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[cli] fix check --fix crash on overlapping diagnostic edits#389

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Kamirus wants to merge 3 commits intomainfrom
kamil/fix-fix
Open

[cli] fix check --fix crash on overlapping diagnostic edits#389
Kamirus wants to merge 3 commits intomainfrom
kamil/fix-fix

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@Kamirus Kamirus commented Mar 5, 2026

Summary

  • Replace TextDocument.applyEdits() with a custom applyDiagnosticFixes() that processes each diagnostic atomically — if any edit overlaps with an already-accepted edit, the entire diagnostic is skipped and retried in the next iteration
  • Ensure --error-format=json is passed last to moc so user-provided flags don't break the fix pipeline
  • Add test case for nested Array.filter<Nat>() calls (overlapping fixable errors)
  • Add regression test for --error-format=human not breaking --fix

Test plan

  • New overlapping edits test: nested Array.filter<Nat>() correctly fixed to ar.filter(f).filter(f)
  • --error-format=human regression test passes

Replace `TextDocument.applyEdits()` (which throws on overlapping edits)
with a custom `applyDiagnosticFixes()` that processes each diagnostic
atomically — if any edit from a diagnostic overlaps with an
already-accepted edit, the entire diagnostic is skipped and retried
in the next iteration.

Also ensures `--error-format=json` is passed last to moc so user-provided
flags like `--error-format=human` don't break the fix pipeline.

Made-with: Cursor
@Kamirus Kamirus requested a review from a team as a code owner March 5, 2026 10:16
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Benchmark Results

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256 pages 16 MiB $({\color{gray}0\%})$ 16 MiB $({\color{gray}0\%})$ 16 MiB $({\color{gray}0\%})$

- Updated the `edit-suggestions` test to reflect changes in expected fixes.
- Added a new test for handling overlapping edits, ensuring correct application of fixes.
- Modified the `edit-suggestions.mo` file to remove unnecessary code and improve clarity.
- Introduced a new `overlapping.mo` file to specifically test overlapping fix scenarios.

These changes improve the robustness of the autofix feature by ensuring it can handle complex cases effectively.

exports[`check --fix M0236: fix output 1`] = `
"Fixed run/M0236.mo (2 fixes: M0236)
"Fixed run/M0236.mo (1 fix: M0236)
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we changed how we count fixes:
moc returns multiple partial edits for a single diagnostic, now we count it as one

do {
let ar = [1, 2, 3];
let _ = Array.filter<Nat>(
Array.filter<Nat>(ar, func(x) { x > 0 }),
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previously it was throwing an exception, because of overlapping edits -- here this line was both changed and removed. Now we pick one and fix the other in the next iteration

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