[Feldt]

h3 gridRing -f newline printed a 0 line for each unused slot of its output array. The CLI sizes that array with maxGridRingSize (6 * k), and near a pentagon the ring has fewer cells, so the library leaves the remaining slots as 0 (the gridRing docs say elements may be left zero). The json branch of the same subcommand already skips zero slots, and so does the newline branch of gridDisk. The newline branch of gridRing did not.

On master:

$ h3 gridRing -c 820807fffffffff -k 1 -f newline
820817fffffffff
82081ffffffffff
820827fffffffff
82082ffffffffff
820837fffffffff
0

The json output of the same call lists only the 5 neighbours of the pentagon. Hexagons near a pentagon hit this too: -c 820817fffffffff -k 2 -f newline prints 11 cells and a 0.

Changes:

• src/apps/filters/h3.c: the gridRing newline branch skips zero entries, the same check gridDisk uses.
• tests/cli/gridRing.txt: new testCliGridRingPentagonNewline, which counts the newline output lines for a pentagon at k = 1 and expects 5. It fails on master (6 lines) and passes with the fix. It counts lines rather than comparing the cell list, because the fallback ring's cell order comes from the gridDisk internals, and Reimplement gridDisk internals with BFS #1217 changes that order.
• CHANGELOG.md: a line under Unreleased / Fixed.

Test:

cmake -Bbuild -DBUILD_TESTING=ON .
cd build && make && ctest -R testCliGridRing --output-on-failure

With the fix, the full ctest run passes in Debug and Release builds with -DWARNINGS_AS_ERRORS=ON on macOS, and make format with clang-format 14 leaves no diff.

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Reviewing files that changed from the base of the PR and between 28d83cd and 3db8eab.

📒 Files selected for processing: 3

• CHANGELOG.md
• src/apps/filters/h3.c
• tests/cli/gridRing.txt

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Walkthrough

The gridRing CLI now skips zero-valued entries in newline output. A CLI test checks that a pentagon cell with -k 1 produces five lines. The Unreleased changelog records the change.

Changes

gridRing newline output

Layer / File(s)	Summary
Filter output and regression test src/apps/filters/h3.c, tests/cli/gridRing.txt, CHANGELOG.md	The newline formatter skips zero-valued entries. A CLI test checks pentagon output with -k 1 and expects five lines. The changelog records the fix.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix

Suggested reviewers: dfellis

Merge Risk: ⚪ Minimal · up to 3db8e

No merge-blocking risk was identified in this narrowly scoped output-format fix.

Pre-merge checks: 5

Check name	Status	Explanation
Description check		The description clearly explains the pentagon-related gridRing newline bug, the code and test changes, and the validation performed.
Title check		The title clearly and concisely identifies the fix for incorrect gridRing CLI newline output near pentagons.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1 files. (2 skipped: 2 unsupported.)

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[coveralls]

coverage: 99.758%. remained the same — Feldt:fix/cli-gridring-newline-zeros into uber:master

[isaacbrodsky]

@Feldt could you sign the CLA so we can merge your change?