, 2019 and Jul 9, 2019.

replies: 4people: 3as markdown or json

McRoberts, John· Jul 9, 2019, 22:09 UTC · lore

I am responsible for generating a list of all files changed between two successive releases of software. I was using 'git diff' but have run into a problem.

Consider the following situation: A development branch comes off of commit A and files are changed three times. A tag (REL1) is placed on the third commit. Then the branch is merged back to master. At this point, master's HEAD is at C (and it remains there). Two development branches are created off of master, the first of which is not important here. In the second one, there are files changed and a tag (REL2) applied.

 
---------------------[I]
 
/      {dev branch}
 
/
 
/
             {master branch}
/
 [A] ---------------------------------[B]------------------------------->[C]
master <HEAD>
   \                               filelist 6                           /  \
    \                                                                  /
\
     \                                                                /
\
      \                                                              /
\
       \                {development branch}                        /
\
        \------->[D]----------------------->[E]-------------------[F]
\------[G]--------[H]
                                                                 REL1
REL2
                fileset 1               fileset 2           fileset 3
fileset 4    fileset 5

At this point, I run 
    'git diff  -m --first-parent --pretty=fuller --decorate=short
--name-only REL2..REL2'

I expect to see only filesets 4 and 5 listed. I also see filesets 1, 2 and 3 showing up. This means that the git diff command is showing files that,in fact, did not change between the two tags. By the way, I verified with a file by file comparison that under REL2 and REL1, the files represented by filesets 1, 2 and 3 had identical contents.

Is there a way around this behavior? (Note: view the diagram in monospace case such as Courier)

Thanks,

Jack McRoberts Configuration Management Software Specialist General Atomics EMS Group Work Phone: 858-522-8342 16969 Mesamint St, Room 86-1023G, San Diego, CA 92127

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Elijah Newren· Jul 9, 2019, 23:13 UTC · re: McRoberts, John · lore

Re: Problem with git diff

Hi John,

On Tue, Jul 9, 2019 at 3:57 PM McRoberts, John <John.McRoberts@ga.com> wrote:

Show 43 quoted lines

>
> I am responsible for generating a list of all files changed between two
> successive releases of software. I was using 'git diff' but have run into a
> problem.
>
> Consider the following situation: A development branch comes off of commit A
> and files are changed three times.  A tag (REL1) is placed on the third
> commit.  Then the branch is merged back to master.  At this point, master's
> HEAD is at C (and it remains there).  Two development branches are created
> off of master, the first of which is not important here.  In the second one,
> there are files changed and a tag (REL2) applied.
>
>
> ---------------------[I]
>
> /      {dev branch}
>
> /
>
> /
>              {master branch}
> /
>  [A] ---------------------------------[B]------------------------------->[C]
> master <HEAD>
>    \                               filelist 6                           /  \
>     \                                                                  /
> \
>      \                                                                /
> \
>       \                                                              /
> \
>        \                {development branch}                        /
> \
>         \------->[D]----------------------->[E]-------------------[F]
> \------[G]--------[H]
>                                                                  REL1
> REL2
>                 fileset 1               fileset 2           fileset 3
> fileset 4    fileset 5
>
> At this point, I run
>     'git diff  -m --first-parent --pretty=fuller --decorate=short
> --name-only REL2..REL2'

Wow, we really, really need to throw errors and warnings when people use crazy range operators with diff.[1][2] What version of git are you using that accepts --decorate=short as an argument to `git diff`? And why in the world does git diff accept --first-parent or --pretty=fuller?!? That's insane for git-diff to swallow that. (#leftoverbits?) Also, I think you meant `REL1` one of the two times you wrote `REL2`, which makes me suspect you may have done some copy-edit-paste and didn't try this actual command.

Show 5 quoted lines

> I expect to see only filesets 4 and 5 listed.  I also see filesets 1, 2 and
> 3 showing up.  This means that the git diff command is showing files that,in
> fact, did not change between the two tags.  By the way, I verified with a
> file by file comparison that under REL2 and REL1, the files represented by
> filesets 1, 2 and 3 had identical contents.

