Re: [Question] Diff text filters and git add

From: Jakub Narebski <jnareb@gmail.com>
Date: Jul 11, 2019, 17:28 UTC
Message-ID: <86h87sa3b6.fsf@gmail.com>
In-Reply-To: <00bb01d5371d$453a8520$cfaf8f60$@nexbridge.com>

"Randall S. Becker" <rsbecker@nexbridge.com> writes:

> On July 9, 2019 5:51 PM, Peff wrote:

[...]

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>> No, textconv only applies when generating a diff to output, and will never
>> impact what's stored in Git.
>> 
>> It sounds like you might want a clean filter instead, to sanitize the file
>> contents as they come into Git (and perhaps a matching smudge filter to
>> convert back to the working-tree version if necessary).
>> 
>> You're talking about "the diff engine" here, but note that git-add would never
>> do a diff at all. It cares only about full sha1s (and optimizes out re-computing
>> the sha1 on each invocation by using stat data). So outside of clean/smudge,
>> there's nothing else going on.
>
> Thanks. I can script this instead. Will do an external diff then
> --assume-unchanged when I detect an equivalence.

If you want to ignore changes, --assume-unchanged (i.e. lying to Git) is a wrong solution, as it can lead to data loss. It is meant as performance optimization.

A better solution would be to use --skip-worktree, which though meant for sparse checkout can be used for ignoring changes. The only problem is that it can prevent some safe operations, like git-stash, because git thinks that it could lead to data loss.

Though I am not sure if they are needed with clean/smudge filter.

Best,

-- 
Jakub Narębski