git log -- <old path> not working

git log -- <old path> not working

[Ville Syrjälä]

Hi,

Just ran into a strange case with the Linux kernel repo
when trying to look up the history for a file that was
later renamed.

$ git log -- drivers/acpi/configfs.c
-> nothing

$ git log --follow -- drivers/acpi/configfs.c
$ git log --full-history -- drivers/acpi/configfs.c
-> works

First time I've seen this fail. Expected behaviour for
some reason, or a bug?

$ git --version 
git version 2.26.2

-- 
Ville Syrjälä
Intel

Re: git log -- <old path> not working

[Junio C Hamano]

Ville Syrjälä <ville.syrjala@linux.intel.com> writes:

> $ git log -- drivers/acpi/configfs.c
> -> nothing
>
> $ git log --follow -- drivers/acpi/configfs.c
> $ git log --full-history -- drivers/acpi/configfs.c
> -> works
>
> First time I've seen this fail. Expected behaviour for
> some reason, or a bug?

Expected.  

In a history is branchy and mergy,

    ---O---o---o---o---o---M---x
        \                 /
         o---A---o---B---o

where A, B and possibly M made changes to PATH,

    $ git log X -- PATH

may show nothing if the PATH at O and M are identical.  This is
described in "History Simplification" section of "git log --help"