From your description, I assume you actually ran something like
  git diff --name-only REL1..REL2

which compares REL2 to the merge base of REL1 and REL2 (yes, this is
totally counter-intuitive to a large percentage of the git userbase,
but it is well documented and hard to change).  Also from your
description, what you seem to want is
  git diff --name-only REL1 REL2

since you want to compare the two endpoints.  Does that help get what you want?

Hope that helps, Elijah

[1] https://public-inbox.org/git/CABPp-BECj___HneAYviE3SB=wU6OTcBi3S=+Un1sP6L4WJ7agA@mail.gmail.com/ [2] https://public-inbox.org/git/CABPp-BGg_iSx3QMc-J4Fov97v9NnAtfxZGMrm3WfrGugOThjmA@mail.gmail.com/

Bryan Turner· Jul 9, 2019, 23:29 UTC · re: Elijah Newren · lore

Re: Problem with git diff

On Tue, Jul 9, 2019 at 4:13 PM Elijah Newren <newren@gmail.com> wrote:

Show 65 quoted lines

>
> Hi John,
>
> On Tue, Jul 9, 2019 at 3:57 PM McRoberts, John <John.McRoberts@ga.com> wrote:
> >
> > I am responsible for generating a list of all files changed between two
> > successive releases of software. I was using 'git diff' but have run into a
> > problem.
> >
> > Consider the following situation: A development branch comes off of commit A
> > and files are changed three times.  A tag (REL1) is placed on the third
> > commit.  Then the branch is merged back to master.  At this point, master's
> > HEAD is at C (and it remains there).  Two development branches are created
> > off of master, the first of which is not important here.  In the second one,
> > there are files changed and a tag (REL2) applied.
> >
> >
> > ---------------------[I]
> >
> > /      {dev branch}
> >
> > /
> >
> > /
> >              {master branch}
> > /
> >  [A] ---------------------------------[B]------------------------------->[C]
> > master <HEAD>
> >    \                               filelist 6                           /  \
> >     \                                                                  /
> > \
> >      \                                                                /
> > \
> >       \                                                              /
> > \
> >        \                {development branch}                        /
> > \
> >         \------->[D]----------------------->[E]-------------------[F]
> > \------[G]--------[H]
> >                                                                  REL1
> > REL2
> >                 fileset 1               fileset 2           fileset 3
> > fileset 4    fileset 5
> >
> > At this point, I run
> >     'git diff  -m --first-parent --pretty=fuller --decorate=short
> > --name-only REL2..REL2'
>
> Wow, we really, really need to throw errors and warnings when people
> use crazy range operators with diff.[1][2]  What version of git are
> you using that accepts --decorate=short as an argument to `git diff`?
> And why in the world does git diff accept --first-parent or
> --pretty=fuller?!?  That's insane for git-diff to swallow that.
> (#leftoverbits?)  Also, I think you meant `REL1` one of the two times
> you wrote `REL2`, which makes me suspect you may have done some
> copy-edit-paste and didn't try this actual command.
>
> > I expect to see only filesets 4 and 5 listed.  I also see filesets 1, 2 and
> > 3 showing up.  This means that the git diff command is showing files that,in
> > fact, did not change between the two tags.  By the way, I verified with a
> > file by file comparison that under REL2 and REL1, the files represented by
> > filesets 1, 2 and 3 had identical contents.
>
> From your description, I assume you actually ran something like
>   git diff --name-only REL1..REL2

Did you mean REL1...REL2 (3 dots)? 2 dots (REL1..REL2) is identical to no dots (REL1 REL2), per the documentation for "git diff":

       git diff [<options>] <commit> <commit> [--] [<path>...]

           This is to view the changes between two arbitrary <commit>.

       git diff [<options>] <commit>..<commit> [--] [<path>...]

           This is synonymous to the previous form. If <commit> on one
side is omitted, it will have the same effect
           as using HEAD instead.

(Forgive me if I'm mistaken here!)

