Hi Eric, Kristoffer, and Phillip,

Thank you for reviewing the v2 of my patch. I appreciate your
thoughtful feedback.

A few days ago, I sent a detailed email addressing each of your
questions and suggestions individually. Before proceeding with v3,
I’d like to consolidate my thoughts on the next possible approach
to respect '.git-blame-ignore-revs' based on Kristoffer's conceptual
explanation.

Hi Abhijeetsingh

For what it’s worth here’s how I imagine this feature could work
conceptually:

Before this feature/change, the effective config for Git use looks like this:

[blame]

No `blame.ignoreRevsFile`.

But with/after it:

[blame]
        ignoreRevsFile=.git-blame-ignore-revs

This is the effective config.  Not what the user has typed out.

If the user types out this:

[blame]
        ignoreRevsFile=.git-blame-more-revs

Then this becomes their effective config:

[blame]
        ignoreRevsFile=.git-blame-ignore-revs
        ignoreRevsFile=.git-blame-more-revs

Now there are two files: the default one and the user-supplied one (this
config variable is documented as being multi-valued: “This option may be
repeated multiple times.”).

§ How to ignore this new default §§§

Considering users who do not want this new default:

[blame]
        ignoreRevsFile=

This is the change they would have to make.  Because a blank/empty
resets/empties the list of files.

Thanks, Kristoffer. Your conceptual explanation gave me a new
perspective on how this feature can be implemented using the
existing configuration flow without disrupting other settings.

Based on Phillip's clue of exploring how this feature would interact
with existing configuration settings and your conceptual workflow,
I explored git_config_set and used it to set the
blame.ignoreRevsFile configuration. This approach aligns well with
the existing configuration logic and provides greater flexibility.

With git_config_set to set blame.ignoreRevsFile:

git blame hello.txt
would consult the default .git-blame-ignore-revs file.

git blame --no-ignore-revs-file hello.txt
would disable the default ignore file.

git blame --no-ignore-revs-file --ignore-revs-file=ignore-list hello.txt
would allow the user to specify a custom ignore list while bypassing
the global list, offering the flexibility you suggested.

This would maintain consistency with Git’s existing behavior, allowing
users to modify configurations with a “last-wins” approach and enabling
both global and custom ignore lists as needed.

I hope this approach is better than my previous one. I look forward to
your thoughts!

Best Regards,
Abhijeetsingh

On Wed, Oct 16, 2024 at 11:37 AM Abhijeetsingh Meena
[off-list ref] wrote:

Hi Phillip,
Thank you for reviewing the patch and providing valuable feedback.
I’d like to address some of your points below:

quoted

Supporting a default file in addition to the files listed in
blame.ignoreRevsFile config setting leaves us in an odd position
compared to other settings which use a fixed name like .gitignore
or have a default that can be overridden by a config setting like
core.excludesFile or require a config setting to enable the feature
like diff.orderFile.

Yes, I now understand that we can solve this by using the existing method for
interacting with configurations, as suggested by you and Kristoffer. We can work
with the existing configuration method like git_config_set to set ignore
revisions file. This (I hope) will also keep it consistent with how
other settings like .gitignore
and core.excludesFile work, making the interaction more predictable for users.

quoted

I've left a couple of code comments below but really
the most important things are to come up with a convincing
reason for changing the behavior and figuring out how
the default file should interact with the config setting.

I agree. After revisiting the use case and the flow, I see now that
the solution can be
more straightforward with git_config_set than my previous approach. This
behavior allows for interaction through the configuration system
without the need to
introduce new options. Kristoffer’s suggestion clarified that handling
.git-blame-ignore-revs
 a default file and allowing it to be overridden or disabled via
--no-ignore-revs-file is sufficient.

quoted

As Kristoffer has pointed out --no-ignore-revs-file should
be sufficient to disable the default file. If it isn't we
should fix it so that it is, not add a new option.

Absolutely, you're right. After revisiting my earlier testing issues,
I realized that the
--no-ignore-revs-file and --no-ignore-rev flag works as intended. My
previous confusion was due to a mistake in my test setup. I agree with your
suggestion that we should not add a new option and instead focus on ensuring
 that the current flag behavior is clear and functions correctly.


Thanks again for your review. I hope this approach is better than my
previous approach.
I’ll make sure the changes are implemented correctly in v3
and test the interaction between the default file and config settings
more thoroughly.
Looking forward to your further thoughts!

Best regards,
Abhijeetsingh

On Sun, Oct 13, 2024 at 8:48 PM Phillip Wood [off-list ref] wrote:

quoted

Hi Abhijeetsingh

On 12/10/2024 05:37, Abhijeetsingh Meena via GitGitGadget wrote:

quoted

From: Abhijeetsingh Meena <redacted>

git-blame(1) can ignore a list of commits with `--ignore-revs-file`.
This is useful for marking uninteresting commits like formatting
changes, refactors and whatever else should not be “blamed”.  Some
projects even version control this file so that all contributors can
use it; the conventional name is `.git-blame-ignore-revs`.

But each user still has to opt-in to the standard ignore list,
either with this option or with the config `blame.ignoreRevsFile`.
Let’s teach git-blame(1) to respect this conventional file in order
to streamline the process.

It's good that the commit message now mentions the config setting. It
would be helpful to explain why the original implementation deliberately
decided not to implement a default file and explain why it is now a good
idea to do so. Supporting a default file in addition to the files listed
in blame.ignoreRevsFile config setting leaves us in an odd position
compared to other settings which use a fixed name like .gitignore or
have a default that can be overridden by a config setting like
core.excludesFile or require a config setting to enable the feature like
diff.orderFile.

I've left a couple of code comments below but really the most important
things are to come up with a convincing reason for changing the behavior
and figuring out how the default file should interact with the config
setting.

quoted

+     /*
+     * By default, add .git-blame-ignore-revs to the list of files
+     * containing revisions to ignore if it exists.
+     */
+     if (access(".git-blame-ignore-revs", F_OK) == 0) {

There are some uses of "access(.., F_OK)" in our code base but it is
more usual to call file_exists() these days.

quoted

+             string_list_append(&ignore_revs_file_list, ".git-blame-ignore-revs");

If the user already has this path in their config we'll waste time
parsing it twice. We could avoid that by using a "struct strset" rather
than a "struct string_list". I don't think we have OPT_STRSET but it
should be easy to add one by copying OPT_STRING_LIST.

quoted

+    echo world >>hello.txt &&
+    test_commit second-commit hello.txt &&

test_commit overwrites the file it is committing so you need to use the
--printf option

        test_commit --printf second-commit hello.txt "hello\nworld\n"

quoted

+    git rev-parse HEAD >ignored-file &&
+    git blame --ignore-revs-file=ignored-file hello.txt >expect &&
+    git rev-parse HEAD >.git-blame-ignore-revs &&
+    git blame hello.txt >actual &&
+    test_cmp expect actual

I have mixed feelings about this sort of differential testing, comparing
the actual output of git blame to what we expect makes it unambiguous
that the test is checking what we want it to.

Best Wishes

Phillip