FA-75644 / Text diff and three-way merge / Member archive

Line mapping through hunks: the line after a changed range is reported as removed · case 04

A comment on the first unchanged line after a hunk is dropped.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Hunks [old_start, old_len, new_start, new_len] use unified conventions (start is the line before when the length is 0) and are sorted. An old line maps to None if it lies in a hunk's old range; otherwise it moves by the sum of new_len - old_len over hunks entirely before it. A zero-length hunk after line s affects lines from s+1 on. Return the mapped line numbers.

Why this case matters

Review tools re-anchor comments on changed files by mapping old line numbers through the diff.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
lines before and after a replacement	`[4, null, null, null, 9]`	`[4, null, null, 8, 9]`	Failed

MEMBER ARCHIVE

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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