Show 14 quoted lines

>
> which compares REL2 to the merge base of REL1 and REL2 (yes, this is
> totally counter-intuitive to a large percentage of the git userbase,
> but it is well documented and hard to change).  Also from your
> description, what you seem to want is
>   git diff --name-only REL1 REL2
>
> since you want to compare the two endpoints.  Does that help get what you want?
>
> Hope that helps,
> Elijah
>
> [1] https://public-inbox.org/git/CABPp-BECj___HneAYviE3SB=wU6OTcBi3S=+Un1sP6L4WJ7agA@mail.gmail.com/
> [2] https://public-inbox.org/git/CABPp-BGg_iSx3QMc-J4Fov97v9NnAtfxZGMrm3WfrGugOThjmA@mail.gmail.com/

Elijah Newren· Jul 9, 2019, 23:35 UTC · re: Bryan Turner · lore

Re: Problem with git diff

On Tue, Jul 9, 2019 at 4:30 PM Bryan Turner <bturner@atlassian.com> wrote:

Show 82 quoted lines

>
> On Tue, Jul 9, 2019 at 4:13 PM Elijah Newren <newren@gmail.com> wrote:
> >
> > Hi John,
> >
> > On Tue, Jul 9, 2019 at 3:57 PM McRoberts, John <John.McRoberts@ga.com> wrote:
> > >
> > > I am responsible for generating a list of all files changed between two
> > > successive releases of software. I was using 'git diff' but have run into a
> > > problem.
> > >
> > > Consider the following situation: A development branch comes off of commit A
> > > and files are changed three times.  A tag (REL1) is placed on the third
> > > commit.  Then the branch is merged back to master.  At this point, master's
> > > HEAD is at C (and it remains there).  Two development branches are created
> > > off of master, the first of which is not important here.  In the second one,
> > > there are files changed and a tag (REL2) applied.
> > >
> > >
> > > ---------------------[I]
> > >
> > > /      {dev branch}
> > >
> > > /
> > >
> > > /
> > >              {master branch}
> > > /
> > >  [A] ---------------------------------[B]------------------------------->[C]
> > > master <HEAD>
> > >    \                               filelist 6                           /  \
> > >     \                                                                  /
> > > \
> > >      \                                                                /
> > > \
> > >       \                                                              /
> > > \
> > >        \                {development branch}                        /
> > > \
> > >         \------->[D]----------------------->[E]-------------------[F]
> > > \------[G]--------[H]
> > >                                                                  REL1
> > > REL2
> > >                 fileset 1               fileset 2           fileset 3
> > > fileset 4    fileset 5
> > >
> > > At this point, I run
> > >     'git diff  -m --first-parent --pretty=fuller --decorate=short
> > > --name-only REL2..REL2'
> >
> > Wow, we really, really need to throw errors and warnings when people
> > use crazy range operators with diff.[1][2]  What version of git are
> > you using that accepts --decorate=short as an argument to `git diff`?
> > And why in the world does git diff accept --first-parent or
> > --pretty=fuller?!?  That's insane for git-diff to swallow that.
> > (#leftoverbits?)  Also, I think you meant `REL1` one of the two times
> > you wrote `REL2`, which makes me suspect you may have done some
> > copy-edit-paste and didn't try this actual command.
> >
> > > I expect to see only filesets 4 and 5 listed.  I also see filesets 1, 2 and
> > > 3 showing up.  This means that the git diff command is showing files that,in
> > > fact, did not change between the two tags.  By the way, I verified with a
> > > file by file comparison that under REL2 and REL1, the files represented by
> > > filesets 1, 2 and 3 had identical contents.
> >
> > From your description, I assume you actually ran something like
> >   git diff --name-only REL1..REL2
>
> Did you mean REL1...REL2 (3 dots)? 2 dots (REL1..REL2) is identical to
> no dots (REL1 REL2), per the documentation for "git diff":
>
>        git diff [<options>] <commit> <commit> [--] [<path>...]
>
>            This is to view the changes between two arbitrary <commit>.
>
>        git diff [<options>] <commit>..<commit> [--] [<path>...]
>
>            This is synonymous to the previous form. If <commit> on one
> side is omitted, it will have the same effect
>            as using HEAD instead.
>
> (Forgive me if I'm mistaken here!)

Yes, thanks. In trying to explain how two and three dots behave contrary to expectation for git diff, I mess up two versus three dots. That's kind of embarrassing...

