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GeezerVison is showing github.com — diff: write a one-line add or delete range as a single number by jayhemnani9910 · Pull Request #308 · uutils/diffutils

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@jayhemnani9910

@jayhemnani9910 jayhemnani9910 commented Oct 20, 2026

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In the normal format a single added or deleted line still comes out as a range:

$ printf 'a\n' > x; printf 'a\nb\n' > y
$ diffutils diff x y
1a2,2
> b
$ diffutils diff y x
2,2d1
< b
$ /usr/bin/diff x y    # GNU diff 3.12
1a2
> b

GNU diff writes 1a2 and 2d1. -e has the same thing: 2,2d instead of 2d. #11 (for #10) fixed this for changed lines (1c1); added and deleted lines were left out.

This adds the one-line cases next to the existing ones in normal_diff.rs ((0, 1) and (1, 0)) and ed_diff.rs ((1, 0)).

Tests: test_single_line_added_or_deleted (normal) and test_single_line_deleted (ed) check the exact output. Both fail on main. cargo test: all pass (285 on main, 289 here; the two new tests run in both the lib and the bin target), including the permutation tests that feed the output to patch and ed. cargo fmt --check is clean, and cargo clippy --all-targets gives the same warnings as on main. I also compared the default and -e output with GNU diff 3.12 over 22 file pairs (single-line and multi-line adds and deletes, blank lines, missing newlines, empty files): the default format matches for all of them now except binary files. -e still writes its hunks top-down with already-shifted line numbers where GNU goes bottom-up; both scripts give the same file, so I left that alone.

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Copilot AI balanced review requested due to automatic review settings October 20, 2026 05:56
Copilot AI reviewed Oct 20, 2026

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sylvestre
sylvestre reviewed Oct 20, 2026
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Comment thread src/normal_diff.rs
let actual_count = result.actual.len();
match (expected_count, actual_count) {
(0, 0) => unreachable!(),
(0, 1) => writeln!(

@sylvestre sylvestre Oct 20, 2026

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could you please run the upstream test suite on it?
TESTS=basic ./tests/run-upstream-testsuite.sh
the whole suite would be even better, it would tell us if it makes more tests pass

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@jayhemnani9910 jayhemnani9910 Oct 29, 2026

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Ran it: the full upstream suite gives the same result on main and on this branch (7 passed, 22 failed, 4 skipped, no test changes). basic fails on both at diff -9999999999999999999999999999 a b, before the range output. Details in the comment below.

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@jayhemnani9910

jayhemnani9910 commented Oct 20, 2026

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Ran the whole upstream suite on main (0019867) and on this branch: same on both, 7 pass, 22 fail, 4 skip, and no test changes its result. basic fails on both because of its -999999999999999999999999999999 option case, before it gets to the range output.
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@jayhemnani9910

jayhemnani9910 commented Oct 21, 2026

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Ran the full upstream suite (release builds) on main and on this branch: 7 passed, 22 failed, 4 skipped on both, and every test has the same result. basic fails on both at diff -9999999999999999999999999999 a b (unrecognized option), before it reaches anything this changes.
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@sylvestre
sylvestre force-pushed the single-line-add-delete branch from fc2b385 to a7a66e7 Compare October 24, 2026 13:00
Copilot AI balanced review requested due to automatic review settings October 24, 2026 13:00
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@sylvestre sylvestre mentioned this pull request Oct 24, 2026
diff: print single-line ranges as one number in normal format #315
Closed
@jayhemnani9910 jayhemnani9910 mentioned this pull request Oct 26, 2026
diff -e: no script at all when a file has no newline at the end #332
Open
sylvestre
sylvestre reviewed Nov 2, 2026
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Comment thread tests/by-util/test_diff.rs Outdated
.stdout("2d1\n< east\n4a4,5\n> up\n> down\n");

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff").arg("/dev/null").arg(&old);

@sylvestre sylvestre Nov 2, 2026

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this one is a multi-line add, not a single-line range
maybe use an empty temp file instead of /dev/null? no need for the cfg!(unix) then

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@jayhemnani9910 jayhemnani9910 Nov 2, 2026

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Done, it now compares an empty temp file with a one-line file, so the range is a real single-line 0a1, and the cfg!(unix) is gone. It prints 0a1,1 without the fix and matches GNU diff with it.

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Copilot AI balanced review requested due to automatic review settings November 2, 2026 18:17
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@jayhemnani9910
diff: test a single-line add with an empty file
ec0e875
@jayhemnani9910

jayhemnani9910 commented Nov 3, 2026

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Rebased. The fix itself is already on main as 42b8ec0, so only the test change you asked for is left here.
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@jayhemnani9910
jayhemnani9910 force-pushed the single-line-add-delete branch from b88ab9c to ec0e875 Compare November 3, 2026 13:53
Copilot AI balanced review requested due to automatic review settings November 3, 2026 13:53
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@sylvestre
sylvestre merged commit fd4147e into uutils:main Nov 7, 2026
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@sylvestre

sylvestre commented Nov 7, 2026

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Thanks for your PR
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@jayhemnani9910 @sylvestre
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