Re: [PATCH] submodule helper list: Respect correct path prefix

Stefan Beller [off-list ref] writes:

On Wed, Feb 24, 2016 at 1:21 PM, Junio C Hamano [off-list ref] wrote:

quoted

Stefan Beller [off-list ref] writes:

quoted

This is a regression introduced by 74703a1e4d (submodule: rewrite
`module_list` shell function in C, 2015-09-02).

Add a test to ensure we list the right submodule when giving a specific
path spec.

Reported-By: Caleb Jorden <redacted>
Signed-off-by: Stefan Beller <redacted>
---

 I developed this on top of current origin/master, though I can backport it
 to 2.7 as well if desired.

 I do not remember the cause why we started to ignore a common prefix.

The code you are removing with this patch is probably an
optimization you copied from builtin/ls-files.c.  When the
optimization is used, the original also limits the list of paths to
those that match the prefix by calling prune_cache(), but perhaps
you didn't have a corresponding code in your copy?

I think that is a good explanation. So do we want to add the pruning
or use this patch to fixup the regression and wait until someone complains
about the speed penalty due to no optimization?

As I do not know offhand if the optimization, especially the pruning
part, applies to the context of this code the same way ls-files does
things (which treats the index read into core as a throw-away data),
we shouldn't even attempt to salvage the faulty half-optimization
until we understand what it involves to make it work.  So "disable
broken optimization and make simple way work correctly" is the good
first step, especially for a fix that is meant to go to 2.7.x
series.

We must first be sure that removing the faulty half-optimization is
the only thing we need to fix this breakage, though ;-)

Thanks.