Show 5 quoted lines

> > which compares REL2 to the merge base of REL1 and REL2 (yes, this is
> > totally counter-intuitive to a large percentage of the git userbase,
> > but it is well documented and hard to change).  Also from your
> > description, what you seem to want is
> >   git diff --name-only REL1 REL2

...though at least I was smart enough to suggest something without dots, which is the only sane way to use git-diff. ;-)

McRoberts, John· Jul 9, 2019, 23:26 UTC · re: Elijah Newren · lore

RE: -EXT-Re: Problem with git diff

Actually, I was actually using git log (not git diff... sorry for the mistake) because I also mine other information I(dates, author, summary, etc)

'git log -m --first-parent --pretty=fuller --decorate=short --name-only REL1..REL2'

That being said, I can work with the git diff output to filter out the irrelevant info. I would still be curious about whether this is a valid use of git log.

Thanks,

Jack McRoberts Configuration Management Software Specialist General Atomics EMS Group Work Phone: 858-522-8342 16969 Mesamint St, Room 86-1023G, San Diego, CA 92127

************************************************************************
CONFIDENTIALITY NOTICE: This communication is intended to be confidential to 
the
person(s) to whom it is addressed. If you are not the intended recipient or 
the agent of the
intended recipient or if you are unable to deliver this communication to the 
intended
 recipient, you must not read, use or disseminate this information. If you 
have received this
communication in error, please advise the sender immediately by telephone and 
delete
this message and any attachments without retaining a copy.
**************************************************************************

-----Original Message-----
From: Elijah Newren <newren@gmail.com>
Sent: Tuesday, July 9, 2019 4:13 PM
To: McRoberts, John <John.McRoberts@ga.com>
Cc: git@vger.kernel.org
Subject: -EXT-Re: Problem with git diff

WARNING:  This message is from an external source.  Evaluate the message 
carefully BEFORE clicking on links or opening attachments.

Hi John,

On Tue, Jul 9, 2019 at 3:57 PM McRoberts, John <John.McRoberts@ga.com> wrote:

Show 46 quoted lines

>
> I am responsible for generating a list of all files changed between
> two successive releases of software. I was using 'git diff' but have
> run into a problem.
>
> Consider the following situation: A development branch comes off of
> commit A and files are changed three times.  A tag (REL1) is placed on
> the third commit.  Then the branch is merged back to master.  At this
> point, master's HEAD is at C (and it remains there).  Two development
> branches are created off of master, the first of which is not
> important here.  In the second one, there are files changed and a tag (REL2) 
> applied.
>
>
> ---------------------[I]
>
> /      {dev branch}
>
> /
>
> /
>              {master branch}
> /
>  [A]
> ---------------------------------[B]------------------------------->[C
> ]
> master <HEAD>
>    \                               filelist 6                           /  \
>     \                                                                  /
> \
>      \                                                                /
> \
>       \                                                              /
> \
>        \                {development branch}                        /
> \
>         \------->[D]----------------------->[E]-------------------[F]
> \------[G]--------[H]
>                                                                  REL1
> REL2
>                 fileset 1               fileset 2           fileset 3
> fileset 4    fileset 5
>
> At this point, I run
>     'git diff  -m --first-parent --pretty=fuller --decorate=short
> --name-only REL2..REL2'

Show 6 quoted lines

> I expect to see only filesets 4 and 5 listed.  I also see filesets 1,
> 2 and
> 3 showing up.  This means that the git diff command is showing files
> that,in fact, did not change between the two tags.  By the way, I
> verified with a file by file comparison that under REL2 and REL1, the
> files represented by filesets 1, 2 and 3 had identical contents.

From your description, I assume you actually ran something like
  git diff --name-only REL1..REL2

which compares REL2 to the merge base of REL1 and REL2 (yes, this is totally 
counter-intuitive to a large percentage of the git userbase, but it is well 
documented and hard to change).  Also from your description, what you seem to 
want is
  git diff --name-only REL1 REL2

since you want to compare the two endpoints. Does that help get what you want?

Hope that helps, Elijah