🔍 Find the first merge commit on the mainline that changed a file

README.md

git log -1 --merges --ancestry-path <commit-A>..HEAD -- path/to/file

✅ When to use:

Use this to identify the first merge commit on the mainline (first-parent path) from <commit-A> to HEAD that touched a specific file. Especially useful when a line disappears due to merge conflict resolution and isn't visible with -S or -G.

🧩 Flag breakdown:

• git log — View commit history
• -1 — Return only the most recent matching commit
• --merges — Filter to merge commits only
• --ancestry-path <A>..HEAD — Follow only the mainline ancestry (parent chain) from A to HEAD
• -- path/to/file — Limit results to commits that changed the specific file