Re: [RFC PATCH] checkout: Force matching mtime between files

> On Fri, Apr 27, 2018 at 10:03 AM, Duy Nguyen <pclouds@gmail.com> wrote:
>> On Wed, Apr 25, 2018 at 5:18 PM, Marc Branchaud <marcnarc@xiplink.com> wrote:
>>>
>>> * In a "file checkout" ("git checkout -- path/to/file"), $1 and $2 are
>>> identical so the above loop does nothing.  Offhand I'm not even sure how a
>>> hook might get the right files in this case.
>>
>> This is a limitation of the current post-checkout hook. $3==0 from the
>> hook lets us know this is not a branch switch, but it does not really
>> tell you the affected paths. If it somehow passes all the given
>> pathspec to you, then you should be able to do "git ls-files --
>> $pathspec" which gives you the exact same set of paths that
>> git-checkout updates. We could do this by setting $4 to "--" and put
>> all the pathspecs in $5+ [1] e.g. "HEAD@{1} HEAD 0 -- path/to/file" in
>> the above example.
>>
>> There is  third case here, if you do "git checkout <tree-ish> --
>> path/to/file" then it cannot be covered by the current design. I guess
>> we could set $3 to '2' (retrieve from a tree) to indicate this in
>> addition to 0 (from index) and 1 (from switching branch) and then $1
>> could be the tree in question (pathspecs are passed the same way
>> above)
>>
>> [1] I wonder if we could have a more generic approach to pass
>> pathspecs via environment, which could work for more than just this
>> one hook. Not sure if it's a good idea though.
>
> Here's a crazy idea -- maybe instead of a list of pathspecs you just
> provide the timestamp of when git checkout started.  Then the hook
> could walk the tree, find all files with modification times at least
> that late, and modify them all back to the the timestamp of when the
> git checkout started.
>
> Would that be enough?  Is that too crazy?