[BUG] Strange git notes completion behaviour

>
> Hi All,
>
> I tried the following in git 2.51.0 on NonStop (big endian x86):
>
> git notes add -m "Test Note" HEAD
> git notes show HEAD
>
> The git notes show reports a completion code of 037777777764 (-12). This
> gets
> hidden by bash, which truncates negative results so it shows as 0, not -12.
> This
> only seems to happen in git notes show, not any other commands or
> sub-commands. I checked in gdb and this is in fact happening. Anywhere I can
> look to try to find where this is failing?
>
> --Randall

>On Tue, Oct 21, 2025 at 5:07 PM <rsbecker@nexbridge.com> wrote:
>>
>> Hi All,
>>
>> I tried the following in git 2.51.0 on NonStop (big endian x86):
>>
>> git notes add -m "Test Note" HEAD
>> git notes show HEAD
>>
>> The git notes show reports a completion code of 037777777764 (-12).
>> This gets hidden by bash, which truncates negative results so it shows
>> as 0, not -12.
>> This
>> only seems to happen in git notes show, not any other commands or
>> sub-commands. I checked in gdb and this is in fact happening. Anywhere
>> I can look to try to find where this is failing?
>>
>> --Randall
>
>Exit code or shell (tab) completion? I'm a bit confused, so maybe someone else is,
>too.

>On Tue, Oct 21, 2025 at 05:52:38PM -0400, rsbecker@nexbridge.com wrote:
>
>> It is the exit code. When in gdb, the return from notes is -12 as
>> above. By the time It gets back to bash, the lower bytes are dropped
>> so I end up with a 0xFF, which bash thinks is a 0, so the exit code is
>> hidden from view. I tried the !!fn construct in a standard alone test program with
>no wisdom gained.
>
>I don't think the "!!fn()" line ever returns here. In the show() function of
>builtin/notes.c (which is what "fn" is pointing to for "git notes show"), we end up
>calling execv_git_cmd() to run "git show". So you are really seeing the exit code of
>something like:
>
>  git show $(git notes list HEAD)
>
>That in turn is propagating the return from show_blob_object(). Which I'd think
>would return "0" here, since it actually showed the blob, though it does look like it
>could return -1 in a few cases.
>
>Another possible point of confusion: that git-show invocation will run a pager. It's
>been a long time since I've looked at that code, but IIRC we try to preserve the exit
>code of the actual Git command (rather than the pager). But you might try:
>
>  git --no-pager notes show HEAD
>
>to see if that behaves differently. I couldn't reproduce the issue at all on my end.

> I tried running with --no-pager. No difference. Interesting:
> 
> git show $(git notes list HEAD)
> 
> works correctly with no error report (from inside gdb), while the run of
> 
> git --no-pager notes show HEAD
> 
> still reports:
> Run till exit from #0  main (argc=5, argv=0x811d000)
>     at /home/jenkinsbuild/.jenkins/workspace/Git_Pipeline/common-main.c:8
> Process (0,896) exited with code 037777777764.
> 
> Is there a path where just an implied return is used? I have seen the optimizer
> return whatever is in an x86 register - rsx and rsi are both 12 at git.c:982
> - on occasion.

>On Wed, Oct 22, 2025 at 10:27:01AM -0400, rsbecker@nexbridge.com wrote:
>
>> I tried running with --no-pager. No difference. Interesting:
>>
>> git show $(git notes list HEAD)
>>
>> works correctly with no error report (from inside gdb), while the run of
>>
>> git --no-pager notes show HEAD
>>
>> still reports:
>> Run till exit from #0  main (argc=5, argv=0x811d000)
>>     at /home/jenkinsbuild/.jenkins/workspace/Git_Pipeline/common-main.c:8
>> Process (0,896) exited with code 037777777764.
>>
>> Is there a path where just an implied return is used? I have seen the optimizer
>> return whatever is in an x86 register - rsx and rsi are both 12 at git.c:982
>> - on occasion.
>
>Not that I know of (and I'd expect the compiler to complain if we ever
>had a code path that didn't return).  It is weird that git-show produces
>the right exit code, but our execvp() of it does not. In your place I
>guess I'd try walking through the debugger all the way down to the exec
>system call (and ideally convincing the debugger to keep going in the
>exec'd process image).

