Re: [PATCH v5 0/2] graph: indent visual roots in graph

>
> When rendering a graph, if the history contains multiple "visual roots",
> actual roots or commits that look like roots (i.e. have their parents
> filtered out) can end up being vertically adjacent to unrelated commits,
> falsely appearing to be related.
>
> A fix for this issue was already attempted [1] a while ago.
>
> This series adds indentation to the visual root commits, so they cannot be
> vertically adjacent anymore making it easier to identify them.
>
> before indentation:
>
>         * A
>         * B1
>         * B2
>         * C1
>         * C2
>
> after indentation:
>
>           * A
>         * B1
>          \
>           * B2
>         * C1
>         * C2
>
> Indents the visual root commits that have still commits to show after them, and
> if they have children it connects them with an edge at a new row.
>
> If there are multiple visual roots adjacent in history, the indentation starts
> with the second one, avoiding redundant indentation of the first one and cascades
> after the second.
>
>         * A
>           * B
>             * C
>         * D1
>         * D2
>
> This series first commit is a cleanup that brings a common function from t4215
> and t6016 to a graph functions file which they both use, so the new test file
> for indentation, t4218, can use it as well.
>
> The lookahead used to set the cascading and avoid extra indentation is not
> completely reliable, as the walker goes through the commits it simplifies the
> history of the current commit and its parents, but it doesn't simplify it
> for the next unrelated or the grandparents. When the walker simplifies the
> history, it removes filtered commits from the history and sets its flags.
> When the next commit is an unrelated commit and its parents will be filtered
> out, for the lookahead the commit is still a child of, it cannot know that the
> next commit once simplified (advancing the walker) it will become a visual root.
> This makes the lookahead fail, failing to set the cascading and starting it
> with the first visual root, carrying an extra indent for the cascade.
>
> given:
>
>         * A unrelated (visual root)
>         * B child of C
>         * C visual root WILL BE FILTERED OUT
>         * D unrelated (visual root)
>
> the actual output is:
>
>           * A
>             * B
>         * D
>
> A test has been added to t4218 and a NEEDSWORK to the lookahead function to
> document this edge case but I'm not that familiar with revision.c. Maybe there's
> a better way to make the lookahead more reliable.

> [1]: https://lore.kernel.org/git/xmqqwnwajbuj.fsf@gitster.c.googlers.com/
>
> V4 DIFF:
>
> - Fixed test to be shown as expected by unsetting COMMIT_GRAPH
>
> Signed-off-by: Pablo Sabater <pabloosabaterr@gmail.com>
> ---
> Pablo Sabater (2):
>       lib-log-graph: move check_graph function
>       graph: indent visual root in graph
>
>  graph.c                                    | 262 ++++++++++++++++
>  t/lib-log-graph.sh                         |   5 +
>  t/meson.build                              |   1 +
>  t/t4215-log-skewed-merges.sh               |  33 +-
>  t/t4218-log-graph-indentation.sh           | 467 +++++++++++++++++++++++++++++
>  t/t6016-rev-list-graph-simplify-history.sh |  25 +-
>  6 files changed, 759 insertions(+), 34 deletions(-)
> ---
> base-commit: 3e65291872de10c3f0bf05ea8c24187e7a71ebf0
> change-id: 20260612-ps-pre-commit-indent-39ca72816382
>
> Best regards,
> --
> Pablo Sabater <pabloosabaterr@gmail.com>