Re: Help with "fatal: unable to read ...." error during GC?

[Paul Smith <paul@mad-scientist.net>]

On Wed, 2018-08-08 at 14:24 -0400, Jeff King wrote:
> If so, can you try running it under gdb and getting a stack trace?
> Something like:
> 
>   gdb git
>   [and then inside gdb...]
>   set args pack-objects --all --reflog --indexed-objects foo </dev/null
>   break die
>   run
>   bt
> 
> That might give us a clue where the broken object reference is coming

Here we go.  I can rebuild with -Og or -O0 if more detailed debugging
is needed; most everything appears to be optimized out:

  ...
Compressing objects: 100% (107777/107777), done.
Writing objects:  54% (274416/508176)   
Thread 1 "git" hit Breakpoint 1, die (err=err@entry=0x5a373a "unable to read %s") at usage.c:119
119     {
(gdb) bt
#0  die (err=err@entry=0x5a373a "unable to read %s") at usage.c:119
#1  0x00000000004563f3 in get_delta (entry=<optimized out>) at builtin/pack-objects.c:143
#2  write_no_reuse_object () at builtin/pack-objects.c:308
#3  0x0000000000456592 in write_reuse_object (usable_delta=<optimized out>, limit=<optimized out>, entry=<optimized out>, f=<optimized out>) at builtin/pack-objects.c:516
#4  write_object (write_offset=<optimized out>, entry=0x7fffc9a8d940, f=0x198fb70) at builtin/pack-objects.c:518
#5  write_one () at builtin/pack-objects.c:576
#6  0x00000000004592f0 in write_pack_file () at builtin/pack-objects.c:849
#7  cmd_pack_objects (argc=<optimized out>, argv=<optimized out>, prefix=<optimized out>) at builtin/pack-objects.c:3354
#8  0x0000000000404f06 in run_builtin (argv=<optimized out>, argc=<optimized out>, p=<optimized out>) at git.c:417
#9  handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:632
#10 0x0000000000405f21 in run_argv (argv=0x7fffffffe210, argcp=0x7fffffffe21c) at git.c:761
#11 cmd_main (argc=<optimized out>, argc@entry=6, argv=<optimized out>, argv@entry=0x7fffffffe448) at git.c:761
#12 0x0000000000404b15 in main (argc=6, argv=0x7fffffffe448) at common-main.c:45