Re: Not understanding with git wants to copy one file to another

From: Harry Putnam <reader@newsguy.com>
Date: Aug 10, 2017, 18:18 UTC
Message-ID: <87efsj70d7.fsf@local.lan>
In-Reply-To: <CAGZ79kbgb2P7KT_b9xuMj1pN1+jsPfH7YSJNDyDB5dY3cwXCQg@mail.gmail.com>

Stefan Beller <sbeller@google.com> writes:

> On Thu, Aug 10, 2017 at 10:03 AM, Harry Putnam <reader@newsguy.com> wrote:

[...]

Harry wrote:

Show 5 quoted lines

>> Here are two that are at least kind of similar but would never be seen
>> as the same:
>>
>> < 192.168.1.43      m2.local.lan       m2       # 00-90-F5-A1-F9-E5
>>> 192.168.1.43    m2.local.lan        m2         # win 7

 Stefan B replied:

Show 10 quoted lines

> The diff machinery has a threshold for when it assumes
> a copy/move of a file. (e.g. "A file is assumed copied when
> at least 55% of lines are equal")
>
> https://git-scm.com/docs/git-diff
>
> See -C and -M option.
>
> git-status seems to use this machinery as well, but does
> not expose the options?

Well, now I'm even more confused. What actually happens? Is either file changed? Is only one file kept?

On the surface it sounds like complete anathema to what git is all about.

However, I know a tool this sophisticated is not doing something just outright stupid... so must be really missing the point here.

I get the way you can make -M stricter or not... but I didn't call git-diff to see that copy thing comeup.

I called git commit.

There must be some way to set stricter guidlines to calling things copies.

But then I must really not get it because it still seems almost silly to consider one file a copy of another if only 55% is the same.

What am I missing?