Re: [PATCH v4 09/10] config: add core.untrackedCache

On Mon, Jan 4, 2016 at 7:09 PM, Junio C Hamano [off-list ref] wrote:

Christian Couder [off-list ref] writes:

quoted

quoted

The real question is what are the problems in implementing this in
the way Duy suggested in the previous discussion.  The answer may
fall into somewhere between "that approach does not work in such and
such cases, so this is the best I could come up with" and "I know
that approach is far superiour, but I have invested too much in this
inferiour approach and refuse to rework it further to make it better."

My question is why should I invest time thinking about and testing
another approach when the current approach seems simpler, less bug
prone, faster and without any downside?

I just tried Duy's approach by moving into read_index_from() the code
I had put in wt_status_collect_untracked() and it doesn't work because
"git status" calls read_index_from() before calling
git_default_core_config().

The interesting parts of the backtraces for both calls are the following:

#0  read_index_from (istate=0x8660a0 <the_index>, path=0x868b90
".git/index") at read-cache.c:1626
#1  0x0000000000530ba3 in read_index (istate=0x8660a0 <the_index>) at
read-cache.c:1404
#2  0x00000000005743e1 in gitmodules_config () at submodule.c:188
#3  0x0000000000431ed0 in status_init_config (s=0x83aa20 <s>,
fn=0x434edd <git_status_config>) at builtin/commit.c:186

#0  git_default_core_config (var=0x86ac00 "core.untrackedcache",
value=0x86ac60 "true") at config.c:695
#1  0x00000000004be761 in git_default_config (var=0x86ac00
"core.untrackedcache", value=0x86ac60 "true", dummy=0x0) at
config.c:1016
#2  0x00000000004cfeba in git_diff_basic_config (var=0x86ac00
"core.untrackedcache", value=0x86ac60 "true", cb=0x0) at diff.c:277
#3  0x00000000004cfc9b in git_diff_ui_config (var=0x86ac00
"core.untrackedcache", value=0x86ac60 "true", cb=0x0) at diff.c:230
#4  0x000000000043524a in git_status_config (k=0x86ac00
"core.untrackedcache", v=0x86ac60 "true", cb=0x83aa20 <s>) at
builtin/commit.c:1313
#5  0x00000000004bf183 in configset_iter (cs=0x8495e0
<the_config_set>, fn=0x434edd <git_status_config>, data=0x83aa20 <s>)
at config.c:1305
#6  0x00000000004bf206 in git_config (fn=0x434edd <git_status_config>,
data=0x83aa20 <s>) at config.c:1317
#7  0x0000000000431ee3 in status_init_config (s=0x83aa20 <s>,
fn=0x434edd <git_status_config>) at builtin/commit.c:187

You can see that in status_init_config(), gitmodules_config() is
called just before git_config().
And unfortunately gitmodules_config() indirectly calls read_index_from().

So indeed it seems very bug prone to me to rely on read_index_from()
being called before git_default_core_config().