Align merge commit diff behavior with first-parent semantics in but-core and update regression coverage#12796
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Align merge commit diff behavior with first-parent semantics in but-core and update regression coverage#12796
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[WIP] [GT-12795] Add test for issue resolution
Use merge-base for merge commit diffs in but-core and add regression coverage
Mar 12, 2026
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Co-authored-by: chatgpt-codex-connector[bot] <199175422+chatgpt-codex-connector[bot]@users.noreply.github.com>
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Blocking the merge of the PR as there is open questions.
At least it's clear now that there is much to be learned and possibly implemented to deal with merges better.
Co-authored-by: Byron <63622+Byron@users.noreply.github.com>
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Updated in 28c909d: I reverted merge-commit diff-base behavior to first-parent semantics (matching |
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Use merge-base for merge commit diffs in but-core and add regression coverage
Align merge commit diff behavior with first-parent semantics in but-core and update regression coverage
Mar 12, 2026
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This PR aligns merge-commit diff behavior with current expected semantics: for commit views, diffs should follow
git show/GitHub-style first-parent behavior rather than merge-base diffing.A previous iteration switched merge commits to merge-base diffing, but follow-up review showed this does not match expected behavior for this codepath.
What changed
but-core::diffso that:None(empty tree),CommitDetails::from_commit_id()ui::commit_changes_with_line_stats_by_worktree_dir()crates/but-core/tests/core/diff/ui.rsto assert first-parent output and stats.Result
Commit diff rendering for merge commits now matches first-parent semantics expected for this view, and tests guard against regressions in that behavior.
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