> What I found is this:
> 
> Git drops into sane_execvp and converts the
> 
> git notes show HEAD
> 
> to
> 
> git show 1aa950256829721750e809788e7b858db79a934a.
> 
> When execvp is called, it immediately fails with a -12 - not returned,
> just terminates. The -12 is an NonStop-specific execvp error indicating
> the process failed because the object is invalid (strange and likely
> an artifact rather than a real problem).

> When I use the arguments as presented to execvp via bash directly, I get:
> 
> error: no note found for object 1aa950256829721750e809788e7b858db79a934a.
>
> There is no commit with that hash. HEAD is actually 3fc1917e0e69b23265f5c49f90fdb6f4ed98f4a3
> so git show is correctly failing. This is Indicating that notes is not invoking git
> correctly.

>On Fri, Oct 24, 2025 at 01:33:02PM -0400, rsbecker@nexbridge.com wrote:
>
>> What I found is this:
>>
>> Git drops into sane_execvp and converts the
>>
>> git notes show HEAD
>>
>> to
>>
>> git show 1aa950256829721750e809788e7b858db79a934a.
>>
>> When execvp is called, it immediately fails with a -12 - not returned,
>> just terminates. The -12 is an NonStop-specific execvp error
>> indicating the process failed because the object is invalid (strange
>> and likely an artifact rather than a real problem).
>
>When you say "object" here, you don't mean a Git object, but rather that
>execvp() could not run the "git" binary for some reason (so the "object"
>here is the on-disk executable)? Just making sure I understand.
>
>> When I use the arguments as presented to execvp via bash directly, I get:
>>
>> error: no note found for object
>1aa950256829721750e809788e7b858db79a934a.
>>
>> There is no commit with that hash. HEAD is actually
>> 3fc1917e0e69b23265f5c49f90fdb6f4ed98f4a3
>> so git show is correctly failing. This is Indicating that notes is not
>> invoking git correctly.
>
>Are you sure you are running "git show" there and not "git notes show".
>Because 1aa950256 should be the blob that the note for HEAD points to, and thus
>does not itself have a note. And "git show" should not be looking up notes at all
>(and the "no note found" message is from builtin/notes.c).

> On October 24, 2025 1:47 PM, Jeff King wrote:
> >On Fri, Oct 24, 2025 at 01:33:02PM -0400, rsbecker@nexbridge.com wrote:
> >
> >> What I found is this:
> >>
> >> Git drops into sane_execvp and converts the
> >>
> >> git notes show HEAD
> >>
> >> to
> >>
> >> git show 1aa950256829721750e809788e7b858db79a934a.
> >>
> >> When execvp is called, it immediately fails with a -12 - not returned,
> >> just terminates. The -12 is an NonStop-specific execvp error
> >> indicating the process failed because the object is invalid (strange
> >> and likely an artifact rather than a real problem).
> >
> >When you say "object" here, you don't mean a Git object, but rather that
> >execvp() could not run the "git" binary for some reason (so the "object"
> >here is the on-disk executable)? Just making sure I understand.
> >
> >> When I use the arguments as presented to execvp via bash directly, I get:
> >>
> >> error: no note found for object
> >1aa950256829721750e809788e7b858db79a934a.
> >>
> >> There is no commit with that hash. HEAD is actually
> >> 3fc1917e0e69b23265f5c49f90fdb6f4ed98f4a3
> >> so git show is correctly failing. This is Indicating that notes is not
> >> invoking git correctly.
> >
> >Are you sure you are running "git show" there and not "git notes show".
> >Because 1aa950256 should be the blob that the note for HEAD points to, and thus
> >does not itself have a note. And "git show" should not be looking up notes at all
> >(and the "no note found" message is from builtin/notes.c).
> 
> I am 100% sure that git notes show is running git show with the notes blob as above.

