FA-75495 / Text diff and three-way merge / Member archive

End-of-file newline diff: a terminated file gains an empty unterminated last line · case 05

Every newline-terminated file shows a phantom empty line with a missing-newline marker.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Split each text on "\n" into [line, terminated] tokens; a final empty piece produces no token, a final non-empty piece is an unterminated token. Diff the token lists with an LCS walk (tokens equal only if text and terminator flag both match, deletions before insertions on ties) and render each op as tag + text, followed by "\ No newline at end of file" after any unterminated token.

Why this case matters

Unified diffs must show a change that only adds or removes the final newline, and mark which side lacks it.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
newline added at end of file	`[" a", "-b", "\\ No newline at end of file", "+b", "+", "\\ No newline at end of file"]`	`[" a", "-b", "\\ No newline at end of file", "+b"]`	Failed

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