>-----Original Message-----
>From: Jeff King <peff@peff.net>
>Sent: October 24, 2025 2:52 PM
>To: rsbecker@nexbridge.com
>Cc: 'D. Ben Knoble' <ben.knoble@gmail.com>; git@vger.kernel.org
>Subject: Re: [BUG] Strange git notes completion behaviour
>
>On Fri, Oct 24, 2025 at 02:38:05PM -0400, rsbecker@nexbridge.com wrote:
>
>> On October 24, 2025 1:47 PM, Jeff King wrote:
>> >On Fri, Oct 24, 2025 at 01:33:02PM -0400, rsbecker@nexbridge.com wrote:
>> >
>> >> What I found is this:
>> >>
>> >> Git drops into sane_execvp and converts the
>> >>
>> >> git notes show HEAD
>> >>
>> >> to
>> >>
>> >> git show 1aa950256829721750e809788e7b858db79a934a.
>> >>
>> >> When execvp is called, it immediately fails with a -12 - not
>> >> returned, just terminates. The -12 is an NonStop-specific execvp
>> >> error indicating the process failed because the object is invalid
>> >> (strange and likely an artifact rather than a real problem).
>> >
>> >When you say "object" here, you don't mean a Git object, but rather
>> >that
>> >execvp() could not run the "git" binary for some reason (so the "object"
>> >here is the on-disk executable)? Just making sure I understand.
>> >
>> >> When I use the arguments as presented to execvp via bash directly, I get:
>> >>
>> >> error: no note found for object
>> >1aa950256829721750e809788e7b858db79a934a.
>> >>
>> >> There is no commit with that hash. HEAD is actually
>> >> 3fc1917e0e69b23265f5c49f90fdb6f4ed98f4a3
>> >> so git show is correctly failing. This is Indicating that notes is
>> >> not invoking git correctly.
>> >
>> >Are you sure you are running "git show" there and not "git notes show".
>> >Because 1aa950256 should be the blob that the note for HEAD points
>> >to, and thus does not itself have a note. And "git show" should not
>> >be looking up notes at all (and the "no note found" message is from
>builtin/notes.c).
>>
>> I am 100% sure that git notes show is running git show with the notes blob as
>above.
>
>Yes, I am, too. What I was asking is when you tried to replicate that using bash
>directly, how did you get a "no note found" message from "git show"? I.e., it
>sounds like you ran the wrong command. Or I am misunderstanding what you you
>meant by "When I use the arguments as presented to execvp via bash directly".

> >> >> When I use the arguments as presented to execvp via bash directly, I get:
> >> >>
> >> >> error: no note found for object
> >> >1aa950256829721750e809788e7b858db79a934a.
> >> >>
> >> >> There is no commit with that hash. HEAD is actually
> >> >> 3fc1917e0e69b23265f5c49f90fdb6f4ed98f4a3
> >> >> so git show is correctly failing. This is Indicating that notes is
> >> >> not invoking git correctly.
> >> >
> >> >Are you sure you are running "git show" there and not "git notes show".
> >> >Because 1aa950256 should be the blob that the note for HEAD points
> >> >to, and thus does not itself have a note. And "git show" should not
> >> >be looking up notes at all (and the "no note found" message is from
> >builtin/notes.c).
> >>
> >> I am 100% sure that git notes show is running git show with the notes blob as
> >above.
> >
> >Yes, I am, too. What I was asking is when you tried to replicate that using bash
> >directly, how did you get a "no note found" message from "git show"? I.e., it
> >sounds like you ran the wrong command. Or I am misunderstanding what you you
> >meant by "When I use the arguments as presented to execvp via bash directly".
> 
> I ran the exact command that git passed to execvp but did so via bash. This is what
> gdb showed:
> 
> Breakpoint 2, sane_execvp (file=0x80aa470 "git", argv=0x8122700)
>     at /home/randall/git/run-command.c:244
> *  244          int exec_id = trace2_exec(file, (const char **)argv);
> (xInspect 0,1011):n
> *  247          if (!execvp(file, argv))
> (xInspect 0,1011):p file
> $1 = (const unsigned char *) 0x80aa470 "git"
> (xInspect 0,1011):p argv[0]
> $2 = 0x81224a0 "git"
> (xInspect 0,1011):p argv[1]
> $3 = 0x8122770 "show"
> (xInspect 0,1011):p argv[2]
> $4 = 0x8122780 "1aa950256829721750e809788e7b858db79a934a"
> (xInspect 0,1011):p argv[3]
> $5 = 0x0
> 
> I assumed that I should give that command a try from bash.